Section FC 6004: Highly Toxic and Toxic Compressed Gases
6004.1 General.
The storage, handling and use of highly toxic and toxic compressed gases shall comply with the requirements of this section.
6004.1.1 Prohibited indoor storage, handling and use by occupancy.
It shall be unlawful to store, handle or use highly toxic and toxic compressed gases in:
1. Group A, E, I, R or U occupancies.
2. Group B office occupancies, F, M or S occupancies, or any other areas of such occupancies that are accessible to the public.
6004.1.2 Gas cabinets.
Gas cabinets containing highly toxic or toxic compressed gases shall comply with the requirements of FC 5003.8.6 and shall be ventilated in accordance with the Mechanical Code.
6004.1.2.1 Capacity limits.
The maximum number of containers located in a single gas cabinet shall not exceed three, except that cabinets containing containers not over 1 pound (0.454 kg) net contents are allowed to contain up to 100 containers.
6004.1.2.2 Fire protection.
Gas cabinets required by FC 6004.2 or 6004.3 shall be protected by a sprinkler system. Alternative fire extinguishing systems shall not be used in lieu of a sprinkler system.
6004.1.3 Exhausted enclosures.
Exhausted enclosures containing highly toxic or toxic compressed gases shall be ventilated in accordance with the Mechanical Code.
6004.1.3.1 Fire protection.
Exhausted enclosures required by FC 6004.2 or 6004.3 shall be protected by a sprinkler system. Alternative fire extinguishing systems shall not be used in lieu of a sprinkler system.
6004.2 Indoor storage, handling and use.
The indoor storage, handling and use of highly toxic or toxic compressed gases shall be in accordance with FC 6004.2.1 through 6004.2.2.10.3.
6004.2.1 Applicability.
The applicability of regulations governing the indoor storage, handling and use of highly toxic and toxic compressed gases shall be as set forth in FC 6004.2.1.1 through 6004.2.1.3.
6004.2.1.1 Quantities not exceeding the maximum allowable quantity per control area.
The indoor storage, handling or use of highly toxic and toxic gases in amounts not exceeding the maximum allowable quantity per control area set forth in FC Table 5003.1.1(2) shall be in accordance with FC 5001, 5003, 6001 and 6004.1.
6004.2.1.2 Quantities exceeding the maximum allowable quantity per control area.
The indoor storage, handling or use of highly toxic and toxic gases in amounts exceeding the maximum allowable quantity per control area set forth in FC Table 5003.1.1(2) shall be in accordance with FC 6001, 6004.1, 6004.2 and FC Chapter 50.
6004.2.1.3 Ozone gas generators.
The indoor use of ozone gas-generating equipment shall be in accordance with FC 6005.
6004.2.2 General indoor requirements.
The general requirements applicable to the indoor storage, handling and use of highly toxic and toxic compressed gases shall be in accordance with FC 6004.2.2.1 through 6004.2.2.10.3.
6004.2.2.1 Container location.
Portable containers shall be located within gas cabinets, exhausted enclosures or gas rooms. All other containers shall be located within gas rooms or exhausted enclosures.
6004.2.2.2 Ventilated areas.
The room or other area in which gas cabinets or exhausted enclosures are located shall be provided with exhaust ventilation. Gas cabinets or exhausted enclosures shall not be used as the sole means of exhaust for any room or area.
6004.2.2.3 Leaking containers.
One or more gas cabinets or exhausted enclosures shall be available on the premises to capture the gas from the containers until such time as the leaking container can be removed from the premises and disposed of lawfully.
Exceptions:
1. Where containers are located within gas cabinets or exhausted enclosures.
2. Where approved containment vessels or containment systems are provided in accordance with the following requirements:
2.1. Containment vessels or containment systems shall be capable of fully containing or terminating a release.
2.2. Trained personnel shall be available at an approved location.
2.3. Containment vessels or containment systems shall be capable of being transported to the leaking container.
6004.2.2.3.1 Location.
Gas cabinets and exhausted enclosures shall be located in gas rooms and connected to an exhaust system.
