for each gpm flow of the discharge pumps and the developed length of the vent from the receiver to the vent stack or the outside air, in accordance with Table RS 16-14. The vent from a receiving tank may be connected to the gravity drainage vent system provided such system is 3 in. or larger.
(e) The relief devices of a pneumatic sewage ejector system shall be connected to an independent relief line vent at least 3 in. in diameter. Such vent shall be carried independently through a roof and shall terminate as required for sanitary vent stacks or stack vents. The mechanism for the relief of the air pressure in the closed sewage receptacle shall have valves, piping, and connection that form a part of the sewage ejector device. The devices shall be sufficient in size to relieve the ejector pit to atmospheric pressure in not more than 10 sec., and the minimum size of such valves and piping shall be 1 1/4 in.
(f) Sump pits or receiving tanks may be constructed of concrete provided the compartment is fully waterproofed and the walls of the pit troweled to a smooth finish. (g) Each sewage ejector or sump discharge shall be provided with a check valve and a gate valve.
P108.7 Sub-Soil Drainage.-Where sub-soil drainage is to be discharged to a public sewer, the sub- soil drains shall discharge into a readily accessible silt and sand interceptor designed by an architect or engineer, the drainage from which shall be disposed of into the gravity drainage system or a sump system. Where the piping from the interceptor is directly connected to the gravity drainage system, such piping shall be provided with an approved and readily accessible backwater valve and shall be connected upstream of a leader or area drain trap. Area drains may be connected to the sub-soil drainage system subject to the provisions of Section P110.2.
P108.8 Drainage Piping Installation.- (a) Pitch of horizontal drainage piping.-Horizontal drainage piping shall be installed in uniform alignment at uniform slopes as follows:
Size of Piping Minimum Slope 2 in. or less 1/4 in. per ft. Over 2 in. 1/8 in. per ft. (b) Change of direction.-
(1) Changes in direction in drainage piping shall be made by the appropriate use of 45 degrees wyes; long sweeps; short sweeps, quarter, sixth, eighth, or sixteenth
bends; or by a combination of these or equivalent fittings. (2) Sanitary tees and quarter bends may be used in drainage lines only where the direction of flow is from the horizontal to the vertical.
(3) Short sweeps will be permitted in drainage piping 3 in. in diameter or larger for any offsets either horizontal or vertical.
(c) Prohibited fittings and connections.-
(1) No running threads, bands, or saddles shall be used in drainage or vent piping. No drainage or vent pipes shall be drilled or tapped.
(2) No fitting, connection, device, or method of installation that retards the flow of water, wastes, sewage, or air in the drainage or vent systems to an extent greater than the normal frictional resistance to flow shall be installed. Double hubs are prohibited for use in drainage piping. No fitting having a hub faced downstream shall be used as a drainage fitting. No tee branch of a drainage fitting shall be used as an inlet branch for wastes. Double sanitary tees may not be used for a fixture connection when a blowout type fixture is connected to one of the inlets. (3) A heel-or side-inlet quarter bend shall not be used as a vent connection fitting in drainage piping when the heel- or side-inlet is placed in a horizontal position.
(4) The expanding or swedging of 3 in. lead bends or stubs to 4 in. size, thereby causing a reduction in pipe wall thickness, is prohibited. Approved 3 in. x 4 in. lead bends and stubs with uniformly proper wall thickness may be used for connections to 4 in. floor flanges, and 4 in. x 3 in. floor flanges may be used for connection to 3 in. lead bends and stubs.
(d) Dead ends.-In the installation of removal or any part of a drainage or vent system, dead ends shall be avoided except where necessary to extend a cleanout so as to be accessible.
(e) Provision for future fixtures.-Drainage and vent piping provisions for future fixture installations shall consist of plugged fittings at the stack, or of piping installed without dead ends.
P108.9 Sanitary Drainage Fixture Units.- (a) Value for fixtures.-Fixture unit values given in Table RS 16-12 shall be employed in computing the total load carried by a soil or waste pipe and shall be used with the tables for sizing soil, waste, drainage, and vent pipes.
(b) Values for continuous or semicontinuous flow.- Fixture unit values for continuous or semicontinuous flow into a drainage system, such as from a pump, ejector, air- conditioning equipment, or similar devices shall be computed on the basis of one fixture unit for each gpm of flow.
