How to Select and Install a Check Valve for a Deep Well Submersible Pump

A check valve is a one-way valve installed in the discharge system of a deep well submersible pump.

It allows water to move upward while the pump is operating and closes when the pump stops. Its purpose is to prevent the water column inside the rising main from flowing back through the pump.

Although the operating principle appears simple, an incorrectly selected or positioned check valve can contribute to:

• Excessive pressure loss
• Valve slam
• Water hammer
• Reverse pump rotation
• Repeated starting under abnormal conditions
• Unstable pressure
• Valve chatter
• Rising-main damage
• Difficult pump removal
• Premature pump or motor wear

The correct valve arrangement depends on the exact pump, flow rate, head, rising-main length, pipe material, installation depth and system-transient behavior.

Do not select a check valve only because its nominal size matches the pump outlet.

What Does a Deep Well Pump Check Valve Do?

When a borehole pump is running, the pressure generated by the pump opens the check valve and pushes water upward through the rising main.

When electrical power is removed, pump speed and flow begin to decrease. The check valve should close before a significant volume of water reverses direction.

A correctly functioning valve helps:

• Retain water in the rising main
• Maintain system pressure
• Limit reverse flow through the pump
• Reduce reverse pump rotation
• Provide more controlled restarting
• Prevent the complete pipe column from draining after every stop

A check valve does not generate pressure or increase pump head. It creates hydraulic resistance and therefore consumes a small amount of head while open.

Its pressure loss must be included in the system calculation.

First Confirm Whether the Pump Has an Integral Check Valve

Many deep well submersible pumps include a check valve at or near the discharge head.

The SLAPK QJ product information identifies check-valve and non-return-valve components in the pump construction. The exact arrangement, material and pressure capability depend on the selected series and model.

Before specifying an additional valve, confirm:

• Complete pump model
• Whether an integral valve is installed
• Valve type
• Valve material
• Full-open flow area
• Pressure rating
• Maximum permitted head above the valve
• Suitability for vertical operation
• Manufacturer instructions for additional valves

Do not assume that every pump contains the same valve simply because the product family has a similar external appearance.

Likewise, do not assume that an integral valve is suitable for every possible installation depth or transient condition.

Check Valve, Non-Return Valve and Foot Valve

The terms “check valve” and “non-return valve” normally describe a valve that permits flow in one direction and prevents reverse flow.

A foot valve is also a type of non-return valve, but it is commonly installed at the suction inlet of a surface pump to retain prime.

A deep well submersible pump does not normally use a suction foot valve in the same way. The pump operates underwater and pushes water upward from below the water level.

The relevant valve is installed on the discharge side of the submersible pump.

Terminology varies between manufacturers and countries, so the technical drawing and flow-direction arrow should take priority over the product name alone.

Why Reverse Flow Is a Problem

If a check valve is absent, stuck open or leaking, the water inside the rising main can flow downward after the pump stops.

This reverse flow may rotate the pump impellers and motor backward.

If the motor restarts while the assembly is still rotating in reverse, the shaft, coupling, impellers and thrust-bearing system can be exposed to severe mechanical stress.

Possible consequences include:

• High starting torque
• Shaft or coupling damage
• Thrust-bearing wear
• Motor overload trips
• Loose pump components
• Unstable starting
• Reduced service life

A leaking valve may also allow the pressure tank or distribution pipeline to lose pressure, causing the pump to restart more frequently.

However, frequent cycling can have other causes. Do not replace the check valve without checking the pressure tank, pressure switch, pipeline and water demand.

Why Fast Valve Closure Can Also Be a Problem

A valve must close quickly enough to limit reverse flow, but closure behavior must suit the hydraulic system.

If a moving water column stops or changes velocity rapidly, a temporary pressure wave can travel through the pipeline. This is called water hammer.

Possible symptoms include:

• A loud bang when the pump stops
• Rising-main movement
• Check-valve impact noise
• Pressure-gauge spikes
• Damaged pipe joints
• Failed seals or gaskets
• Repeated valve failure
• Wellhead vibration

Water hammer severity depends on more than the valve itself.

Relevant factors include:

• Water velocity
• Rising-main length
• Actual pipe internal diameter
• Pipe material and elasticity
• Valve closing time
• Amount of reverse flow before closure
• Pump deceleration
• Check-valve location
• Static lift
• System pressure
• Air pockets
• Pressure tanks or surge vessels
• VFD stopping settings

A “fast-closing” valve is not automatically a non-slam solution. Its moving element, spring, flow velocity and installation orientation must be considered together.