6004.2.2.4 Local exhaust for portable containers.
A means of local exhaust shall be provided to capture leaks from portable containers. The local exhaust shall consist of portable ducts or collection systems designed to be applied to the site of a leak in a valve or fitting on the container. The local exhaust system shall be located in a gas room. Exhaust shall be directed to a treatment system in accordance with FC 6004.2.2.7.
6004.2.2.5 Piping and controls – stationary containers.
In addition to the requirements of FC 5003.2.2, piping and controls on stationary containers shall comply with the following requirements:
1. Pressure relief devices shall be vented to a treatment system designed in accordance with FC 6004.2.2.7.
Exception: Pressure relief devices on outdoor containers provided exclusively for relieving pressure due to fire exposure are not required to be vented to a treatment system provided that:
1. The material in the container is not flammable.
2. The container is not located in a diked area with other containers containing combustible materials.
3. The container is located not less than 30 feet (9144 mm) from combustible materials or structures or is shielded by a fire barrier complying with the requirements of FC 6004.3.2.1.1.
2. Filling or dispensing connections shall be provided with a means of local exhaust. Such exhaust shall be designed to capture fumes and vapors. The exhaust shall be directed to a treatment system in accordance with FC 6004.2.2.7.
3. Stationary containers shall be provided with a means of excess flow control on all container inlet or outlet connections.
Exceptions:
1. Inlet connections designed to prevent backflow.
2. Pressure relief devices.
6004.2.2.6 Gas rooms.
Gas rooms shall comply with the requirements of FC 2703.8.4 and both of the following requirements:
1. The exhaust ventilation from gas rooms shall be directed to an exhaust system.
2. Gas rooms shall be protected throughout by a sprinkler system. Alternative fire extinguishing systems shall not be used in lieu of a sprinkler system.
6004.2.2.7 Treatment systems.
The exhaust ventilation from gas cabinets, exhausted enclosures and gas rooms, and local exhaust systems required by FC 6004.2.2.4 and 6004.2.2.5 shall be directed to a treatment system. The treatment system shall be utilized to handle the accidental release of gas and to process exhaust ventilation. The treatment system shall be designed in accordance with FC 6004.2.2.7.1 through 6004.2.2.7.5 and Chapter 5 of the Mechanical Code.
Exceptions:
1. Highly toxic and toxic gases – storage. A treatment system is not required for containers in storage when the following controls are provided:
1.1. Valve outlets are equipped with gas-tight outlet plugs or caps.
1.2. Handwheel-operated valves have handles secured to prevent movement.
1.3. Approved containment vessels or containment systems are provided in accordance with FC 6004.2.2.3.
2. Toxic gases – use. Treatment systems are not required for toxic gases supplied by portable containers not exceeding 1,700 pounds (771 kg) water capacity when the following controls are provided:
2.1. A listed or approved gas detection system with a sensing interval not exceeding 5 minutes.
2.2. A listed or approved automatic-closing fail-safe valve located immediately adjacent to container valves. The fail-safe valve shall close when gas is detected at the permissible exposure limit (PEL) by a gas detection system monitoring the exhaust system at the point of discharge from the gas cabinet, exhausted enclosure, ventilated enclosure or gas room. The gas detection shall comply with the requirements of FC 6004.2.2.10.
6004.2.2.7.1 Design.
Treatment systems shall be capable of diluting, adsorbing, absorbing, containing, neutralizing, burning or otherwise processing the contents of the largest compressed gas container. Where a total containment system is used, the system shall be designed to handle the maximum anticipated pressure of release to the system when it reaches equilibrium.
6004.2.2.7.2 Performance.
Treatment systems shall be designed to reduce the maximum allowable discharge concentrations of the gas to one-half immediate dangerous to life and health (IDLH) at the point of discharge to the atmosphere. Where more than one gas is emitted to the treatment system, the treatment system shall be designed to handle the worst-case release based on the release rate, the quantity and the IDLH for all compressed gases stored or used.
