Pipette feeling a little off? A 2-minute inspection can tell you what’s wrong before it becomes a major problem

The proper and efficient operation of your pipette is crucial to the accuracy of your results, and keeps costs down by preventing costly repairs.

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Conducting a 2-minute inspection on your pipette can reveal what’s wrong and help you get the service you need. We’ve included Gilson’s 2-Minute Inspection procedure to guide you along.

Ready to get started?

pipette_serialSTEP 1 : Check the Records

Use the serial number to identify the pipette and to determine its age, then check your laboratory records for the date of last servicing.

STEP 2 : General Appearance

pipetman_explodedIs the operating-rod bent or corroded?
It may have been dropped or been subjected to excessive exposure to corrosive liquid or vapours during decontamination.

Are the volumeter dials incorrectly aligned? Are the number unclear?
Autoclaving changed the appearance and function (the body must not be autoclaved).

Is the tip-ejector corroded or broken?
It may have been subjected to excessive exposure to corrosive liquid or vapours during decontamination.

Is there physical or chemical damage to the tip holder?
It may have received repeated blows, or been dropped or been subjected to excessive exposure to corrosive liquid or vapours during decontamination.

STEP 3 : Check Functions

Large volume adjustment

  1. Set volume at maximum (i.e. nominal volume) assessing the movement of the friction ring
  2. Activate the push-button to test movement during aspirate and dispense strokes

Possible issues:

Irregular movement?
Hitching, due to damage to the friction ring

No displacement?
Bent operating rod

Jerky movement?
Corroded, dirty or scratched piston

Volumeter adjustment

Go through the entire range. The settings should correspond to the pipette’s useful volume range (minimum to nominal volume).

Possible issues:

No adjustment?
Possibly caused by autoclaving.

Incorrect volume setting?
May be caused by misindexing; pipette adjustment screw has been incorrectly reassembled.

Tip-ejection system

  • Fit tip and depress tip-ejector button
  • Observe function of tip-ejector
  • Disassemble tip-ejector

Possible issues:

No movement?
Broken return spring

Improper fit?
Not tight enough

Can’t disassemble?

pipetman_liquidSTEP 4 : Leak Test

  1. Fit the pipette tip
  2. Set volume at maximum (i.e. nominal volume)
  3. Pre-rinse by aspirating and dispensing wate, several times
  4. Aspirate water
  5. Hold the pipette in the vertical position for 20 seconds
  6. For models P2 to P200, re-immerse in the test liquid; fluid level in tip should remain constant
  7. Observe if a drop or a leak appears at the orifice of the tip

Are either tip or tip holder leaking?

  • The end of the tip holder may be scratched/damaged (mechanical or chemical)
  • The tip may fit imporperly due to the use of non-manufacturer tips
  • Organic solvent, vapour pressure

STEP 5 : Disassembly and Reassembly


  1. Eject the tip
  2. Pull the tip-ejector down
  3. Unscrew the connecting nut
  4. Separate the handle from the bottom part
  5. Remove the piston from the tip-holder

Check to see if the piston surface is corroded, scratched or damaged. Also check the piston seal and o-ring for mechanical damage or chemical attack.


To avoid losing or damaging fragile parts, reassemble the pipette immediately. Be sure to respect the correct order of parts: the piston seal should always be positioned before the O-ring. You should never disassemble the body (handle) of the pipette!

We hope this guide will help you assess your current pipette lineup.

For on-site inspections, preventative maintenance, or to schedule calibration and service, drop us a line. Mandel’s Service team is ready to help keep your lab running smoothly.

Email Mandel Service

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