Common Check-Valve Types

Swing Check Valve

A swing check valve uses a hinged disc that opens with forward flow and closes when flow reverses.

Advantages can include:

• Simple construction
• Low pressure loss when fully open
• Availability in large sizes

Potential limitations include:

• The disc may travel a relatively long distance.
• Significant reverse flow can develop before closure.
• The disc may slam against the seat.
• Some designs are sensitive to installation orientation.
• Large external dimensions may restrict borehole clearance.

A conventional swing check valve is not automatically suitable for installation inside a narrow vertical well.

Spring-Loaded Check Valve

A spring-loaded valve uses a spring to move the closing element toward the seat as forward flow decreases.

Possible advantages include:

• Shorter closing travel
• Reduced dependence on gravity
• Suitability for vertical pipelines when approved
• Faster response to decreasing flow

Possible disadvantages include:

• Additional opening pressure
• Higher head loss
• Spring corrosion or fatigue
• Sensitivity to sand and deposits

Spring material must be compatible with the water.

Poppet Check Valve

A poppet valve uses an axially moving closure element.

A properly designed poppet valve can offer controlled closing and compact installation. It is frequently considered for vertical pump discharge service.

Selection should confirm:

• Flow capacity
• Spring force
• Seat material
• Guide construction
• Resistance to sand
• Maximum pressure
• Installation direction

Silent or Non-Slam Check Valve

Silent and non-slam valves are designed to close before substantial reverse velocity develops.

The term does not guarantee identical performance across manufacturers.

Request the manufacturer’s data for:

• Closing behavior
• Minimum flow
• Pressure loss
• Permitted orientation
• Pressure class
• Water quality
• Operating temperature
• Cycle life

A valve marketed as “silent” may still produce hydraulic shock if it is incorrectly sized or installed in an unsuitable system.

Ball Check Valve

A ball check valve uses a free or guided ball to close the flow passage.

Ball designs are common in some wastewater and solids-handling applications, but they may create significant pressure loss or be unsuitable for a narrow deep-well rising main.

Use only a valve specifically approved for the pump duty and installation orientation.

Step 1: Confirm the Design Flow

Select the check valve at the actual operating flow, not only from the pump outlet size.

The review should include:

• Minimum continuous flow
• Normal operating flow
• Maximum expected flow
• VFD operating range
• Startup and shutdown conditions

An oversized valve may not open fully at low flow. The closing element can remain partially open and become unstable.

An undersized valve can create:

• High velocity
• Excessive head loss
• Noise
• Erosion
• High spring force
• Accelerated seat wear

The selected valve should operate stably across the complete intended flow range.

Step 2: Check the Valve Flow Coefficient and Head Loss

Every open check valve creates pressure loss.

Head loss depends on:

• Valve type
• Internal passage area
• Flow rate
• Water velocity
• Opening position
• Spring force
• Internal geometry
• Surface condition

Use the manufacturer’s flow coefficient, pressure-loss curve or tested performance data.

Do not assume the valve has negligible resistance.

Valve loss must be added to:

• Straight-pipe friction
• Elbow and reducer loss
• Flowmeter loss
• Wellhead fittings
• Control-valve loss

These losses form part of the total dynamic head.

A valve with the same nominal diameter as the rising main can still have a much smaller internal flow area.

Step 3: Check Pressure Rating

The valve must withstand the highest credible pressure, not only normal operating pressure at the wellhead.

Review:

• Pump shutoff head
• Static water-column pressure
• Normal operating pressure
• Required outlet pressure
• Water-hammer pressure
• Test pressure
• Valve position in the rising main
• Pressure created if another valve leaks or fails
• Applicable safety factor

The pressure near a deeply installed pump can differ greatly from the pressure observed at the surface.

Confirm the pressure rating of:

• Valve body
• Seat
• Spring
• Shaft or guide
• Threaded or flanged connection
• Gaskets
• Fasteners

The valve and rising-main connection should be rated as a complete assembly.

Step 4: Select Compatible Materials

Valve materials should match the water chemistry and other system components.

Possible body materials include:

• Cast iron
• Ductile iron
• Carbon steel
• Bronze
• Stainless steel
• Engineered plastics

Internal components may use:

• Stainless-steel springs
• Elastomer seats
• Bronze guides
• Plastic or composite poppets

Material selection should consider:

• Chloride concentration
• pH
• Dissolved oxygen
• Salinity
• Temperature
• Sand content
• Drinking-water requirements
• Galvanic interaction
• Expected service life

Do not assume SS304 is suitable for every groundwater source. More aggressive water may require SS316L, duplex stainless steel or another verified material.

