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LCD-display with max.
contrast and background lighting.
All internal components
easily accessible from the front.
User friendly, menu driven.
The right device for
any leak test method and leak test application:
JWF series 40 leak test panels
In automatic dry air leak testing the part to be tested ist
subjected to a pressure and it is established wether air is
escaping. The escaping air however, cannot be directly
measured, only its effects, i.e. either the pressure
variation which results from the air leaving the workpiece -
which is detached from the compressed air source (pressure
measurement), or the quantity of air continuing to flow into
the workpiece - which is connected to the compressed air
source (flow rate measurement). These are different variants
for both pressure and flow rate measurement.
Pressure Measurement
In industrial leak
testing, pressure measurement is the most common used method.
With small test chambers, leaks can be detected down to 0.1
cm³/min.
The relative pressure or
absolute pressure method allows a compact test unit and the
minimum possible volume of the measuring system itself. It
is also distinguished by high operational reliability and a
wide measuring range. The test signal definition depends on
the pressure used.
In the differential
pressure method at higher test pressures, a greater accuracy
can be obtained than with the absolute pressure method, as
the test signal definition is independent of the test
pressure used.
With measurement of the
pressure drop with overpressurisation of the test piece the
usual operating conditions are simulated.
In measuremetn of the
pressure rise in the partial pressure test method the
disturbing influences due to temperature variations or
volumetric instability of the sealing device or of the
workpiece are smaller than in measurement of the pressure
drop. Measurement of the pressure rise in the excess
pressure method (capsule method) manages without a levelling
stage. Moreover, in this case the test pressure used is not
limited by the measuring range of the measuring element, as
it is not subjected to the test pressure.
Flow Rate Measurement
Whereas in pressure
measurement, the test signal becomes smaller with increasing
test volume, flow rate measurement delivers a test signal
independent of the quantity of the test volume. This is an
advantage in calibration: the test signal corresponds to the
air flow rate flowing through the calibration leak. Here it
is no longer necessary to know exactly the quantity of the
test volume connected during the calibration process and to
allow for determining the leakage rate.
As a rule, measurement of
the volumetric flow rate (e.g. pressure drop across a screen)
is not used for leak testing, but for flow control such as
for example, in monitoring free passage in gas systems which
are tested by the pressure drop method with the same
measuring element (differential pressure sensor) in a
subsequent measurement for leaking.
In measurement of the mass
flow rate (thermal measuring methods) the test signal is not
only independent of the mass flow rate (thermal measuring
methods) the test signal is not only independent of the size
of the test volume, but also of the degree of test pressure.
The test signal here corresponds directly to the
leakage rate in standard cm³/min. The leakage rate does not
- as in pressure measuring methods - have to be calculated.
Service friendly concept
All of the interior of
the panel is easily accessible from the front. Therefore
service work can be done without problems and saving time. |
