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7500 Series Manual
Operation Mode
After the purge timer counts down, SV shuts off and K1 is energized.
If enclosure pressure drops below P3, the SV is energized and will stay energized for the value of HYST
(%, leakage compensation). If HYST is set to 0, leakage compensation is turned off. However, Program 4
is usually used when a continuous purging through the enclosure is required during operation mode.
If enclosure pressure drops below P1, K1 remains on and an alarm will sound. K2 can be set to P- or
Alarm to indicate below safe or operating pressure.
If enclosure pressure goes above P4, K1 remains. If K2 is setup as Alarm, K2 will energize.
6.5.5 Program 5
Program 5 is used in combustible dust atmospheres.
Pre-Purge
The purge valve (SV) does not come on during this operation. In a dust atmosphere, purging is not
required. Instead, the enclosure must be cleaned of all combustible dust and then pressurized.
The menu screen will show "CLEAN ENCLOSURE." The enclosure should be cleaned and then
pressurized before pressing the SET button.
The enclosure pressure has to be above P1 (minimum 0.65 in wc / 1.6 mbar for dust atmospheres) for
the SET button to work.
Operation Mode
After cleaning out and pressurizing the enclosure, the menu shows "CLEAN ENCLOSURE." To see the
enclosure pressure, press the Down or Up button. Pressing the SET button will energize K1.
If enclosure pressure drops below P2, the SV is energized and will stay energized for the value of HYST
(%, leakage compensation). If HYST is set to 0, leakage compensation is turned off. Compensation for
leakages is allowed in a dust atmosphere because the enclosure is safe at this point.
If enclosure pressure drops below P1, K1 remains on and an alarm will sound. K2 can be set to P- or
Alarm to indicate below safe or operating pressure.
If enclosure pressure goes above P4, K1 remains. If K2 is setup as Alarm, then K2 will energize.
Warning!
If enclosure pressure is below P1 when K1 is used to provide power to the enclosure during operation, K1
will remain energized. An alarm is required and must be located such that an operator will be notified of the
alarm.
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