Selection of valves for water supply and drainage pipelines
Created on 2025.12.08
(I) Valves used on water supply pipelines are generally selected based on the following principles:
- For pipe diameters not exceeding 50mm, globe valves are recommended; for diameters over 50mm, gate valves or butterfly valves should be adopted.
- For regulating flow and water pressure, regulating valves or globe valves are preferred.
- For sections requiring low water resistance (such as on suction pipes of pumps), gate valves are suggested.
- For pipeline segments where bidirectional water flow is required, gate valves or butterfly valves must be used, and globe valves cannot be employed.
- In areas with limited installation space, butterfly valves or ball valves are recommended.
- On frequently opened and closed pipeline segments, globe valves are preferable.
- On large diameter pump discharge pipes, multifunctional valves are recommended.
(II) The following parts of water supply pipelines should have valves installed:
- Introduction pipe segment from municipal water supply pipelines to residential area water supply pipelines.
- At nodes of outdoor loop networks in residential areas, according to segmentation requirements. When loop segments are too long, sectional valves are recommended.
- Starting ends of branch pipes connected from residential area main water supply pipes or household connection pipes.
- Household inlet pipes, water meters, and all distribution risers (bottom of risers, top and bottom ends of vertical loop network risers).
- Branch mains of loop networks, connecting pipes running through branched networks.
- Starting ends of distribution pipes extending from indoor water supply pipes to households, communal bathrooms, etc., and when there are three or more distribution points on a distribution branch pipe.
- Outlet pipes of pumps, suction pipes of self-priming pumps.
- Inlet and outlet pipes, drainage pipes of water tanks.
- Supply pipes for equipment (like heaters, cooling towers, etc.).
- Distribution pipes for sanitary fixtures (such as toilets, washbasins, showers, etc.).
- Certain accessories, such as automatic air release valves, pressure relief valves, water hammer eliminators, pressure gauges, sprinkler taps, etc., before and after pressure reducing valves and backflow preventers.
- Drain valves should be installed at the lowest point of the water supply network.
(III) Check valves should generally be selected based on their installation location, water pressure before the valve, sealing performance after closing, and the magnitude of water hammer caused by closing:
- When water pressure before the valve is low, swing-type, ball-type, and plunger-type check valves are recommended.
- For strict sealing requirements after closing, check valves with closing springs are recommended.
- To mitigate closing water hammer, fast-closing silent check valves or slow-closing check valves with damping devices are recommended.
- The disc or core of the check valve should be able to close under gravity or spring force.
(IV) Check valves should be installed on the following sections of water supply pipelines:On introduction pipes; on inlet pipes of sealed water heaters or water-using equipment; on pump discharge pipes; on outlet sections of tanks, towers, elevated reservoirs that share one pipe for inlet and outlet.Note: If a pipeline backflow preventer is installed, it is unnecessary to install a check valve.
(V) The following parts of water supply pipelines should have air vent devices:
- For intermittently used water supply networks, automatic air vents should be installed at the end of the network and at the highest point.
- Where there are obvious ups and downs in the water supply network that can accumulate air, automatic air vents or manual valves for air release should be installed at peak points.
- For pneumatic water supply installations using automatically refilled pneumatic water tanks, an automatic air vent should be installed at the highest point of the distribution network.
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