Design and compliance for oxygen cylinders and their enclosures can be a challenge for staff, designers and facilities personnel.

Image courtesy of ASHE

Oxygen, either piped in a closed system or as a compressed gas in cylinders, plays an important role in health care facilities for treatment in many patients. 

While it is not considered a flammable gas, oxygen is an oxidizer, which means that it will accelerate a fire if introduced at a higher content than exists in air (the normal oxygen content in air is 21%). 

While piped oxygen systems are typically fixed infrastructures, design and compliance for oxygen cylinders and their enclosures (where required) can be a challenge for staff, designers and facilities personnel. 

Cylinder regulations

Regulations for oxygen cylinders are based on the volume of gas present (designated in cubic feet in the U.S.). As expected, the more volume of gas present, the more requirements that apply. 

There are many different sizes of cylinders utilized for oxygen in health care facilities ranging from an E-cylinder (approximately 23 cubic feet of oxygen) to an H-cylinder (approximately 244 cubic feet of oxygen). Other cylinder sizes include A, B or D. 

As required by the Centers for Medicare & Medicaid Services (CMS), health care facilities must comply with the 2012 edition of the National Fire Protection Association’s NFPA 101®, Life Safety Code®, and the 2012 edition NFPA 99, Health Care Facilities Code. 

The following considerations help facilities professionals explore the requirements for oxygen being stored in cylinders in a health care occupancy and how they can be sure their facilities comply:

Full, partial or empty. A critical aspect of oxygen use and storage is related to identifying each cylinder as full or empty. In an emergency, it is critical for staff to easily identify which cylinders are full. NFPA 99 section specifically requires that empty cylinders be “marked to avoid confusion and delay if a full cylinder is needed in a rapid manner.” 

This can be accomplished through an integral pressure gauge, individual signage or separated group signage (for cylinders being stored together). In the past, some accreditation organizations have recommended separation or signage to meet the “rapid manner” requirement. NFPA 99 section requires that empty and full cylinders are segregated from each other when stored in the same enclosure. 

While NFPA 99 does not specifically address partial cylinders, The Joint Commission (TJC) provides some guidance in this area. They allow an organization to perform a risk assessment leading to a policy that identifies how the organization will identify and store partial cylinders. If the organization deems fit to store full and partial cylinders together in the same enclosure, TJC will allow it as long as it is identified in the hospital policy. 

If this is not desirable, another option might be to utilize a separate storage rack for full, partial and empty cylinders with appropriate identification if a facility has the space for it. The facility’s local or state authority having jurisdiction (AHJ) should also be consulted during the risk assessment stage to determine if they have specific concerns or requirements that may vary from NFPA 99, such as those that exist in the International Fire Code.

In-use versus storage. Another important aspect of dealing with oxygen cylinder compliance is determining what is in-use versus what is storage. NFPA 99-2012 section answers that small size oxygen cylinders (A, B, D or E) that are securely mounted to a cylinder stand or to medical equipment designed to receive and hold compressed gas cylinders are considered in-use and not subject to the storage provisions. 

Similarly, section addresses cylinders available for immediate patient use in patient care areas (e.g., an individual cylinder located in a patient room) that are secured to prevent tipping or damage and are also considered in use. CMS confirmed this position in a memorandum (S&C-07-10) in January 2007. Other oxygen cylinders not fitting one of the descriptions discussed previously will be considered storage.

Storage of less than/equal to 300 cubic feet. In patient care areas, NFPA 99 section 11.3.3 will allow up to 300 cubic feet (approximately 12 E-size cylinders) of nonflammable gas, which includes oxygen, in 22,500 square feet of floor area outside of a storage enclosure. 

While the code specifically states 22,500 square feet of floor area, this aligns with the requirements for the maximum size of a smoke compartment required by NFPA 101 for health care occupancies. The cylinders shall be secured against tipping or damage, and other general precautions outlined in NFPA 99 shall be followed. 

CMS confirmed this position in the S&C-07-10 memorandum as well. It is likely during an accreditation survey managers have seen surveyors counting oxygen cylinders not considered “in-use” within a smoke compartment to confirm compliance.

Storage greater than 300 cubic feet but less than 3,000 cubic feet. NFPA 99-2012 section 11.3.2 addresses requirements for storing nonflammable compressed gases greater than 300 cubic feet but less than 3,000 cubic feet (up to approximately 120 E-size cylinders or 12 H-size cylinders of oxygen). 

The cylinders can be stored outdoors in an enclosure or in an enclosed interior space using non- or limited-combustible construction with doors capable of being secured. If storing oxygen cylinders outdoors, NFPA 99 section will require protection from weather including water, snow and ice accumulation, to prevent rusting, as well as temperature extremes. A cover/roof for the exterior enclosure, as well as some separation between the ground and the cylinders, is often helpful in meeting these requirements. 

Oxidizing gases such as oxygen shall be separated from combustibles or materials in the same enclosure by one of the following options: a minimum of 20 feet, a minimum of 5 feet in a fully sprinklered storage room or enclosed in a gas cabinet with a minimum 30-minute fire rating. 

The protective mesh that sometimes is provided to protect the cylinders during transportation should be removed if considered combustible. The cylinders shall also not be stored with any flammable gas, liquid or vapor. 

The enclosure will require regulation of temperature to prevent the oxygen cylinders from reaching 130 degrees Fahrenheit. If other compressed gases are located in this room with different requirements (e.g., nitrous oxide or carbon dioxide), the worst-case temperature requirements will apply. Oxygen-cylinder valve protection caps shall remain until placed in use. Smoking, open flames and electric heating elements shall be prohibited from the interior storage rooms and within 20 feet of the exterior enclosures. 

