As of this writing, NFPA is advertising the 2002 revision of the NFPA 99 Healthcare Facilities standard, and this article will help you understand the changes.

Issue: 4/02

Author's Note: The information on which this article is based comes from my recollection of the discussions and the published information provided by NFPA during the normal revision cycle. As a result, the final document may differ in details from what is written here. You should not rely on this article without reference to the final published document. I do not speak for the committee or the NFPA, and this article represents only my opinion on what is most significant in this revision.

As of this writing, NFPA is advertising the 2002 revision of the NFPA 99 Healthcare Facilities standard and accepting preorders (go to The actual date for shipment is still up in the air. However, the cycle is complete and a new standard is on the way.

So why write an article now? Ordinarily it would be best to wait until everyone gets to see the final document. (In fact we do urge precisely that--save the article to review alongside your new book when it arrives.) So, why now?

In our opinion, the 2002 version represents the most extensive revision of the med gas chapter since the incorporation of NFPA 56F and 56K into NFPA 99 in 1983. The 2002 version is not just a routine revision, it is a total, word-for-word rewrite. Every word, every diagram, every table has been touched. The format is vastly different; and above and beyond the format revisions, there are over 40 substantive technical changes (i.e. changes which may result in changing something we do today). It seems worthwhile to preview and understand what is about to land on our desks.

The Manual of Style

NFPA as an organization is pursuing a strategy towards becoming a more widely recognized international standards organization. To do this, it is felt that its documents need to be written more along the lines of other international standards. These guidelines for writing all future NFPA standards are embodied in the "Manual of Style" (MOS), issued by NFPA in 2000 and revised at least once since then. Although this is an internal NFPA document used primarily by the committees and NFPA staff, it is available from the NFPA should you be interested in seeing a copy.

Regardless of why NFPA issued the MOS, following it was an appalling problem. Many people have lamented over the years that a rewrite was necessary. Without a doubt, the chapter had become more cumbersome and harder to understand with each revision cycle. There were paragraphs with vast numbers of requirements all choked together in a single paragraph. As a random example, here's 4- (g) from the 1999 version:

"(g)Accessories. Compressor systems for medical air shall be equipped with intake filter-mufflers of the dry type, aftercoolers or air dryers, or both, line filter(s) appropriate for the intake air conditions and compressor type, pressure regulators, and a pressure relief valve set at 50 percent above nominal line pressure to ensure the delivery of medical air (see definition of Medical Air in Section 2-2).

The medical air receiver shall be provided with a three-valve bypass to permit service to this device without shutting down the medical air system.

Dryer systems shall be, at a minimum, duplexed and valved to permit isolation of individual components to allow for maintenance or repair in the event of failure, while still continuing to adequately treat the flow of air. Under normal operation, only one dryer shall be open to airflow with the other dryer valved off. Each dryer system shall be designed to provide air at a maximum dew point of 35 degrees F (1.7 degrees C) at the peak calculated demand of the system. [See 4-] System design shall preclude formation of liquid water in the air line.

Aftercoolers, where required, shall be duplexed and provided with individual condensate traps. The receiver shall not be used as an aftercooler or aftercooler trap.

Where more than two devices are provided, the peak calculated demand shall be met with the largest single unit out of service.

Final line filters located upstream of the final line regulators shall be duplexed with appropriate valves to permit service to these devices without shutting down the medical air system. Each of the filters shall be sized for 100 percent of the system peak calculated demand at design conditions and shall be rated for a minimum of 98 percent efficiency at 1 micron. These filters shall be equipped with a continuous visual indicator showing the status of the filter element life.

All final line regulators shall be multiplexed with isolating valves to permit service to the regulator without completely shutting down the gas piping system. Each of the regulators shall be sized for 100 percent of the system peak calculated demand at design condition."

However, the sheer enormity of rewriting the whole chapter had prevented any committee from tackling the task (remember that all NFPA committees are volunteers). No less an effort than rewriting the chapter word for word would do, which of course would be superimposed on one of the most active revision cycles in the history of the chapter (a record 317 public proposals were received and acted on this cycle).

The task was finally taken on (with understandable reluctance) by a sub-group of the whole that put in hundreds of hours under the guidance of NFPA staff to re-write the document and simultaneously integrate the changes as they were approved. No, the results are probably not perfect, but if you've ever struggled with trying to make sense of NFPA 99 Chapter 4, you'll have plenty of reason to thank the MOS Taskforce.

The significant requirements of the MOS that you'll see reflected in the final document include:

  • A document must be written to be convenient for and comprehensible to enforcers.

  • Each numbered paragraph has one requirement, or at most, a very limited number of very tightly related requirements. No longer can multiple requirements be tumbled into hodgepodge paragraphs for the user to tease apart.

  • The NFPA has gone metric, so measurements are listed metric first followed by english in parentheses.

  • The definitions no longer contain enforcement criteria as such--an innocuous sounding change with important consequences.

