© 2018 - Best Purging Systems Corporation
Page 8 of 14 BPS YZ102 IOM-R1.0
Customer Supplied Alarm
C
NO
NC
Typical Pressure Switch Wiring Diagram
Purge Unit Set Up
1. Ensure Protected Enclosure Power is OFF, Enclosure
Pressure Control Valve and Purge Control Valve are
closed and Protective Gas Supply is ON.
2. Test the Purge Vent, Model PV-2, for proper operation.
Using the eraser end of a pencil or similar object, insert
test object from inside the enclosure to confirm vent
relief ball is operating properly. Note: For side mounted,
Model PV-2-S, remove plug from bottom of tee fitting to
test vent relief ball operation.
3. Close and Seal Protected Enclosure.
4. Slowly turn Enclosure Pressure Control Valve CCW until
a “Safe” 0.25” w.c. reading is shown on the Enclosure
Pressure Indicator. Note: Should Enclosure Pressure
Control Valve require more than a quarter turn to obtain
a “safe” enclosure pressure, carefully check all enclosure
connections and doors for leakage. Seal as needed.
5.
Ensure a Minimum 60 psi reading on the Purge Injection
Pressure Gauge, adjust regulator if required.
6. Open the Purge Control Valve fully. The Enclosure Pressure
Gauge will go off scale to the high side, this normal.
7.
During Purge cycle, confirm minimum 60 psi reading
on Purge Injection Pressure Gauge, adjust regulator if
required.
8. Close Purge Control Valve fully. The Enclosure Pressure
Indicator should return to a “Safe” 0.25” w.c. reading.
9.
Calculate total protected enclosure volume (when empty).
Determine Purge Time required (5 minutes minimum).
Required Exchange Time/Enclosure Volume
4 Volumes
1 minute per 1.0 cf
5 Volumes
1 minute per 0.8 cf
10. Mark purge time on Unit start up instruction name tag
using a permanent marker.
11. Set up is complete. Remove any test equipment and
proceed to Optional Enclosure Pressure Switch Set up
if required.
Pressure Switch Set Up
1. The following directions are for purge models with the
suffix -W or -B which are supplied with a flame proof
differential pressure switch (DPS).
The differential pressure switch is intended solely for loss
of safe pressure alarm and should not be used to control
power to the protected enclosure.
IMPORTANT NOTE
2. Connect alarm system wiring to the DPS via rigid
conduit and seal or other approved wiring method for
the classified location.
3. The DPS provides a Form C Dry NO, NC and C contact
Note: -B switches require 120V AC or 24V DC power
to operate.
4. The alarm system should be connected in a fail safe
configuration.
Pressurization Unit Set Up
Protected Enclosures
Cross Ventilation Diagram
Required
Purge Vent
Enclosure Reference Tubing
Purge
Unit
Unit Supply Tubing
Protective
Gas Supply
Header