Other general safety precautions for cylinders outlined in NFPA 99 will apply as well, including protection against tipping or damage. NFPA 99 section will also require precautionary signage indicating the presence of oxidizing gases that is readable from 5 feet away on each door to the enclosure. Additional signage may be required as applicable for other medical gases that may be present in the enclosure.

Storage equal to/greater than 3,000 cubic feet. Storage of nonflammable compressed gases equal to or greater than 3,000 cubic feet will require compliance with NFPA 99-2012 sections and 

The enclosures shall be designed to allow access for hand trucks or carts to move cylinders and equipment in and out of the space, and the space access (e.g., doors, gates or other method) shall be secured. 

If oxygen cylinders are stored outside, the enclosure shall be constructed of non- or limited-combustible materials with a minimum of two entries/exits. If the cylinders are stored inside, the enclosure shall be provided with a one-hour fire barrier rating including 60-minute-listed opening protectives (e.g., doors, dampers of other penetrations). 

Subsequent editions of NFPA 99 has updated the opening protective requirement fire rating to 45 minutes. This should be discussed with the appropriate AHJ. 

Interior finishes in the interior enclosure shall be non- or limited-combustible types. The enclosures shall comply with NFPA 70®, National Electrical Code®, for ordinary locations and shall be provided with electrical power from the essential electrical system. 

Additionally, electrical devices shall be protected from physical damage. This can be accomplished through a protective barrier around the device or locating the device at a height that a cylinder, container or equipment required to move the cylinders will not come into contact with the device. 

If heat is required to the room, indirect means is required (e.g., steam or hot water). The enclosure shall be provided with racks, chains and/or other fastenings to secure all cylinders from falling. Any racks, shelves or supports in the enclosure shall be constructed of non- or limited-combustibles. Temperature regulation will be required as described above in the enclosure with less than 3,000 cubic feet. 

Other general safety precautions for cylinders outlined in NFPA 99 and other requirements previously discussed as well as appropriate signage dependent on what other gases may be stored within the enclosure will also apply.

Ventilation. Outdoor enclosures equal to/greater than 3,000 cubic feet of gas storage will require ventilation per NFPA 99 section Outdoor storage locations surrounded by solid (impermeable) walls shall have protected ventilation openings at the base of each wall to allow for free air circulation. Walls that are shared with other enclosures or buildings do not require openings. 

Interior enclosures equal to/greater than 3,000 cubic feet of gas storage will require ventilation per NFPA 99 section using either natural or mechanical exhaust. If using the natural ventilation option, NFPA 99 section will require that two non-closeable louvered openings shall be provided, each having 24 square inches of opening for each 1,000 cubic feet of gas to be stored within the enclosure. 

Each louver shall be a minimum of 72 square inches. One louver shall be located within one foot of the floor and the other within one foot of the ceiling, located to allow for crossflow. Openings shall be direct to the outside without any ductwork. 

As discussed previously, other considerations for design include a maximum and minimum temperature within the enclosure. If the enclosure has wet sprinkler protection, consideration should be given to maintaining the minimum 40 degrees Fahrenheit required by NFPA 13, Standard for the Installation of Sprinkler Systems, for an automatic sprinkler system. Other considerations can be given to enclosures utilizing a dry barrel sprinkler, dry sprinkler system or anti-freeze sprinkler system.

If the mechanical ventilation option is utilized, NFPA 99 section will require continuous exhaust to maintain a negative pressure within the enclosure. One cubic foot per minute (cfm) of ventilation per 5 cubic feet of gas stored within the enclosure shall be provided with a minimum of 50 cfm and a maximum of 500 cfm. Inlets shall be unobstructed and located within 1 foot of the floor to draw air. 

Dedicated exhaust is not required, but the system cannot connect with any space that contains flammable materials. Additionally, any ductwork must be noncombustible construction. 

The exhaust fan shall be supplied with power from the essential electrical system. Makeup air shall be provided by one of the following: noncombustible ductwork transferred from adjacent spaces that do not include flammable or combustible material; a corridor under the door up to 50 cfm or 15% of the room exhaust per NFPA 90A; or any building ventilation system that does not contain flammable or combustible vapors.  

As in the previous discussion, maximum and minimum temperatures must be considered depending on other medical gases or systems (e.g., fire sprinkler systems) present in the enclosure.

Other considerations. Some other general NFPA 99 requirements when dealing with oxygen cylinders include: using cylinders in the order in which they were received; and protecting the cylinders from contact with oil or grease, or contamination from dirt/dust, and following the Compressed Gas Association (CGA) G-4, Oxygen, requirements.

An involved process

Oxygen cylinder storage and use can be a very involved process, and it often takes a team within each health care facility to help regulate compliance. 

In addition, health care facilities often store and use many other nonflammable gases, oxidizers and flammable gases that require attention. While an increase in volume of oxygen cylinder storage comes with increased requirements, often so does adding other medical gases to the same enclosure. 

As with all areas of regulatory compliance, a risk assessment and discussion with appropriate staff is a good place to start with education and creating policies. 

When health care facilities professionals run into complex situations or specifics not addressed in the codes, a conversation with the AHJ, regulatory accreditation organization and/or CMS can help clarify things. 

Health facilities professionals should remember to document everything agreed upon and save it in a location to access during future surveys. 

Mark Chrisman, PE, is health care practice director and vice president at Henderson Engineers, Lenexa, Kan. He can be reached at