Page
14
ML442 | v5k
Expo Technologies UK
T: +44 (0) 20 8398 8011
Expo Technologies US
T: +1 (440) 247 5314
Expo Technologies China
T: +86 532 8906 9858
5.2 Leakage Compensation Systems (LC)
Open the Leakage Compensation Valve (LCV) fully, turn anti-
clockwise.
Clockwise will reduce the flow and anti-clockwise will increase the
airflow.
Open the supply regulator SLOWLY and allow the PE pressure to rise
until the RLV opens.
Check that the RLV opens at or below the figure specified in the
documentation.
Note tolerance of
2 mbarg / 0.8” WC / 200Pa
Repeat the test several times.
Figure 13 Leakage Compensation Valve
Open the supply regulator to between 4 and 8 barg / 60 and 115 psi / 400 and 800 kPa and
the purging flow will start.
Check that the internal logic gauge reads 2 bar /30 psi / 200 kPa
At this time the "alarm/pressurized” indicator should be green and the "purging” indicator should
be yellow. If the yellow indicator remains black the flow through the RLV is below the minimum
for which the flow sensor has been calibrated. Check the air supply pressure at
the inlet to
the control unit while purging is taking place
. It must be above the minimum specified.
The purge timer will start as soon as the "purging" indicator turns yellow. Check that the time
delay between the “purging” indicator turning yellow and the application of power to the PE is
not less than the minimum time required purging the PE. Times in excess of the minimum are
permitted and a tolerance of +20% is normally acceptable. If the time is too short it must be
increased accordingly.
After the power has been applied via the CU, the purging valve will close and the air flow into
the enclosure will be controlled by the LCV. The initial setting of fully open will normally be too
high. It should now be adjusted to set the PE pressure and leakage. There are three possible
situations:
Air continues to come out through the RLV Spark Arrestor after power has been applied in
considerable quantity. The LCV is much too far open and the air flow is holding the RLV
open continuously.
Close the LCV slowly. The PE pressure will start to fall as the flow decreases but eventually
the RLV will close and the enclosure pressure rise again. At this point the RLV may start to
open intermittently as the PE pressure rises to the point where it exceeds the RLV opening
pressure. When the RLV opens the pressure will fall quickly to the point where the RLV re-
closes and the enclosure pressure starts to rise again. This is entirely normal for this type of
RLV.
If the RLV is opening intermittently the LCV is slightly too far open. When the RLV opens
the enclosure pressure falls quickly to the point where the RLV re-closes and the enclosure
pressure starts to rise again. This is entirely normal for this type of RLV and shows that it is
working correctly.
Continue then to close the LCV until the cycling stops and the enclosure pressure starts to
fall. Carefully adjust the LCV until the PE pressure is approximately 50% of the RLV opening
pressure and stable. This pressure may be around 5 mbarg / 2” WC / 500 Pa and will be
the "normal working pressure".