  • There is nothing in the body of the chapter which is not enforceable. The annex, therefore, now contains most of the tables and all of the figures. Conversely, everything in the annexes is non-mandatory and meant only to be explanatory or to expand on the text. Nothing in an annex is enforceable.

Compare the section of the 2002 draft, which is roughly equivalent to the section shown previously: Aftercoolers. Aftercoolers, where required, shall be provided with individual condensate traps. The receiver shall not be used as an aftercooler or aftercooler trap. Aftercoolers shall be permitted to be constructed of ferrous and/or non-ferrous materials. Anti-vibration mountings shall be installed for aftercoolers as required by equipment dynamics or location and in accordance with the manufacturer's recommendations. Medical Air Receivers. Receivers for medical air shall meet the following requirements:

    (1) Be made of corrosion resistant materials or otherwise made corrosion resistant.

    (2) Comply with Section VIII, Unfired Pressure Vessels, of the ASME Boiler and Pressure Vessel Code.

    (3) Be equipped with a pressure relief valve, automatic drain, manual drain, sight glass, and pressure indicator.

    (4) Be of a capacity sufficient to prevent the compressors from short-cycling. Medical Air Dryers. Medical air dryers shall meet the following requirements:

    (1) Be designed to provide air at a maximum dew point which is below the frost point (0 degrees C {32 degrees F}) at any level of demand.

    (2) Be sized for 100 percent of the system peak calculated demand at design conditions.

    (3) Be permitted to be constructed of ferrous and/or non-ferrous materials.

    (4) Be provided with anti-vibration mountings installed as required by equipment dynamics or location and in accordance with the manufacturer's recommendations. Medical Air Filters. Medical air filters shall meet the following requirements:

    (1) Be appropriate for the intake air conditions.

    (2) Be located upstream of the final line regulators.

    (3) Be sized for 100 percent of the system peak calculated demand at design conditions and shall be rated for a minimum of 98 percent efficiency at 1 micron or greater.

    (4) Be equipped with a continuous visual indicator showing the status of the filter element life.

    (5) Be permitted to be constructed of ferrous and/or non-ferrous materials. Compressors complying with shall be provided with:

    (1) Coalescing filters with element change indicators.

    (2) Charcoal absorbers with colormetric hydrocarbon indicators. Medical Air Regulators. Medical air regulators shall meet the following requirements:

    (1) Be sized for 100 percent of the system peak calculated demand at design condition.

    (2) Be permitted to be constructed of ferrous and/or non-ferrous materials.

    (3) Be equipped with a pressure indicator indicating delivery pressure."

You will quickly see that the resulting rewrite of NFPA 99 is vastly more clear and leaves many fewer ambiguities than any NFPA med gas document you've ever seen. While it can never be without "room for interpretation" and there undoubtedly remain loopholes and flaws, the general feeling is that the document is going to be vastly easier to understand and apply.

Most significantly, this document is enforcer friendly. That means that even an enforcer who is not especially expert in medical gas will generally be able to read and understand the requirements. Since they are now arranged as one paragraph, one requirement, there is less of the "three paragraphs that bear" problem which plagued the earlier versions. State inspectors and others responsible for the inspection of these systems should be relieved to see the improvements adopted in their jurisdictions.

Finding Your Way

The MOS had impact beyond simply rewriting the new medical gas chapter; it also altered the entire order of the document. Some of the things you'll want to note:

  • Look for the definitions in Chapter 3 instead of 2.

  • Look for the medical gas section in Chapter 5 instead of Chapter 4.

  • Look to find the Occupancy Chapters (formerly 12 for Hospitals, 13 for "Other" Healthcare Facilities, 16 for Nursing Homes, 17 for Limited Care Facilities and 20 for Freestanding Birthing Centers) moved to 13, 14, 17, 18 and 21, respectively.

  • Don't look for the appendices; they're renamed "annexes."

  • Don't look for a separate vacuum section. Vacuum and pressure gases are now tightly integrated. A fundamental shift in this edition was to seek the areas in which the systems are similar rather than to emphasize their differences.

  • To find Level 1 requirements, look in sections numbered 5.1. Level 2 will be found in 5.2, and Level 3 in 5.3. Similar requirements across levels will generally be found in similarly numbered paragraphs; for example, to find requirements for outlets in Level 1, look in 5.1.5. For Level 2, go to 5.2.5 and Level 3 go to 5.3.5.

An Overview of Major Changes

While the document was being revised to fit the MOS, the usual revision cycle was underway. The 317 odd Public Proposals included many of substantial importance.

A sampling of these changes follows; please note there are many more than those shown! (This listing comes from the preprint published in the NFPA "Report on Comments." Final wording may appear differently in the final document.)

  • The source sections for manifolds and bulk stations were extensively re-written, adding some requirements and reorganizing for clarity.

