Common Valves for Pump Suction and Discharge Lines

Valves on pump suction and discharge lines do much more than just open or close the pipe. Their main jobs include:

1. Start-up and shutdown protection Closing the discharge valve during start-up greatly lowers the motor starting torque and stops overload. Closing it during shutdown stops reverse flow that could harm the impeller.

2. Flow regulation Carefully adjusting the valve opening lets the system match real demand.

3. Safety and backflow prevention Check valves automatically stop reverse flow.

1. Gate Valve – The​ Preferred Isolation Valve for Large-Diameter Lines
Gate valves remain the most popular isolation valves on pump suction and discharge lines, especially in diameters ≥ DN50. They give a straight flow path with almost no pressure drop when completely open.

Operating principles and types
A wedge or parallel gate moves up or down across the flow by a stem. Rising-stem types clearly show valve position, while non-rising-stem ones stay compact and fit well in buried or tight spaces.

Typical use at pumps
Mainly used for simple on/off isolation. On the discharge side, always place a check valve downstream so reverse flow cannot happen when the gate valve stays closed.

2. Globe Valve – Precise Flow Control for Smaller Lines
Globe valves become the usual pick when throttling or frequent operation is necessary, mostly in lines ≤ DN50.

Operating principle
A disc or plug moves straight against a seat. The fluid must change direction (usually 90° twice). This creates higher pressure drop but offers excellent shut-off and control.

Types
Straight-pattern (most common), angle-pattern (for 90° turns), and Y-pattern or DC designs that lower pressure loss.

3. Check Valve – Essential Backflow Prevention on Discharge
Check valves (non-return valves) are required on nearly every pump discharge line. They protect the pump from reverse rotation and water hammer during power loss or shutdown.

Common designs
· Swing check: low pressure drop, good for large sizes and clean fluids

· Lift check: better sealing at low flow, used in smaller sizes or higher pressure

· Silent (nozzle) check: spring- or weight-assisted closing to reduce slam and water hammer

· Tilting-disc or dual-plate: compact, low head loss, now very common in new systems

Selection tips
Match the valve’s pressure drop and closing speed to pump inertia and system slowdown rate. This keeps water hammer as small as possible.

4. Butterfly Valve – Compact and Cost-Effective for Large Diameters
Butterfly valves provide fast operation (quarter-turn) and light weight. They work perfectly for large-diameter, low-to-medium pressure jobs.

Types
· Concentric (centerline) — cheap, suitable for water service up to ~PN16

· Eccentric (single/double/triple offset) — better performance, tighter shut-off, longer seat life in tough service

5. Ball Valve – Full-Port, Low-Loss, High-Integrity Shut-Off
Ball valves deliver true full-bore flow with nearly zero pressure drop and very tight sealing.

Types
· Floating ball (common up to ~DN200, medium pressure)

· Trunnion-mounted (for bigger sizes and higher pressures)

Typical applications
High-pressure systems, thick fluids, slurries, or where pigging is needed. Now often chosen when tight shut-off and regular operation matter most.