The SLAPK catalogue lists several possible materials for check-valve components, including cast iron, stainless-steel grades and bronze. The final material must be confirmed for the ordered pump and water analysis.

Step 5: Verify Installation Orientation

A valve must be installed in the flow direction marked by its manufacturer.

For a vertical rising main, the permitted flow direction is normally upward. However, not every valve design is approved for vertical installation.

Check:

• Flow arrow
• Upward-flow approval
• Minimum orientation requirements
• Spring or gravity dependence
• Required straight-pipe length
• Access for servicing
• Connection tightening procedure

Installing a valve backward can prevent flow and cause the pump to operate against a closed discharge.

Possible results include overheating, high pressure, motor overload and damage to pump components.

Do not rely on the external shape alone. Verify the cast, stamped or printed flow arrow before lowering the assembly.

Step 6: Check Borehole Clearance

A valve that is hydraulically suitable must also fit inside the well.

Verify the maximum outside dimension of:

• Valve body
• Threads
• Flanges
• Bolts
• Couplings
• Reducers
• Cable guards
• Power cable
• Cable clamps
• Splice
• Lifting attachments

The valve or its coupling may be wider than the pump or rising main.

Compare the complete installed envelope with the minimum measured casing internal diameter.

Allow for:

• Casing joints
• Internal welds
• Well deviation
• Mineral deposits
• Liners
• Deformation
• Retrieval clearance

A theoretical metal-to-metal fit is not sufficient.

Step 7: Confirm Mechanical Load Capacity

The rising main and its joints support a substantial suspended load.

The check-valve connection may be exposed to:

• Pipe weight
• Water-column weight
• Pump and motor weight
• Cable weight
• Starting and stopping forces
• Pressure thrust
• Water hammer
• Installation and retrieval loads

Threaded connections must have suitable engagement and mechanical strength.

Flanged connections require the correct:

• Flange rating
• Bolt material
• Bolt torque
• Gasket
• Alignment
• Corrosion protection

Do not use the valve body as an unverified lifting point.

Where Should the First Check Valve Be Installed?

The first step is to confirm whether the pump already contains an integral discharge check valve.

If an external first valve is required, it is often installed near the pump discharge, but the exact distance must follow the pump and valve manufacturer’s instructions.

Factors affecting the position include:

• Turbulence at the pump outlet
• Required straight-pipe length
• Pump discharge connection
• Ability to release trapped air
• Valve access
• Borehole clearance
• Pipe-joint arrangement
• Hydraulic transient behavior

Do not install the valve at an arbitrary distance simply because that position is convenient during assembly.

Are Additional Check Valves Required?

Some deep installations use additional check valves along the rising main.

However, there is no universal number or spacing suitable for every well.

The decision should consider:

• Pump setting depth
• Static and dynamic water levels
• Rising-main length
• Pipe material
• Pipe pressure class
• Flow velocity
• Valve pressure rating
• Water-hammer analysis
• Pump manufacturer instructions
• Valve manufacturer instructions
• Local installation requirements
• Maintenance and retrieval plan

Adding more valves does not automatically improve protection.

Multiple valves can introduce:

• Additional friction loss
• More potential leakage points
• Trapped pressure between valves
• Valve chatter
• Complex transient interaction
• Difficult fault diagnosis
• More components to retrieve

If one valve closes earlier than another, the water columns between valves can behave differently during shutdown.

For deep, long or high-flow systems, use a hydraulic transient analysis rather than a fixed spacing rule.

Should a Check Valve Be Installed at the Wellhead?

A surface check valve may be required by the system design or local installation standard.

Before adding one, review the complete downhole valve arrangement.

A surface valve can retain pressure in the distribution system, but it may also conceal a leaking downhole valve. Pressure can become trapped between valves, and the interaction may increase hydraulic shock in some configurations.

Confirm:

• Purpose of the surface valve
• Existing integral pump valve
• Downhole line valves
• Pressure-tank location
• Pressure-switch connection
• Wellhead piping arrangement
• Drain and service requirements
• Applicable code

Do not add a surface check valve solely to stop rapid cycling without diagnosing the cause.

Check Valve and Gate Valve Have Different Functions

The SLAPK installation diagram shows both a check valve and a gate valve at the wellhead.

They are not interchangeable.

A check valve:

• Operates automatically
• Allows flow in one direction
• Prevents reverse flow

A gate valve:

• Is manually or mechanically operated
• Is used to isolate the pipeline
• May be used during commissioning or maintenance
• Should normally be fully open during regular pump operation unless the system is specifically designed for throttling

A gate valve does not automatically close when the pump stops.

