Centrifuge Packet V2

Equipment*Packet:*Laboratory(Centrifuge*UMDNS*#:(18631((Date*of*Creation:(September(21,(2015(Creator:(Complied(by(Cassandra(Stanco(for*Engineering(World(Health((EWH)***Equipment*Packet*Contents:*This(packet(contains(information(about(the(operation,(maintenance,(and(repair(of(laboratory(centrifuges.((Part*I:*External*From*the*Packet:** 1. An*Introduction*to*Centrifuges:*(PowerPoint(*Part*II:*Included*in*this*Packet:** 1. Operation*and*Use:*a. Brief(Overview:(Analyzer,(Laboratory,(Hematology,(Blood(Grouping((p.(3)(b. Introduction(to(Blood(and(Its(Components((p.(4S8)(c. Introduction(to(Laboratory(Centrifuges((p.(9S14)(d. Operation(and(Use(of(Centrifuges((p.(15S19)(2. Diagrams*and*Schematics:*a. Figure(1:(Centrifuge(Components((p.(21)*b. Figure(2:(Centrifuge(Rotors((p.(22)*c. Figure(3:(Composition(of(the(Blood((p.(23)*3. Preventative*Maintenance*and*Safety:*a. Centrifuge(Preventative(Maintenance((p.(25)(b. Laboratory(Centrifuge(Safety((p.(26S27)(4. Troubleshooting*and*Repair:**a. Centrifuge(Troubleshooting(Flowchart((p.(29)*b. Centrifuge(Troubleshooting(Table((p.(30S31)*5. Resources*for*More*Information*a. Video(Tutorials(and(Links((p.(33)*b. Bibliography((p.(34)** (** *




1. Operation*and*Use*of*Centrifuges****Featured*in*this*Section:***((Malkin,(Robert.(Medical(Instrumentation(in(the(Developing(World.(Engineering(World(Health,(2006.((((( Openstax(College.(“Components(of(Blood.”(From(the(publication:(Biology.(Rice(University:(2013,(pgs.(1195R1199.(((Wikipedia.(“Laboratory(Centrifuge.”(Wikipedia,(p.(1R12.(Retrieved(from:(https://en.wikipedia.org/wiki/Laboratory_centrifuge((((WHO.(“Analyzer,(Hematology,(Blood(Grouping,(Automated.”(From(the(publication:(Core(Medical(Equipment.(Geneva,(Switzerland,(2011.(((((( **(* ** *




http://www.who.int/medical_devices/en/index.html
© Copyright ECRI Institute 2011 (not including the GMDN code and device name).


Reproduced with Permission from ECRI Institute’s Healthcare Product Comparison System.


© Copyright GMDN Agency 2011. GMDN codes and device names are reproduced with permission from the GMDN Agency.


C
or


e
m


ed
ic


al
e


qu
ip


m
en


t -
In


fo
rm


at
io


n Health problem addressed
Blood grouping systems perform basic blood processing tests
that include ABO grouping and subgrouping, Rh and other
red cell phenotyping, and antibody detection. These tests
determine factors that can cause transfusion reactions such
as red cell hemolysis, anaphylaxis, and other immunologic and
nonimmunologic effects.


Product description
Floor-standing or benchtop device includes a rack or tray onto
which patient blood sample tubes are loaded; the samples are
mixed with reagents to determine blood type and the results are
displayed on a monitor; cabinets or compartments store reagent
vessels; a monitor, keyboard, mouse, and printer (or entire
computer) may be connected for programming, data entry, and
to view and print testing results.


Principles of operation
Blood tube containing ethylenediamine-tetraacetic acid (EDTA)
anticoagulant is loaded onto the analyzer, and the operator
usually centrifuges them to separate the RBCs from the plasma.
Automated analyzers typically resuspend the RBCs in saline and
load the diluted samples onto microplates to which reagents
(known antisera) have been added. Blood group identity occurs
when the known antiserum, containing antibodies, clumps
(agglutinates) RBCs that have a corresponding antigen. Bar-
code labels provides a means of sample tracking.


Operating steps
Technicians load tubes into the sample tray and keep reagents
fi lled; tests are programmed either via a touchscreen panel on
the instrument, a computer, or the required test information is
on the tube’s printed bar code.


Reported problems
Operators should be aware of the risk of exposure to potentially
infectious bloodborne pathogens during testing procedures and
should use universal precautions, including wearing gloves, face
shields or masks, and gowns.


Use and maintenance
User(s): Laboratory technician
Maintenance: Biomedical or clinical engineer
Training: Initial training by manufacturer and
manuals


Environment of use
Settings of use: Hospital, blood bank, clinical
laboratory
Requirements: Line power, water supply,
benchtop or fl oor space, biohazard disposal


Product specifi cations
Approx. dimensions (mm): 1,000 x 1,750 x
900
Approx. weight (kg): 50-500
Consumables: Reagents, blood tubes
Price range (USD): 115,000 - 225,000
Typical product life time (years): 5-7
Shelf life (consumables): EDTA: 1 year


Types and variations
Benchtop or fl oor-standing


Analyzer, Laboratory, Hematology, Blood Grouping, Automated
UMDNS GMDN
16817 Analyzers, Laboratory, Hematology, Blood Grouping,


Automated
56712 ABO/Rh(D) blood grouping analyser IVD,


automated


Other common names:
Blood type analyzer, ABO blood typing system, AB0 blood typing system;Blood Grouping System


WHO. “Analyzer, Hematology, Blood Grouping, Automated.” From the publication: Core Medical Equipment.


Geneva, Switzerland, 2011.


2




body and its organs including the brain (systemic circulation). In amphibians, gas exchange also occurs
through the skin during pulmonary circulation and is referred to as pulmocutaneous circulation.
As shown in Figure 40.4b, amphibians have a three-chambered heart that has two atria and one ventricle
rather than the two-chambered heart of fish. The two atria (superior heart chambers) receive blood from
the two different circuits (the lungs and the systems), and then there is some mixing of the blood in the
heart’s ventricle (inferior heart chamber), which reduces the efficiency of oxygenation. The advantage
to this arrangement is that high pressure in the vessels pushes blood to the lungs and body. The mixing is
mitigated by a ridge within the ventricle that diverts oxygen-rich blood through the systemic circulatory
system and deoxygenated blood to the pulmocutaneous circuit. For this reason, amphibians are often
described as having double circulation.
Most reptiles also have a three-chambered heart similar to the amphibian heart that directs blood to the
pulmonary and systemic circuits, as shown in Figure 40.4c. The ventricle is divided more effectively
by a partial septum, which results in less mixing of oxygenated and deoxygenated blood. Some reptiles
(alligators and crocodiles) are the most primitive animals to exhibit a four-chambered heart. Crocodilians
have a unique circulatory mechanism where the heart shunts blood from the lungs toward the stomach
and other organs during long periods of submergence, for instance, while the animal waits for prey or
stays underwater waiting for prey to rot. One adaptation includes two main arteries that leave the same
part of the heart: one takes blood to the lungs and the other provides an alternate route to the stomach
and other parts of the body. Two other adaptations include a hole in the heart between the two ventricles,
called the foramen of Panizza, which allows blood to move from one side of the heart to the other, and
specialized connective tissue that slows the blood flow to the lungs. Together these adaptations have
made crocodiles and alligators one of the most evolutionarily successful animal groups on earth.


In mammals and birds, the heart is also divided into four chambers: two atria and two ventricles, as
illustrated in Figure 40.4d. The oxygenated blood is separated from the deoxygenated blood, which
improves the efficiency of double circulation and is probably required for the warm-blooded lifestyle
of mammals and birds. The four-chambered heart of birds and mammals evolved independently from a
three-chambered heart. The independent evolution of the same or a similar biological trait is referred to
as convergent evolution.


