9.4 Protecting Specific Connections: Beverage Dispensers, Boilers, Sprinklers, Irrigation & Equipment

Beverage dispensers (IPC 608.17.1)

Carbonated beverage dispensers (608.17.1.1): each water supply connection must be protected by a backflow preventer conforming to ASSE 1022, or by an air gap. The part of the device downstream of the second check valve, and the piping downstream, shall not be affected by carbon dioxide gas.

Why it matters: carbon dioxide dissolved in water forms carbonic acid. If carbonated water backs up into copper or copper-alloy piping, it can dissolve copper and poison people who drink from the dispenser. That is why the downstream materials must resist CO₂, and why installers use stainless steel or plastic tubing there instead of copper. Table 608.1 lists the ASSE 1022 device as a low-hazard backpressure and backsiphonage preventer for sizes 1/4 to 3/8 inch.

Coffee machines and noncarbonated drink dispensers (608.17.1.2): an ASSE 1022 or ASSE 1024 backflow preventer, or an air gap.

Boilers and heat exchangers (IPC 608.17.2 and 608.17.3)

• Boilers: the potable supply to a boiler must have a backflow preventer with an intermediate atmospheric vent conforming to ASSE 1012, ASSE 1081 or CSA B64.3. This applies whether the boiler is residential or commercial.
• Where conditioning chemicals are introduced into the boiler system, the potable connection must be protected by an air gap or an RP assembly (ASSE 1013, AWWA C511 or CSA B64.4).
• Heat exchangers: those using an essentially toxic transfer fluid must be separated from potable water by double-wall construction with an air gap open to the atmosphere between the walls. Those using an essentially nontoxic fluid may be single-wall.

A boiler fill valve (pressure-reducing valve) lowers pressure for the boiler but is not a backflow preventer.

Automatic sprinkler and standpipe systems (IPC 608.17.4 and 608.17.4.1)

The potable supply to sprinkler and standpipe systems must be protected by:

• a double check backflow prevention assembly;
• a double check fire protection backflow prevention assembly; or
• a reduced pressure principle fire protection backflow prevention assembly.

Exceptions:

1. Systems installed as part of the water distribution system under the IPC (for example, some residential sprinkler systems), without a fire department connection, need no isolation.
2. Deluge, preaction and dry pipe systems need no isolation of the water distribution system.

608.17.4.1 additives or nonpotable source: where a system under continuous pressure contains chemical additives or antifreeze, or is connected to a nonpotable secondary water supply, protection must be an RP assembly or an RP fire protection assembly. Where additives or antifreeze are in only part of the system, the RP may isolate that part. Where the system is not under continuous pressure, an air gap or an ASSE 1001 atmospheric vacuum breaker is required.

Detector assemblies (double check detector, ASSE 1048; RP detector, ASSE 1047) add a bypass meter that shows unauthorized use or leaks.

Lawn irrigation (IPC 608.17.5)

The potable supply must be protected by an atmospheric vacuum breaker, a pressure vacuum breaker assembly, or an RP assembly.

• Valves shall not be installed downstream from an atmospheric vacuum breaker. An AVB on an irrigation system therefore goes on each zone, downstream of its zone valve, at least 6 inches above the highest head.
• A PVB on the main supply ahead of the zone valves must have its critical level at least 12 inches above all downstream piping and heads (608.14.5).
• Where chemicals are introduced into the system, such as fertilizer injection, the supply must be protected by an RP assembly. Vacuum breakers do not protect against the backpressure an injector pump can create.

Other required connections (IPC 608.17.6 to 608.17.10)

Fixtures and equipment covered elsewhere

• Hospital fixtures (608.3.1): an RP, an atmospheric or spill-resistant vacuum breaker, or an air gap. Bedpan washer hose vacuum breakers at least 5 feet above the floor; hose vacuum breakers in health care or laboratory areas at least 6 feet.
• Health care (609.4 and 609.5): vacuum breakers are installed per 608.16.4, and fixture-specific rules govern water closet and clinical sink supplies.
• Specialty fixtures (423.1, as amended by Virginia): baptisteries, ornamental and lily pools, aquariums, fountain basins, swimming pools, footbaths and pedicure baths with water supplies must be protected under 608.
• Clothes washers (406.1) and dishwashers (409.2): an integral air gap or a backflow preventer per 608.
• Bidets (408.2): an air gap or one of the listed backflow preventers.
• Garbage can washers (417.1): an air gap or one of the listed backflow preventers.
• Water treatment equipment (608.4 and 611.2): discharge through an air gap.
• Yard hydrants that drain into the ground (608.8): protected by an RP or PVB and identified.

Summary table