DN300 suction pipe shall be equipped with an electric gate valve.Valve seals in water supply systems shall be synthetic rubber; recycled rubber and asbestos are prohibited.Use CR, NBR, EPDM at ≤55℃.Use EPDM or higher heat-resistant materials for 55℃–80℃, complying with GB/T 21873

Principles for Selecting Water Supply Pipeline Valves：

1. Valves of DN300 and below should preferably use gate valves.

2. Valves of DN600 and above should preferably use butterfly valves.

3. Valves from DN300 to DN600 can use gate valves or butterfly valves depending on the situation.

Before installation：

1. Verify valve model & specification comply with design. Check applicability per manual; conduct hydro/pneumatic test if needed.

2. Check packing, gland bolt adjustment, stem and disc mobility. Ensure tight sealing; inspect threaded valves. Reject defective ones.

3. Clean debris inside valves.