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MV & LV SERIES ENGINEERED DRY CHEMICAL FIRE EXTINGUISHING SYSTEM
OPERATION, DESIGN, & SERVICE MANUAL
REV C
Document # DOC324
Issued: April 26, 2018
Revised: March 22, 2022
UL FILE # EX27541
Section 4 System Installation
4.1.3 Installing Nozzles
Nozzle type is determined based upon the hazard being protected and flow calculations made by the Janus Design
Suite software during the system design. All dry chemical nozzles are male NPT thread (except the TFP nozzle,
which is female NPT) and must be installed as designed according to the guidelines covered under section 3.
Due to the thrust generated from a nozzle, a rigid hanger or support must be located within 12 in (305 mm) of the
nozzle to prevent pipe movement and/or nozzle rotation during discharge.
4.1.4 Installing Cylinder Assembly
Position the cylinder assembly against the back channel so that the pressure gauge faces out.
Secure the mounting strap into the back channel with the bracket held horizontally. Fasten the strap with the
supplied 3/8"-16 1-1/4" cap screw and 3/8" twirl nut.
4.1.4.1 Installing Pressure Gauge Assembly
Prior to installing the pressure gauge assembly, both the o-ring on the assembly connection and the inside of the
pressure gauge connection on the cylinder valve must be lightly lubricated with Molykote 55 by Dow Corning
(P/N 19056) or equivalent. Teflon tape shall not be used.
Install the pressure gauge assembly into the pressure gauge connection and tighten the swivel nut until it mates
with the valve face. When the swivel nut is almost tight, the pressure gauge assembly will upset the Schrader valve.
e O-ring on the pressure gauge assembly immediately seals to prevent loss of dry chemical.
Once the pressure gauge assembly is connected, it should be used to check the pressure inside the cylinder. A
pressure drop of more than 10% indicates the cylinder assembly must be recharged or replaced. Pressure should
be 500 psig (34.48 bar) at 70°F (21°C). Refer to Table 6.2.1.1 in Appendix B for normal pressures at other
temperatures.
Any time the pressure gauge assembly is removed from the cylinder valve, the assembly o-ring must be replaced
with a new o-ring (P/N 98791 - Pack of 25). Prior to re-installing the pressure gauge assembly, both the new
o-ring and the inside of the pressure gauge connection on the cylinder valve must be lightly lubricated with
Molykote 55 by Dow Corning (P/N 19056) or equivalent.
4.1.4.2 Installing Low-Pressure Supervisory Switch Assembly
Prior to installing the low-pressure supervisory switch assembly, both the o-ring on the assembly connection and
the inside of the switch connection on the cylinder valve must be lightly lubricated with Molykote 55 by Dow
Corning (P/N 19056) or equivalent. Teflon tape shall not be used.
Install the low-pressure supervisory switch assembly into the low-pressure supervisory connection and tighten
the swivel nut until it mates with the valve face. When the swivel nut is almost tight, the low-pressure supervisory
switch assembly will upset the Schrader valve. e O-ring on the low-pressure supervisory switch assembly
immediately seals to prevent loss of dry chemical.
Any time the low-pressure supervisory switch assembly is removed from the cylinder valve, the assembly o-ring
must be replaced with a new o-ring (P/N 98791 - Pack of 25). Prior to re-installing the low-pressure supervisory
switch assembly, both the new o-ring and the inside of the switch connection on the cylinder valve must be lightly
lubricated with Molykote 55 by Dow Corning (P/N 19056) or equivalent.
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