November 17, 2025 at 5:26 pm

NFPA 99 – Chapter 15 Warning Systems

I am looking for clarification on how this group interprets this code Reference:

15.4.2.10 Warning Systems (Oxygen and Nitrous Oxide).
Category 2 warning systems shall comply with 5.2.9, except as follows:

(1) Warning systems shall be permitted to be a single alarm panel.(2) The alarm panel shall be located in an area of continuous surveillance while the facility is in operation.(3) Pressure and vacuum switches/sensors shall be mounted at the source equipment with a pressure indicator at the master alarm panel.
I have interpreted this to mean that the single master alarm panel requires a sensor at the source equipment with its signal displaying the system pressure at the master alarm panel, and this sensor would alarm high and low at the master alarm panel.

I have a gas equipment supplier that believes this to mean that a switch can be located at the main line near the source equipment, and a sensor installed downstream of the emergency shutoff valve that displays system pressure on the combination master/area alarm panel also meets this requirement.

Let me know how you all interpret this code reference.

Johnny Ma
January 12, 2026 at 5:28 am

I think it depends on how source equipment supply, According to 15.4.2.6.2 Where a central medical gas supply system supplies two treatment facilities, each facility shall be provided with an emergency shutoff valve located in that treatment facility so as to be accessible from all use-point locations in an emergency. which means if the gas equipment supplies two treatment, the switches/sensors cannot be installed at downstream of emergency shutoff valve, otherwise, The alarm wouldn’t indicate operation condition of source.

NFPA 99 – Chapter 15 Warning Systems

Johnny Ma

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