Mechanical and Electrical Systems Essay
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SizingSanitaryDrainageandVentPiping.ppsPowerPoint® Presentation
Chapter 4-*
PowerPoint® Presentation
Chapter 4
Sizing Sanitary Drainage and Vent Piping
One-Story, One-Family Dwelling • Duplex Residence • Multifamily Dwelling • Multistory Building Bathroom Stack • Two-Story Industrial Building Bathroom Piping • Two-Story Office Building Bathroom Piping
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A typical one-story, one-family dwelling consists of a bathroom with water closet, lavatory, and bathtub, kitchen sink, laundry tray, and floor drain.
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A typical one-story, one-family dwelling may consist of a bathroom (with water closet, lavatory, and bathtub) and kitchen sink on the first floor, and a laundry tray and floor drain with 2″ trap in the basement. See Figure 4-1. The dfu values for the fixtures in the dwelling are based on the Drainage Fixture Unit Values for Common Plumbing Fixtures table.
Individually vented fixture traps provide greater protection from trap siphonage and back pressure.
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In some jurisdictions, additional venting may be necessary to satisfy plumbing code requirements. See Figure 4-2. All fixtures except the floor drain are vented. The building drain from the stack is 4″ pipe with a 4″ cleanout at the inside of the foundation wall. A 2″ branch pipe serves the floor drain, laundry tray, and stand pipe.
The plumbing plan of a typical two-story residence shows individual venting of all fixtures.
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Two-story, one-family dwellings typically include plumb-
ing fixtures on both floors as well as in a basement. The first floor may have a water closet, lavatory, and kitchen sink, and the second floor has a water closet, lavatory, and bathtub. A laundry tray and floor drain are located in the basement. See Figure 4-3.
A no-hub vented closet tee offsets a water closet on a lower floor from the stack to properly vent the water closet.
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The first-floor water closet is set off to the side of the 3″ stack. The water closet drains into a 3″ sanitary tee and a wye in the stack. The water closet may be connected using a vented closet tee or cross. A vented closet tee and vented closet cross are specially designed fittings for offsetting a water closet on a lower floor from the stack to properly vent the water closet. See Figure 4-4. Vented closet tees and crosses are available with side openings to accept the wastes of other fixtures on the same floor. Waste from the lavatory on the first floor is drained by 1 1/4″ pipe into either a wye below the closet bend or into the side opening of the vented closet tee.
A duplex residence typically includes similar plumbing fixtures on each floor of the duplex.
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A duplex residence contains similar plumbing fixtures on each floor or area of the duplex. See Figure 4-5. Each floor of the duplex consists of a kitchen with a sink, and a bathroom with a water closet, lavatory, and bathtub. The basement consists of a bathroom with a water closet and a lavatory, two laundry trays, and a floor drain.
Back-to-back bath-rooms are common in multifamily dwellings such as an apartment.
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One of the stacks in a multifamily dwelling serves the bathrooms for the four units. See Figure 4-6. The waste portion of the soil stack is 3″ pipe, since only two water closets discharge their waste at one story or branch interval. The vent portion of the soil stack can be reduced to 2″ pipe through the roof if there is another full-size stack in the building.
Fixtures can be individually vented in multifamily dwellings with back-to-back bathrooms.
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Individually vented fixtures virtually eliminate siphonage and back pressure in a drainage system. See Figure 4-7. In this installation, the back-to-back lavatory waste pipe is reduced to 1 1/2″ pipe with a 1 1/4″ common vent for the two lavatories. The bathtubs are vented with a 1 1/4″ common vent pipe, while discharging their waste into
1 1/2″ waste pipes. The remainder of the waste and vent piping and sizing is the same as the waste and vent pipe sizing in Figure 4-6.
A separate kitchen waste stack may be installed in a multi-family dwelling to convey kitchen waste.
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A kitchen waste stack may be installed in a multifamily dwelling to convey kitchen waste. See Figure 4-8. A 2″ pipe is used for the lowest portion of the waste stack because it receives 8 dfu of discharge (4 kitchen sinks × 2 dfu = 8 dfu). The portions of the stack that receive only the waste from first-floor kitchen sinks and only the waste from the second-floor kitchen sinks are sized as 2″ pipe. Per the Maximum Size for Soil and Waste Stacks table, a 1 1/2″ waste stack cannot be used, since only 2 dfu are permitted to drain into a 1 1/2″ waste stack on any one floor or branch interval.
The bathtubs in a multistory bathroom stack may be wet vented through the lavatory waste pipe.
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Some multistory buildings, such as hotels, require only a bathroom stack. Bathroom waste and vent pipe connec-tions are individually vented, similar to bathroom waste and vent piping in a residence. The bathtub trap is wet vented through the lavatory waste pipe. See Figure 4-9.
Public and private buildings may have gender-specific facilities.
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In public and some private buildings, gender-specific bathroom facilities must be provided. A women’s bathroom typically includes water closets and lavatories, while a men’s bathroom includes water closets, lavatories, and urinals. See Figure 4-10. The men’s bathroom, located on the first floor, contains two water closets, two wall-hung urinals with 2″ traps, and two lavatories that are located on the same wall. The women’s bathroom, located on the second floor, contains four water closets and four lavatories. The women’s bathroom fixtures are located on the same wall as the men’s bathroom fixtures.
A waste and vent pipe installation for a typical two-story office building has men’s and women’s bathrooms back-to-back on each floor.
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Buildings with a larger occupancy require a larger number of fixtures to provide adequate facilities for the occupants. If possible, the men’s and women’s bathrooms are located back-to-back on each floor so the waste and vent piping can be economically installed. See Figure 4-11.
Water closet supporting chair carrier fittings are used to support wall-hung water closets.
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Each of the men’s bathrooms contains four wall-hung water closets, two urinals with 2″ traps, three lavatories, and a 2″ floor drain between the urinals. Each of the women’s bathrooms contains five wall-hung water closets, four lavatories, and a 2″ floor drain between the first and second water closet stalls. The wall-hung water closets in both bathrooms are back-to-back on a common wall, while the other fixtures are on the opposite bathroom walls. Wall-hung water closet supporting chair carrier fittings are available in a variety of styles to accommodate most installations. See Figure 4-12.