6004.2.2.7.3 Sizing.
Treatment systems shall be sized to process the maximum worst-case release of gas based on the maximum flow rate of release and the entire contents from the largest container utilized.
6004.2.2.7.4 Stationary containers.
Stationary containers shall be labeled with the maximum rate of release for the compressed gas contained based on valves or fittings that are inserted directly into the container. Where multiple valves or fittings are provided, the maximum flow rate of release for valves or fittings with the highest flow rate shall be indicated. Where liquefied compressed gases are in contact with valves or fittings, the liquid flow rate shall be utilized for computation purposes. Flow rates indicated on the label shall be converted to SCF.
6004.2.2.7.5 Portable containers.
The maximum flow rate of release for portable containers shall be calculated based on the total release from the container within 5 minutes for containers with nonliquefied content and 30 minutes for containers with liquefied content. When portable containers are equipped with approved excess flow or reduced flow valves, the worst-case release shall be determined by the maximum achievable flow from the valve as determined by the valve manufacturer or compressed gas supplier. Reduced flow and excess flow valves shall be permanently marked by the valve manufacturer to indicate the maximum design flow rate. Such markings shall indicate the flow rate for air under normal temperature and pressure.
6004.2.2.8 Emergency power.
Emergency power shall be provided in accordance with the Electrical Code and the Building Code where any of the following systems are required:
1. Exhaust ventilation system.
2. Treatment system.
3. Gas detection system.
4. Smoke detection system.
5. Temperature control system.
6. Fire alarm system.
7. Emergency alarm system.
Exception: Emergency power is not required for mechanical exhaust ventilation, treatment systems and temperature control systems where approved fail-safe engineered systems are installed.
6004.2.2.9 Automatic fire detection system – highly toxic compressed gases.
An approved automatic fire detection system shall be installed in rooms or areas where highly toxic compressed gases are stored or used. Activation of the detection system shall sound a local alarm. The fire detection system shall comply with the requirements of the Building Code.
6004.2.2.10 Gas detection system.
A gas detection system shall be provided to detect the presence of gas at or below the permissible exposure limit (PEL) or ceiling limit of the gas for which detection is provided. The system shall be capable of monitoring the discharge from the treatment system at or below one-half the IDLH limit.
Exception: A gas detection system is not required for toxic gases when the physiological warning properties for the gas are at a level below the accepted PEL for the gas.
6004.2.2.10.1 Alarms.
The gas detection system shall initiate a local alarm and transmit a signal to a continuously attended control station on the premises whenever it detects the presence of the gas in the atmosphere. The alarm shall be both visual and audible and shall provide warning both inside and outside the area where gas is detected.
Exception: Signal transmission to a continuously attended control station is not required where not more than one container of highly toxic or toxic gas is stored.
6004.2.2.10.2 Shutoff of gas supply.
The gas-detection system shall automatically close the shutoff valve at the source on 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 are:
1. Operated at pressures less than 15 pounds per square inch gauge (psig) (103.4 kPa).
2. Continuously attended.
3. Provided with readily accessible emergency shutoff valves.
6004.2.2.10.3 Valve closure.
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. Under all other circumstances, shutoff valves shall comply with the following automatic closure requirements:
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 container of specific gas detected supplying the manifold shall automatically close.
6004.3 Outdoor storage, handling and use.
The outdoor storage, handling and use of highly toxic and toxic compressed gases shall be in accordance with FC 6004.3.1 through 6004.3.4.
6004.3.1 Applicability.
The outdoor storage, handling and use of highly toxic and toxic compressed gases shall be in accordance with FC 6004.3.1.1 through 6004.3.1.3.
6004.3.1.1 Quantities not exceeding the maximum allowable quantity per control area.
The outdoor storage, handling or use of highly toxic and toxic gases in amounts not exceeding the maximum allowable quantity per control area set forth in FC Table 5003.1.1(4) shall be in accordance with FC 5001, 5003 and 6001.
