Perma Pure Mini-GASS 2812T - Manual (Page 33)

APPENDIX F
Z-Purge operation
System Description -
The Z-Purge option for the MG-2812T Gas Sampling System is based on an industry
standard Bebco model 1001A Z-purge panel. It is intended to allow the general purpose
enclosure of the MG-2812T to be used in Class I, Division 2 hazardous areas. While the
Z-Purge system is not complicated, there are a few components that need to be
understood to ensure proper and safe operation. Located on the front panel of the
sampling system is a red alarm indicator light. When lit, it indicates that the pressure in the
enclosure has dropped to an unacceptable level and power should be disconnected from
the system. The indicator light is controlled by a differential pressure switch that senses
the pressure difference between the inside and outside of the enclosure. The switch is
factory adjusted to turn the alarm light on and internally disconnect power from the
sampling system when the pressure indicated on the Z-purge gage falls below the “Safe”
range. Located on the front panel of the Z-Purge enclosure are the two main components
of the system; the adjustable pressure regulator that controls purge gas flow to the
sampling system enclosure, and the pressure gage that indicates when the pressure in
the sampling system enclosure is in an acceptable or “Safe” range. Two connections
between the Z-Purge and sampling system enclosures are required to 1) allow purge air
flow to the sampling system enclosure and 2) communicate the sampling system
enclosure pressure level back to the Z-Purge gage. The second connection also allows
the purge air flow to be vented through a metering orifice to the atmosphere.
System Setup-
1. Connect a 10-125 psig compressed air source to the 1/4” NPT port on the right side of
the Z-Purge enclosure.
2. Connect the two lines from the Z-purge enclosure to the sampling system enclosure.
3. Make all appropriate plumbing connections to the sampling system enclosure.
4. If it is necessary to adjust or check the temperature controller setting, a Z-Purge over-
ride switch is provided. This switch is located beneath the sampling system control
panel. When placed in the “Setup” (ON) position, power is supplied to the sampling
system control circuit regardless of the state of the Z-Purge pressure switch. Once
setup of the sampling system has been completed, this switch must be returned to the
“Z-Purge enable” (OFF) position for proper operation of the Z-Purge system.
It is very important that the heated line inlet connection is pressure tight. If this
connection is not sealed, the Z-Purge system will not operate properly.
The system is calibrated to use connection tubes of this length and diameter.
They should not be substituted with other length or diameter tubes.