P. 770.270.1394 F. 770.270.2389 865 Marathon Parkway Lawrenceville GA 30046
Instructions
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Before Operating
Combo V24
Combo V24 Centrifuge
Features
The LW Scientific combination centrifuge is a quiet and sturdy unit designed for rapid microhematocrit, test tube, or
microtube separations. It is available with or without a digital tachometer and with 4 rotor choices. The variable speed
function allows blood tubes, urine tubes, microtubes, and microhematocrit tubes to be spun at different G-forces as
outlined by C.L.I.A. regulations.
Remove the centrifuge from the shipping container and inspect for any possible shipping damage. If the centrifuge
appears to be damaged, please contact your distributor immediately.
Read and complete the online warranty form. The warranty form documents your purchase. Failure to fill out
warranty form may void any warranty claims on the unit.
The screw and washer in the motor shaft are for shipping only. Please remove and use the Thumbscrew for all
normal operation.
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*CLMA recommends that your hematocrit centrifuge
PVC accuracy be calibrated quarterly using the
HemataCHEK reference control kit. Refer to
HemataCHEK product insert for calibration procedures.
Visit www.LWScientific.com
to order.
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Recommended Fluid Speeds & Times:
Blood – 4000 rpms – 7 to 10 minutes
Urine – 1700 rpms – 5 to 10 minutes
Fecals – 1500 rpms – 6 minutes
Microhematocrits – 12,000 rpms – 3 to 4 minutes.
*Note: Speed/time may vary based on tubes, tube size, anticoagulants,
varying regulations, etc. Speeds are general industry recommended
standards. Please refer to your own regulatory specific test tube
requirements for the most accurate protocol.
** Combo V24 is available in non-tach and digital tach versions. For
exact rpm measurement, a tachometer is required.
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Place the centrifuge on a sturdy, level surface. Verify that there are no loose objects or packing material in the tube
chamber. DO NOT PLUG UNIT IN.
Select a rotor and slide it down over the motor shaft, ensuring that the slot in the bottom of the rotor lines up with
cross pin on the motor shaft. The shaft should be lubricated with a fine layer of common grease every few months
for easy rotor changes.
Test-tube and Microtube Rotors: After seating the rotor properly on the motor shaft cross pin, tighten the chrome
thumbscrew down on the rotor. Do not over-tighten.
Microhematocrit Rotor: Place the cover plate onto the rotor by sliding it down over the center shaft. ( WARNING: The
rotor cover plate is not threaded and will not hold the rotor in place during operation. ) Next, tighten the chrome thumbscrew down onto the rotor. Do not over-tighten.
Your Combo was pre-calibrated before it was shipped from LW Scientific. If future calibration is needed, the following
procedure requires a hand-held tachometer (for the non-tach unit) and should only be performed by a qualified
technician or the LW Scientific Service & Repair department. Close and latch the lid by pressing on the front center of
the lid until it clicks (to open, press down again until it clicks).
Operation
Warranty
Selecting and Changing Rotors
Verify that the switch is in the “OFF” position and plug the AC power cord into the appropriate approved and properly grounded
AC outlet.
DO NOT INSERT TUBES AT THIS TIME! Ensure that the Speed Selector Switch is in the correct position: LOW “L” for test
tube rotors (1,000-4,000 rpms) or HIGH “H” for microhematocrit and microtube rotors (12,000 rpms). WARNING: Spinning
the 12 or 24-place test tube rotor at high speeds (above 4,000 rpm) can cause tube breakage and centrifuge damage.
With rotor installed, turn the power switch on, set the speed dial to the lowest setting, and turn the timer to 10 minutes. The
unit should begin spinning with a smooth whirring sound with little or no vibration. Next, turn the speed dial up to high. If there
are loud or unusual sounds, or if you experience excessive vibration, DO NOT OPERATE -- contact your dealer or LW
Scientific, Inc.
Spin only balanced loads. Make sure that tubes are placed opposite each other. Proper sample balancing will improve sample
separation and will extend the life of the centrifuge. Out of balance loads may damage the centrifuge.
Support your tubes: Tubes must always be supported from the bottom and never hanging by their caps. Use the large
tube sleeves for larger tubes and the small sleeve inserts for smaller tubes. Rubber tube cushions are also available
from LW Scientific for supporting short tubes in the large tube sleeves.
Ready for operation: Load your tubes and set timer for desired time, and set speed dial for desired speed. When spinning the
24 -place hematocrit rotor, keep the speed setting at maximum for rapid and complete separations in 3-4 minutes.
Using the Electric Brake: After the timer bell rings, you may press and hold the brake button to slow the rotor down. Pressing
the brake sends reverse electric current to the motor and will slow the rotor to a stop within 20-30 seconds. When you notice
the rotor has come to a stop, release the brake...otherwise, it will spin in reverse.
P. 770.270.1394 F. 770.270.2389 865 Marathon Parkway Lawrenceville GA 30046
Reading Microhematocrits
Care, Maintenance, Trouble-Shooting
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Use only quality test tubes. Lower-quality plastic or glass tubes may fracture and release their contents into the tube
chamber
Never force a tube into the tube shields. Some plastic conical test tubes are too large and should not be used.
