Selection and location of valves

（1） The valves used on the water supply pipeline are generally selected according to the following principles:

1. When the pipe diameter is not greater than 50mm, stop valve should be used, and gate valve and butterfly valve should be used when the pipe diameter is greater than 50mm

2. When the flow and water pressure need to be adjusted, the regulating valve and stop valve should be used

3. Gate valve should be used for parts requiring small water flow resistance (such as the suction pipe of water pump)

4. Gate valve and butterfly valve shall be used on the pipe section where the water flow needs two-way flow, and stop valve shall 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, the stop valve should be used

7. Multi function valve should be used on the outlet pipe of water pump with large diameter

（2） The following parts of the water supply pipeline shall be provided with valves:

1. The water supply pipeline of residential area is from the lead-in pipe section of municipal water supply pipeline

2. The nodes of the outdoor circular pipe network in the residential area shall be set according to the separation requirements. When the annular pipe section is too long, sectional valves should be set

3. The starting end of the branch pipe from the main water supply pipe in the residential area or the starting end of the household pipe

4. Household pipe, water meter and branch risers (bottom of riser, upper and lower ends of riser of vertical annular pipe network)

5. Branch pipe of annular pipe network and connecting pipe through branch pipe network

6. The starting end of the distribution pipe from the indoor water supply pipe to the residents, public toilets, etc. shall be set when there are 3 or more water distribution points on the water distribution branch pipe

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

8. Inlet and outlet pipes and drain pipes of water tank

9. Water inlet and make-up pipe of equipment (such as heater, cooling tower, etc.)

10. Water distribution pipe of sanitary appliances (such as urinal, urinal, washbasin, shower, etc.)

11. Some accessories, such as automatic exhaust valve, pressure relief valve, water hammer eliminator, pressure gauge, front of sprinkler, front and back of pressure reducing valve and backflow preventer, etc

12. A drain valve should be set at the lowest part of the water supply network

（3） Generally, the check valve shall be selected according to its installation position, water pressure in front of the valve, sealing 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 selected

2. When the sealing performance after closing is required to be tight, the check valve with closing spring should be selected

3. When it is required to weaken and close the water hammer, the quick closing silencing check valve or the slow closing check valve with damping device should be selected

4. The valve break or valve core of the check valve shall be able to close automatically under the action of gravity or spring force

（4） Check valves shall be set on the following pipe sections of the water supply pipeline:

On the lead-in pipe; On the water inlet pipe of closed water heater or water equipment; Water pump outlet pipe; The inlet and outlet pipes share the water tank, water tower and outlet pipe section of the highland pool of one pipe.

Note: the pipe section equipped with pipeline backflow preventer does not need to be equipped with check valve.

（5） Exhaust devices shall be set at the following parts of the water supply pipeline:

1. For the water supply network used intermittently, automatic exhaust valve shall be set at the end and highest point of the network

2. For the pipe section with obvious fluctuation and accumulation of air in the water supply network, automatic exhaust valve or manual valve has been set at the peak point of this section

3. For the pneumatic water supply device, when the automatic air replenishing pneumatic water tank is adopted, the highest point of its water distribution network shall be equipped with an automatic exhaust valve