  • Indoor locations for manifolds are to be ventilated by fans or blowers, and those are to draw from a location within 300 mm (1 foot) of the floor. The exceptions are small systems (<85k liters (3,000) ft3) or less, and air manifolds when located by themselves.

  • Fans and blowers used for gas system ventilation must be powered from the Essential Electrical System, as must the source equipment itself.

  • Locations with natural ventilation must have two openings--one near the floor and one near the ceiling.

  • Portions of oxygen systems operating above 300 psig may not be fitted with polymer-lined cylinder leads. Right now that will usually mean copper pigtails for these manifolds.

  • Relief valves may be piped into a common line, but that line must have a cross sectional area equal to the sum of the cross sectional areas of all the valve outlets.

  • The location for the relief line discharge is specified.

  • Relief valve vent lines must be made of copper, purged and brazed.

  • What source(s) can be located with what other source(s) has been strictly defined (e.g. a manifold may be placed with a bulk gas systems but not with an air compressor, etc.).

  • Locations for nitrous or carbon dioxide must be kept above -7 degrees C (20 degrees F) and all manifolds must be kept below 130 degrees F.

  • Locations containing motor-driven equipment must be ventilated to prevent accumulation of heat.

  • There is a whole new set of requirements regarding the siting and equipment pad for bulk oxygen systems.

  • Outdoor locations must be ventilated on all sides. This is particularly timely as facilities try to increase the security of these installations.

  • There is a new quasi-alarm called a Local Signal defined. Manifolds and bulk stations are required to have a minimum suite of these "local signals," pressure gauges, etc.

  • It will be permissible to locate a manifold and its reserve header in separate locations.

  • Bulk oxygen systems will be required to have a liquid level low local signal and a master alarm for the main tank--not just the reserve or secondary as now.

  • There will need to be an Emergency Oxygen Inlet Connection (EOSC) on each building of a multi-building campus. But for the first time there is also another way to meet the EOSC requirement--an In-Building Emergency Reserve, which might be a manifold inside the building.

  • Medical Air purity is specified in the body of the text. This seemingly subtle change is huge in its potential consequences.

  • Medical Air can be used for supplied air respiration (e.g. for hoods and masks for the medical staff in isolation rooms or decontamination areas).

  • Piping within the medical air compressor system (upstream of the source valve) will need to be cleaned and suitable for oxygen.

  • Medical Air sources will need to be designed to provide a dew point below 0 degrees C (32 degrees F) at any level of demand.

  • Three-way valves are permitted to isolate or select redundant components.

  • Piping within the medical vacuum pump system (downstream of the source valve) will need to be copper (most any copper is okay--a list is given--but copper only).

  • Dielectric couplings are permitted in specialized locations.

  • WAGD Systems will have a lag alarm.

  • A new system, "Instrument Air," is defined. Instrument Air is air for running tools as a substitute for nitrogen. It has a defined purity and is designed to mimic nitrogen. Thus the compressor must produce 200 psi or more, and the air must be dried to -40 degrees.

    Instrument air systems may be duplex compressors or simplex compressors with a high-pressure cylinder backup. There is a whole section on these systems in the proposed standard.

Installation Guidelines

  • Takeoffs shall be vertical or greater than 45 degrees off the line.

  • A whole set of procedures for operating the nitrogen purge during brazing will be included.

  • Installers would have to qualify to a procedure as contained in ASSE/ANSI 6010.

  • The use of "roll-grooved" and gasketed joining methods will be permitted in vacuum only (with some limitations).

  • Plastic vacuum lines are explicitly permitted in Level 3 Vacuum.

  • Rules have been defined for vacuum pipeline assembly in Level 3, which allows a variety of methods to be used.

  • Changes to Level 3 oxygen and nitrous oxide bring them into line with Level 2 for installation and testing, so the degree of care needed will be greatly enhanced for these systems.

Testing, Verification and Maintenance

  • An important qualification regarding repair work has been made: where such work involves cutting and brazing, it must be treated as new work for the purposes of testing. Otherwise, specific tests are required which are a limited subset of the larger testing regime. This will take some of the heat off simple, like-for-like replacement maintenance.

  • Verifiers must now be qualified to ASSE/ANSI 6030.

  • Particulate testing is now slightly less stringent. Instead of the 0.1 mg/m3 previously allowed, the standard now permits up to 1 mg/m3 of matter in the weighed filter test.

  • Carbon Monoxide monitors must be tested and calibrated at least annually.

Annexes and Other Things

  • All laboratory requirements (old Level 4) have been removed to Chapter 11, where whatever laboratory requirements NFPA has will now be found.

  • All the figures have been revised to be friendlier for the non-specialist and to bring them more in line with the standard itself.

  • The NFPA vacuum sizing methodology previously found in Appendix C has been removed.

There are many more changes, but this should let you have a taste of what's coming. We believe this will be the best '99 ever, and we who live with these standards everyday are sure looking forward to the improvement!