MIL-DTL-24416C(SH)
2.4 Order of precedence. In the event of a conflict between the text of this document and the references cited
herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws
and regulations unless a specific exemption has been obtained.
3. REQUIREMENTS
3.1 First article test. When specified (see 6.2.b), a sample shall be subjected to first article inspection in
accordance with 4.2.
3.2 Material. The material for wet chemical systems and all associated components shall comply with
standards UL 300, NFPA 17A, and NFPA 96. When a definite material is not designated, the contractor shall select
the best material commercially available that meets the requirements specified herein.
3.2.1 Quality. The material shall be uniform in quality and free from defects that affect performance,
serviceability, or appearance, such as lumps, kinks, splits, abrasions, scrapes, corroded surfaces, and impurities.
3.2.2 Combustion and corrosion resistance. Unless otherwise specified, material shall be inherently non-
combustible and corrosion resistant or treated to provide protection against heat and corrosion.
3.2.3 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally
preferable materials should be used to the maximum extent possible, provided that the material meets or exceeds the
operational and maintenance requirements, and promotes economically advantageous life cycle costs.
3.3 Environmental considerations.
3.3.1. Operational temperatures. Operating devices shall be designed to function properly through a minimum
temperature range from 32 °F to 120 °F (0 °C to 49 °C) or the temperature range specified in the manufacturer's
listed installation manual and maintenance manual if the manufacturer's range is greater.
3.3.2 Corrosion. Exposed parts of system installed in the area protected by the extinguishing agent spray shall
be constructed of corrosion resistant material.
3.3.3 Shock. The wet chemical system and all associated components shall meet the Grade B shock acceptance
requirements of MIL-S-901 when subjected to the test of 4.5.2.
3.3.4 Vibration. The wet chemical system and all associated components shall meet the Type I vibration
requirements of MIL-STD-167-1 when subjected to the test of 4.5.3. In addition to the acceptance criteria in MIL-
STD-167-1, the pressure switches shall perform as specified in 3.4.6, and the pressure gauges shall be accurate
within 4 percent of the true pressure over the central half of the scale range and within 6 percent of the true pressure
over the rest of the scale range.
3.4 Design and construction. Wet chemical systems and all associated components shall be listed under
UL 300, and shall meet the requirements of NFPA 17A, NFPA 96, and manufacturer's pre-engineered wet chemical
system installation and maintenance manuals. The components of the wet chemical extinguishing system include
extinguishing agent, extinguishing agent cylinder, expellant gas cylinder (when applicable), cylinder discharge
valves, discharge nozzles, remote manual actuation devices, pressure switches, pressure gauges, distribution piping,
cable, conduit, pulleys, mounting hardware, fusible links, cylinder actuating mechanism, and an interface for fryer
automatic shut-off device. Unless otherwise specified (see 6.2.c), the supplier shall provide the dimensional
requirements for system installation and operation required for the wet chemical system to perform its function.
Wet chemical system and all associated components shall be accessible for inspection, maintenance, and recharge.
The wet chemical system shall be outfitted with a visual indicator that provides operational status of the wet
chemical system (i.e., "ready" or "requires recharging"). Systems and components supplied under this specification
shall be listed under UL 300 by the manufacturer for use with APC in the concentration of 42.4 percent K2CO3 and
52.8 percent H2O using the criteria specified in the procurement (see 6.2.d).
3.4.1 Extinguishing agent. The wet chemical system shall use APC for the extinguishing agent.
3.4.2 Extinguishing agent cylinder. Extinguishing agent cylinders shall have the ability to be refilled with
extinguishing agent.
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