Method of determining an internal volume of a filter or bag device, computer program product and a testing apparatus for performing the method

A computer program product comprising:

• non-transitory computer-readable instructions, which when loaded and executed on a suitable system, is configured to perform the steps of:
• pressurizing a filter or bag device to a first pressure (p1) lower than a proof pressure by supplying a test gas,
• pressurizing said device to the proof pressure (pp), and at the same time, measuring the mass flow (m) of test gas,
• determining the gas temperature (T), and
• determining the internal volume (V) based on the equation for ideal gases, such that:
• V=m×R×T/(po−p1)
• wherein V is the internal volume, m is the mass flow, R is the gas constant, T is the gas temperature, pp is the proof pressure and p1 is the first pressure.

A testing apparatus for determining an internal volume (V) of a filter or bag device (10), the testing device comprising:

• a test gas inlet (52) connectable to a test gas supply (30),
• a test gas outlet (51) in gas communication with the test gas inlet (52) for supplying the test gas to the internal volume (V) of the filter or bag device (10),
• a flow meter (57) in communication with the test gas inlet (52) and the test gas outlet (51) for determining a mass flow (m) of the test gas,
• at least one pressure sensor (22, 24) for determining a first pressure (p1) and a proof pressure (p0) that is higher than the first pressure (p1), and
• a control device for determining the internal volume (V) of a filter or bag device (10) to be tested on the basis of at least the first pressure, the proof pressure and the mass flow or volumetric flow of test gas based on the equation for ideal gases, such that:
• V=m×R×T/(pp−p1)
• wherein R is the gas constant and T is the gas temperature.