Leak Rate Test

Introduction

The Leak Rate Test is used for verifying the internal tightness of the pump and helps identifying parts which may have caused a leak.

System requirements

Test Principle

A solvent can be chosen from available solvent channels and a maximum target pressure can be defined at which the test will be run. Typically, this is the maximum pressure specified for the pump. The test can be run with any solvent compatible to the pump.

Before the test, the pump is flushed with solvent in order to remove air bubbles, as air bubbles are compressed during the test and therefore would appear as leaks. Using a degasser is highly recommended.

Initially, the pressure is increased to about 100 bar below the target pressure, which has been set for the test.

Then piston 1 is brought to its rear position. An increasing flow is delivered by piston 1. In case of a leak, the pressure will drop initially as long as the flow rate delivered by the piston is lower than the leak rate. As soon as the flow rate of the piston exceeds the leak rate, the measured pressure will increase again. Therefore the minimum pressure of that curve segment corresponds to the flow and leak rate at that time and the leak rate is measured. Compare to the description of the system pressure test (System Pressure Test).

Subsequently, piston 2 is moved to its rear position, then piston 2 delivers and the measurement is done as described for piston 1.

For a binary pump (G1312B/C, G7112B, K1312B, G4782A), the test is run for both pump heads for channels A and B.