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How to select cast iron valves 2021/09/26 09:40:21


A.) Valves used on water supply pipelines are generally selected according to the following principles:


① When the pipe diameter is not more than 50mm, a Stop valve should be used, and when the pipe diameter is more than 50mm, a gate valve or butterfly valve should be used.

② Control valves and stop valves should be used when the flow or water pressure need to be adjusted.

③ For parts that require low water flow resistance (such as on the suction pipe of a water pump), a gate valve should be used.

④ Gate valves and butterfly valves should be used on pipe sections where water flow needs to flow in both directions, and stop valves should not be used

⑤ Butterfly valves and ball valves should be used in places where the installation space is small.

⑥ In the pipe section that is frequently opened and closed, a stop valve should be used.

⑦ A multi-function valve should be used on the outlet pipe of the pump with a larger diameter.


B. ) Valves should be installed at the following locations on the water supply pipeline:


① The water supply pipeline of the residential quarter is from the introduction pipe section of the municipal water supply pipeline.

② The nodes of the outdoor loop pipe network of the residential quarter should be set up according to the separation requirements. When the loop pipe section is too long, a segmented valve should be installed.

③ The beginning of the branch pipe connected from the main water supply pipe of the residential area or the beginning of the household pipe.

④ Household pipes, water meters and branch risers (the bottom of the riser, the upper and lower ends of the riser of the vertical ring pipe network)

⑤ The branch pipes of the ring pipe network and the connecting pipes through the branch pipe network.

⑥ The end of the water distribution pipe connecting the indoor water supply pipe to the households, public toilets, etc., and the water distribution point on the water distribution branch pipe is set when there are 3 or more.

⑦ Outlet pipe of water pump, suction pump of self-filling water pump

⑧ The inlet and outlet pipes and drain pipes of the water tank

⑨ The water inlet and make-up pipes of equipment (such as heaters, cooling towers, etc.)

⑩ Water distribution pipes for sanitary appliances (such as urinals, 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 pressure reducing valve and backflow preventer, etc.

⑫ A drain valve should be installed at the lowest point of the water supply network


C. ) Check valves should generally be selected according to factors such as their installation location, water pressure in front of the valve, airtight performance requirements after closing, and the size of the water hammer caused by closing.

① If the water pressure in front of the valve is small, the swing, ball and shuttle check valves should be selected.

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 the shut-off water hammer, a quick-closing silencing check valve or a slow-closing check valve with a damping device should be selected

④ The valve break or spool of the check valve should be able to close automatically under the action of gravity or spring force


D.)  Check valves shall be provided on the following pipe sections of the water supply pipeline:


On the introduction pipe; on the inlet pipe of a closed water heater or water equipment; on the outlet pipe of a water pump; on the outlet pipe section of the water tank, water tower, and highland pool where the inlet and outlet pipes are combined.


Note: There is no need to install a check valve in the pipe section equipped with a pipe backflow preventer.


E.)  Exhaust devices should be installed in the following parts of the water supply pipeline:


1. For the water supply pipe network used intermittently, the end and highest point of the pipe network should be equipped with automatic exhaust valves


2. There are obvious undulating pipe sections in the water supply pipe network that accumulate air, and automatic exhaust valves or manual valves have been set up at the peak points of this section.


3. Air pressure water supply device. When automatic air-supply air pressure water tank is used, the highest point of the water distribution pipe network should be equipped with an automatic exhaust valve

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