How NFPA 99-2015 changes affect mechanical design

NFPA 99-2015 has a few changes that mechanical engineers should pay close attention to.

Mike Zorich, PE, LEED AP; IMEG Corp., Rock Island, Ill.

This article is peer-reviewed.Learning objectives

NFPA 99: Health Care Facilities Code applies to all health care facilities other than home care. The code is intended for professionals involved in the design, construction, maintenance, and inspection of health care facilities in addition to the design, manufacture, and testing of appliances and equipment used in patient-care rooms of the health care facilities.

NFPA 99-2015 continues to build upon the risk-based categories established in the 2012 edition. As many health care designers are aware, the 2012 edition of NFPA 99 experienced a major overhaul. The intent of the upgrade was to elevate NFPA 99-2012 from a standard to a code, allowing it to be incorporated into a local jurisdiction’s code by itself instead of being referenced from NFPA 101: Life Safety Code.

The 2012 edition eliminated all previous occupancy-based chapters and replaced them with Chapter 4: Fundamentals, which established risk categories 1 through 4. The change meant NFPA 99 would no longer be applied based upon the name of an occupied space, but rather applied based upon a risk category. Unchanged in the 2015 edition, the risk category is determined by the impact of system failure on patients and caregivers within a facility space. The higher the risk to occupants in the event of system loss, the stricter the requirements to ensure the system is not lost.

While the overall structure and majority of the content remain the same between the 2012 and 2015 NFPA 99 editions, slight modifications have been made throughout the code in the latest version. The changes in the 2015 edition that are of most importance to a health care mechanical designer appear in Chapter 5: Gas and Vacuum Systems; Chapter 7: Information Technology and Communications Systems; and Chapter 9: HVAC. Chapter 8: Plumbing, which was added in the 2012 edition of NFPA 99 with the intent that it be used to support the local plumbing codes for health care facilities, has not been modified in the 2015 edition.

Chapter 5: Gas and vacuum systems

Figure 1: Section, Auxiliary Source Connection, states that all medical-gas source systems be provided with an auxiliary source connection point of the same size as the main line, located on the patient side of the source valve. The section further stipulates that the connection consists of a tee and a normally closed secured valve. All graphics courtesy: IMEG Corp.As in the 2012 edition, NFPA 99-2015 divides Chapter 5 into three sections corresponding to Category 1, Category 2, and Category 3 systems.

Category 1 systems are the most critical and are required to be available continuously for patient life support, even during the loss of normal power sources or failure of other hospital systems. It is important to note that Chapter 5 does not include a Category 4 system (no impact on patients) because a failure of a gas and vacuum system would have at least some impact on the patient. The minimum risk level for a gas and vacuum system, therefore, is Category 3 (failure may cause discomfort).

NFPA 99-2015 adds new criteria in Chapter 5 to help define a Category 1, Category 2, and Category 3 piped gas and vacuum system. The intent of the change is to ensure that when a facility is performing a risk assessment as defined in Chapter 4, the risk assessment is not being used to lower the level of safety. For example, prior to the 2015 edition, it may have been possible for a facility performing a risk assessment to define a medical-gas system as Category 2 even though deep sedation was administered to the patient. Because of the changes to the 2015 code, this situation would now be required to be classified as Category 1.

The added language in Chapter 5 of the 2015 edition is to be used in addition to the risk-category definitions in Chapter 4 when conducting the risk assessment of a facility’s gas and vacuum systems.

Other updates in Chapter 5 affect storage temperatures, auxiliary-source connections, master medical-gas alarms, and instrument air.

For all three categories of medical-gas systems under section, the 2015 code changed the maximum storage temperature of gas cylinders from 130° to 125°F to match the Compressed Gas Association recommendations. Under section, the 2015 edition also has modified the minimum storage temperature for nitrous oxide and carbon dioxide cylinders from -20° to 20°F.

Section, Auxiliary Source Connection, was added in the 2015 edition for medical-gas systems. The section states, “All source systems shall be provided with an auxiliary source connection point of the same size as the main line, which shall be located immediately on the patient side of the source valve.” The section further stipulates that the connection shall consist of a tee and a normally closed secured valve (see Figure 1). The intent of this addition is to provide a facility with a simpler and safer means to change out service equipment. It is important to note that this additional source requirement does not modify or remove the requirements of the emergency oxygen-supply connection referenced in Section This section remains unchanged from the 2012 edition.

Section, Master Medical Gas Alarm, was revised to differentiate between the wired and wireless communication between the two mandatory master alarm panels and the initiating device. Under either wired or wireless communication, the intent of the code remains unchanged: that should one of the mandatory master alarm panels fail, its failure does not disable any signal on the other mandatory master alarm panel.

NFPA 99-2015 also has added a dedicated section for instrument air under Section 5.1.13, Category Support Gases. This section was added to avoid the confusion between nitrogen, which is a medical gas, and instrument air, which is a support gas. Instrument air is not mandated to be provided, but when it is provided, it shall comply with the requirements of NFPA 99.

Furthermore, when support equipment, such as operating room booms or control panels, require gas to operate, a facility has the option of providing either instrument air or nitrogen. However, because it is uncommon and usually unnecessary for a facility to use both an instrument air system and a nitrogen system, NFPA 99 recommends a decision be made to use the one system that best meets the facility’s needs.



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