BRAND PLT Pipette Leak Testing Units

from BrandTech Scientific, Inc.

BRAND PLT Pipette Leak Testing Units2703970 703970 703975 703976 703977 703978 703979

The most frequent cause of inaccuracy in piston-operated pipettes is leakage.

  • This arises from damage either to the seals, pistons, or tip cones.
  • Often not detectable by the naked eye, leaks lead to significant volume errors.
  • The BRAND pipette leak tester (PLT unit) for air displacement pipettes finds even the smallest leaks within seconds.
  • Air-displacement pipettes must be checked at regular intervals and the results must be compared with the ISO 8655-2 error limits.
  • However, a calibration certificate only reflects the results at the time of testing.
  • The time between these calibrations is crucial, since leaks can occur at any time.
  • Well over 80% of pipettes sent in for repair have leaks and are outside their volume tolerances, even if they don’t drip.
  • While the PLT unit cannot replace regular gravimetric testing, daily pipette checks can provide a safeguard during the periods between calibrations.
  • Even the smallest leaks are detected! Process reliability for the pipettes is thus significantly improved.

Leak rates, their detection and quantification.

  • The leak rate is a measure of the quantity of material that flows through a leak per unit time.
  • For air-displacement pipettes the PLT unit determines the rate through a differential pressure measurement, i.e., after creating a negative pressure, the pressure rise over a given time is measured.
  • The leak rate is determined by considering complex physical relationships.
  • Calculation of the limit values resident in the PLT must include factors such as the dead volume of the pipette/tip system, flow cross section of the pipette tip, pressure rise per unit time, pipette volume and type, etc.
  • The pV value is the product of the pressure and the volume of a certain quantity of a gas at the prevailing temperature.
  • This is a measure of the quantity of material or the mass of the gas.
  • The leak rate QLis the ratio of the pV value and the period of time during which the gas flows through a path cross-section.
  • For the pipette test, hPa ml/s is a suitable unit for the leak rate.
  • A leak rate of e.g., 1 hPa ml/s at an air pressure of 1000 hPa (approx.atmospheric pressure) means a volume loss of about 1 µl/s.

Easy To Use.

  • Menu-driven software, combined with a jog wheel and affirmative/negative buttons make it easy to select the correct test parameters, pressure units or language (English, Spanish or German).

A Diagnostic Tool.

  • To check the overall pipette system, the test is conducted with mounted, unused tip.
  • When a leak has been identified, the test can be repeated without a tip to determine whether the leak arises from the tip cone/tip coupling region.
  • Additionally static or dynamic (piston operated during test procedure) testing can also help localize source of leaks when detected.
  • The ability to test multichannel pipettes four channels at a time, or individually increases the throughput of testing, and assisting in the diagnosis of faulty channels.

Pass/Fail Determination.

  • The limit values referenced during testing represent a warning limit, from which significantly lower volume values can also be determined gravimetrically.
  • This is one quarter of the volume tolerances, according to ISO 8655-2.
  • The limit value for the leak volume of a given pipette allows the leak rate to be calculated.
  • These calculations, which are based on over 35 years of experience in the development and production of pipettes, include the dead volume and the intake characteristics, among other things.
  • If the pipette is mechanically defect-free, clean, and the test is carried out properly with the BRAND PLT unit, then the instrument is within the ISO 8655-2 tolerances.

Ordering Information:

  • PLT unit (Pipette Leak Testing Unit) includes one adapter each for testing air-displacement pipettes with tip (mounted) and without tip, 2 plugs, 3 replacement PE filters for the pipette adapters, universal AC adapter, quality certificate and operating manual.
  • Multichannel adapter sold separately.

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