Large-Diameter Gate Valves at Raw Water Intake for Waterworks

As a type of linear-motion isolation valve, the gate valve can either completely shut off or allow fluid flow through a pipeline. It is commonly used for isolation operations in potable water supply systems and plays a critical role at the raw water intake head. In the primary pump station (raw water intake station) of a water treatment plant, large-diameter gate valves are typically installed inside a valve chamber and, together with the suction well and pump house, form an essential part of the intake system. The design of the valve chamber must accommodate sufficient space for the chamber itself, for valve operation and maintenance, and for sealing; the top of the valve assembly must be at least 300 mm below the chamber cover to ensure safe construction and inspection.

Main Functions

Various valves at the raw water intake pump room: a NRS gate valves, a pump control valve (for slow shut control) and a butterfly valve are installed in series with the intake pump.

At raw water intakes, gate valves act as the primary process valves at the headworks and normally remain fully open—only being closed for annual maintenance or pipeline rerouting. Manually operated, non rising stem (NRS) & resilient seated design in sizes ranging from DN 1200 to DN 1600 (and up to DN 3000 for very high flows) accommodate large intake volumes. Their full-bore construction produces significantly lower head loss than butterfly valves, making them ideal for long-distance, large-diameter pipelines where energy efficiency is critical. In emergencies or when reverse flow is required, these valves can rapidly isolate or redirect water, and when paired with three-way manifolds, they give operators flexible control over flow paths to maintain continuous supply and protect water quality.

Layout of Pump Room & Valve Chamber

Raw water pumping rooms are typically composed of three main elements—an intake (suction) well, a pump house, and a dedicated valve chamber (or switching well)—the latter of which houses the pipeline isolation valves to keep them protected from exposure in the river or inside the pump house, simplifying centralized management and flood protection. Inside the valve chamber, gate valves ranging from DN 300 to DN 3000 are installed along with stem-extension mechanisms, handwheels or actuators, and ample service clearance, while a sealed, non-slip, load-bearing cover at the top ensures safe access for both personnel and vehicles.

Standards, Materials & Design Features

Ductile iron flanged NRS & resilient seat gate valves, made to AWWA C515, 48″ (DN 1200), electric actuated, supplied to Guyana.

When selecting gate valves for raw water intakes, ductile-iron bodies coated with fusion bonded epoxy (FBE) and stainless steel stems are commonly used to combine mechanical strength with corrosion resistance in buried or damp environments. These valves are generally designed in accordance with a series of international standards such as BS 5163/EN 1074-2, AWWA C515, DIN 3352, and EN 1171, etc. Both knife-gate and wedge-gate styles are popular—wedge-gates being particularly valued for their self sealing ability and tolerance of small solids—while NRS design minimizes chamber-height requirements in confined or underground installations. For remote or automated operation, electric or pneumatic actuators can be fitted, and stem extensions added to bring controls up to the valve-cover level, ensuring convenient above-ground access.