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Feeding unit
When used in conjunction with the testo 324 leakage measuring
instrument, the feeding unit (gas bladder) enables leakage
measurement to be carried out independently of the gas supply.
3.1.
Physical principles
3.1.1.
Physical influence of temperature on the pressure to
be measured
Temperature fluctuations and positional changes have an effect on
the measuring accuracy of pressure measurements. The following
should therefore be observed:
✓ The entire measurement system must be adapted to the
ambient temperature and to the temperature of the line system
to be tested.
✓ The temperature of the measurement system and the line
system must remain stable during measurement.
Example of temperature influence:
with a test pressure of 100 hPa and an air pressure of 1000 hPa,
the ambient temperature changes from +22 °C to +23 °C. The air in
the test system expands and the test pressure increases by
3.73 hPa. The temperature influence on the pressure change is
unaffected by the test volume.
3.1.2.
The standardised measurement result of the testo
324 relating to temperature influences
The testo 324 leak rate measuring instrument certified to
DVGW G 5952 enables measuring values to be reproduced.
Comparable results based on the standardised reference operating
pressure of 23 mbar are always achieved. The volume measured
during the test is based on a reference temperature of 20 °C and
the current air pressure.
A change in the ambient temperature therefore has no influence on
the measuring values!
The ambient temperature and the relevant test gas or medium for
each test section must nevertheless show a constant temperature
prerequisites for use, and acknowledges that the re-sale,
export, import etc. in particular in countries without wireless
permits, is his responsibility.
3 Specifications
11
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