We often get asked: Do I need to install a gas detector in the room?
Well, it’s pretty easy in my state, as in most cases we have dealt with, the state fire/HAZMAT code required it. The code includes basic requirements for ALL gas detection systems and covers:
- construction documents,
- equipment,
- power connections, emergency and standby power,
- sensor locations, gas sampling,
- system activation,
- signage,
- fire alarm system connections,
- maintenance, testing, and sensor calibration
For example, meat production facilities use Nitrogen or CO2 in their packaging system to ensure the packaging is void of Oxygen. This should be a red flag for safety: we are using an inert gas to ensure the inside of the packaging is free of Oxygen (e.g., it prevents the meat from losing its original color). What happens if this inert gas leaks into the work area? Can it also deplete the oxygen in the atmosphere they are breathing?
Simply stated, YES, it can, and when it happens, NO ONE will be the wiser that it is happening until it is too late.
Unfortunately, OSHA has not kept up with the times and does NOT have a standard for this type of hazard. So I go to my trusty state codes, which are almost always some adaptation of the International Fire, Mechanical, and Building code(s).
In Chapter 53 of the IFC, we find the requirements for this type of asphyxiation hazard:
5307.2.1 Gas detection system. In rooms or areas not provided with ventilation in accordance with Section 5307.2, a gas detection system complying with Section 916 or, where approved, an oxygen depletion alarm system, either of which initiates audible and visible alarm signals in the room or area where sensors are installed, shall be provided. |
For those wondering if this code would apply to the use of N2 or CO2 in the manner I described above, here is the application of the Chapter 53, section 5307:
| SECTION 5307 – COMPRESSED GASES NOT OTHERWISE REGULATED 5307.1 General. Compressed gases in storage or use NOT regulated by the material-specific provisions of Chapters 6, 54, 55, and 60 through 67, including asphyxiant, irritant, and radioactive gases, shall comply with this section in addition to other requirements of this chapter. |
Here are the specifics for our Gas Detection and Oxygen Depletion Alarm Systems…
NOTE: Most states have FREE access to their state codes, but you can also get FREE access to the full 2021 IFC here
| 916.1 Gas detection systems Gas detection systems required by this code shall comply with Sections 916.2 through 916.11. |
These critical safety requirements apply to ALL gas detection systems, including those installed in minor operations and extensive industrial facilities.
| 916.2.1 Construction documents Documentation of the gas detection system design and equipment to be used that demonstrates compliance with the requirements of this code shall be provided with the application for the permit. |
The permit application must include the
- design drawings and
- equipment data sheets
in order to document that the gas detection system conforms to the code requirements.
| 916.3 Equipment Gas detection system equipment shall be designed for use with the gases being detected and shall be installed in accordance with the manufacturer’s instructions. |
The equipment used in the gas detection or oxygen depletion system is specific to the type of gas being used and detected.
The system installation is to conform to the manufacturer’s specific equipment instructions so that it will operate as required.
| 916.4 Power connections Gas detection systems shall be permanently connected to the building electrical power supply or shall be permitted to be cord connected to an unswitched receptacle using an approved restraining means that secures the plug to the receptacle. |
The electric power supply for the gas detection system is to be installed permanently so that it can operate continuously as required.
As an alternative, subject to the approval of the AHJ, the power supply can be connected to an outlet that does NOT have a separate ON-OFF switch on the condition that it has an acceptable fixed restraint.
| 916.5 Emergency and standby power Standby or emergency power shall be provided or the gas detection system shall initiate a trouble signal at an approved location if the power supply is interrupted. |
The gas detection system is to have a standby or emergency electric power supply.
However, if it is not provided and the normal power supply is interrupted, the system must transmit a trouble signal to an approved location.
This implies that ACTION is necessary should the detection system lose power.
Remove the hazard from the area or remove the humans from the area.
| 916.6 Sensor locations Sensors shall be installed in approved locations where leaking gases are expected to accumulate. |
Each individual gas detection sensor is to be located where leaks are anticipated to occur.
The locations are to be acceptable to the AHJ.
| 916.7 Gas sampling Gas sampling shall be performed continuously. Sample analysis shall be processed immediately after sampling, except as follows: For HPM gases, sample analysis shall be performed at intervals not exceeding 30 minutes. For toxic gases that are not HPM, sample analysis shall be performed at intervals not exceeding 5 minutes, in accordance with Section 6004.2.2.7. Where a less frequent or delayed sampling interval is approved. |
The required performance of the gas detection system sampling is that it is to be constant and without delay.
However, this section provides three (3) situations where the gas sampling is allowed to be less than continuous.
| 916.8 System Activation A gas detection alarm shall be initiated where any sensor detects a concentration of gas exceeding the following thresholds: For flammable gases, a gas concentration exceeding 25 percent of the lower flammability limit (LFL). For non-flammable gases, a gas concentration exceeding one-half of the IDLH, unless a different threshold is specified by the section of this code requiring a gas detection system. Upon activation of a gas detection alarm, alarm signals or other required responses shall be as specified by the section of this code requiring a gas detection system. Audible and visible alarm signals associated with a gas detection alarm shall be distinct from fire alarm and carbon monoxide alarm signals. |
The required local alarm is intended to alert occupants to a hazardous condition in the vicinity of the inside storage room or area.
The alarm is NOT intended to be an evacuation alarm but MUST BE MONITORED to hasten emergency personnel response.
| 916.9 Signage Signs shall be provided adjacent to gas detection system alarm signaling devices that advise occupants of the nature of the signals and actions to take in response to the signal. |
This section requires informational signs to communicate
- the type of alarm and
- what action is to be taken upon activation
| 916.10 Fire alarm system connections Gas sensors and gas detection systems shall not be connected to fire alarm systems unless approved and connected in accordance with the fire alarm equipment manufacturer’s instructions. |
This section requires that where gas sensors and gas detection systems are approved to be connected to a fire alarm system, they are only to be connected in conformance to the equipment manufacturer’s written instructions.
This ensures that the fire alarm system will operate as required in response to the independent operation of the gas detection system.
| 916.11 Inspection, testing, and sensor calibration Inspection and testing of gas detection systems shall be conducted not less than annually. Sensor calibration shall be confirmed at the time of sensor installation and calibration shall be performed at the frequency specified by the sensor manufacturer. |
This section provides the maximum allowable inspection and testing frequency. The annual test and inspection requirement confirms that the system is operating properly and will function as designed. All system components are to be verified at the time of the inspection, with the exception of the sensor calibration. The required frequency of the calibration of the sensors is to be in accordance with the manufacturer’s instructions.
And let’s not forget the pipe, hose, and tubing labeling requirements for these inert gases…
| 5303.4.3 Piping systems Piping systems shall be marked in accordance with ASME A13.1. Markings used for piping systems shall consist of the content’s name and include a direction-of-flow arrow. Markings shall be provided at each valve; at wall, floor, or ceiling penetrations; at each change of direction; and at NOT LESS THAN every 20 feet (6096 mm) or fraction thereof throughout the piping run. Exceptions: 1. Piping that is designed or intended to carry more than one gas at various times shall have appropriate signs or markings posted at the manifold, along the piping and at each point of use to provide clear identification and warning. 2. Piping within gas manufacturing plants, gas processing plants, refineries and similar occupancies shall be marked in an approved manner. |
Related Articles: