5.2 Zone Valves & Zone Valve Box Assemblies
Key Takeaways
All station outlets and inlets must be supplied through a zone valve that has a wall between it and the outlets it controls, is operable from a standing position, and is visible and accessible at all times.
A zone valve may not be hidden behind normally open or closed doors, placed in the room it controls, or placed in rooms or closets that can be closed or locked.
Each Category 1 space needs a zone valve in each gas and vacuum line; in anesthetizing locations the zone valves go immediately outside each room.
Piping on the patient side of a zone valve may serve outlets only on the same story, and closing one zone must not affect any other zone.
Zone valves are installed in valve boxes with removable covers, with a pressure or vacuum indicator on the outlet side of each zone valve.
The Purpose of a Zone Valve
A zone valve controls the gas or vacuum to one area. In a fire, a leak, or an outlet failure, clinical staff, not just the maintenance department, may need to shut it off within seconds. Every location rule below exists so the valve can be found, reached, and operated by the right person at the right moment.
Placement Rules for Every Zone Valve
All station outlets and inlets must be supplied through a zone valve, placed as follows:
| Must | Must not |
|---|---|
| Have a wall between the valve and the outlets it controls | Be installed in the room with the outlets it controls |
| Be readily operable from a standing position | Be hidden from plain view, such as behind a normally open or normally closed door |
| Be visible and accessible at all times | Be installed in rooms, areas, or closets that can be closed or locked |
These rules work together. The wall keeps a person who is closing the valve out of the fire or gas release, while a visible, unlocked, standing-height valve means nobody needs a key or a ladder.
Category 1 Spaces and Anesthetizing Locations
A zone valve in each medical gas and vacuum line is required for each Category 1 space:
- In patient care spaces that are not anesthetizing locations, the zone valves go immediately outside the area or zone being controlled.
- In anesthetizing locations, they go immediately outside each room.
A suite of six operating rooms therefore gets a zone valve box outside each OR, not one box for the whole suite. An ICU may be zoned as an area, with its zone valve box immediately outside the unit, typically at the entrance staff use.
Arrangement on the Patient Side
Piping on the patient side of a zone valve must be arranged so that:
- Shutting off one zone does not affect the supply to any other zone or to the rest of the system.
- The zone serves outlets and inlets only on the same story.
- All gas delivery columns, hose reels, ceiling tracks, control panels, pendants, booms, and other special installations are on the patient side of the zone valve.
Zone Valve Box Assemblies
| Requirement | Detail |
|---|---|
| Enclosure | Zone valves go in valve boxes with removable covers large enough to allow manual operation of the valves |
| Securing in special areas | In areas such as psychiatric or pediatric units, zone valves may be secured with AHJ approval to prevent inappropriate access |
| Flammable gases | Valves for nonflammable medical gases may not share a zone valve box with valves for flammable gases |
| Indicator | A pressure or vacuum indicator goes on the station outlet/inlet side of each zone valve |
| Security exemption | Zone valve box valves are the one group exempt from the general valve-securing rule (they must stay operable by staff) |
Labeling: zone valve box assemblies are labeled with the rooms, areas, or spaces they control, for example "ZONE VALVES FOR THE (GAS) SERVING (ROOMS)." The label must be visible from outside through the cover or replicated on the outside, but never fixed to the removable cover. A label on the cover can be lost or put back on the wrong box after service.
Alarm Sensors Near Zone Valves
Area alarm sensors (Section 5.4) are installed relative to zone valve boxes:
- For Category 1 spaces other than anesthetizing locations, sensors go on the patient or use side of each zone valve box assembly.
- For anesthetizing locations where moderate sedation, deep sedation, or general anesthesia is given, sensors may go on either the source side or the patient side of each room's zone valve box.
Installation and Testing Notes
- Zone valves arrive with copper tube extensions and purge ports on both sides. Braze to the extensions under nitrogen purge, following the valve manufacturer's instructions on heat and valve position.
- During the verifier's valve test, each zone valve is closed to confirm it controls only the outlets listed on its label. A zone that also shuts off an outlet in the next room is a piping or labeling error that must be fixed before the system goes into service.
- Keep the area in front of zone valve boxes clear. Equipment parked in front of a box makes it "not accessible at all times."
Scenario Check
A design places the zone valve box for an ICU inside the unit's clean supply room, which has a self-closing, keypad-locked door. This fails twice: the box is in a room that can be locked, and it is not visible at all times. Moving it to the corridor wall just outside the unit entrance, at standing height, with nothing obstructing it, meets the rules.
Where must the zone valves for an operating room in which general anesthesia is given be located?
Inside the operating room near the anesthesia machine
In the suite's locked anesthesia workroom
At the riser serving the surgical floor
Immediately outside each operating room
A zone valve box is proposed inside a clean-utility closet that has a lockable door, just outside a patient wing. What is the problem?
Zone valves may not be in rooms or closets that can be closed or locked
Zone valve boxes must be mounted above ceilings
Zone valves may only be installed in corridors on the floor below the zone
There is no problem as long as charge nurses and maintenance staff carry keys
Where must the pressure or vacuum indicator for a zone valve be installed?
On the source side of the zone valve, toward the riser
Inside the area alarm panel only
On the patient (outlet) side of the zone valve
At the master alarm panel
Sections you finish are checked off in the contents.