40.2 | Components of the Blood


By the end of this section, you will be able to:


• List the basic components of the blood
• Compare red and white blood cells
• Describe blood plasma and serum


Hemoglobin is responsible for distributing oxygen, and to a lesser extent, carbon dioxide, throughout the
circulatory systems of humans, vertebrates, and many invertebrates. The blood is more than the proteins,
though. Blood is actually a term used to describe the liquid that moves through the vessels and includes
plasma (the liquid portion, which contains water, proteins, salts, lipids, and glucose) and the cells (red
and white cells) and cell fragments called platelets. Blood plasma is actually the dominant component
of blood and contains the water, proteins, electrolytes, lipids, and glucose. The cells are responsible for
carrying the gases (red cells) and immune the response (white). The platelets are responsible for blood
clotting. Interstitial fluid that surrounds cells is separate from the blood, but in hemolymph, they are
combined. In humans, cellular components make up approximately 45 percent of the blood and the liquid
plasma 55 percent. Blood is 20 percent of a person’s extracellular fluid and eight percent of weight.


The Role of Blood in the Body
Blood, like the human blood illustrated in Figure 40.5 is important for regulation of the body’s systems
and homeostasis. Blood helps maintain homeostasis by stabilizing pH, temperature, osmotic pressure,
and by eliminating excess heat. Blood supports growth by distributing nutrients and hormones, and by
removing waste. Blood plays a protective role by transporting clotting factors and platelets to prevent
blood loss and transporting the disease-fighting agents or white blood cells to sites of infection.


CHAPTER 40 | THE CIRCULATORY SYSTEM 1195


Openstax College. “Components of Blood.” From the publication: Biology. Rice University: 2013, pgs. 1195-1199.


3




Figure 40.5 The cells and cellular components of human blood are shown. Red blood cells deliver
oxygen to the cells and remove carbon dioxide. White blood cells—including neutrophils, monocytes,
lymphocytes, eosinophils, and basophils—are involved in the immune response. Platelets form clots
that prevent blood loss after injury.


Red Blood Cells
Red blood cells, or erythrocytes (erythro- = “red”; -cyte = “cell”), are specialized cells that circulate
through the body delivering oxygen to cells; they are formed from stem cells in the bone marrow.
In mammals, red blood cells are small biconcave cells that at maturity do not contain a nucleus or
mitochondria and are only 7–8 µm in size. In birds and non-avian reptiles, a nucleus is still maintained
in red blood cells.


The red coloring of blood comes from the iron-containing protein hemoglobin, illustrated in Figure
40.6a. The principal job of this protein is to carry oxygen, but it also transports carbon dioxide as well.
Hemoglobin is packed into red blood cells at a rate of about 250 million molecules of hemoglobin per
cell. Each hemoglobin molecule binds four oxygen molecules so that each red blood cell carries one
billion molecules of oxygen. There are approximately 25 trillion red blood cells in the five liters of
blood in the human body, which could carry up to 25 sextillion (25 × 1021) molecules of oxygen in
the body at any time. In mammals, the lack of organelles in erythrocytes leaves more room for the
hemoglobin molecules, and the lack of mitochondria also prevents use of the oxygen for metabolic
respiration. Only mammals have anucleated red blood cells, and some mammals (camels, for instance)
even have nucleated red blood cells. The advantage of nucleated red blood cells is that these cells can
undergo mitosis. Anucleated red blood cells metabolize anaerobically (without oxygen), making use of
a primitive metabolic pathway to produce ATP and increase the efficiency of oxygen transport.


Not all organisms use hemoglobin as the method of oxygen transport. Invertebrates that utilize
hemolymph rather than blood use different pigments to bind to the oxygen. These pigments use copper
or iron to the oxygen. Invertebrates have a variety of other respiratory pigments. Hemocyanin, a blue-
green, copper-containing protein, illustrated in Figure 40.6b is found in mollusks, crustaceans, and some
of the arthropods. Chlorocruorin, a green-colored, iron-containing pigment is found in four families of
polychaete tubeworms. Hemerythrin, a red, iron-containing protein is found in some polychaete worms
and annelids and is illustrated in Figure 40.6c. Despite the name, hemerythrin does not contain a heme
group and its oxygen-carrying capacity is poor compared to hemoglobin.


1196 CHAPTER 40 | THE CIRCULATORY SYSTEM


This content is available for free at https://cnx.org/content/col11448/1.9
Openstax College. “Components of Blood.” From the publication: Biology. Rice University: 2013, pgs. 1195-1199.


Text


4




Figure 40.6 In most vertebrates, (a) hemoglobin delivers oxygen to the body and removes some
carbon dioxide. Hemoglobin is composed of four protein subunits, two alpha chains and two beta
chains, and a heme group that has iron associated with it. The iron reversibly associates with


oxygen, and in so doing is oxidized from Fe2+ to Fe3+. In most mollusks and some arthropods, (b)
hemocyanin delivers oxygen. Unlike hemoglobin, hemolymph is not carried in blood cells, but floats
free in the hemolymph. Copper instead of iron binds the oxygen, giving the hemolymph a blue-green
color. In annelids, such as the earthworm, and some other invertebrates, (c) hemerythrin carries
oxygen. Like hemoglobin, hemerythrin is carried in blood cells and has iron associated with it, but
despite its name, hemerythrin does not contain heme.


The small size and large surface area of red blood cells allows for rapid diffusion of oxygen and carbon


dioxide across the plasma membrane. In the lungs, carbon dioxide is released and oxygen is taken in by


the blood. In the tissues, oxygen is released from the blood and carbon dioxide is bound for transport


back to the lungs. Studies have found that hemoglobin also binds nitrous oxide (NO). NO is a vasodilator


that relaxes the blood vessels and capillaries and may help with gas exchange and the passage of red


blood cells through narrow vessels. Nitroglycerin, a heart medication for angina and heart attacks, is


converted to NO to help relax the blood vessels and increase oxygen flow through the body.


A characteristic of red blood cells is their glycolipid and glycoprotein coating; these are lipids and


proteins that have carbohydrate molecules attached. In humans, the surface glycoproteins and glycolipids


on red blood cells vary between individuals, producing the different blood types, such as A, B, and O.


Red blood cells have an average life span of 120 days, at which time they are broken down and recycled


in the liver and spleen by phagocytic macrophages, a type of white blood cell.


White Blood Cells
White blood cells, also called leukocytes (leuko = white), make up approximately one percent by volume


of the cells in blood. The role of white blood cells is very different than that of red blood cells: they are


primarily involved in the immune response to identify and target pathogens, such as invading bacteria,


viruses, and other foreign organisms. White blood cells are formed continually; some only live for hours


or days, but some live for years.


The morphology of white blood cells differs significantly from red blood cells. They have nuclei and


do not contain hemoglobin. The different types of white blood cells are identified by their microscopic


appearance after histologic staining, and each has a different specialized function. The two main groups,


both illustrated in Figure 40.7 are the granulocytes, which include the neutrophils, eosinophils, and
basophils, and the agranulocytes, which include the monocytes and lymphocytes.


CHAPTER 40 | THE CIRCULATORY SYSTEM 1197


Openstax College. “Components of Blood.” From the publication: Biology. Rice University: 2013, pgs. 1195-1199.


5




Figure 40.7 (a) Granulocytes—including neutrophils, eosinophils and basophils—are characterized
by a lobed nucleus and granular inclusions in the cytoplasm. Granulocytes are typically first-
responders during injury or infection. (b) Agranulocytes include lymphocytes and monocytes.
Lymphocytes, including B and T cells, are responsible for adaptive immune response. Monocytes
differentiate into macrophages and dendritic cells, which in turn respond to infection or injury.


