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Basics of NFPA 99 changes for hospital design

How engineers should navigate the changes to the 2018 edition of NFPA 99

By Tom Divine, PE, LEED AP June 19, 2020
Courtesy: ShauLin Hon, Slyworks Photography, Johnston, LLC

Learning Objectives

  • Learn the details of specific changes to NFPA 99-2018.
  • Understand the general impact of changes to requirements for gas and vacuum systems.
  • Know the limited impact of the sweeping changes to the chapter covering electrical systems.

The 2018 edition of NFPA 99: Health Care Facilities Code, continues to build on the risk-based approach to facility design that had been established in the 2012 edition. This article addresses changes to the 2018 edition that affect the design of mechanical, electrical, plumbing and fire protection systems in health care facilities, specifically covering chapters in the code that directly affect those disciplines.

Chapter 4 is also included to capture its clarification of responsibility for risk assessments, which has from time to time been presumed to fall to the design team. New Chapter 15, Dental Gas and Vacuum Systems, is not covered here, due its limited applicability to health care facility design.

Major changes include requirements for oxygen concentrators and corrugated metal tubing in Chapter 5, Gas and Vacuum Systems, and the reorganization of Chapter 6, Electrical Systems.

Minor changes appear in chapters dedicated to plumbing, heating, ventilation and air conditioning and fire protection.

Chapter 4: Fundamentals

NFPA 99 Chapter 4 was introduced in the 2012 edition, where it presented the transition from occupancy-based to risk-based requirements. Chapter 4 mandated risk assessments and defined risk categories for activities, systems and equipment based on the outcomes of those assessments. In the 2015 edition, Section stated that the “governing body” held the responsibility for determining the risk categories of patient care spaces.

That nomenclature resulted in a level of confusion among users of the code. Some interpreted it to mean that local authority having jurisdiction or state accreditation boards were responsible for producing those risk assessments. The intent of the code is that the governing body of the health care facility itself has that responsibility. That intent is clarified in new Section 4.2.1, which requires that the “health care facility’s governing body shall establish the processes and operations that are planned for the health care facility.” New Section calls for risk assessment to be provided to the AHJ for its review where the AHJ requires it.

Figure 1: A hybrid operating room, incorporating sophisticated imaging technology into the operating theater, began operations in a major urban hospital in the southwestern United States last year. This room was part of a larger renovation, encompassing five new operating rooms, two hybrid operating rooms, blood bank, pharmacy, central sterile processing unit, post-operative care and an oral surgical clinic. Courtesy: ShauLin Hon, Slyworks Photography, Johnston, LLC

Figure 1: A hybrid operating room, incorporating sophisticated imaging technology into the operating theater, began operations in a major urban hospital in the southwestern United States last year. This room was part of a larger renovation, encompassing five new operating rooms, two hybrid operating rooms, blood bank, pharmacy, central sterile processing unit, post-operative care and an oral surgical clinic. Courtesy: ShauLin Hon, Slyworks Photography, Johnston, LLC

Chapter 5: Gas and Vacuum Systems

NFPA 99 Section relaxes the requirement for exits in an outdoor central supply system or storage of positive-pressure gases, requiring two exits only when the area of the installation exceeds 200 square feet. The 2015 edition had required two exits regardless of the area, leading to convoluted designs for small facilities. Note, though, that still requires two exits for cryogenic for bulk cryogenic liquid systems, regardless of size.

Section and (10) clarify requirements for heating of central supply systems and positive-pressure gas storage locations. The previous edition called for heating by indirect means, without any quantitative description of requirements. The 2018 edition prohibits fuel-fired equipment in the gas source or storage room and restricts the temperature of the heating element to 266°F. Steam, hot water and electric heating systems meeting this requirement are permissible in this application.

Section requires that unconnected gas cylinders be stored in locations that comply with, covering design and construction of storage locations, and with, covering ventilation for those locations. Section, Storage, which encompasses, is cited in as applying to both new and existing systems. Under the 2015 edition of NFPA 99, this requirement would apply to existing systems. The 2018 edition adds text stating that approved existing systems shall be permitted to continue in service, abrogating this specific requirement for existing storage locations.

Requirements for oxygen concentrators are new to the 2018 edition. Oxygen concentrators have not been addressed in previous editions of NFPA 99, though they’ve been covered in standards used outside the United States for several years. Oxygen concentrators take on a special importance in areas that are not easily serviced by oxygen suppliers. The specific requirements for oxygen concentrators are too numerous and complex to allow a detailed description here, so references to the code itself are provided instead.

Requirements for concentrator units appear in Section Additional requirements for oxygen central supply systems using concentrators are stated in Master alarm requirements for central supply systems using concentrators are found in Section describes requirements for operating controls and for operating alarms and local signals. NFPA 99 Section covers requirements for local alarms when concentrators are part of the central supply system.

New requirements for inlet filtration of central supply systems for vacuum appear in Section The intent of vacuum filtration is to restrict the movement of particulates in the vacuum system and thereby provide a measure of protection for persons maintaining or inspecting vacuum equipment. While the code requires that the filters shall be installed on the patient side of the vacuum producer — the vacuum pump — it doesn’t state whether the filters should be upstream or downstream of the receiver, leaving this decision to the system designer.

