When selecting a laboratory to fulfill your calibration needs, you need to be sure they can supply you with accurate and reliable results. The technical competence of a laboratory depends on a number of factors.
Technically competent laboratories will have all of the following elements fully developed:
Gilson Pipetman are unique in using a Dry-Seal system with precision manufactured seal and ‘O’ ring. This avoids the use of grease to produce an air-tight seal. Grease may contain contamination. Pipetman can be cleaned and seals and o-rings replaced without altering the calibration.
However, if you grease a pipette and then remove the grease for cleaning, the amount of grease re-applied may vary and could alter the calibration of the pipette.
CPR always replaces seals and ‘O’ rings during servicing as recommended by Gilson to maintain high levels of accuracy and precision.
Other service agencies may use grease to obtain an air-tight seal rather than replacing parts. Pipetman is not designed as a greased system and this quick fix will have a long term detrimental effect on pistons and tip holders with a loss of calibration over time.
For mechanical reasons, pipettes can only deliver samples accurately over a limited range of volumes for each particular model. It is essential to check linearity when the pipette is serviced to ensure correct functionality at both the upper and lower limits of the pipettes capacity.
Even with CPR’s most basic level of service, volumes are checked at both extremes of a pipettes range, to ensure both accuracy and linearity. To increase their throughput some other service agents only perform checks at a single mid-point volume with three or five weighings, and even issue calibration certificates based on these minimal readings. As the majority of pipettes are variable volume how can you ensure that a pipette is linear across it’s specification range by testing only one volume?