Granulocytes contain granules in their cytoplasm; the agranulocytes are so named because of the lack
of granules in their cytoplasm. Some leukocytes become macrophages that either stay at the same site
or move through the blood stream and gather at sites of infection or inflammation where they are
attracted by chemical signals from foreign particles and damaged cells. Lymphocytes are the primary
cells of the immune system and include B cells, T cells, and natural killer cells. B cells destroy bacteria
and inactivate their toxins. They also produce antibodies. T cells attack viruses, fungi, some bacteria,
transplanted cells, and cancer cells. T cells attack viruses by releasing toxins that kill the viruses. Natural
killer cells attack a variety of infectious microbes and certain tumor cells.


One reason that HIV poses significant management challenges is because the virus directly targets T
cells by gaining entry through a receptor. Once inside the cell, HIV then multiplies using the T cell’s own
genetic machinery. After the HIV virus replicates, it is transmitted directly from the infected T cell to
macrophages. The presence of HIV can remain unrecognized for an extensive period of time before full
disease symptoms develop.


Platelets and Coagulation Factors
Blood must clot to heal wounds and prevent excess blood loss. Small cell fragments called platelets
(thrombocytes) are attracted to the wound site where they adhere by extending many projections and
releasing their contents. These contents activate other platelets and also interact with other coagulation
factors, which convert fibrinogen, a water-soluble protein present in blood serum into fibrin (a non-
water soluble protein), causing the blood to clot. Many of the clotting factors require vitamin K to work,
and vitamin K deficiency can lead to problems with blood clotting. Many platelets converge and stick
together at the wound site forming a platelet plug (also called a fibrin clot), as illustrated in Figure
40.8b. The plug or clot lasts for a number of days and stops the loss of blood. Platelets are formed
from the disintegration of larger cells called megakaryocytes, like that shown in Figure 40.8a. For each
megakaryocyte, 2000–3000 platelets are formed with 150,000 to 400,000 platelets present in each cubic
millimeter of blood. Each platelet is disc shaped and 2–4 μm in diameter. They contain many small
vesicles but do not contain a nucleus.


1198 CHAPTER 40 | THE CIRCULATORY SYSTEM


This content is available for free at https://cnx.org/content/col11448/1.9


Openstax College. “Components of Blood.” From the publication: Biology. Rice University: 2013, pgs. 1195-1199.


6




Figure 40.8 (a) Platelets are formed from large cells called megakaryocytes. The megakaryocyte
breaks up into thousands of fragments that become platelets. (b) Platelets are required for clotting
of the blood. The platelets collect at a wound site in conjunction with other clotting factors, such as
fibrinogen, to form a fibrin clot that prevents blood loss and allows the wound to heal.


Plasma and Serum
The liquid component of blood is called plasma, and it is separated by spinning or centrifuging the blood


at high rotations (3000 rpm or higher). The blood cells and platelets are separated by centrifugal forces


to the bottom of a specimen tube. The upper liquid layer, the plasma, consists of 90 percent water along


with various substances required for maintaining the body’s pH, osmotic load, and for protecting the


body. The plasma also contains the coagulation factors and antibodies.


The plasma component of blood without the coagulation factors is called the serum. Serum is similar
to interstitial fluid in which the correct composition of key ions acting as electrolytes is essential for


normal functioning of muscles and nerves. Other components in the serum include proteins that assist


with maintaining pH and osmotic balance while giving viscosity to the blood. The serum also contains


antibodies, specialized proteins that are important for defense against viruses and bacteria. Lipids,


including cholesterol, are also transported in the serum, along with various other substances including


nutrients, hormones, metabolic waste, plus external substances, such as, drugs, viruses, and bacteria.


Human serum albumin is the most abundant protein in human blood plasma and is synthesized in the


liver. Albumin, which constitutes about half of the blood serum protein, transports hormones and fatty


acids, buffers pH, and maintains osmotic pressures. Immunoglobin is a protein antibody produced in the


mucosal lining and plays an important role in antibody mediated immunity.


CHAPTER 40 | THE CIRCULATORY SYSTEM 1199


Openstax College. “Components of Blood.” From the publication: Biology. Rice University: 2013, pgs. 1195-1199.


7




Laboratory centrifuge 1


Laboratory centrifuge


A tabletop laboratory centrifuge


Uses Separation


Related items Gas centrifuge
Ultracentrifuge


A laboratory centrifuge is a piece of laboratory equipment, driven by a motor, which spins liquid samples at high
speed. There are various types of centrifuges, depending on the size and the sample capacity.


Like all other centrifuges, laboratory centrifuges work by the sedimentation principle, where the centripetal
acceleration is used to separate substances of greater and lesser density.


Operation


A 19th century hand cranked laboratory centrifuge.


Increasing the effective gravitational force will more rapidly and
completely cause the precipitate ("pellet") to gather on the bottom
of the tube. The remaining solution is called the "supernate" or
"supernatant".


The supernatant liquid is then either quickly decanted from the
tube without disturbing the precipitate, or withdrawn with a
Pasteur pipette. The rate of centrifugation is specified by the
acceleration applied to the sample, typically measured in
revolutions per minute (RPM) or g. The particles' settling velocity
in centrifugation is a function of their size and shape, centrifugal
acceleration, the volume fraction of solids present, the density
difference between the particle and the liquid, and the viscosity.


The use of a centrifuge is known as centrifugation.


Wikipedia. “Laboratory Centrifuge.” Wikipedia, p. 1-12. Retrieved from: https://en.wikipedia.org/wiki/


Laboratory_centrifuge


Introduction to Laboratory Centrifuges


8




Laboratory centrifuge 2


Types


Laboratory centrifuge


There are various types of centrifugation:


• Differential centrifugation, often used to separate
certain organelles from whole cells for further
analysis of specific parts of cells


• Isopycnic centrifugation, often used to isolate
nucleic acids such as DNA


• Sucrose gradient centrifugation, often used to purify
enveloped viruses and ribosomes, and also to
separate cell organelles from crude cellular extracts


There are different types of laboratory centrifuges:


• Microcentrifuges
(devices for small tubes from 0.2 ml to 2.0 ml (micro
tubes), up to 96 well-plates, compact design, small
footprint; up to 30.000 g)


• Clinical centrifuges
(devices used for clinical applications like blood
collection tubes, low-speed devices)


• Multipurpose benchtop centrifuges
(devices for a broad range of tube sizes, high
variability, big footprint)


• Stand alone centrifuges


(heavy devices like ultra-centrifuges)


Many centrifuges are available with (regrigerated device)or without cooling function. There are different providers
of laboratory centrifuges like Eppendorf, Thermo-Heraeus, Thermo-Sorvall, Hettich, Beckmann-Coulter or Sigma.


History
English military engineer Benjamin Robins (1707-1751) invented a whirling arm apparatus to determine drag. In
1864, Antonin Prandtl invented the first dairy centrifuge in order to separate cream from milk. In 1879, Gustaf de
Laval demonstrated the first continuous centrifugal separator, making its commercial application feasible.


Different sizes of centrifuges were developed. The range of applications varied from Liter-scale to Milli-Liter-scale.


Regarding the laboratory microcentrifuge, in 1962 the Hamburg-based company “Netheler & Hinz Medizintechnik”
(nowadays known as “eppendorf”) developed the “Microliter System” for laboratory usage. Besides the first piston
stroke pipette, based on the work of Dr. Schnittger (Marburg/ Germany), the plastic-made micro test tube and the
first microcentrifuge (model 3200) were introduced for applications in routine analysis labs in microliter scale. This
first real microcentrifuge had one control knob for the time and space for up to 12 micro test tubes in a fixed-angle
rotor. Common up-to-date features like cooling, programming, automatic imbalance detection, noise reduction, or
changeable rotor systems were completely missing.