At least two filter units or bundles are required, with isolation to allow one filter to serve the system while the other is replaced. Filter efficiency is specified at “0.03 micron and 99.97% HEPA,” though “0.03 micron” may well be a typographical error, intended to be “0.3 micron.” Also required are a means to allow the user to observe accumulations of liquids — typically a sight glass — and a petcock to relieve vacuum in the filter canister.

A new section was added to Annex A: Explanatory Material, connected to Section, clarifying that the intent of the requirement that a zone valve be “readily operable from a standing position,” is that it be operable by a person of average height, standing in front of the valve, with both feet on the floor. It appears that some operators may have tried to certify zone valves mounted high on the wall, under the theory that an operator standing on a ladder or stepstool was “in a standing position.”

New Section permits corrugated medical tubing for positive-pressure Category 1 systems, in addition to hard-drawn seamless copper Type L and Type K. The tubing must be listed and the listing must include testing to demonstrate that CMT systems can be consistently gas-purged with results comparable to hard-drawn copper medical gas tubing.

The CMT must also meet an array of criteria specified in, and Installation restrictions for CMT appear in new Sections and Turns, offsets and direction changes in CMT systems shall be implemented with fittings, or by tubing bends no tighter than the tubing’s listed minimum bend radius. Mechanically formed, drilled and extruded tee-branch connections are prohibited in CMT systems.

A number of errata have been identified in Chapter 5 and its corresponding entries in Annex A: Explanatory Material. All of those errata are erroneous or outdated references to other locations in the code.

Figure 2: Copper gas piping is shown in the ceiling space of a hospital. Courtesy: Johnston, LLC

Figure 2: Copper gas piping is shown in the ceiling space of a hospital. Courtesy: Johnston, LLC

Chapter 6: Electrical Systems

NFPA 99 Chapter 6 was reorganized. The changes to Chapter 6 are almost exclusively editorial, with very little in the way of substantive changes to requirements. The intent of the reorganization was to make Chapter 6 more logical and usable. The numbering system was simplified, with fewer subheadings. Some portions were relocated to place them with related requirements. Chapter 6 had accumulated a number of duplications and many of those were removed. Related requirements were brought together. Other goals of the reorganization were to bring the chapter into closer compliance with NFPA 99 style guidelines and to change the flow to a more risk-based approach.

One of the consequences of the extensive editorial reorganization is the difficulty of identifying substantive revisions in any meaningful way. Nearly all of the text has been altered, but the requirements remain almost entirely unchanged. The nature and extent of the revisions don’t allow for comparing sections in the previous edition to identify changes. Consequently, every section in the 2018 edition’s Chapter 6 is marked as revised. Due to the difficulty of identifying substantive revisions in the code and the small number of changes, an effort is made here to describe all of the substantive changes to Chapter 6. Nevertheless, this list it may be incomplete.

Section shows requirements for receptacles in “clinical laboratories.” A new section in Annex A: Explanatory Material defines a clinical laboratory as “a space where diagnostic tests are performed as part of patient care.” The corresponding section in NFPA 99-2015,, appeared to apply to laboratories in general. The revision clarifies that this section applies only to clinical laboratories and not, for example, research laboratories that may be house in the health care facility. The receptacle requirements are unchanged.

The 2012 and 2015 editions of NFPA 99 both declared in Section that “operating rooms shall be considered to be a wet procedure location, unless a risk assessment conducted by the health care governing body determines otherwise.” This default designation as wet procedure locations triggered requirements for special electric shock protection, typically in the form of isolated power systems or ground fault circuit interrupters.

In the 2018 edition, that requirement survives unchanged as Section New text in Section clarifies that special electric shock protection is not required in the operating room if a risk assessment determines that the room is not a wet procedure location.

Section 6.5.2 requires that Category 2 spaces served by either a Type 1 or a Type 2 essential electrical system be served from a transfer switch, and at least one other circuit that is served from either the normal power distribution system or from a different transfer switch. This requirement is new to the 2018 edition. Previous editions contained a similar prescription for Category 1 spaces, requiring circuits specifically from the critical branch and from either normal or from a separate critical branch transfer switch; however, no such requirement existed in the previous editions for Category 2 spaces.

Category 2 spaces may be served from either a Type 1 or a Type 2 EES, as provided in 6.5.1. A Type 2 EES has only two branches and does not have a critical branch, as described in Therefore, the requirement for Category 2 spaces does not reference a specific branch. The requirements for the life safety branch sharply limit the types of loads that it may serve, so this requirement will nearly always be met with circuits from the equipment branch.

