16
SNA-Series Tankless Heater
Installation
10/17/2014
Keltech •
215-1815 Rev. B; ECN 130011
IS Installation continued…
All quarter turn latches in the door of the PE must be fully latched for proper operation . Power to the PE must be
turned off before opening the enclosure .
WARNING! This Pressurized Enclosure shall not be opened unless the area is known to be free of
flammable materials or unless all devices within have been de-energized.
Power shall not be restored after the enclosure has been opened until the enclosure has been purged for allotted
time (See Tables 5 & 6) . Time begins when pressure indicator turns green after the door of the enclosure has been
closed and fully latched .
WARNING! Ignition of potentially explosive gas/air mixtures may result if power is turned on before the
allotted purge time!
Expo Technologies CF systems have a Minimum Pressure Sensor set to a pressure of at lease 0 .1" WC ( .25bars) . When
the PE pressure is above this set point the sensor produces a positive Pressurized signal . This is displayed on the Red/
Green indicator located on the Purge System . This signal can be used to operate an electrical contact for a remote Alarm .
This signal may be supplied to the pressure operated switch suitable for Intrinsically Safe circuit in accordance (See Figure
6) . When the enclosure pressure falls below the set point of the sensor, the Pressurized signal is removed, and the Alarm
conditions occurs . This Alarm must be located where it can be readily observed according to NFPA496 requirements .
No
valves may be fitted between the Expo Technologies system and the alarm switch.
WARNING! Never turn on the power without purging first, unless you have proved the interior of the PE is gas
free and checked that the “Pressurized” indicator is green!
Commissioning Test
Commissioning Leakage Compensation (LC) and Continuous Flow/High Purge Keltech Options EXP2LC
and EXP2 Systems:
1 . Open the air or gas supply shutoff valve .
2 . Adjust the Flow Control Valve (FCV) so that the enclosure pressure rises to the point where the "Pressurized"
indicator turns green .
3 . Lower the PE pressure until the Pressurized indicator turns Red .
4 . Open the FCV again and set the PE pressure to a level somewhere between the Minimum Pressure
Sensorset point and the RLV opening pressures . This working pressure is not critical . Enough pressure to keep
the“Pressurized” indicator Green is sufficient .
5 . On EXP2 and EXP2LC Purge Systems the timing function if performed by the user . The user must ensure that
the time delay between the indicator turning Yellow and the application of power to the PE is not less than the
minimum time required to purge the PE as shown in the Tables 5 & 6 .
Normal Operation:
Turn the air supply valve ON to start or OFF to stop the system . The user must close the Power
Switch only after the enclosure has been pressurized and purged sufficiently to ensure that the interior of the enclosure
is gas free . It is the operator’s responsibility to shut off the power as soon as possible after a pressure failure .
PURGE TIME CHART - EXP2 Option
for use with EXPO Mini Z Purge 1ZCF/bp/IS
Model/Enclosure
Group Size
Cubic
Feet
Volume
Exchanges
X 4
Orifice
Size
Orifice
No .
Purge
Time
(Minutes)
SNA-36-54
10
40
0 .9
#2
44
SNA-63
12 .5
50
0 .9
#2
55
SNA-72-108
10
40
0 .9
#2
44
SNA-126-144
12 .5
50
0 .9
#2
55
PURGE TIME CHART - EXP2LC Option
for use with EXPO Mini Z Purge 1ZLC/bp/IS
Model/Enclosure
Group Size
Cubic
Feet
Volume
Exchanges
X 4
Purge
Time
Minutes
SNA-36-54
10
40
6
SNA-63
12 .5
50
6
SNA-72-108
10
40
6
SNA-126-144
12 .5
50
6
TABLE 5
TABLE 6