The “Microliter System” was the starting point for a broad range of tools for the molecular lab, developed by all
different kinds of biotech and labware companies.


Wikipedia. “Laboratory Centrifuge.” Wikipedia, p. 1-12. Retrieved from: https://en.wikipedia.org/wiki/


Laboratory_centrifuge


9




Laboratory centrifuge 3


Design


A large laboratory centrifuge.


Laboratory centrifuges are used in chemistry, biology, and


biochemistry for isolating and separating solids from liquids in a


suspension. The solids can be insoluble compounds, biomolecules,


cell organelles, or whole cells. They vary widely in speed and


capacity. They usually comprise a rotor containing two, four, six,


or many more numbered wells within which centrifuge tubes may


be placed.


When a suspension in a centrifuge tube is centrifuged, the solids


settle at the bottom of the centrifuge tube; having a tapered wall


helps to concentrate the solids, making it easier to decant the


supernatant solution, leaving the solids.


Generally spoken, there are two main types of rotors:


Fixed-angle rotor
The rotor (mainly made of aluminium) is very compact. There are


boreholes with a specific angle (like 45°) within the rotor. These


boreholes are used for the sample tubes.


Swing-out rotor (= horizontal rotor)
The rotor looks like a cross with gondolas, called buckets. Within these buckets, different tubes can be centrifuged.


For a safe centrifugation, a specific adadpter for every tube shape is mandatory.


The rotor is closed by a rotor lid. The rotor is located in a rotor chamber which is covered by a metall centrifuge lid.


The open lid prevents the motor from turning the rotor when the rotor chamber is open. During the run, the lid is


locked. The lid protects the user from being injured by touching a rapidly spinning rotor. The rotor chamber and the


lid of high quality centrifuges are robust enough to survive a rotor failure at full speed. This robustness protects the


user and the laboratory from crashing fragments in case the rotor fails catastrophically. After a rotor crash, a


centrifuge should not be reused as the enormous forces during a crash may have damaged essential parts of the


device.


The rotor must be balanced by placing samples or blanks of equal mass opposite each other. Since most of the mass


is derived from the solvent, it is usually sufficient to place blanks or other samples of equal volume. As a safety


feature, some centrifuges may stop turning when wobbling is detected (automatic imbalance detection, see Safety).


Centrifuge tubes
Centrifuge tubes or centrifuge tips are tapered tubes of various sizes made of glass or plastic. They may vary in
capacity from tens of millilitres, to much smaller capacities used in microcentrifuges used extensively in molecular


biology laboratories. The most commonly encountered tubes are of about the size and shape of a normal test tube (~


10 cm long). Microcentrifuges typically accommodate microcentrifuge tubes with capacities from 250 μl to 2.0 ml.


These are exclusively made of plastic.


Glass centrifuge tubes can be used with most solvents, but tend to be more expensive. They can be cleaned like other


laboratory glassware, and can be sterilized by autoclaving. Plastic centrifuge tubes, especially microcentrifuge tubes


tend to be less expensive. Water is preferred when plastic centrifuge tubes are used. They are more difficult to clean


thoroughly, and are usually inexpensive enough to be considered disposable.


Wikipedia. “Laboratory Centrifuge.” Wikipedia, p. 1-12. Retrieved from: https://en.wikipedia.org/wiki/


Laboratory_centrifuge


10




Laboratory centrifuge 4


Microcentrifuge tubes


Microcentrifuge tube with Coomassie Blue
solution


Microcentrifuge tubes or microfuge tubes are small, cylindrical
plastic containers with conical bottoms, typically with an integral snap
cap. They are used in molecular biology and biochemistry to store and
centrifuge small amounts of liquid. As they are inexpensive and
considered disposable, they are used by many chemists and biologists
as convenient sample vials in lieu of glass vials; this is particularly
useful when there is only a small amount of liquid in the tube or when
small amounts of other liquids are being added, because
microcentrifugation can be used to collect the drops together at the
bottom of the tube after pipetting or mixing.


Made of polypropylene,[1] they can be used in very low temperature
(-80 °C to liquid nitrogen temperatures) or with organic solvents such as chloroform. They come in many different
sizes, generally ranging from 250 μL to 2.0 mL. The most common size is 1.5 mL. Disinfection is possible (1 atm,
120 °C, 20 minutes) and is commoly performed in works related to DNA or microbes, where purity of the sample is
of utmost importance. Due to their low cost and the difficulty in cleaning the plastic surface, they are usually
discarded after each use.


Eppendorf tube has become a genericized trademark for microfuge tubes or microcentrifuge tubes. Eppendorf is a
major manufacturer of this item, but is not the only one.


Three microcentrifuge tubes: 2 mL, 1.5 mL and
200 μL (for PCR).


Four screw-top microcentrifuge tubes.


Safety
The load in a laboratory centrifuge must be carefully balanced. Small
differences in mass of the load can result in a large force imbalance
when the rotor is at high speed. This force imbalance strains the
spindle and may result in damage to centrifuge or personal injury.
Some centrifuges have an automatic rotor imbalance detection. The
control software immediately discontinue the run when imbalance
appears.


Before starting a centrifuge, an accurate check of the rotor lockage as
well as the lid lockage is mandatory. Centrifuge rotors should never be
touched while moving, because a spinning rotor can cause serious
injury. Modern centrifuges generally have features that prevent
accidental contact with a moving rotor as the main lid is locked during
the run.


Because of the kinetic energy stored in the rotor head during high
speed rotation, those who have experienced the loss of a rotor inside of
an ultracentrifuge compare the experience to having a bomb explode
nearby.


When handling dangerous samples(like biohazard), the lid of the rotor
needs to have a special gasket (aerosol-tight) to prevent contamination of the laboratory. The rotor can be loaded
with the samples within a hood and the rotor lid is fixed on the rotor. Afterwards, the aerosol-tight system of rotor
and lid is transferred to the centrifuge. Fixation of the rotor within the centrifuge is done without opening the rotor
lid again. After the run, the rotor (incl. lid) is removed from the centrifuge to the hood (closed system) for further
steps.


Wikipedia. “Laboratory Centrifuge.” Wikipedia, p. 1-12. Retrieved from: https://en.wikipedia.org/wiki/


Laboratory_centrifuge


11




Laboratory centrifuge 5


Theory
Protocols for centrifugation typically specify the amount of acceleration to be applied to the sample, rather than
specifying a rotational speed such as revolutions per minute. The acceleration is often quoted in multiples of g, the
acceleration due to gravity at the Earth's surface. This distinction is important because two rotors with different
diameters running at the same rotational speed will subject samples to different accelerations.


The acceleration can be calculated as the product of the radius and the square of the angular velocity.


Relative centrifugal force is the measurement of the force applied to a sample within a centrifuge. This can be
calculated from the speed (RPM) and the rotational radius (cm) using the following calculation.


g = RCF = 0.00001118 × r × N2


where:


g = Relative centrifuge force
r = rotational radius (centimetre, cm)
N = rotating speed (revolutions per minute, r/min)


To avoid having to perform a mathematical calculation every time, one can find nomograms for converting RCF to
rpm for a rotor of a given radius. A ruler or other straight edge lined up with the radius on one scale, and the desired
RCF on another scale, will point at the correct rpm on the third scale. Example [2] Based on automatic rotor
recognition, up to date centrifuges have a button for automatic conversion from RCF to rpm and vice versa.


See also
• Centrifuge
• Centrifugation
• Gas centrifuge
• Separation
• Ultracentrifuge


External links
• RCF Calculator and Nomograph [3]


• Centrifugation Rotor Calculator [4]


• Selection of historical centrifuges [5] in the Virtual Laboratory of the Max Planck Institute for the History of
Science


References
[1] "Chemical Stability of Disposables" (http:/ / www. eppendorfna. com/ utilities/ enewsletter. asp?ENLUID=e200606& REFUID=AP04) (pdf).


