1.4 Risk Categories & Category 1, 2, and 3 Piped Systems
Key Takeaways
Risk categories run from Category 1 (failure likely to cause major injury or death) to Category 4 (no impact on patient care).
The governing body classifies risk categories using a documented risk assessment procedure. No documented assessment is required when Category 1 is selected.
Category 2 piped systems are limited to minimal sedation, moderate sedation, or no sedation; deep sedation and general anesthesia are not permitted.
In Category 2 systems, medical air compressors and medical-surgical vacuum may be simplex if the facility develops an emergency plan for losing them.
Category 2 and Category 3 warning systems may use a single alarm panel located where it is under continuous surveillance while the facility operates.
Categories Come From Risk, Not Building Type
NFPA 99 Chapter 4 sets requirements by asking what happens to people when a system fails. The health care facility's governing body establishes the processes and operations the facility plans to perform. It then conducts risk assessments and assigns the categories.
| Risk category | Failure of the equipment or system is... |
|---|---|
| Category 1 | Likely to cause major injury or death of patients, staff, or visitors |
| Category 2 | Likely to cause minor injury |
| Category 3 | Not likely to cause injury, but can cause discomfort |
| Category 4 | Has no impact on patient care |
Key procedural points:
- The governing body classifies categories by following and documenting a defined risk assessment procedure.
- Where the AHJ requires it, the risk assessment must be provided to the AHJ for review.
- A documented risk assessment is not required where Category 1 is selected. Choosing the most protective category needs no paperwork justification.
- The governing body also designates the patient care spaces (Category 1 through 4 spaces), anesthetizing locations, and wet procedure locations.
The installer does not decide a system's category. The drawings and specifications reflect the facility's decision. Your job is to know which rules follow from it.
What Changes Between Category 1, 2, and 3 Piped Systems
Section 5.1 is the full rule set for Category 1 piped gas and vacuum systems. Sections 5.2 and 5.3 mostly refer back to 5.1 and list exceptions.
Category 2 systems are permitted only when all of these are true:
- Only moderate sedation, minimal sedation, or no sedation is performed. Deep sedation and general anesthesia are not permitted.
- Losing the piped gas or vacuum is likely to cause minor injury.
- The systems serve Category 2 patient care space.
Category 3 systems are permitted only when minimal sedation or no sedation is performed. Moderate sedation, deep sedation, and general anesthesia are excluded. Losing the system must not be likely to cause injury, though it can cause discomfort, and the systems must serve Category 3 patient care rooms.
| Feature | Category 1 | Category 2 | Category 3 |
|---|---|---|---|
| Sedation permitted | Any, including general anesthesia | Minimal or moderate, or none | Minimal or none |
| Medical air compressors, dryers, aftercoolers, filters, regulators | At least duplex; serve peak demand with the largest unit out | May be simplex, with an emergency plan for loss of medical air | Medical air compressor systems per NFPA 99 are among the permitted sources |
| Medical-surgical vacuum source | At least two pumps; serve peak demand with the largest out | May be simplex, with an emergency plan | May be simplex, with an emergency plan; emergency power per NFPA 99 Section 6.6 and NFPA 70 |
| Oxygen from concentrators | Per 5.1.3.9 arrangements | May use two sources, one of them a cylinder header holding one average day's supply | Concentrator supply units are permitted sources |
| Warning system | Master (two panels), area, and local alarms | May be a single alarm panel in an area of continuous surveillance while the facility operates | May be a single combined master/area panel in an area of continuous surveillance |
| Alarm sensors | At the required master and area locations | Mounted at the source equipment, with a pressure indicator at the master panel | Mounted at the source equipment, with a pressure indicator at the master panel |
| Valves, outlets, distribution, labeling, testing | Full 5.1 rules | Same as Category 1 | Same as Category 1 |
Tip
The last row is the one installers miss most. Category 2 and Category 3 systems may be built with simpler sources and alarms, but their tube, brazing, nitrogen purge, valves, labeling, installer tests, and verification follow the same Category 1 sections. "It's only a Category 2 clinic" never permits relaxed brazing or a skipped standing pressure test.
Reading a Project Through Its Categories
Consider an ambulatory surgery center that performs procedures under general anesthesia. Its operating rooms are anesthetizing locations where loss of oxygen or vacuum could cause major injury, so those systems are Category 1. Category 1 brings two master alarm panels, area alarms for the anesthetizing locations, duplex sources, and a zone valve outside each operating room.
Next, consider an endoscopy clinic that performs only moderate sedation. If its governing body's documented risk assessment places the spaces in Category 2, the clinic may use a simplex vacuum pump and a single alarm panel. It must have an emergency plan for loss of vacuum, and its piping and testing are unchanged.
A dental office that performs only minimal sedation may qualify for Category 3 systems. Dental-specific gas and vacuum provisions are in NFPA 99 Chapter 15.
Where the Facility's Plan Shows Up
The emergency plans required for simplex Category 2 equipment are facility documents. They describe what staff do if the single compressor or pump fails, such as portable suction or cylinder air. The installer should never treat a simplex source as permission for a lower-quality installation. The redundancy exception covers source equipment only.
Under NFPA 99, which sedation levels may be performed in spaces served by Category 2 piped gas and vacuum systems?
Any level, provided area alarms are installed
Minimal and moderate sedation only, or no sedation
Deep sedation and moderate sedation, but not general anesthesia
Minimal sedation only
A Category 2 clinic's design shows a single medical air compressor and a single vacuum pump. What does NFPA 99 require for this arrangement to be acceptable?
Nothing extra, because Category 2 sources are always simplex
An in-building emergency reserve holding 24 hours of medical air at the source
Facility emergency plans for losing medical air and medical-surgical vacuum
A second master alarm panel to compensate for the missing redundancy
A hospital's governing body decides that every patient care space in a new tower will be Category 1. What does NFPA 99 say about documenting that decision?
A documented risk assessment is not required where Category 1 is selected
A documented risk assessment must be filed with the AHJ before permits are issued
The installer must document the risk assessment on the as-built drawings for the AHJ
The verifier must approve the risk assessment before testing
Sections you finish are checked off in the contents.