6. Leakage rates and utility life measurements
lumes a manual test pump can be used. The choice should be such that the
pressure change is at least 5 hPa. Boyle’s law returns the following equation
for the wanted volume V
pipe:
whereby:
Vpipe wanted pipe volume, max 1000.0 l
Vsample sample volume, default 0.100 l, e.g. with 100 ml medical syringe
Δp max pressure difference in Pa caused by the taking of the sample
pabs absolute air pressure, entered manually under the Setup menu
(default 1013 hPa)
Figure 6.2 – Connections for determining the pipe volume V
pipe
, with a 100
ml medical syringe (left) or a manual test pump (right)
6.1.1 Determination of the volume of the nozzle
The pressure difference Δp will be measured. It should amount to at least 200
Pa, to get an exact measuring result. Therefore, the volume of the nozzle
V
Sample
must at least amount to 1/500 of the pipe volume. In this case, the ex-
pected error of the result of the volume measurement is equal to the inaccu-
racy of the DC 2000
PRO
which is 3% of the measured value. A higher pressure
will provoque longer stabilization periods during the temperature compensati-
on and possible leakages will have more influences.
The following table will give you some guiding values for the determination of
V
pipe
= V
sample
. ( - 1)
Temp = const
p
akt
Dp
(3)
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