TABLE I
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---|---|---|
MINIMUM AIR GAPS FOR GENERALLY
USED PLUMBING FIXTURES
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Minimum Air Gap
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Fixture
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When not affected by near wall1
(inches)
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When not affected by near wall2
(inches)
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Lavatories and other fixtures with effective
openings not greater than 1/2 in. diameter
|
1.0
|
1.50
|
Sink, laundry trays, goose-neck bath faucets
and other fixtures with effective openings not greater than 3/4 in.
diameter
|
1.5
|
2.25
|
Over rim bath fillers and other fixtures with
effective openings not greater than 1 in. diameter
|
2.0
|
3.0
|
Drinking water fountains - single orifice 7/16
(0.437) in. diameter or multiple orifices having total area of 0.150
sq. in. (area of circle 7/16 in. diameter)
|
1.0
|
1.50
|
Effective openings greater than 1 in.
|
(3)
|
(4)
|
Notes:
| |
l
|
Side walls, ribs, or similar obstructions do not affect air
gaps when spaced from inside edge of spout opening a distance greater
than three times the diameter of the effective opening for a single
wall, or a distance greater than four times the diameter of the effective
opening for two intersecting walls.
|
2
|
Vertical walls, ribs, or similar obstructions
extending from the water surface to or above the horizontal plane
of the spout opening require a greater air gap when spaced closer
to the nearest inside edge of spout opening than specified in Note
1 above. The effect of three or more such vertical walls or ribs has
not been determined. In such cases, the air gap shall be measured
from the top of the wall.
|
3
|
Two times the diameter of effective openings.
|
4
|
Three times the diameter of effective openings.
|
TABLE II
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---|---|
SIZES OF OVERFLOW PIPES
FOR WATER SUPPLY TANKS
| |
Minimum capacity
of water supply line to tank
|
Diameter of overflow pipe
(inches ID)
|
0-50 gpm
|
2
|
50-150 gpm
|
2 1/2
|
100-200 gpm
|
3
|
200-400 gpm
|
4
|
400-700 gpm
|
5
|
700-1,000 gpm
|
6
|
Over 1,000 gpm
|
8
|
TABLE III
| |
---|---|
CROSS-CONNECTIONS WHERE PROTECTIVE DEVICES
ARE REQUIRED
AND CRITICAL LEVEL (C-L) SETTINGS FOR
VACUUM BREAKERS[1]
| |
Fixture or equipment
|
Method of installation
|
Aspirators and ejectors
|
C-L at least 6 in. above flood level of receptacle
served
|
Dental units
|
On models without built-in vacuum breakers -
C-L at least 6 in. above flood rim of bowl
|
Dishwashing machines
|
C-L at least 6 in. above flood level of machine.
Install on both hot and cold water supply line
|
Flushometers (closet & urinal)
|
C-L at least 6 in. above top of fixture supplies
|
Garbage can cleaning machine
|
C-L at least 6 in. above flood level of machine.
Install on both hot and cold water supply lines
|
Hose outlets
|
C-L at least 6 in. above highest point on hose
line
|
Laundry machines
|
C-L at least 6 in. above flood level of machine.
Install on both hot and cold water supply lines
|
Lawn sprinklers
|
C-L at least 12 in. above highest sprinkler
or discharge outlet
|
Steam tables
|
C-L at least 6 in. above flood level
|
Tank and vats
|
C-L at least 6 in. above flood level rim or
line
|
Trough urinals
|
C-L at least 30 in. above perforated flush pipe
|
Flush tanks
|
Equip with approved ball cock; where ball cocks
touch tank water, equip with vacuum breaker at least 1 in. above overflow
outlets; where ball cock does not touch tank water, install ball cock
outlet at least 1 in. above overflow outlet or provide vacuum breaker
as specified above
|
Hose bibbs (where aspirators or ejectors could
be connected)
|
C-L at least 6 in. above flood level of receptacle
served
|
Notes:
| |
1
|
Critical level (C-L) is defined as the level
to which the vacuum breaker may be submerged before backflow will
occur. Where the C-L is not shown on the preventer, the bottom of
the device shall be taken as the C-L.
|
TABLE IV
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---|---|
Partial List of Cross-Connections Which
May Be Subject to Backpressure
| |
Chemical lines
|
Pumps
|
Dock water outlets
|
Steam lines
|
Individual water supplies
|
Swimming pools
|
Industrial process water lines
|
Tank and vats-bottom inlets
|
Pressure tanks
|
Hose bibbs
|