Technical data
30.
2.3.3 Compressed Nitrogen
Cylinders of compressed nitrogen can provide a clean, dependable, and most importantly, dry source of
pneumatic pressure in special systems. High pressure nitrogen cylinders can typically be rented from a local
source, with rental fees varying by supplier and bottle size. By replacing oxygen in the system piping with
nitrogen, the chemical process that results in corrosion is severely mitigated, thereby extending the life-span
of steel piping. Nitrogen is also effective in preventing the formation of ice on the inside of piping for freezer
systems. The Reliable Model A-2 Pressure Maintenance Device (2.4.1.), the NS-Pak (2.4.3.), and the Nitrogen
Regulating Device (2.4.4.) serve to regulate and supervise compressed nitrogen pneumatic supplies.
2.3.4 Nitrogen Generator
Pipe corrosion is a common problem within dry and preaction fire protec-
tion systems when supervised by traditional compressed air. Nitrogen
Generation Systems can be used to provide corrosion inhibiting super-
visory pressure to the system to mitigate problematic sprinkler pipe cor-
rosion. Reliable offers these systems in partnership with South-Tek Sys-
tems, Wilmington NC.
South-Tek Systems designs and manufactures the N2-Blast® - Corro-
sion Inhibiting System specifically for dry and preaction fire protection
systems. The N2-Blast produces 98%+ pure Nitrogen and introduces it
to the dry or preaction system. In doing so, oxygen and moisture are
displaced from the piping. The N2-Blast effectively inhibits electrochemi-
cal, galvanic and Microbiologically Influenced Corrosion (MIC), as well as
freeze-ups and ice plugs.
The N-2 Blast generator incorporates a nitrogen storage tank, and the Re-
liable Model A-2 Pressure Maintenance Device (2.4.1) serves to regulate
and supervise the compressed nitrogen pneumatic supply.
2.4 Pressure Maintenance Equipment
Automatic pressure maintenance devices are used to maintain the correct operating pressure in dry and
preaction* systems, and in dry pilot lines used for releasing special systems. The devices described below
eliminate the need for manual refilling of a system to overcome small leaks or variable pressures due to tem-
perature changes.
*Single interlock preaction systems with 20 or less sprinklers are not required to be supervised with pneumatic
pressure.
2.4.1 Model A-2 Pressure Maintenance Device
The Reliable Model A-2 Device is designed for use where a clean and dependable source of com-
pressed gas is available, such as an owners plant air supply, a tank mounted air compressor with
a pressure control switch, or cylinders of compressed nitrogen gas. The regulator in the Model A-2
Device will reduce the pressure from an acceptable gas source (175 psi/12 bar maximum) to the pres-
sure required for the system. The Model A-2 Device will maintain a constant pressure in the system,
regardless of fluctuations in the supply source being used. The A-2 has a built in strainer that prevents
foreign matter from entering the regulator and check valve which may interfere with their normal op-
eration. Shut-off valves permit servicing of the strainer and regulator without impairing the sprinkler
system, and a bypass valve permits rapid restoration of the required system pressure after service or
operation. The bypass valve must be closed and shut-off valves open for proper automatic operation.
Approvals and technical data for the Model A-2 Pressure Maintenance Devices can be found on Reli-
able Automatic Sprinkler Company Bulletin 254.
Figure 29 Figure 30
Figure 31
Figure 32