Valve selection principles used in water supply pipelines
1. When the pipe diameter is not greater than 50mm, a globe valve should be used, and when the pipe diameter is greater than 50mm, a gate valve and a butterfly valve should be used.
2. When the flow and water pressure need to be adjusted, a regulating valve and a stop valve should be used.
3. The gate valve should be used for parts requiring small water flow resistance (such as on the suction pipe of the water pump)
4. Gate valves and butterfly valves should be used on the pipe sections where the water flow needs to flow in both directions, and stop valves should not be used.
5. Butterfly valve and ball valve should be used for parts with small installation space
6. On the pipe section that is often opened and closed, a stop valve should be used
7. Multi-function valves should be used on the outlet pipes of pumps with larger diameters
(2) The valve setting position on the water supply pipeline
1. The water supply pipe of the residential area is introduced from the introduction pipe of the municipal water supply pipe
2. The nodes of the outdoor annular pipe network in the residential area shall be set according to the separation requirements.When the annular pipe section is too long, a segmented valve should be installed
3. The starting end of the branch pipe connected from the main water supply pipe of the residential area or the starting end of the household pipe
4. Household pipe, water meter and each branch riser (the bottom of the riser, the upper and lower ends of the vertical ring pipe network riser)
5. The branch pipe of the annular pipe network and the connecting pipe running through the branch pipe network
6. The starting end of the water distribution pipe from the indoor water supply pipeline to the households, public toilets, etc., and the water distribution points on the water distribution branch pipe are set when there are 3 or more water distribution points.
7. The outlet pipe of the water pump, the suction pump of the self-priming water pump
8. The inlet, outlet and drain pipes of the water tank
9. Water supply pipes for equipment (such as heaters, cooling towers, etc.)
10. Water distribution pipes for sanitary appliances (such as toilets, urinals, washbasins, showers, etc.)
11. Some accessories, such as automatic exhaust valve, pressure relief valve, water hammer eliminator, pressure gauge, sprinkler, etc., before and after the pressure reducing valve and backflow preventer, etc.
12. A drain valve should be set at the lower part of the water supply pipe network
(3) Selection of check valve
The check valve should generally be selected according to its installation location, water pressure in front of the valve, airtight performance requirements after closing, and the size of water hammer caused by closing:
1. When the water pressure in front of the valve is small, swing, ball and shuttle check valves should be used
2. When the airtight performance after closing is strictly required, a check valve with a closing spring should be selected.
3. When it is required to weaken and close the water hammer, a quick-closing muffler check valve or a slow-closing check valve with a damping device should be selected.
4. The valve or valve core of the check valve should be able to close by itself under the action of gravity or spring force
(4) Set the check valve in the water supply pipeline
On the inlet pipe; on the inlet pipe of a closed water heater or water equipment; on the outlet pipe of the pump; on the outlet pipe section of the water tank, water tower, and highland pool where the inlet and outlet pipes are combined with one pipe.
Note: The pipe section equipped with the pipe backflow preventer does not need to be equipped with a check valve.
(5) The position of the exhaust device for the water supply pipeline
1. For the water supply pipe network that is used intermittently, automatic exhaust valves should be set at the end and higher points of the pipe network.
2. The pipe section of the water supply pipe network with obvious fluctuations and accumulation of air has been equipped with an automatic exhaust valve or a manual valve for exhaust at the peak point of this section.
3. Air pressure water supply device, when using automatic air supply air pressure water tank, the higher point of its water distribution pipe network should be equipped with an automatic exhaust valve