Fuel cell systems were permitted as an alternate source for an EES in the 2015 edition, in Section, provided that they could energize load within 10 seconds of an outage, had at least one redundant unit, had an adequate on-site fuel supply and a continuing source of fuel and were backed up with a portable generator connection. In practice, fuel cells are rarely appropriate for health care use due to their generally small capacities, their inability to meet the 10-second rule from a cold start and the difficulty of storing adequate amounts of their gaseous fuels. NFPA 99-2018 also permits fuel cells and adds the requirement that they be listed for emergency use, in Section

The 2015 edition, in Section, requires that main circuit breakers and feeder circuit breakers be inspected annually and periodically exercised in a program established in accordance with manufacturer’s recommendations. This same requirement appears in the 2018 edition in Section, along with the additional requirement that those breakers also be maintained in accordance with manufacturer’s instructions and industry standards. This requirement is specifically noted as applicable to both new and existing facilities, as part of 6.7.4, in Section 6.1.3(12)

Chapter 8: Plumbing

NFPA 99-2018 Chapter 8 has only one revision. Section 8.3.6 requires that special water systems comply with FGI guidelines or with, “the applicable ANSI-reviewed standard.” The 2015 edition was less specific, calling for compliance with Facility Guidelines Institute guidelines or “other appropriate publicly reviewed nationally published standards.”

Figure 3: A 2-megawatt generator was installed indoors at a medical facility. Courtesy: Johnston, LLC

Figure 3: A 2-megawatt generator was installed indoors at a medical facility. Courtesy: Johnston, LLC

Chapter 9: HVAC

Chapter 9 shows limited revisions, with few substantive changes.

In the 2015 edition, Section requires that exhaust fans be connected to the essential electrical system. NFAP 99-2018, using the same section number, adds a requirement that a risk assessment be conducted for installations without an essential system to determine whether continuous operation must be provided by some alternate means.

Section revises requirements for medical plume evacuation. Three alternative methods of evacuation are provided in the 2015 edition: a dedicated exhaust to discharging outside the building, high-efficiency particulate air filtering and direct connection to a return or exhaust duct and sterilization by chemical and thermal and return to the space.

The 2018 edition revises each of those methods. For dedicated exhaust systems to the outdoors, exhaust must be 25 feet from building openings or places of assembly, at an elevation different from air intakes, in a location where prevailing conditions won’t divert the exhaust to occupied areas or prevent dispersion. For connection to existing return or exhaust systems with HEPA filtering, the 2018 edition adds a requirement for gas phase filtration. In the third alternative, the requirement for sterilization is replaced with a point of use smoke evacuator for air cleaning.

Figure 4: A zone valve box is shown installed in a hospital corridor. Courtesy: Johnston, LLC

Figure 4: A zone valve box is shown installed in a hospital corridor. Courtesy: Johnston, LLC

Chapter 16: Features of Fire Protection

Features of Fire Protection appeared as Chapter 15 in the 2012 and 2015 editions. It was renumbered as Chapter 16 to make way for the new Chapter 15, Dental Gas and Vacuum Systems.

The most interesting change to Chapter 16 in the 2018 edition is Section, which allows for omission of fire alarm notification appliances, both audible and visual, in patient care spaces, when a risk assessment indicates that their presence may adversely affect patient care and an alternative means of notification is provided. This section was numbered in the 2015 edition, which allowed visual notification appliances to be used in lieu of audible appliances in critical care areas.

The new section is much broader; it allows patient care spaces to be occupied without visual or audible fire alarm notification appliances, provided that a risk assessment warrants it and some means of alternative notification is provided.

It has long been the practice in hospital design to omit notification appliances from patient sleeping rooms, with good reason. For higher acuity patients, the decision of whether to evacuate will likely depend as much on the patient’s medical needs as on any physical threat. It would seem unwise to expose the patient or visiting family, to signals that would initiate mandatory evacuation in any other milieu.

However, until now, there have been no references to this practice in any of the codes. There is often quite a bit of confusion in the permit process, as the fire marshal tries to reconcile the needs of patients with the black-letter requirements of the codes. While few local jurisdictions enforce NFPA 99, this provision gives design and construction teams a leg to stand on in discussions with local authorities about notification appliances in patient sleeping rooms.

Figure 5: Gas outlets were installed in the headwall of a patient bed location. Courtesy: Johnston, LLC

Figure 5: Gas outlets were installed in the headwall of a patient bed location. Courtesy: Johnston, LLC

Four new sections covering portable fire extinguishers have been added to Chapter 16. These sections describe requirements for fire extinguishers in specialty spaces. In MRI rooms and associated spaces, extinguishers must be nonferrous, to avoid unwanted or even catastrophic, interaction with strong magnetic fields ( In kitchens and other cooking areas, where there is, “a potential for fires involving combustible cooking media,” Class K extinguishers, specifically designed for fires in animal or vegetable fats, are required (

Clean agent fire extinguishers are required in telecommunications entrance and equipment rooms to avoid damage to electronic equipment ( Clean agent or water mist extinguishers are required in operating rooms ( It is worth noting that carbon dioxide extinguishers comply with definition of clean agent as defined in NFPA 10: Standard for Portable Fire Extinguishers and that definition is copied into NFPA 99 (3.3.23).

Tom Divine, PE, LEED AP
Author Bio: Tom Divine is a senior electrical engineer at Johnston, LLC. He is a member of the Consulting-Specifying Engineer editorial advisory board.