How to Select the Right Check Valve for a Pump Installation
A check valve is one of the most important and frequently overlooked components in any pump installation. Its job is straightforward: allow flow in one direction and prevent it from reversing, but the consequences of specifying the wrong check valve type, or failing to include one where it is needed, range from nuisance water hammer and noise through to serious pump damage and system failure.
Understanding the options available and the factors that determine the right choice makes a significant difference to long term system reliability.
Why Check Valves Matter in Pump Systems
When a pump stops, the pressure differential across it collapses and the inertia of the fluid in the discharge pipework can cause flow to reverse. In a system without a check valve, this reverse flow passes back through the pump, spinning the impeller in the wrong direction. Repeated reverse spin cycles accelerate wear on shaft seals, bearings, and the impeller itself, shortening pump service life and increasing maintenance frequency. In systems with multiple pumps operating in parallel, check valves on each pump discharge prevent the output of one running pump being short-circuited back through a stopped pump in the same manifold.
Check Valve Types and Their Applications
Several check valve types are available, each suited to different installation conditions and flow characteristics:
- Swing check valves use a hinged disc that swings open under forward flow and closes under gravity and reverse pressure. Well suited to horizontal pipe runs with moderate to high flow velocities, though not appropriate for vertical downward flow.
- Lift check valves use a disc or ball that lifts vertically off its seat under forward flow. Typically used in vertical upward flow orientations and more tolerant of fast closing conditions than swing checks.
- Wafer check valves use two spring-loaded half disc plates that snap closed rapidly when flow stops. Their fast closing action reduces the water hammer effect and compact body profile makes them easy to install between flanges; preferred in high-pressure or high-inertia systems.
- Ball check valves use a rubber or plastic ball that seals against a seat under reverse pressure. They handle viscous or slurry-containing media better than disc-based types and are common in chemical dosing and sewage pumping applications.
Key Selection Criteria
Choosing the right check valve requires confirming several parameters before specifying: pipe orientation, since swing checks have installation restrictions; flow velocity, as some types may not fully open or may chatter at low velocities; water hammer sensitivity in long discharge lines or high-pressure systems; media compatibility for the valve body, disc, and seat; and the pressure and temperature rating against actual system conditions.
A comprehensive selection of check valves for industrial and commercial applications is available across all principal types in both plastic and metal construction.
Common Installation Mistakes
The most frequent installation errors with check valves are fitting a swing check in a vertical downward flow orientation, undersizing the valve relative to the pipe diameter, and installing the valve too close to a pump outlet where turbulent flow conditions affect seating performance. Check valves should generally be installed at least five pipe diameters downstream of a pump outlet to allow flow to stabilise before reaching the valve.
Frequently Asked Questions
Does every pump installation require a check valve?
Not every installation requires one, but wherever reverse flow could damage the pump or connected equipment, contaminate the supply, or cause water hammer on shutdown, a correctly specified check valve is an essential component.
What is water hammer and how does a check valve prevent it?
Water hammer is the pressure surge that occurs when flowing fluid is suddenly stopped or reversed; fast-closing wafer check valves and spring-assisted designs close before significant reverse flow develops, reducing the magnitude of the pressure transient.
Can a check valve be installed in any pipe orientation?
Not all types: swing check valves have orientation restrictions and should not be installed in vertical downward flow; wafer and lift check valves are more flexible in their installation orientation.
How often do check valves need to be inspected or serviced?
Check valves should be inspected periodically to confirm the disc or ball mechanism is operating freely and sealing correctly; in high-flow or frequently cycling systems, more regular inspection of seating surfaces is advisable.
Final Thoughts
Check valve selection is a straightforward process when the key parameters are established correctly: pipe orientation, flow velocity, water hammer risk, media compatibility, and pressure rating. Getting these right at the specification stage prevents the most common causes of check valve and pump failure.
For engineers and contractors sourcing check valves and associated pipeline components for pump installations, a comprehensive range of products is available through specialist industrial valve and pipeline component suppliers in both plastic and metal specifications across all standard sizes.
