VACUUM LEAK DETECTOR
VLXE .. Ex M and VLXE .. Ex MMV
28/07/2020
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4.3 Air
Leaks
If an air leak occurs (in the outer or inner wall, above the liquid level),
the vacuum pump switches on to restore the operating vacuum. If the
leak causes the incoming air to exceed the pump’s capacity limit, the
pump remains on continuously.
Increasing leak rates lead to a further decrease in pressure (with the
pump running) until the Alarm ON switching value is reached. This
triggers the visual and audible alarms.
4.4 Liquid
Leaks
In case of a liquid leak, the liquid enters the interstitial space and col-
lects in the low point of the interstitial space.
The incoming liquid decreases the vacuum, which causes the pump
to turn on and evacuate the interstitial space(s) until the operating
vacuum is reached. The process repeats itself until the liquid stop
valve in the suction line closes.
Because of the vacuum that still exists on the measuring line side,
additional stored or conveyed product or water is sucked into the in-
terstitial space, the measuring line, and, if applicable, into a pressure
compensation vessel. This causes the vacuum to drop until the
“Alarm ON” pressure is reached. This triggers the visual and audible
alarms.
Comment: It is also an option to use a liquid sensor in conjunction
with a solenoid valve instead of the liquid stop valve. The liquid alarm
is then triggered when the sensor comes into contact with liquid.
4.5 Pressure increase above atmospheric pressure in interstitial space when using a leak
detector VLXE .. MV-Ex, acc. to chapter 3.5.1 f) as well as 3.5.2
If a pressure increase of more than 50 mbar above atmospheric pres-
sure occurs in the interstitial space, the solenoid valve in the suction
or connection line is closed and the pump switches off.
The pressure increase is indicated visually and acoustically (pressure
build-up alarm).
For the version up to 90 bar (additional pressure switch and solenoid
valve), the additional pressure switch is actuated in the case of a fast
pressure increase, which immediately closes the solenoid valve to
protect the leak detector from inadmissibly high pressures. The pres-
sure build-up alarm is triggered; if the additional pressure switch is
connected via the probe contacts, the probe alarm is also shown.
Design and Function
Summary of Contents for VLXE Ex M Series
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