Medical Gas Installations

NFPA rules challenge gas suppliers.

By David Edge

Rules and codes regarding medical gas systems historically have evolved due to changes in technology, safety concerns, equipment performance issues and accidents. The most recent changes in both mandates and industry practices have occurred due to accidents at health care facilities. These events prompted changes in two of the industry's most recognized regulatory bodies: the National Fire Protection Association (NFPA) and the Food and Drug Administration (FDA). Though the FDA's new draft guidelines have taken center stage recently, close attention must also be paid to NFPA's requirements, which are key to ensuring the safety and performance of medical gas systems at health care facilities.

NFPA 99 Standard
The medical gas industry's most recognized code is NFPA 99 Standard for Health Care Facilities. Its function is to minimize the hazards of fire, explosion and electrical failures in health care facilities that serve human beings. Chapter Five of the 2002 edition identifies the hazards of medical gases, establishing rules for safe handling and storage of medical gases, and outlining the criteria for the storage and equipment configurations that deliver medical gases at a health care facility. Two of the most notable new NFPA 99 requirements are:

1. The requirement for local alarms, a visual indication of the monitored conditions at the source, in addition to the master alarm panels located inside the facility. The general requirements are defined in 5.1.3.4.7 of NFPA 99 with further details provided in the sections dealing with specific system configurations.
2. The requirement to individually support high-pressure gas cylinders per 5.1.3.3.2(7). The 1999 edition required only that they be adequately secured.

To accurately apply these and other current NFPA guidelines, distributors must first clearly define an installation's application requirements to determine what items they must act on. Once application details have been finalized, the next step in creating a compliant system is to identify into what NFPA level category the installation will fall.

A typical layout of a medical gas bulk delivery system depicting both high and low pressure backup options. All Level 1 and 2 systems that utilize bulk liquid storage require a reserve system with a minimum of an average day's supply of additional product.

NFPA Categories
NFPA 99 identifies three separate categories of piped gas systems: Level 1, Level 2 and Level 3. Earlier revisions defined a fourth category, Level 4, for laboratories that has since been redefined in a separate chapter.

Level 1 — These systems provide patient gases, or vacuum, that if interrupted would place patients in “imminent danger of morbidity or mortality.” Because of the degree of risk, Level 1 systems are the most complex and require safeguards and redundancies to insure trouble-free operation, as well as local and central master alarms to alert staff of a potential for system failure.

Level 2 — These systems supply gases, or vacuum, that if interrupted would place patients “at manageable risk of morbidity or mortality.” Level 2 patient gas central supply systems, while having less inherent risk, must comply with the same NFPA regulations as Level 1 systems.

Level 3 — These systems are those that if interrupted “would terminate procedures, but would not place patients at risk of morbidity or mortality.” Level 3 systems are less complex and do not require reserve supplies; however, warning systems, albeit reduced, are still required. Fairly rigorous rules still apply to labeling, storage considerations, material selection and installation methods and cannot be treated with any less care.

Storage
Once an installation's NFPA level classification has been defined, system supply and control choices can be addressed. When planning a central supply system, distributors must determine the most effective product storage method for their application. High-pressure gas cylinders are an infrequent, but possible, choice. They are rarely used as a primary supply source because of the relatively large storage area they require.

Many small facilities or low-use accounts (i.e., nursing homes, inpatient care facilities) are best served by installing liquid cylinders with an automatic switchover manifold. Accounts requiring more product than liquid cylinders can practically supply will require bulk storage.

Larger applications containing a stationary tank for the primary supply require either a liquid or high-pressure cylinder manifold reserve. Gas cylinders are often used as the reserve supply for small and medium-size customers. New regulations require cylinders to be individually supported, rather than chained together as a group.

Control Equipment
The choice of control equipment is largely dependent upon the supply system selection. Systems utilizing high-pressure cylinders as their primary source consist of two independent cylinder headers complete with check-valves, regulators, a master isolation valve and safety relief valve. A pressure switch is required to indicate switchover from the primary to the secondary bank, as is a duplex final line regulator assembly. No reserve manifold is required with this system.

Liquid cylinders typically consist of two banks of up to six liquid cylinders total (two minimum), equally split between a primary and secondary header connected to an automatic switchover system. An appropriate number of high-pressure cylinders serves as the reserve connected just downstream of the automatic switching system. Local alarms (visual indication), as well as provisions to activate in-house master alarms, are required to indicate when switchover from primary to secondary supply has occurred, when the reserve is in use, and when it reaches low pressure.

Larger applications require a stationary tank for the primary supply and either a liquid or high-pressure cylinder manifold reserve. Proper tank sizing is important to balance the need to minimize fill frequency with the need to avoid product loss for both the primary and reserve supply (if liquid bulk is chosen for the reserve). Multiple vaporizers with manual or automatic switching may be needed for the primary supply vaporization. An intermediate safety relief valve is required at the interface of the primary and reserve supply just upstream of the duplex final line regulator assembly. Both local signals and indoor master alarms are required to indicate when primary supply contents fall below one day's supply (liquid level), reserve is in use, reserve contents are low, and reserve internal pressure is low (when liquid bulk is the reserve supply).

Compliance
Because of updates and changes, many functioning, existing systems may not be in total compliance with the latest regulations. However, it is not necessary to immediately upgrade all non-compliant systems. NFPA 99 states: “An existing system that is not in strict compliance with the provisions of this standard shall be permitted to be continued as long as the authority having jurisdiction has determined that such use does not constitute a distinct hazard to life.”

The authority having jurisdiction is defined as the office, organization or individual responsible for approving equipment, materials, an installation or a procedure. In many cases, this is the local fire marshal. If it is deemed that any part of the system has to be replaced, requiring opening the system and subsequent brazing, retesting and a third-party inspection will be necessary and could result in the inspector ordering other upgrades to bring the system into current compliance.

Distributors of medical gases must be aware of the many restrictions placed on them by various governing sources and apply these changes to their own business. By gaining a good working knowledge, distributors can maintain not only a “leg up” in their compliance programs, but also plan to maintain a competitive advantage.