Applications Note 05. Eppendorf. June 2005. .
[2] http:/ / aquaticpath. umd. edu/ nomogram. html
[3] http:/ / www. djblabcare. co. uk/ djb/ info/ 6/ user_tools
[4] http:/ / www. changbioscience. com/ cell/ rcf. html
[5] http:/ / vlp. mpiwg-berlin. mpg. de/ technology/ search?-max=10& -title=1& -op_varioid=numerical& varioid=3


Wikipedia. “Laboratory Centrifuge.” Wikipedia, p. 1-12. Retrieved from: https://en.wikipedia.org/wiki/


Laboratory_centrifuge


12




Article Sources and Contributors 6


Article Sources and Contributors
Laboratory centrifuge  Source: http://en.wikipedia.org/w/index.php?oldid=357922728  Contributors: A. B., Brews ohare, Cell-72, Gidklio, Heeero60, J.delanoy, Karelj, Kierano, Kkmurray,
Labfreak71, Mah159, Mike.lifeguard, Nmnogueira, Rifleman 82, Sardanaphalus, Schaxel, Seanghosh, Sfan00 IMG, Temporaluser, Terrydiehard, The Anome, Wolfkeeper, 12 anonymous edits


Image Sources, Licenses and Contributors
Image:19thCentrifuge.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:19thCentrifuge.JPG  License: GNU Free Documentation License  Contributors: User:Kierano
File:Centrifuga Hermle 2.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Centrifuga_Hermle_2.jpg  License: Public Domain  Contributors: User:Karelj
Image:Beckman J2-MI.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Beckman_J2-MI.jpg  License: Creative Commons Attribution-Sharealike 2.5  Contributors: Nuno Nogueira
(Nmnogueira) Original uploader was Nmnogueira at en.wikipedia


Image:Coomassie solution.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Coomassie_solution.jpg  License: Creative Commons Attribution 2.0  Contributors: FlickrLickr,
FlickreviewR, Nilfanion, Nina, PatríciaR, Rmhermen, TimVickers


Image:Eppendorf tubes.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Eppendorf_tubes.jpg  License: Creative Commons Attribution-Sharealike 2.5  Contributors: Masur
Image:Screw Top Microcentrifuge Tubes.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Screw_Top_Microcentrifuge_Tubes.jpg  License: GNU Free Documentation License
 Contributors: User:Zephyris


License
Creative Commons Attribution-Share Alike 3.0 Unported
http:/ / creativecommons. org/ licenses/ by-sa/ 3. 0/


Wikipedia. “Laboratory Centrifuge.” Wikipedia, p. 1-12. Retrieved from: https://en.wikipedia.org/wiki/


Laboratory_centrifuge


13




Medical Instruments in the Developing World Malkin


3.3 Centrifuges and Electrical Motors


3.3.1 Use and Principles of Operation
If a liquid contains particles, the particles will eventually sink to the bottom under the force of
gravity. A centrifuge more rapidly separates particles from liquid by rotating a liquid to simulate
a higher force of gravity. Either a liquid/liquid or a liquid/solid mixture can be separated with
the substance of higher density migrating towards the outer part of the centrifuge. Centrifuges
vary in size, in speed of the rotation, how long they will run, temperature and angles of rotation
of the samples.



A small, table-top, electric centrifuge is common in the developing world. However, smaller clinics
may have only a hand-cranked centrifuge.




A centrifuge consists of a base and an inner spinning cylinder in which the substance to be
separated is placed. Some centrifuges have timers that automatically turn off after a set period
of time and some also have high precision speed regulators to control the speed with which the
centrifuge spins. Centrifuges can be used to prepare a substance for analysis or to analyze the
particle content. There are two types of preparative centrifuges: mechanical and electrical. Of
the analytical centrifuges, the only one used in medicine is the microhematocrit, used for
separating plasma from the blood suspension.



With the lid of this centrifuge tipped back, you can see the four tubes where the specimen or
dummy tubes would be placed. When the rotor turns, the tubes will tip out at an angle. The
small round dot just beyond the white interior (center bottom) is an interlock that prevents the
unit from spinning if the lid is open






Equipment Found in the Clinical Laboratory

The simplest centrifuges have a single speed motor, a mechanical timer and a rotor that holds
the samples at a preset angle of 20 to 40 degrees. For user safety, the lid of the centrifuge
should have an interlock on it so that the unit will not spin with the lid in the up position.



A simple rotor is made from metal with 4, 6 or 8 holes drilled into it at an angle where the
samples are placed. Balancing the rotor is very important. If the user has only a few samples to
be spun down they may have to use “dummy tubes” to properly balance the load. Since the
motor shaft is attached to the rotor, uneven loads can cause motor damage and uneven speeds.
Another type of rotor has sample carriers that are vertical at rest but when spun move out to 20
to 40 degrees.



The simplest centrifuges have a single speed ranging from 2,500 to 10,000 RPM. Low speed
centrifuges have RPM rates up to 12,000 RPM, high speed units go up to 35,000 RPM and the
ultrahigh speed can reach 125,000 RPM. The simplest variable speed centrifuges will have a
rheostat speed control, which may be non-linear. Most of the newer variable speed centrifuges
have built in tachometers that provide the users with a speed indication. More sophisticated
speed control systems can involve SCR’s, stepper motors and servo systems.



Most high speed and all ultrahigh speed units are refrigerated because the friction caused by the
air on the samples will dry them out and change the results.



Centrifuges have a timer that is either electronic or mechanical built into the controls. Depending
upon the centrifuge, the time can be set from seconds to days. If no time is selected the
centrifuge will probably not run. Also, the centrifuge may have a time delay on the start where it
will not start to spin for several seconds after the RPM rate and timer are set and the start button
pushed.


3.3.2 Common Problems
Any part of the centrifuge may cause a problem. However, not every part of the centrifuge can
or should be repaired. After eliminating the timer, rotor and most of the rest of the machine, the
only repairable part of the centrifuge which needs much further explanation is the motor.



If the timer is at fault, often the only practical solution in the field is to bypass the timer (so the
centrifuge always turns when switched on), and instruct the staff to use manual timing. As
personnel are generally plentiful in the developing world hospital, this solution is typically well
accepted by the staff, especially if they have been attempting to operate without any centrifuge
at all.



If the rotor is cracked or bent, it should not be repaired. There are tremendous forces developed
in a centrifuge. If the rotor is weakened or off balance by being bent, the machine could be
destroyed and the staff injured in the process.



Mechanical centrifuges typically only need lubricating and cleaning to return them to use. If a
piece is broken, it often cannot be repaired.



All centrifuges produced after 1990 are required to have an interlock system that does not allow
the rotor to spin unless the cover is closed. Some of these interlock systems are very simple; a
solenoid that pushes a rod through a hole in the cover latch is common. Others are more
complicated and may involve several solenoids, flexible cables and a clock. The clock can be tied
to the RPM indicator and will not release the solenoids until a set time has elapsed after the
speed drops to zero. These timed units may give the appearance of failure because the operator






Medical Instruments in the Developing World Malkin
cannot immediately open the lid. Check the manual, if available, to confirm both the delay and if
that delay is adjustable.



There is always a temptation to defeat a broken interlock system. This should only be done for
clinical laboratory departments that have no alternative centrifuge and then only after careful
consultation with the technician who will be using the machine. Affix a picture on top of the
machine showing a damaged finger and an open lid so that all future users will know about this
danger.


3.3.3 Motors
The inside of a simple centrifuge is nothing more than a motor and a few switches. This more
sophisticated centrifuge includes two fans (additional motors) and a small bit of electronics (not
shown).



