N.Y.C. Admin. Code § BC 918: Section BC 918: Gas Detection Systems

918.1 Gas detection systems.

Gas detection systems, including systems designed to detect flammable, toxic, asphyxiants and other gases, required by the New York City Construction Codes or the New York City Fire Code, shall comply with Sections 918.2 through 918.10 of this code.

918.2 Design and installation.

Gas detection systems shall be designed and installed in accordance with this code, the New York City Electrical Code, and manufacturer's instructions. Such systems shall be inspected, tested and maintained in accordance with the New York City Fire Code.

918.2.1 Construction documents.

Construction documents for gas detection systems shall be submitted for review and approval to the Fire Department prior to system installation. Construction documents shall include, but not be limited to, the following:

1. Gas detection system devices and equipment.

2. Engineering evaluation.

3. Items required by Section 907.1.1, as applicable.

918.3 Equipment.

Gas detection system devices and equipment shall be designed for use with the particular gas being detected.

918.4 Reserved.

918.5 Emergency power.

Gas detection systems shall be provided with emergency power in accordance with the New York City Fire Code and Chapter 27 of this code.

918.6 Sensor locations.

Where leaking gases are expected to accumulate, sensors shall be installed in approved locations in accordance with the New York City Fire Code and NFPA 72.

918.7 Gas sampling.

Gas detection systems shall perform continuous gas sampling. Sample analysis shall be processed immediately after sampling, except as follows:

1. For HPM gases, sample analysis shall be performed at intervals not exceeding 30 minutes.

2. For toxic gases, sample analysis shall be performed at intervals not exceeding 5 minutes in accordance with the Section 6004 of the New York City Fire Code.

3. Where a less frequent or delayed sampling interval is approved by the Fire Commissioner.

918.8 System activation.

Gas detection systems shall activate and initiate an alarm system in compliance with the requirements of Sections 918.8.1 and 918.8.2.

918.8.1 Activation thresholds.

A gas detection system alarm shall be initiated when a sensor detects a concentration of gas exceeding the following thresholds unless otherwise specified in this code or the New York City Fire Code:

1. For flammable gases, a gas concentration exceeding 25 percent of the lower flammability limit (LFL).

2. For nonflammable gases, a gas concentration exceeding one-half of the immediately dangerous to life and health (IDLH) concentration.

918.8.2 Alarm signals.

The gas detection system shall initiate a local alarm and transmit a signal to a constantly attended control station when a short-term hazard condition is detected. The alarm shall be both visible and audible and shall provide warning both inside and outside the area where gas is detected. The audible alarm shall be distinct from all other alarms.

918.8.3 Shutoff of gas supply.

The gas detection system shall automatically close the shutoff valve at the source of gas supply piping and tubing related to the system being monitored for whichever gas is detected.

Exception: Automatic shutdown is not required for reactors utilized for the production of highly toxic or toxic compressed gases where such reactors comply with all of the following:

1. Operated at pressures less than 15 pounds per square inch gauge (psig) (103.4 kPa).

2. Constantly attended.

3. Provided with readily accessible emergency shutoff valves.

918.8.4 Valve closure.

The automatic closure of shutoff valves shall be in accordance with the following:

1. When the gas-detection sampling point initiating the gas detection system alarm is within a gas cabinet or exhausted enclosure, the shutoff valve in the gas cabinet or exhausted enclosure for the specific gas detected shall automatically close.

2. Where the gas-detection sampling point initiating the gas detection system alarm is within a gas room and compressed gas containers are not in gas cabinets or exhausted enclosures, the shutoff valves on all gas lines for the specific gas detected shall automatically close.

3. Where the gas-detection sampling point initiating the gas detection system alarm is within a piping distribution manifold enclosure, the shutoff valve for the compressed container of specific gas detected supplying the manifold shall automatically close.

Exception: When the gas-detection sampling point initiating the gas detection system alarm is at a use location or within a gas valve enclosure of a branch line downstream of a piping distribution manifold, the shutoff valve in the gas valve enclosure for the branch line located in the piping distribution manifold enclosure shall automatically close.

918.9 Reserved.

918.10 Fire alarm system connections.

Gas detection systems shall be connected to and monitored at the Fire Command Center or fire alarm control unit where required or provided. Where a Fire Command Center or fire alarm control unit is not required or provided, an approved gas detection system control panel or annunciator shall be installed at the building main front entrance. A gas detection system shall be monitored by a central supervising station. Gas detection supervisory and alarm signals shall be transmitted as separate and distinct signals to the central supervising station.