Leak rates and their detection
The leak rate is a measure of the quantity of material that flows through a leak per time unit. 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.
PLT unit software
The optional PLT unit software, also called PLTconnect, is a program to facilitate the documentation of leak tests, which are carried out with the PLT unit from BRAND. Measured values from the test result of the PLT unit will be automatically transferred to the program. The result is displayed as a test certificate and stored in the program. Thus, the documentation of your test results will be significantly facilitated.
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 time unit, pipette volume and type, etc.
The leak rate QL
The leak rate QL is the ratio of the pV value and the period of time during which the gas flows through a path cross-section.
The pV value
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 volume loss
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 means a volume loss of about 1 μl/s.