§ 172.035 MINIMUM PROTECTION.

   (A)   When backflow or backsiphonage prevention devices are required by this code, the prevention devices shall provide a minimum level of protection as provided below.

Cross-Connection Rated by Degree of Hazard for Commonly Encountered Equipment, Fixtures, Facilities and Their Use. (For a more complete list, refer to the Manual of Cross-Connection referenced in section 008.01E9a)
DIRECT OR INDIRECT POTABLE WATER CONNECTIONS
	Hazard
	High	Low
I.   Subject to Back Pressure
A.   Pumps, tanks and lines handling:
1.   Sewage	x
2.   Toxic substances	x
3.   Nontoxic substances		x
B.   Water connection to steam and steam boiler:
1.   Boiler or steam connection to toxic substances	x
2.   Boiler or steam connection to nontoxic substances (boiler blowoff through air gap)		x
II.   Not Subject to Back Pressure
A.   Sewer-connected water line (not subject to waste stoppages)	x
B.   Low inlets to receptacles containing:
1.   Toxic substances	x
2.   Nontoxic substances		x
C.   Coils or jackets used as heat exchangers in compressors in lines carrying:
1.   Sewage	x
2.   Toxic substances	x
3.   Nontoxic substances		x
D.   Flush valve toilets or urinals	x
E.   Toilet, urinal tanks and approved bath tubs		x
F.   Bidets, sitz tanks or spa, therapy and roman pools not otherwise isolated by design or backflow protectors	x
G.   Trough urinals		x
H.   Valved outlets or fixtures with hose attachments that may constitute a cross-connection to:
1.   Toxic substances	x
2.   Nontoxic substances
I.   Aspirators that may constitute a cross-connection to:		x
1.   Toxic substances	x
2.   Nontoxic substances		x
III.   Other Equipment and Facilities Subject to a Variety of Backflow Conditions
A.   Lawn sprinkling systems that may constitute a cross-connection to:
1.   Toxic substances	x
2.   Nontoxic substances		x
B.   Fire suppression systems employing toxic chemicals	x
C.   Soft drink dispenser or bar carbonators	x
D.   Radiological, photographic, dental, medical, biological or chemical laboratories or facilities	x
E.   Swimming pools	x
F.   Tank truck loading station	x

 

PERMITTED BACKFLOW ASSEMBLIES, DEVICES AND METHODS
Assembly, Device or Method	Degree of Hazard				Installation
	Low		High
	Backsiphonage	Back Pressure	Backsiphonage	Back Pressure
Air gap	x	x	x	x	Shall be a minimum of 1 inch but not less than 2 times the diameter of the effective spout opening when not affected by side walls and 3 times the diameter of the effective opening when affected by side walls. Side walls will be assumed to not affect the air gaps when they are spaced horizontally a distance greater than 4 times the effective opening from the spout opening.
Atmospheric Vacuum Breaker	x		x		Upright position, No valves downstream. Minimum of 6 inches or listed distance above all downstream piping and flood level rim of receptor.
Double Check Valve Assembly	x	x			Horizontal unless otherwise listed. Requires 1 foot below and sufficient side and head room for testing and maintenance with a maximum of 5 feet above the ground, work floor or a permanently installed working platform with stairs or ladder affixed. Does not discharge water.
Pressure Vacuum Breaker Assembly	x		x		Upright position. May have valves downstream. Minimum of 12 inches above all downstream piping and flood level rim of receptor. May discharge water.
Reduced Pressure Principle Backflow Prevention Assembly	x	x		x	Same as Double Check Valve Assembly above except may discharge water and wherever installed, provision for draining away at least 2 times the rated gallons per minute of the device shall be made.
Dual Check Valve	x	x			Residential service only, and where high hazards are not known to exist on the premises. Properly protected lawn sprinkling systems are assumed to be low hazard for this purpose. Dual checks are not subject to annual inspection unless so stipulated by the manufacturer. Otherwise, reasonable inspection periods will be assumed to be every 5 years.

 

   (B)   Provided, however, this shall be a minimum standard of protection. When, in the opinion of the Water Commissioner/Public Works Commissioner, a different level of protection would be more appropriate, the Water Commissioner/Public Works Commissioner shall prescribe the method of backflow or backsiphonage protection.

(Prior Code § 3-127)