If you purchased a microhematocrit rotor, it includes a Reader Disc, which allows the tubes to be read directly from the rotor.
After the rotor has stopped, remove the cover plate by unscrewing the chrome thumbscrew and lifting the cover plate
straight up.
Place the reader disc over the hematocrit tubes, and adjust the disc until the 0% line is lined up with the bottom of the fluid
in the tube to be read.
While keeping the 0% line positioned at the bottom of the fluid, turn the disc until the 100% line aligns with the top of the fluid.
Read the separation line in the middle for your microhematocrit results.
Never hang a tube by its cap. Always make sure the tubes are supported by the bottom of the shield, or with a
rubber cushion.
Use only 75mm capillary tubes with the 24-place hematocrit rotor.
Clean the inside of the centrifuge regularly. Always unplug electrical power before cleaning. Whenever there is a tube
breakage or a spill, it is recommended that the inside of the centrifuge be cleaned, and if possible, disinfected (do not
immerse the electrical components in any liquid).
Motor and electrical maintenance: The Combo V24 utilizes a brushed motor, which includes bearings that are
permanently lubricated. Likewise, the electrical components were designed for high reliability and should not need
regular service, other than brush replacement. However, if repairs should be needed, please contact LW Scientific,
Inc.
If the centrifuge will no longer maintain speed, inspect and/or replace the brushes. When inspecting/replacing
brushes, always blow out the motor/brush area with canned air. Excessive dust, dirt, and hair can interrupt the
brush contact and decrease performance.
If you find it difficult to change rotors, apply a small amount of grease to the shaft of the motor or to the core of the rotor. Do
not use oil or spray lubricants such as WD-40.
Light comes on - Will not spin: Check to make certain the lid safety switch (near the back right hinge) is engaged.
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With the power on and the timer set, depress the button with your finger. If the rotor spins, turn the safety switch button
counter-clockwise to raise the height and allow it to contact the lid when it is closed.
No light - Not spinning: Confirm that your power source is working. Check the 8 amp fuse and replace if the filament
is broken. Speed slows down or stops...the brushes may need to be replaced on the motor after 1000 +/- hours of use
if speeds have decreased. Contact LW Scientific to purchase new brushes (part #CMP-BRSH-PR77).
With proper care and maintenance, the Combo V24 centrifuge will
provide years of laboratory grade service. Please follow these
recommended guidelines:
Because of the safety issues with high g-forces in a centrifuge, it is recommended that rotors be inspected every 6
months for corrosion and fatigue. If there is any indication of wear, the rotor should be removed from service. Contact
LW Scientific for return instructions, so the rotor can be evaluated by an LW Scientific technician for repair or replacement. It is also recommended that after 2 years of service rotors and tube shields be returned to LW Scientific for
inspection. Following these procedures will ensure safety of lab personnel as well as extend the life of the centrifuge.
NOTE: Plastic tube shields should be replaced at least once a year. Tube shields should be inspected once a month for
wear or damage. Tubes that are being used in high volume should be replaced every three months or sooner.
Speed Calibration
With the red high/low switch on the front of the unit on low, the speed dial on maximum, and a tube rotor with tube shields in
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place, adjust the VR-I rheostat on the circuit board up to 4000 RPMs.
With the red high/low switch on the front of the unit on high, the speed dial on maximum, and a Hematocrit rotor in place, adjust
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the Vr-h rheostat on the circuit board up to 12000 RPMs.
Brush Replacement
Unplug the centrifuge, and turn it on its side.
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Remove the feet and all Phillips head screws holding the metal base plate in place.
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Using a flat head screwdriver, remove the two black caps on the bottom part of the motor.
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Using your fingers, pull the brush out of the recessed hole that the black caps were removed from. The brushes consist of springs
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with a graphite bar on them.
Place the new brushes in the recessed hole, and replace the black caps. Be careful not to overtighten. Black caps could break.
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(See image).
Replace the metal plate and the feet.
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Your Combo V24 is now ready to use.
Specifications
Max. Speed (HIGH):
Max. Speed (LOW):
Max. Volume:
Input Voltage:
Fuse:
Height:
Width:
Depth:
Weight:
Boxed dimensions:
Boxed weight:
12,000 RPM (+/- 600)
4,000 RPM (+/- 200)
24 3ml to 15ml test tubes
24 75mm capillary tubes
24 2ml microtubes
110v or 220v
8 amp / 250 volt
8.7 inches
10.6 inches
12.5 inches
15.8 lbs.
11.5 x 10 x 7 inches
23 lbs.
Test Tube Rotor
Urine
Blood
Microtube Rotor
Microhematocrit Rotor
RPM’s
500
1,000
1,400
1,750
2,000
2,250
2,500
2,750
3,000
3,250
3,500
3,750
4,000
12,000
12,000
G-Force (RCF)
37
151
296
462
603
764
943
1141
1358
1594
1849
2122
2415
12,900
14,500
MKT-7.5.3-L-076 | Rev 2
P. 770.270.1394 F. 770.270.2389 865 Marathon Parkway Lawrenceville GA 30046
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