6004.3.1.2 Quantities exceeding the maximum allowable quantity per control area.
The outdoor storage, handling or use of highly toxic and toxic gases in amounts exceeding the maximum allowable quantity per control area set forth in FC Table 5003.1.1(4) shall be in accordance with FC 6001 and 6004.3 and FC Chapter 50.
6004.3.1.3 Ozone gas generators.
The outdoor use of ozone gas-generating equipment shall be in accordance with FC 6005.
6004.3.2 General outdoor requirements.
The outdoor storage, handling and use of highly toxic and toxic compressed gases shall be in accordance with FC 6004.3.2.1 through 6004.3.2.7.
6004.3.2.1 Location.
Outdoor storage, handling or use of highly toxic or toxic compressed gases shall be located in accordance with FC 6004.3.2.1.1 through 6004.3.2.1.3.
Exception: Compressed gases located in gas cabinets complying with the requirements of FC 5003.8.6 and 6004.1.2 and located 5 feet (1524 mm) or more from buildings and 25 feet (7620 mm) or more from an exit discharge.
6004.3.2.1.1 Distance limitation to exposures.
Outdoor storage, handling or use of highly toxic or toxic compressed gases shall not be located within 75 feet (22 860 mm) of a lot line, public street, private road, exit discharge or building not associated with the manufacture or distribution of such gases, unless all of the following conditions are met:
1. Storage is shielded by a 2-hour fire-resistant barrier which interrupts the line of sight between the storage and the exposure.
2. The 2-hour fire-resistant barrier shall be located at least 5 feet (1524 mm) from any exposure.
3. The 2-hour fire-resistant barrier shall not have more than two sides at approximately 90-degree (1.57 rad) directions, or three sides with connecting angles of approximately 135 degrees (2.36 rad).
6004.3.2.1.2 Openings in exposed buildings.
Where the storage, handling or use area is located within 75 feet (22 860 mm) of a building not associated with the manufacture or distribution of highly toxic or toxic compressed gases, openings into such building other than for piping are not allowed above the height of the top of the 2-hour fire-resistant barrier or within 50 feet (15 240 mm) horizontally from the storage area whether or not shielded by a fire barrier.
6004.3.2.1.3 Air intakes.
Any area used for storage, handling or use shall not be located within 75 feet (22 860 mm) of air intakes.
6004.3.2.2 Leaking containers.
The requirements of FC 6004.2.2.3 shall apply to outdoor containers. Gas cabinets and exhausted enclosures shall be located within or immediately adjacent to outdoor storage, handling or use areas.
6004.3.2.3 Local exhaust for portable containers.
Local exhaust for outdoor portable containers shall be provided in accordance with FC 6004.2.2.4.
6004.3.2.4 Piping and controls – stationary containers.
Piping and controls for outdoor stationary containers shall be in accordance with FC 6004.2.2.5.
6004.3.2.5 Treatment systems.
The treatment system requirements set forth in FC 6004.2.2.7 shall apply to highly toxic or toxic gases located outdoors.
6004.3.2.6 Emergency power.
The requirements for emergency power set forth in FC 6004.2.2.8 shall apply to highly toxic or toxic gases located outdoors.
6004.3.2.7 Gas detection system.
The gas detection system requirements set forth in FC 6004.2.2.10 shall apply to highly toxic or toxic gases located outdoors.
6004.3.3 Outdoor storage weather protection for portable containers.
Weather protection in accordance with FC 5004.13 shall be provided for portable containers located outdoors and not within gas cabinets or exhausted enclosures. The storage area shall be protected throughout by a sprinkler system.
Exception: A sprinkler system is not required when:
1. all materials under the weather protection structure, including hazardous materials and the containers in which they are stored, are noncombustible.
2. the weather protection structure is located not less than 30 feet (9144 mm) from combustible materials or structures or is separated from such materials or structures using a fire barrier complying with the requirements of FC 6004.3.2.1.1.
6004.3.4 Outdoor use of portable containers.
Portable containers in outdoor use shall be located in gas cabinets or exhausted enclosures.
