4. The distance then, between this established “spill level” and the end of the lowest water supply pipe/spout, is the air-gap.
5. The minimum air-gap (“Y”) is the distance between the supply pipe/spout and the “spill level” established in the receptacle/fixture.
6. The “spill level” shall be a distance no greater that one half of the distance measured as “Y,” (½ “Y”) above the discharge opening in the receptacle/fixture. Therefore, the air-gap between the supply pipe/spout and the highest portion of the opening that discharges to the atmosphere shall be a distance no greater than one and one half “Y” (1 ½ “Y”).
Note: In any case, regardless if the end of the pipe/spout is cut square or at an angle, the air-gap is the distance between the lowest end of the pipe/spout and the “spill level” of the receptacle/fixture.
The measurement for this air-gap, however, could be as much as 3 times the diameter of the pipe/spout depending upon the number of near walls. The distance of a near wall is a relationship to the diameter of the pipe/spout and the measurement from the wall to the closest side of the pipe/spout:
1. If there is one near wall, and the distance between that near wall and the closest edge of the supply pipe/spout is greater than 3 times the diameter of the supply pipe/spout, then the minimum air-gap is 2 times the diameter of the supply pipe/spout.
2. If there is one near wall, and the distance to the closest edge of the supply pipe/spout is less than 3 times the diameter of the pipe/spout, then the minimum air-gap is 3 times the diameter of the supply pipe/spout.
3. If there are 2 near walls, and the distance between the near wall(s) and closest edge of the supply pipe/spout is greater than 4 times the diameter of the supply pipe/spout, then the minimum air-gap is 2 times the diameter of the supply pipe/spout.
4. If there are 2 near walls, and the distance to the closest edge of the supply pipe/spout is less than 4 times the diameter of the supply pipe/spout, then the minimum air-gap is 3 times the diameter of the supply pipe/spout.
It has been determined that 2 or more near walls generally have little effect on the need to increase the air-gap to more than 3 times the diameter of the supply pipe/spout.
Note: See the following sketches as examples of an air-gap with pipe/spouts terminating above the flood level rim of the receptacle/fixture, of an air-gap with pipe/spouts terminating below the flood level rim of the receptacle/fixture and of an air-gap with pipe/spouts when terminating by one near wall.
A-382.41 (5)-1. AIR-GAP WITH PIPE/SPOUT(S) ABOVE FLOOD LEVEL RIM OF RECEPTACLE/FIXTURE.
Minimum 1 inch
or
two times the pipe diameter, whichever is greater
WATER SUPPLY AIR-GAP ASME 112.1.2
A-382.41 (5)-2. AIR-GAP WITH PIPE/SPOUT(S) BELOW FLOOD LEVEL RIM OF RECEPTACLE/FIXTURE.
2 inch diameter water supply
If distance is 3 times or greater than the diameter of water supply (2 inch), then the air-gap is 2 times the diameter of the water supply, (i.e., 2 X 2 = 4 inches)
If the distance is less than 3 times the diameter of the water supply (2 inch), then the air-gap is 3 times the diameter of the water supply, (i.e., 3 X 2 = 6 inches)
A PARTIAL TABLE FOR THE SELECTION OF BACKFLOW PROTECTION *
*Any situation may be subject to an alternate approval.
1 If less than 15 pounds steam or 30 pounds water and nontoxic chemicals.
2 If greater than 15 pounds steam or 30 pounds water and toxic chemicals.
3 Requires backflow protection even if there is a plain end spout.
4 Requires separate water supply terminating without a hose thread, or the manufacturer must provide a bleed device to connect to the janitor sink faucet spout.
5 Or, provide bottled water conversion unit.
6 For outlets other than the required ASSE 1019 hydrants.
7 If provided with hose threads or serrated nipple.
8 Faucet meeting ASME A112.18.1M that includes backflow protection requirements.
9 Hydrants that bleed into the ground and hydrants that are flush with the grade are prohibited.
A-382.41 (5) (f)-1. CROSS CONNECTION CONTROL ASSEMBLY INSTALLATION.
A-382.41 (5) (f)-2. CROSS CONNECTION CONTROL ASSEMBLY INSTALLATION.
A-382.41 (5) (f)-3. CROSS CONNECTION CONTROL ASSEMBLY INSTALLATION.
A-382.41 (5) (f)-4. CROSS CONNECTION CONTROL ASSEMBLY INSTALLATION.
A-382.41 (5) (f)-5. CROSS CONNECTION CONTROL ASSEMBLY INSTALLATION.
A-382.50 (3) (b) 5. OPTIONS FOR TEMPERATURE CONTROL IN HEALTH CARE FACILITIES. The following sketches provide options for fail safe installations at the bathing and shower fixture and temperature control at handwashing fixtures.
A-382.51 (3) MOBILE HOME SITES AND PARKS. Mobile home building sewer and water service connections.
Frost sleeves terminate 2 inches above grade
