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11 - 4 VENTILATING THE DRAINAGE SYSTEM
Transcript of 11 - 4 VENTILATING THE DRAINAGE SYSTEM
1.) Main soil and waste vent
2.) Main vent
3.) Individual vent
4.) Unit vent
5.) Circuit or loop vent
6.) Relief vent
7.) Yoke vent
8.) Wet Vent
9.) Looped vent
10.) Local vent
11.) Utility vent
TWO MAJOR CLASSIFICATIONS OF VENTILATION
1.) Main Soil and Waste Vents
- vent pipe used to ventilate the soil and waste pipes
2.) Relief and Yoke Vent
- only serve the fixture trap indirectly
- maintains the balance of atmospheric pressure inside the waste pipe system
GENERAL CONDITIONS IN INSTALLING
1.) Must be installed as direct as possible.
2.) Short radius fittings should be avoided, because it reduces the flow of air.
3.) As much as possible, long horizontal line must be avoided.
4.) Generally, it should have the same as diameter as the soil or waste pipe.
MAIN SOIL AND WASTE VENT
- portion of the soil stack above the highest installed fixture branch extending through the roof
- serves as the terminal for the main t and other vents of the system
11 - 4 VENTILATING THE DRAINAGE SYSTEM
The ways and forms of ventilation depends upon the location of the fixtures or how they are combined or grouped.
Economically, various methods of ventilation could be adopted by group venting. It is permitted provided, that every trap is ventilated as recommended by the NATIONAL PLUMBING CODE.
1.) Individual or back vent
2.) Unit vent
3.) Circuit or Loop vent
4.) Wet vent
5.) Looped vent
- types of ventilation whose main purpose is to protect the trap seal against back pressure and siphoning
NATIONAL PLUMBING CODE
Extension of Soil or Waste Stack to the Roof Provides that:
"All roof extensions of soil or waste stack shall run full size at least 30 centimeters above the roof and when the roof is used for other purposes than weather protection, such extension shall not be less than 2 meters above the roof... the roof terminal of any stack or vent, if within 3 meters of any door, window, scuttle, or air shaft, shall extend at least 1 meter above the same."
THE MAIN VENT
- portion of the vent pipe system, serving as terminal for the smaller forms of individual and grouped fixture trap ventilation
- also referred to as COLLECTING VENT LANE
- the drainage system is a combination of WASTE PIPE, VENT PIPE, and WATER SUPPLY
SIZE OF THE MAIN VENT
A large volume of water flowing through the waste pipe, require a greater quantity of air moving at higher velocity to maintain atmospheric pressure.
Long runs of vent pipe, reduces the flow and volume of air, because of the friction between the air in motion, and the interior surface of the pipe. The most logical methods in finding the size of the vent pipe, is through UNIT SYSTEM, as established by the SUB COMMITTEE ON PLUMBING presented in the RECOMMENDED MINIMUM REQUIREMENTS.
GENERAL CONDITIONS FOR MAIN VENT INSTALLATION
1.) The main vent shall be in full size at their base to the main soil or waste pipe or below the lowest fixture branch. It shall be extended undiminished in size above the roof, or shall be connected with the main soil vent, at least 1 meter above the highest fixture branch.
2.) The main vent shall also serve as a relief vent for any anticipated back pressure. It must be free form offsets to allow free movement of air and well supported on each floor, if not embedded in concrete column, walls, or partitions.
HOW TO USE TABLE 11 - 1
Determine the size of the main vent that will serve 30 fixture units.
1.) Referring to Table 11-1, it appears that a 63mm (2 1/2") pipe could serve up to 36 fixture units.
2.) Therefore, specify a 63mm diameter pipe for the main vent pipe.
- also referred to as BACK VENT
- portion of the vent pipe system that serves as a single trap and connected closer to the trap directly underneath and back of the fixture, and reconnected into the main vent above the overflow line of the fixture it serves
- the most effective means of venting fixture trap to prevent minus or plus pressure
INDIVIDUAL VENT FOR LAVATORY, SINK, ETC.
NATIONAL PLUMBING CODE
Distances of vent from trap seal provides that:
1.) No trap seal shall be placed more than 1.5 meters horizontal developed length form its vent.
2.) The distance should be measured along the central line of the waste or soil pipe form the vertical inlet to the trap to the vent opening.
3.) The vent opening form the soil or waste pipe, except for water closets and similar fixtures, should not be the dip of the trap.
