SGB VL-H9, Руководство пользователя

Страница: 16 / 50

M.:
Date: Feb. 98
Page: 10
Vacuum Leak Detector
VL - H9
SGB Sicherungsgerätebau
GmbH
57076 Siegen
4 Functional description
4.1 General
(1) The vacuum leak detector VL-H9 indicates any leakage in the leak detector device by pressure
rise (leak detector, connection lines with fittings and interstitial space).
(2) The vacuum pump installed in the leak detector generates a vacuum via the suction line. Such
vacuum is controlled via the measuring line by a pressure switch which is also installed in the
leak detector.
(3) In general, a slow pressure rise is caused by slight leakage due to the installation. When
reaching the trip pressure 'Pump On', the vacuum pump is activated and the interstitial space is
evacuated until the trip pressure 'Pump Off' is reached again. In normal operation, the vacuum
varies between the two control limits with short running times and longer rest periods for the
pump, depending on the pressure tightness of the complete system.
(4) In a case where due to ingress of air the pressure in the monitored system rises to the trip value
'Alarm On', an optical and acoustic alarm is activated.
(5) When the pressure drops to the trip value 'Alarm Stop', the alarm is cancelled (e.g. functional
check).
(6) If leakage occurs and liquid gets into the interstitial space, the pressure will rise and the vacuum
pump will be activated by the pressure switch. When the liquid is evacuated and reaches the
liquid trap in the suction line, the trap is closed. This prevents the vacuum pump from generating
a vacuum in the interstitial space. The pressure in the interstitial space will rise due to the follow-
on liquid until the alarm is activated.
(7) The factory-set trip values of the pressure switch for operation of the leak detector are given in
table 1.
Trip value Vacuum in mbar Vacuum in Pa
Alarm „On“ 370 +/- 40 37000 +/- 4000
Alarm „Off“ 420 +/- 40 42000 +/- 4000
Pumpe „On“ 450 +/- 40 45000 +/- 4000
Pumpe “Off“ 500 +/- 40 50000 +/- 4000
Table 1: Trip values of the pressure switch
1
1
The trip values for ALARM STOP and PUMP ON measured during the functional check may be higher or lower than those indicated,
provided that the value measured on site for ALARM STOP is lower than the value for PUMP OFF, and that the value for PUMP ON is
higher that the value measured for ALARM ON.
16 von 50