The heart of the centrifuge is the motor. Almost all variable speed electrical motors in the
developing world work on the same principle, whether they are in a centrifuge or any other piece
of equipment (fixed speed motors, such as pumps and compressors are often of the induction
type, not discussed here). The motor works by passing electrical current through electro-
magnets attached to a rotating shaft. Stationary, permanent magnets attract or repel the
electro-magnets depending on the orientation of the magnetic fields. The fields’ orientations are
switched such that the electro-magnets are progressively attracted to the permanent magnets
around the circle, bringing the shaft of the motor around with them.



If a magnet is placed within another magnet, it can be made to rotate around a shaft by aligning
the magnets to repel each other. If the polarity of the rotating magnet is then switched, the shaft
and magnet will continue to rotate, and the device will be a motor. In order to switch the polarity,
brushes contact commuters, the brushes and commuter forming switches. As the shaft rotates, the
brushes contact different commuter parts, alternating the polarity of the rotating magnet.




In general, the engineer in the field will not be called upon to rebuild an electrical motor. Almost
every major city in the developing world has a shop that can accomplish this task. However,
most motors use carbon brushes to make electrical contact with the electro-magnets on the




Equipment Found in the Clinical Laboratory

rotating part of the motor. These brushes wear down over time and need to be replaced. The
brushes can be replaced by the field engineer.



Brushes should only be replaced with brushes of the same size. Do not use undersize brushes as
they may wear unevenly and score the shaft of the motor. Brushes are held against the shaft via
spring pressure, if the spring weakens, breaks or is missing the motor may not spin. If the caps
holding the brushes in place become loose or cracked, that can also cause the brushes to lose
contact and the motor will not run at all or will not run consistently.



Brushes that are installed properly and with the correct tension make the brushes wear evenly
and have a bright almost shinny look on the contact end. If the brushes are defective or not
making good contact the contact face of the brush will be dull and not smooth. Both brushes
should be removed from the unit and compared when troubleshooting.



The shaft is held in the center of the permanent magnets by bearings. These are not often the
cause of the problem, but in certain cases they can cause noise as the shaft rattles instead of
being held in place. Bearings can be removed and replaced. Most developing world cities have
motor repair shops which can replace or repair the bearings.



Besides the brushes and the motor bearings, many motor systems, including centrifuges, will
have braking systems. If the rotor of a centrifuge, for example, was left to stop on its own, it
could take a long period of time for the rotor to drop from 100,000 RPM to zero. To cut the time
most units have a brake. The brake is not a mechanical device, as on your car. In some
systems, the brake is a resistor that is temporarily placed across the motor. The motor is
essentially operating as generator, with the mechanical energy coming from the spinning rotor
and the electrical energy dumping into the resistance.



Motors are sometimes used in a 50 Hz country, despite being designed for 60 Hz use. In general,
this causes few problems in centrifuges. In other applications, it can cause overheating. If
possible lower the voltage about 10% on these motors to reduce heating.



In more sophisticated systems, the brake reverses the electrical field in the electro-magnets to
make them attempt to spin the rotor in the opposite direction. The operator has to energize the
switch and should only hold the switch in the reverse or stop position for a few seconds at a
time.


3.3.4 Suggested Testing
The centrifuge creates tremendous forces inside the vessel when in use. If the rotor were to
break or become dislodged, it could damage the machine or injure the user. Therefore, you
should perform some safety testing before releasing the device for use.



First, check that the lid cannot be opened when the rotor is turning. Never release a centrifuge
which can be opened while the rotor is turning without a thorough discussion of the dangers with
the staff. If this is the only centrifuge that the hospital has at its disposal, you may have to
release the device for use without a safety interlock.



Second, you should insure that the device can spin up to speed and brake without excessive
noise. Be sure to balance the rotor (with equal amounts of water-filled vials on each side) before
turning it on. Check the rotor for cracks or bends before starting the centrifuge. Particular
attention has to be paid to centrifuges that have rotors that can be changed out. The users have
been known to not fully tighten down the knob securing the rotor to the motor shaft causing
severe damage to the device and lab when the rotor broke loose while spinning.





Medical Instruments in the Developing World Malkin

The ideal test for a centrifuge is a tachometer used to verify the rpm. However, you can make an
approximate measurement of the centrifuges speed without one. Under light from a fluorescent
bulb that runs on 60 Hz. current, the gage shown below will give you an accurate reading when you
are running at one of the speeds on the gage. The “flashing” of the fluorescent bulb at 120 Hz will
cause one of the bands to appear to stop moving at the RPM indicated by that band. The gage will
not work with an incandescent light bulb.



To use the gage, photocopy it, cut it out, and place it on the spindle. You may need to cover it in
clear packing tape to make it stiffer. Spin up the centrifuge until one of the bands has stopped,
mark that spot on the speed control knob. Count the bands from the inside to note which band has
stopped. You can increase the speed and find the next time that this same band stops. This speed
corresponds to twice the marked RPM. Likewise, you can find speeds which are three, four or more
times what is marked by counting the number of times the bands stop as you increase the RPM’s.
To determine the RPM, stop the centrifuge, read the band, and multiply by the number of times it
stopped as you were increasing the rotation. You’ll need to try this a few times before getting
consistent results.









2.*Diagrams*and*Schematics*of*Centrifuges****Featured*in*this*Section:***(((Malkin,(Robert.(Medical(Instrumentation(in(the(Developing(World.(Engineering(World(Health,(2006.((** OpenStax(College.(“1901(Composition(of(Blood.jpg.”(Wikimedia(Commons.(Retrieved(from:(https://commons.wikimedia.org/wiki/File:1901_Composition of Blood.jpg(* * *




Centrifuge Preventative Maintenance


Introduction to Centrifuges


Introduction to Centrifuges


Introduction to Centrifuges


Figure 1: Centrifuge


Components


WHO. “Chapter 7: Centrifuge.” From the publication: Maintenance


Manual for Laboratory Equipment, WHO: 2008, pgs. 45-49.


17




M A I N T E N A N C E M A N U A L F O R L A B O R AT O R Y E Q U I P M E N T


47


Types of rotors
Centrifuges use many diff erent types of rotors. Among the
most commonly used are the following:


Type of rotor Characteristics Transversal cross-section
Fixed angle rotors. These are general purpose rotors. They keep tubes at a fi xed


angle [α] which by design, is specifi ed between 20 and 45
degrees. They are used for sediment sub-cellular particles.
The angle shortens the trajectory of the particles and the
centrifugation time compared to the swinging buckets
rotors.


Swinging buckets rotors. These are used for carrying out isopycnic studies (separation
by density) and rate-zonal studies (separation by
sedimentation coeffi cient), where maximum resolution of
the zones is required for the sample.


Vertical tube rotors. This type of rotor keeps tubes parallel to the rotational axis.
Thus, separate bands are formed across the tube’s diameter,
not its length. These rotors are used for carrying out
isopycnic studies and in some cases, zonal limit separations
where a short centrifugation time is important. These rotors
use specially designed tubes.


Almost vertical tube rotors. This type of rotor is designed for gradient centrifugation
when some sample components do not participate in
the gradient. The small angle of these rotors reduces the
centrifugation time in comparison to fi xed angle rotors.


Position in
Rotation


Position
at Rest


r


WHO. “Chapter 7: Centrifuge.” From the publication: Maintenance Manual for Laboratory


Equipment, WHO: 2008, pgs. 45-49.


