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7500 Series Manual
6.7 Minimum Enclosure Pressure “P1”
In accordance with the applicable standards and tolerances on the 7500 pressure sensor, the minimum
operating pressures are as follows:
Gas environments: 0.25 in wc (0.63 mbar)
Dust environments: 0.65 in wc (1.63 mbar)
When enclosure pressure drops below P1 during operation mode, the power has to be interrupted. If not, an
alarm has to be generated to address the problem.
6.8 Alarm Pressure “P2”
If enclosure pressure drops below P2 during operation mode, the solenoid valve will energize until pressure
goes above P2+HYST. Therefore, leakage compensation has to be implemented.
If leakage compensation is not used, the P2 can sound an alarm to indicate that pressure is dropping.
P2 can be adjusted to above P1 and Below P3 values.
6.9 Purging Pressure “P3”
The purging timer starts when enclosure pressure is above P3. If the pressure is above P3, purging will start
and finish uninterrupted. If the enclosure pressure is below P3, the purging timer will not start. If the pressure
drops below P3 during purging, the purging timer will immediately reset to its beginning time and will not start
timing down until pressure is above P3. P3 can be adjusted to above P2 and below P4 values.
6.10 Maximum Internal Pressure “P4”
If enclosure pressure is above P4, the display will read ‘MAX’ to indicate that maximum pressure has been
achieved. Regardless of the action of the solenoid valve (purging, leakage compensation), the solenoid valve
will de-energize and will not come on until enclosure pressure goes below P4. This action may cause the
solenoid valve to oscillate on and off. If this happens, it should be noted as a maximum pressure problem.
If K1 was on before P4 was reached, it will remain on after enclosure pressure is above P4. P4 is adjusted
above P3. Maximum setting is 9.99 in wc (24.86 mbar).
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