17
17
set-up procedure
CLASS I VOLUME EXCHANGE TIME CHART
MEASURED FLOW
REqUIRED EXCHANGE TIME
0.10 SCFM / 6 SCFH
40 Minutes per Cubic Foot
0.25 SCFM / 15 SCFH
16 Minutes per Cubic Foot
0.50 SCFM / 30 SCFH
8 Minutes per Cubic Foot
0.75 SCFM / 45 SCFH
5.5 Minutes per Cubic Foot
1 SCFM / 60 SCFH
4 Minutes per Cubic Foot
2 SCFM / 120 SCFH
2 Minutes per Cubic Foot
3 SCFM / 180 SCFH
1.5 Minutes per Cubic Foot
4 SCFM / 240 SCFH or greater 1 Minute per Cubic Foot
notE:
The volume exchange time chart is based on a
four (4) enclosure volume exchange. Multiply the required
exchange time above by 2.5 for applications requiring a
ten (10) volume exchange (motors).
Regardless of enclosure volume or system flow rate, it is
required that operators withhold power to the enclosure
while inducing Class I exchange, for at least five (5) minutes.
Normal exchange time calculations should be doubled if
large obstructions block inert gas flow.
The Start-Up Instruction Nameplate Exchange Time Slot
will be blank, but the unit may feature a set of direct factor
nameplates with self-adhesive backing such as “TEN
MINUTES”, for application to the start-up instructions,
dependent on how the system was specified and purchased.
Field modification of this nameplate, to show a direct factor,
is acceptable as noted above if the method used to mark the
nameplate does not deface the instructions listed. Materials
used for the marking must be indelible and withstand
prevailing environmental conditions.
notE:
If pressure setting is difficult to stabilize or set,
(see page 20, “Troubleshooting Procedures”).
5. Install and tighten all bolts on the pressure loss alarm
switch (if utilized). Ensure the conduit is sealed with
approved compounds. Energize power to Switch and
alarm system (if utilized) and test the function of the
alarm system.
Class II pressurization set-up
Class I purging set-up
HElpFUl HInts
the term “safe” pressure for purposes of this manual
is defined as follows;
Class I = a minimum .25 inch of water column pressure.
Class II = a minimum 1.0 inch of water column pressure.
Regulator may be in the locked position upon arrival.
to adjust regulator, pull handle to outward position.
1. Close the Enclosure Pressure Control Regulator fully by
turning counterclockwise (CCW).
2. Temporarily connect the inert gas supply to a 0 to 250
SCFH flowmeter. Connect the outlet of the flowmeter
to the Enclosure Pressure Control Regulator.
3. Check operation of Enclosure Protection Vent (if utilized).
4. Seal enclosure(s) and adjust Enclosure Pressure Control
Regulator by opening slowly clockwise (CW) to set a
“Safe” pressure on the Enclosure Pressure Indicator.
notE:
If pressure setting is difficult to stabilize or set,
(see page 20, “Troubleshooting Procedures”).
5. When safe enclosure pressure is stabilized, measure
flow of inert gas supply through Protection System, to
calculate required exchange time, based on the Class I
exchange time chart.
6. Install and tighten all bolts on the pressure loss alarm
switch (if utilized). Ensure the conduit is sealed with
approved compounds. Energize power to Switch and
alarm system (if utilized) and test the function of the
alarm system.
7. Cease testing and remove test equipment
(Flowmeter).
8. Connect the inert gas supply directly to the Enclosure
Pressure Control Regulator.
IMpoRtant notE
operators must secure wrist or stop watch to manually
time Exchange Cycle for Class I applications.
1. Close the Enclosure Pressure Control Regulator fully,
by turning it counterclockwise (CCW).
2. Remove all traces of combustible dust from the protected
enclosure.
3. Check operation of Enclosure Protection Vent (if utilized).
4. Seal enclosure(s) and adjust Enclosure Pressure Control
Regulator by opening slowly clockwise (CW) to set a
“Safe” pressure on the Enclosure Pressure Indicator.
to test the vent’s operation, gently prod the vent flapper
open with a soft pointed object, ( example: eraser end
of a pencil) ensuring that the vent valve works freely. on
vertically configured vents, this can be accomplished
from within the protected enclosure. side mounted
-90 configured vents can be tested by removing the
conduit plug at the bottom of the mounting tee. Multiple
operations require only one test per day if enclosure
is not opened or left unattended.
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