(b) Installation. Approved devices to protect against backflow backsiphonage shall be installed at all fixtures and equipment where backflow or backsiphonage may occur and where a minimum air gap cannot be provided between the water outlet to the fixture or equipment and its flood-level rim. Devices for the prevention of backflow shall be installed as follows.
(1) Vacuum breakers. Vacuum breakers shall be installed with the critical level at least six inches above the flood level rim of the fixture they serve and on the discharge side of the last control valve to the fixture. No shutoff valve or faucet shall be installed on the discharge side of the vacuum breaker. For closed equipment or vessels such as pressure sterilizers the top of the vessels shall be treated as the flood level rim but a check valve shall be installed on the discharge side of the vacuum breaker.
(2) Reduced pressure principle backflow preventer. A reduced pressure principle type backflow preventer may be installed subject to full static pressure.
(3) Devices of all types.
(A) Backflow and backsiphonage preventing devices shall be accessibly located, preferably in the same room with the fixture they serve. Installation in the utility or service spaces, provided they are readily accessible, is also permitted.
(B) No installation shall be made in pits or other locations not properly drained, unless specifically authorized by the installation instructions of the backflow prevention device.
(4) Connections not subject to back pressure. Where a water connection is not subject to back pressure, a vacuum breaker shall be installed on the discharge side of the last valve on the line serving the fixture or equipment. A list of some conditions requiring protective devices of this kind is given in Table 1, “Cross-Connections Where Protective Devices are Required and Critical Level (C-L) Settings for Vacuum Breakers”.
(5) Connections subject to back pressure. Where a potable water connection is made to a line, fixture, tank vat, pump or other equipment with a hazard of backflow or backsiphonage where the water connection is subject to back pressure, and an air gap cannot be installed, the Building Official/Code Enforcement Officer may require the use of an approved reduced pressure principle backflow preventer assembly or double check valve assembly. A partial list of such connections is shown in Table 2.
(6) Automatic fire suppression system.
(A) All new installations of automatic fire suppression systems of 15 heads or more or having a Fire Department connection shall be protected from backflow with-an approved double check valve assembly.
(B) Any fire suppression system into which chemicals of any type (corrosion, antifreeze and the like) can be added shall be protected at the service connection with an approved reduced pressure principle assembly.
(C) In lieu of such protection, an antifreeze loop may be individually protected with an approved reduced pressure principle assembly in addition to proper service line protection.
(Ord. 1051, passed 9-5-1989)