HORIZONTAL DEVELOPMENT LENGTH
INDIVIDUAL VENT FOR BATHTUB AND SHOWER
INDIVIDUAL VENT FOR WATER CLOSET
On Branch and Individual Vent, the Plumbing Code provides that:
"No vent shall be less than 38mm (1 1/2") diameter except for a 32mm (1 1/4") diameter waste pipe. The vent pipe shall be of the same diameter size as the waste pipe, and in no ca must a branch or main vent have a diameter less than 1/2 that of the soil or waste pipe served, nor shall the length of a branch vent of a given diameter exceed the maximum length permitted for the main vent serving the same size of vent stack."
On Vent Pipe Grades and Connections the Code further states that:
"All vents and branch bent pipes shall be free from drops or sags and shall be so graded and connected so as to drip back water to the soil or waste pipe gravity. Where vent pipes connect to a horizontal soil or waste pipe, the vent branch shall be taken off above the center line of the pipe and whenever practicable, the vent pipe must rise vertically or at angle 45° to the vertical up to the point 15 centimeters above the fixture it is venting before offsetting horizontally or connecting to the branch main waste or soil vent."
- that portion of a vent pipe system that ventilates two fixture traps that discharges into a sanitary cross with deflectors
- another form of individual vent, with identical form of back venting, having the same principles in functions
- common to fixture trap serving apartment and hotel toilet particularly, on fixtures with identical position and measurements
UNIT VENT OF WATER CLOSETS
UNIT VENT OF WALL HUNG FIXTURE
UNIT VENT FOR BATHTUB INSTALLATION
CIRCUIT OR LOOP VENT
- employed where two or more fixture traps are installed on a horizontal soil or waste branch
- commonly used on buildings with more facilities, and battery of fixtures
CIRCUIT VENT FOR A BATTREY OF FIXTURES
CIRCUIT VENT FOR A BATTERY OF 16 WATER CLOSETS
A group of 5 lavatories is to be circuit vented. Find the size of the circuit vent pipe.
1.) Solve for the total fixture unites of the 5 lavatories. Refer to table 5-1; 5 lavatories X 1 unit = 5 units.
2.)Refer to table 11-3. Under 2nd column 8 fixture unites require 38mm vent pipe.
3.) Specify 38mm diameter circuit vent pipe.
On Circuit Vent for a battery of water closets, the Code says that:
"No more than 8 water closets or other fixtures shall be allowed on any circuit or loop vent. If there are 14 or 16 water closets which are to be vented, two pieces of 100mm pipe should be installed."
For Circuit or Loop Vents, the Code also provides that:
"Circuit or loop vent is permitted provided that a branch soil or waste pipe to which two and not more than 8 water closets, pedestal urinals, trap standard slop sinks, or shower stalls are connected in a series, may be vented by a circuit or loop vent, which should be taken off in front of the last fixture connection.
Where fixtures discharge above such branch, each branch shall be provided with a Relief Vent one half the diameter of the soil or waste stack, taken off into front of the fixture connection."
- installed to ventilate the soil and waste pipe and the connecting branches of rather than the fixture traps
- the installation of the relief vent depends upon the good judgement of the plumber, to wherever back pressure is most likely to occur
CIRCUIT- RELIEF VENT ON SOIL BRANCH
On Relief Vent, the Plumbing Code provides that:
1.) Waste branches which are circuit vented, shall be provided with relief vent.
2.) The base of the soil track on tall building installation is susceptible to back pressure, due to the large volume of water rushing down inside the pipe. Hence, a Relief Vent in this portion of the installation is necessary.
3.) Relief Vent may be installed at interval in the soil pipe having changes in directions.
RELIEF VENT FOR TALL BUILDING
4.) On long vertical soil pipe, a Relief Vent is installed at 3 to 5 floor intervals. In this manner of installation, the Relief Vent is sometimes referred to as YOKE or BY- PASS VENTILATION.
5.) Relief Vent serving a circuit vented branch, should have at least one half the diameter of the said soil pipe, but in no case, be less than 38mm diameter. For instance, if the soil pipe is 100mm the relief vent is 50mm but in no case, be less than 38mm diameter.
RELIEF VENT FOR HOUSE DRAIN
6.) A relief vent used on a change of direction, and at the base of the soil pipe, shall have a diameter equal to the main vent, and in no case, the relief vent be less than 50mm diameter.
7.) Yoke Vent between the main vent and the soil pipe at 5 floor intervals must have equal pipe diameter, as the main vent.
THE RELIEF AND YOKE VENT
- one type of ventilation use on fixtures in a room away form partitions
- common to beauty parlor, barber shop, dental clinic, and operating room
- size of looped vent is also determined in the same manner as that of the individual vent