Figure 2: Centrifuge Rotors


18






3.*Preventative*Maintenance*and*Safety*of*Centrifuges***Featured*in*this*Section:*****Cooper,(Justin(and(Alex(Dahinten(for(EWH.(“Centrifuge(Preventative(Maintenance.”(From(the(publication:((Medical(Equipment(Troubleshooting(Flowchart(Handbook.(Durham,(NC:(Engineering(World(Health,(2013.( ***Occupational(Safety(and(Health(Administration.(“Laboratory(Safety:(Centrifuges.”(OSHA.(Last(update:(August,(2011.(Retrieved(from:(https://www.osha.gov/Publications/laboratory/OSHAquickfactsRlabRsafetyRcentrifuges.pdf(* ** *




EQUIPMENT)Centrifuge*Preventative*Maintenance)!Preventive!Maintenance!Checklist!!1. Lubricate!and!clean!motor.!2. Clean!case.!3. Inspect!power!cords!and!plugs.!4. Inspect!controls!and!switches.!5. Insure!appropriate!menu!settings!for!proper!use.!6. Insure!tightness!of!rotor.!7. Check!lights!and!indicators.!8. Verify!that!alarms!are!operating!properly.!!9. Insure!interlock!is!functioning.!10. If!refrigerated,!insure!temperature!reading!is!working.!11.!Replace/repair!gaskets,!seals,!and!vacuum!pump!(if!applicable).!!


Cooper, Justin and Alex Dahinten for EWH. “Centrifuge Preventative Maintenance.” From


the publication: Medical Equipment Troubleshooting Flowchart Handbook. Durham, NC:


Engineering World Health, 2013.


Introduction to Centrifuges


Centrifuge Preventative Maintenance


21




The majority of all centrifuge accidents result from user error.
To avoid injury, workers should follow the manufacturer’s
operating instructions for each make and model of centrifuge
that they use.
Follow these steps for the safe operation of centrifuges:
■ Ensure that centrifuge bowls and tubes are dry.
■ Ensure that the spindle is clean.
■ Use matched sets of tubes, buckets and other equipment.
■ Always use safety centrifuge cups to contain potential


spills and prevent aerosols.
■ Inspect tubes or containers for cracks or flaws before using


them.
■ Avoid overfilling tubes or other containers (e.g., in fixed


angle rotors, centrifugal force may drive the solution up
the side of the tube or container wall).


■ Ensure that the rotor is properly seated on the drive shaft.
■ Make sure that tubes or containers are properly balanced


in the rotor.
■ Only check O-rings on the rotor if you are properly trained.
■ Apply vacuum grease in accord with the manufacturer’s


guidelines.
■ Do not exceed the rotor’s maximum run speed.
■ Close the centrifuge lid during operation.


continued on page 2


Qu
ick


Fa
ct


s Laboratory SafetyCentrifuges
Centrifuges, which operate at high speed, have great
potential for injuring users if not operated properly.
Unbalanced centrifuge rotors can result in injury or
death. Sample container breakage can release aerosols
that are harmful if inhaled.


Occupational Safety
and Health Administration
www.osha.gov 1-800-321-6742


For assistance, contact us.We can help. It’s confidential.


OSHA 3406 8/2011
DSG


The majority of
all centrifuge
accidents result
from user error.


Occupational Safety and Health Administration. “Laboratory Safety: Centrifuges.” OSHA. Last update: August, 2011. Retrieved


from: https://www.osha.gov/Publications/laboratory/OSHAquickfacts-lab-safety-centrifuges.pdf


Laboratory Centrifuge Safety


22




Qu
ick


Fa
ct


s Laboratory SafetyCentrifugescontinued from page 1


Occupational Safety
and Health Administration
www.osha.gov 1-800-321-6742


For assistance, contact us.We can help. It’s confidential.


OSHA 3406 8/2011
DSG


■ Make sure that the centrifuge is operating normally before
leaving the area.


■ Make sure that the rotor has come to a complete stop
before opening the lid.


When centrifuging infectious materials, wait 10 minutes after
the rotor comes to a complete stop before opening the lid. If
a spill occurs, use appropriate decontamination and cleanup
procedures for the spilled materials. Report all accidents to
your supervisor immediately.


When centrifug-
ing infectious
materials, wait
10 minutes after
the rotor comes
to a complete
stop before
opening the lid.


Occupational Safety and Health Administration. “Laboratory Safety: Centrifuges.” OSHA. Last update: August, 2011. Retrieved


from: https://www.osha.gov/Publications/laboratory/OSHAquickfacts-lab-safety-centrifuges.pdf


23




4.*Troubleshooting*and*Repair*of*Centrifuges****Featured*in*this*Section:****Cooper,(Justin(and(Alex(Dahinten(for(EWH.(“Autoclave(Troubleshooting(Flowchart.”(From(the(publication:(Medical(Equipment(Troubleshooting(Flowchart(Handbook.(Durham,(NC:(Engineering(World(Health,(2013.((((Malkin,(Robert.(Medical(Instrumentation(in(the(Developing(World.(Engineering(World(Health,(2006.((** *




EQUIPMENT)
Centrifuge)Troubleshooting)


!Diagnostic*flowchart*


!


C


e


n


t


r


i


f


u


g


e



T


r


o


u


b


l


e


s


h


o


o


t


i


n


g



F


l


o


w


c


h


a


r


t


C


o


o


p


e


r


,



J


u


s


t


i


n



a


n


d



A


l


e


x



D


a


h


i


n


t


e


n



f


o


r



E


W


H


.





C


e


n


t


r


i


f


u


g


e



T


r


o


u


b


l


e


s


h


o


o


t


i


n


g



F


l


o


w


c


h


a


r


t


.






F


r


o


m



t


h


e



p


u


b


l


i


c


a


t


i


o


n


:




M


e


d


i


c


a


l



E


q


u


i


p


m


e


n


t




T


r


o


u


b


l


e


s


h


o


o


t


i


n


g



F


l


o


w


c


h


a


r


t




H


a


n


d


b


o


o


k


.



D


u


r


h


a


m


,



N


C


:




E


n


g


i


n


e


e


r


i


n


g



W


o


r


l


d



H


e


a


l


t


h


,



2


0


1


3


.




2


5





C H A P T E R 7 C E N T R I F U G E


50


6. Verify the actual rotation speed against the selected
one using a normal load. The testing is done with
a tachometer or a photo tachometer. If the hatch
is not transparent, the procedure indicated by the
manufacturer must be followed.


7. Con fi rm the functioning of the brake system.
8. Verify the functioning of the refrigeration system in


refrigerated centrifuges. The following are the most
important activities:
a) Check the selected temperatures. These should


not vary by more than 3 °C from the temperatures
measured on the digital thermometer.


b) Verify the state of the air intake filter. If the
fi lter is obstructed, clean or substitute with an
equivalent.


c) Conduct a detailed cleaning of the di ff using wing of
the condenser to eliminate the fi lth deposited. This
maintains the heat transference rate according to
the design specifi cations. If abnormal functioning
is detected, seek assistance from a specialized
service technician.


Note: Avoid spilling liquids on control keys. The keys must
be operated with the fi ngertips: The operator should avoid
using fi ngernails, as this can result in the perforation of their
protective membrane.


Every six months:
Verify the state of the motor’s brushes, if the centrifuge has
a motor with brushes. Substitute with new ones (with the
same specifi cations as the original) if necessary. Perform this
routine every six months.


Tools and required instrumentation
In order to carry out the maintenance inspections normally
required for a centrifuge, the following tools or instruments
are necessary:
1. A key for tightening and slackening the rotor’s nuts.
2. An electrical safety analyzer or an instrument for


measuring escaping current.
3. A timer.
4. An electronic thermometer with exactitude of 0.5°C for


refrigerated centrifuges.
5. A tachometer or photo tachometer.


TROUBLESHOOTING TABLE
Rotors 1


PROBLEM PROBABLE CAUSE SOLUTION
Severe vibration. The rotor is unbalanced. Balance the rotor’s load. Fill all the opposite tubes


with the same level of liquid of same density.
Distribute the weight of the opposite tubes
symmetrically.
Load fi xed angle or vertical tube rotors
symmetrically.