A check valve should not be used as the main maintenance-isolation valve.

Check Valve and Pressure Tank Interaction

In a pressure system, the pressure tank stores water and limits motor cycling.

The check valve helps keep water from returning down the well, while the pressure tank supplies small demands without immediately restarting the pump.

An incorrect arrangement can cause:

• Rapid cycling
• Pressure-switch chatter
• Loss of stored pressure
• Delayed pressure response
• Trapped pressure
• Misleading pressure readings

The pressure switch should sense the correct system pressure and be coordinated with the pressure tank, check valves and control panel.

A failed pressure tank can cause frequent starting even when the check valve is working properly.

Check Valve Considerations With a VFD

A VFD changes pump acceleration and deceleration.

Controlled speed changes may reduce some hydraulic shocks, but poor settings can also create unstable valve behavior.

Review:

• Minimum continuous speed
• Minimum valve-opening flow
• Acceleration time
• Deceleration time
• Sleep mode
• Restart pressure
• Valve closing response
• Flow reversal
• Pressure-sensor location

At low flow, a spring-loaded valve may remain partly open and chatter.

Do not assume that a VFD removes the need for a check valve or surge analysis.

Air and Gas Considerations

Air trapped in a vertical pipeline affects pressure response and valve behavior.

Air may enter through:

• A falling well level
• Pump vortexing
• Leaking pipe joints
• Dissolved gas released from the water
• Maintenance work
• An empty rising main during commissioning

Uncontrolled air can cause:

• Intermittent flow
• Pressure fluctuations
• Valve impact
• Reduced pump performance
• Inaccurate flow measurements

The system designer should determine whether air-release or vacuum-control equipment is required.

Do not drill holes in a check valve or rising main unless the pump manufacturer provides a documented air-management procedure.

Pre-Installation Inspection

Before lowering the pump, inspect the valve.

Check:

• Correct model and size
• Pressure rating
• Material
• Flow direction
• Freedom of movement
• Seat condition
• Spring condition
• Internal cleanliness
• Connection threads or flanges
• Outside dimensions
• Manufacturer markings

Remove transport protection and foreign material.

Do not install a valve containing welding debris, sealant, sand or packaging material.

If threaded sealant is used, prevent excess material from entering the flow passage.

Commissioning Checks

During initial operation, record:

• Pump flow
• Discharge pressure
• Motor current
• Starting behavior
• Stopping behavior
• Valve noise
• Pressure fluctuation
• Time required to build pressure
• Pressure decay after shutdown
• Evidence of reverse flow

Observe the pressure gauge when the pump stops.

A rapid pressure drop may indicate:

• A leaking check valve
• Rising-main leak
• Pipeline leak
• Pressure-tank problem
• Water demand downstream

A pressure spike or loud impact may indicate a transient problem, but a standard pressure gauge may not capture a very short pressure event. High-speed pressure measurement may be required.

Signs of Check-Valve Problems

Possible symptoms include:

• Pump starts too frequently
• Pressure falls after shutdown
• Loud bang when the pump stops
• Reverse rotation
• Delayed restart
• Unstable flow
• Valve chatter
• Higher-than-expected head loss
• Pump fails to deliver rated flow
• Rising-main movement
• Repeated valve replacement
• Debris found on the valve seat

Do not diagnose from one symptom alone.

For example, low flow can result from a blocked valve, but it can also be caused by incorrect rotation, low voltage, worn pump components, excessive head or a restricted pipeline.

Common Check-Valve Selection Mistakes

Selecting Only by Nominal Pipe Size

The internal flow area and pressure-loss characteristics can vary greatly between valves of the same nominal size.

Ignoring the Pump’s Integral Valve

Adding valves without confirming the existing construction can create unnecessary loss and complex transient behavior.

Installing the Valve Backward

Always verify the flow arrow before assembly.

Ignoring Pressure Loss

Valve loss adds to total dynamic head and can change the actual pump operating point.

Selecting Only by Normal Pressure

Check shutoff pressure, static pressure, test pressure and credible transient pressure.

Assuming Every Valve Works Vertically

Confirm the manufacturer’s permitted orientation.

Applying a Universal Valve-Spacing Rule

Spacing depends on the complete hydraulic system and manufacturer instructions.

Installing Too Many Valves

Additional valves can increase friction, trap pressure and complicate shutdown behavior.