TABLE RS 16-12 SANITARY DRAINAGE FIXTURE UNIT VALUES a
Fixture Unit
Fixture or Group Value
Automatic clothes washer (2 in. standpipe) ...3 Bathroom group consisting of a lavatory, bathtub or shower stall, and a water closet (direct flushometer valve)………8 Bathroom group consisting of a lavatory, bathtub or shower stall, and a water closet (flush tank) ... 6 Bathtub with or without overhead shower ...2 Combination sink and wash tray ...3 Dental unit or cuspidor ...1 Dental lavatory ...1 Drinking fountain ...1/2 Dishwasher, domestic type ... 2 Floor drain ... 2b* Kitchen sink, domestic type ... 2 Lavatory ... 1 Lavatory (barber shop, beauty parlor or surgeon's) ... 2 Lavatory, multiple type (wash fountain or wash sink), per each equivalent lavatory unit or set of faucets ...2 Laboratory cup sink ... 1 Laboratory sink ... 2 Laundry tray (1 or 2 compartment) ...2 Shower stall ...2 Shower (group) per head ...2 Sink (surgeon's) ...3 Sink (flushing rim type, direct flush valve) ... 6 Sink (service type with trap standard) ... 3 Sink (service type with P trap) ...2 Sink (pot, scullery, or similar type) ...…... 4 Urinal (1 in. flush valve) pedestal ...6 Urinal (3/4 in. flush valve) stall or wall hung ...4 Urinal (flush tank) ...4 Water closet (direct flush valve) ... 6 Water closet (flush tank) ...4 Unlisted fixture, 1 1/4 in. fixture drain and 1 1/2 in. trap size ...1 Unlisted fixture, 1 1/2 in. fixture drain or trap size... 2 Unlisted fixture, 2 in. fixture drain or trap size ...3 Unlisted fixture, 2 1/2 in. fixture drain or trap size ... 4 Unlisted fixture, 3 in. fixture drain or trap size ...5 Unlisted fixture, 4 in. fixture drain or trap size ...6
Note-
a See section P108.9(b) for method of computing unit values for devices with continuous or semicontinuous flows. b
Any floor drains provided in an elevator vestibule or in an elevator shaft shall be excluded from being counted as fixture units.
*Local Law 26-2004.
P108.10 Sizing the Sanitary Drainage Piping.- (a) Drainage piping.-Sizes shall not be less than those permitted in Table RS 16-13, using the fixture unit values of Table RS 16-12.
(b) Sewer piping.-When more than one building house drain discharges into a private sewer within the property line, the sewer may be sized on a design basis and the slope of the sewer shall be predicated on the size selected, but in no case shall the slope be less than that required to produce a velocity in the sewer of less than 3 fps. (c) Minimum size of soil and waste stacks.-No soil or waste stack shall be smaller than the largest horizontal branch connected thereto, except that a 4 in. x 3 in. water closet connection shall not be considered as a reduction in pipe size.
(d) Provision for future fixtures.-When provision is made for the future installation of fixtures, those provided for shall be considered in determining the required sizes of drain and vent pipes.
(e) Minimum size of underground drainage piping.- No portion of the drainage system installed underground or below a basement or cellar floor on ground shall be
less than 2 in. in diameter, except that drip pipes may be 1 in. if of copper or brass.
(f) Sizing of offsets in drainage piping.-
(1) OFFSETS OF 45 DEGREES OR LESS.-An offset in a vertical stack, with a change of direction of 45 degrees or less from the vertical, may be sized as a straight vertical stack.
(2) OFFSETS OF MORE THAN 45 DEGREES.-A stack with an offset of more than 45 degrees from the vertical shall be sized as follows:
a. The portion of the stack above the highest offset shall be sized as required for a regular stack based on the total number of fixture units above the offset. b. The offset shall be sized as required for a building house drain (Table RS 16-13).
c. The portion of the stack below the offset shall be sized the same as the offset or based on the total number of fixture units on the entire stack, whichever is the larger.
d. A relief vent for the offset shall be installed as provided in section P109.12 and in no case shall a horizontal branch drain connect to the stack within 2 ft.
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