The speed selected is near the rotor’s critical speed
range.


Select a rotation outside of the critical speed range.


The rotor is incorrectly mounted. Verify the rotor’s assembly. Test that it is well
adjusted.


There is a lack of lubrication in the rotor’s supports. Lubricate the pivoting axis according to the
manufacturer’s recommendation. For e.g. each 250
centrifugation procedures.


Rotor covers, canister or cubes diffi cult to loosen
after centrifugation.


A vacuum is being produced during centrifugation. Open the ventilation line in the upper part of the
rotor or bucket to eliminate the vacuum.


The rings are contaminated with fi lth, dried
lubricants or metallic particles.


Perform routine cleaning of the rings and lubricate.
Use recommended products recommended by the
manufacturers.


1 Rotors and Tubes for Beckman Coulter J2, J6 and Avanti® J series centrifuges, User’s Manual, Palo Alto, California, The Spinco Business Center of Beckman Coulter, 2001.


WHO. “Chapter 7: Centrifuge.” From the publication: Maintenance Manual for Laboratory


Equipment, WHO: 2008, pgs. 45-49.


Centrifuge Troubleshooting Table


26




M A I N T E N A N C E M A N U A L F O R L A B O R AT O R Y E Q U I P M E N T


51


Tubes
PROBLEM PROBABLE CAUSE SOLUTION


The tubes leak. The covers are badly secured. Adjust the covers.
The tubes are too full. The meniscus must be lower in order to prevent


leaks.
The maximum recommended level has been
exceeded in the open tubes.


Verify the volume and speed recommendations for
the centrifugation.


A defi cient seal is presumed in the rapid seal tubes. Press lightly, after heat sealing (only if the contents
are not aff ected). If leaks are visible, seal again.


The tubes are cracked or broken. The tubes can be broken or become fragile if they are
used below the recommended temperature.


If the sample is frozen, warm to 2 °C before
centrifuging. Evaluate how the tubes behave at low
temperatures before centrifuging.


The tubes become fragile with age and use. Discard expired tubes, use new ones.


Various systems
PROBLEM PROBABLE CAUSE SOLUTION


The main switch is in the on position but the
centrifuge is not functioning.


There is no power to the instrument. Verify the power supply.


The centrifugue cover cannot be opened. The centrifuge is off . Turn the centrifuge ON. Press the handle and open
the cover.


The balance indicator is activated. The load to be centrifuged is unbalanced. Balance the load to centrifuge.
The centrifuge is not levelled. Level the centrifuge.


There is a vibration at low speed. The rotor adjustment mechanism is slack. Correctly adjust the fastening system.
The load is unbalanced. Verify the balance of the load to be centrifuged.
The selected speed is close to the rotor’s resonance
point.


Select a more elevated rotation speed or use a
diff erent type of rotor.


There are fl uctuations in the rotation speed. The transmission belts are in a bad condition (*). Turn o ff the centrifuge. Verify the condition and state
of the belts. The belts must be tempered.


The rotation speed does not reach the selected
speed.


The brushes are defective. Turn off the centrifuge. Verify the condition of the
brushes. If this is the problem, put new brushes with
the same specifi cations as the originals.


The speed control calibration is maladjusted. Adjust the speed control calibration.
The chamber is cold but the rotor is warm. The temperature is incorrectly selected. Verify the temperature selection.
The display which signals the state of the brushes
is on.


The brushes are in a bad condition. Turn off the centrifuge. Verify the condition of the
brushes. Substitute the brushes by others with the
same specifi cation.


(*) Valid procedure in centrifuges with potential belt transmission system.


WHO. “Chapter 7: Centrifuge.” From the publication: Maintenance Manual for Laboratory


Equipment, WHO: 2008, pgs. 45-49.


Centrifuge Troubleshooting Table


27




5.*Resources*for*More*Information*about*Centrifuges****Featured*in*this*Section:***(((Lab(Tricks,(“How(to(Use(a(Centrifuge(Safety.”(Posted(January(18,(2010.(Retrieved(from:(https://www.youtube.com/watch?v=IhJNFGfsUus( ***WHO.(“Centrifuges:(Basic(Principles.”(Maintenance(and(Repair(of(Laboratory,(Diagnostic(Imaging,(and(Hospital(Equipment((WHO:(1996).(((




*Resources*for*More*Information:(**Internal*Resources*at*library.ewh.org:*For*more*information*about*maintenance*and*repair*of*laboratory*centrifuges*please*see*these*resources*in*the*BMET*Library!*( 1. WHO.(“Centrifuges:(Basic(Principles.”(Maintenance(and(Repair(of(Laboratory,(Diagnostic(Imaging,(and(Hospital(Equipment((WHO:(1996).(*External*Resources:(( 2. Centrifuge*Operation*and*Common*Mistakes:*This(video(demonstrates(the(proper(usage(of(a(centrifuge,(while(also(highlighting(common(mistakes.(The(four(major(points(of(this(video(are:((1.(Use(the(right(tubes(2.(Balance(the(tubes(3.(Secure(the(rotor(lid(4.(Check(centrifuge(settings.(Lab*Tricks,*“How*to*Use*a*Centrifuge*Safety.”*Posted*January*18,*2010.*Retrieved*from:** * https://www.youtube.com/watch?v=IhJNFGfsUus((((




Centrifuge*Bibliography:*((Cooper,(Justin(and(Alex(Dahinten(for(EWH.(“Centrifuge(Preventative(Maintenance.”(From(the(publication:((Medical(Equipment(Troubleshooting(Flowchart(Handbook.(Durham,(NC:(Engineering(World(Health,(2013.(((Cooper,(Justin(and(Alex(Dahinten(for(EWH.(“Centrifuge(Troubleshooting(Flowchart.”(From(the(publication:(Medical(Equipment(Troubleshooting(Flowchart(Handbook.(Durham,(NC:(Engineering(World(Health,(2013.(* Malkin,(Robert.(Medical(Instrumentation(in(the(Developing(World.(Engineering(World(Health,(2006.((* (Occupational(Safety(and(Health(Administration.(“Laboratory(Safety:(Centrifuges.”(OSHA.(Last(update:(August,(2011.(Retrieved(from:(https://www.osha.gov/Publications/laboratory/OSHAquickfactsRlabRsafetyRcentrifuges.pdf(((OpenStax(College.(“Components(of(Blood.”(From(the(publication:(Biology.(Rice(University:(2013,(pgs.(1195R1199.(( OpenStax(College.(“1901(Composition(of(Blood.jpg.”(Wikimedia(Commons.(Retrieved(from:(https://commons.wikimedia.org/wiki/File:1901_Composition of Blood.jpg(((WHO.(“Centrifuges:(Basic(Principles.”(Maintenance(and(Repair(of(Laboratory,(Diagnostic(Imaging,(and(Hospital(Equipment((WHO:(1996).((( WHO.(“Chapter(7:(Centrifuge.”(From(the(publication:(Maintenance(Manual(for(Laboratory(Equipment,(WHO:(2008,(pgs.(45R49.((( WHO.(“Analyzer,(Hematology,(Blood(Grouping,(Automated.”(From(the(publication:(Core(Medical(Equipment.(Geneva,(Switzerland,(2011.((( WHO.(“Use(of(Centrifuges.”(From(the(Publication:(“Laboratory(Biosafety(Manual,(Third(Edition.”(WHO:(Geneva,(2004.(((Wikipedia.(“Laboratory(Centrifuge.”(Wikipedia,(p.(1R12.(Retrieved(from:(https://en.wikipedia.org/wiki/Laboratory_centrifuge(




Copyright 2016, Engineering World Health