Ignoring Sand and Sediment

Particles can prevent complete valve closure or damage the seat and guide.

Forgetting Borehole Clearance

The valve body, coupling or flange may be the widest part of the assembly.

Treating Valve Slam as a Noise Problem Only

A loud closure can indicate a damaging pressure transient.

Replacing the Valve Without Checking System Cycling

Frequent starting may be caused by a failed pressure tank, pressure switch or pipeline leak.

Example Check-Valve Review

Assume a borehole pump will deliver water through a long vertical rising main to a surface pressure system.

The engineer should:

1. Confirm whether the selected pump contains an integral check valve.
2. Obtain the valve type, pressure rating and flow-loss data.
3. Calculate the actual operating flow and velocity.
4. Include valve loss in total dynamic head.
5. Check pump shutoff pressure and transient pressure.
6. Confirm material compatibility with the water analysis.
7. Verify that the valve is approved for vertical upward flow.
8. Check the complete outside diameter against the casing.
9. Review whether an external first valve is required.
10. Evaluate any proposed additional valves as a complete system.
11. Coordinate the valve arrangement with the pressure tank and VFD.
12. Observe pressure and valve behavior during commissioning.

The final selection cannot be made from outlet diameter and well depth alone.

Information Required for a Check-Valve Review

Provide the following information to the pump and valve supplier:

• Complete pump model
• Pump performance curve
• Required flow
• Total dynamic head
• Pump shutoff head
• Well depth
• Pump installation depth
• Static and dynamic water levels
• Rising-main material
• Actual pipe internal diameter
• Total pipe length
• Pipe pressure class
• Pump discharge connection
• Existing integral check-valve details
• Proposed valve type and size
• Valve pressure rating
• Valve flow coefficient
• Water temperature
• Water analysis
• Sand content
• Starting method
• VFD operating range
• Pressure-tank details
• Wellhead arrangement
• Local installation standard

Frequently Asked Questions

Does every deep well pump need a check valve?

A system normally requires reverse-flow protection, and many borehole pumps include an integral discharge check valve. Confirm the exact pump construction before adding another valve.

Should the valve be the same size as the pump outlet?

Not automatically. The valve must suit the actual flow, pressure loss, pressure rating, connection and installation clearance.

Where should the first external valve be installed?

It is commonly positioned near the pump discharge when required, but the exact location should follow the pump and valve manufacturer’s instructions.

How many check valves should a deep well use?

There is no universal quantity. The answer depends on installation depth, pipe length, pressure, velocity, valve rating and transient behavior.

Can too many check valves cause problems?

Yes. Additional valves increase friction and can create trapped pressure, chatter and complicated water-hammer behavior.

Can a check valve stop water hammer?

A correctly selected valve may reduce reverse flow and valve slam, but water hammer is a system-transient problem. Pipe length, velocity, valve timing, VFD settings and surge-control equipment must also be considered.

Why does pressure fall after the pump stops?

Possible causes include a leaking check valve, rising-main leak, distribution leak, pressure-tank problem or continuing water demand.

Can a check valve be installed horizontally?

Only if the specific valve is approved for that orientation. A downhole rising-main valve is normally reviewed for vertical upward flow.

Does a VFD eliminate the check valve?

No. The system still requires appropriate reverse-flow control. The valve must operate reliably across the intended speed and flow range.

Can sand damage a check valve?

Yes. Sand can erode the seat, obstruct movement and prevent full closure. Check the pump’s permitted sand content and well condition.

Conclusion

A deep well pump check valve must be selected as part of the complete pumping system.

The final arrangement should:

• Confirm whether the pump already contains an integral valve.
• Match the actual flow range.
• Limit unnecessary pressure loss.
• Withstand operating, shutoff and transient pressure.
• Close without excessive reverse flow or impact.
• Use materials compatible with the water.
• Operate in the required orientation.
• Fit inside the borehole with all connections.
• Coordinate with the rising main, pressure tank and controls.
• Be tested during commissioning.

Do not choose or position check valves from a universal spacing rule.

The pump manufacturer, valve supplier and system designer should review the actual installation depth, flow, pressure, pipeline and water-hammer conditions before the pump is lowered into the well.

Request a Deep Well Pump and Check-Valve Review

Send SLAPK your required flow and head, well depth, pump installation depth, static and dynamic water levels, rising-main diameter and material, voltage, frequency, starting method and water analysis.

Our engineers can recommend a suitable QJ or SP borehole pump and confirm the pump outlet, integral check-valve construction and installation information required for your system review.

Contact SLAPK for a borehole pump recommendation