What's the difference between a swing check valve and a spring check valve?

A swing check valve closes by gravity on a hinged disc, which limits it to horizontal or vertical up-flow installation. A spring check valve (also called an inline or spring-loaded check) closes with a mechanical spring instead of gravity, so it seals in any orientation, including vertical down-flow. Swing checks generally have lower headloss; spring checks generally close faster and more reliably.

Which check valve has the lowest headloss?

Swing check valves typically have the lowest headloss among common check valve types because flow passes through a relatively open, straight bore. Spring-loaded, wafer, and ball-check designs all introduce some additional restriction from the spring mechanism or reduced flow path, though the difference is usually modest at normal operating flows. Exact figures are product- and size-specific — check the manufacturer's datasheet for your selected valve.

Can a wafer check valve replace a swing check valve?

Often, yes, and for space-constrained installations a wafer check is frequently the better choice — it's compact, works in any orientation, and typically closes faster than a swing check because it's spring-assisted. The tradeoffs are slightly higher headloss and a design that sits between two flanges rather than having its own flanged body, which matters for maintenance access.

What is a foot valve used for?

A foot valve is a check valve installed at the submerged inlet end of a suction line, usually paired with a strainer, to keep the pump primed by holding water in the suction line when the pump shuts off. It's a specialized application of check valve function rather than a distinct internal mechanism — most foot valves use a swing or spring-loaded design inside a strainer-equipped body.

Is a ball check valve good for dirty or viscous fluids?

Ball check valves handle viscous, dirty, or intermittent flows reasonably well because the ball's self-centering, self-cleaning action resists fouling better than a flat disc-and-seat arrangement. They're common in small-line and metering applications for that reason, though they're less common at larger municipal pipe sizes.

Check Valve Types Compared

"Check valve" isn't a spec — it's a category. Swing, inline/spring, wafer, ball-check, and foot valve all do the same basic job (let flow go one way, block the reverse), but the mechanism inside each one is different enough that picking the wrong type is one of the most common misapplications we see, right alongside picking the wrong material or seal. Here's the short answer first, then the mechanics behind it.

Which Check Valve Do You Need?

Start here. Find your situation, then jump to the type for the full writeup.

Type	Best for	Orientation limits	Cracking pressure	Headloss	Cost tier
Swing check	Horizontal or vertical up-flow lines where low headloss matters and periodic rebuild is fine — the default for most AWWA C508 municipal work	Horizontal or vertical up-flow only	Low — opens under minimal forward pressure since gravity is the only resistance	Low — straight-through bore	Low to moderate
Inline / spring check	Smaller lines, chemical feed and dosing loops, anywhere orientation isn't guaranteed horizontal	Any orientation	Moderate — set by spring rate, check the listed rating	Moderate — spring resistance and reduced flow path	Low to moderate
Wafer (dual-plate) check	Tight axial space between flanges, larger pipe sizes that need a compact, faster-closing option	Any orientation	Moderate — spring-assisted	Moderate	Moderate
Ball check	Small lines carrying debris-prone, viscous, or intermittent flow — sampling lines, metering, skid packages	Depends on design — confirm with manufacturer; many are orientation-flexible	Moderate to higher, depending on ball weight/spring	Moderate — flow path curves around the ball	Low (small sizes)
Foot valve	The submerged inlet of a suction line — keeping the pump primed between cycles	Vertical, submerged installation by design	Low to moderate	Moderate — strainer screen adds resistance	Moderate

Cracking pressure, headloss, and pressure rating are product- and size-specific — the table describes general tendencies by valve type, not a guaranteed number for any listed product. Check the individual product's datasheet before specifying, or send us the application and we'll confirm.

The five common types, in more detail

Swing check

A hinged disc swings open under forward flow and shut by gravity when flow stops or reverses. Straight-through bore, low headloss. Limited to horizontal and vertical up-flow — gravity has to pull the disc closed, and it can't do that reliably in vertical down-flow. Full mechanism and orientation physics in our swing check valve guide.

Inline / spring-loaded check

A poppet or disc held against the seat by a spring, pushed open once forward flow pressure exceeds the spring's cracking pressure. The spring does the closing work instead of gravity, so these seal in any orientation, including vertical down-flow. Common in brass, stainless, and PVC for smaller lines and chemical feed.

Wafer (dual-plate) check

Two spring-loaded half-discs hinge on a center post and install between two pipe flanges rather than carrying flanged ends of their own. Compact axial length wins where a swing check's body length won't fit, and the spring assist generally closes faster. Common in larger ductile iron sizes for water and wastewater.

Ball check

A free-floating or spring-assisted ball seats against a machined orifice; forward flow lifts it clear. Self-centering geometry resists fouling better than a flat disc-and-seat, so ball checks handle viscous or intermittent flows well — common in small-line, metering, and pump discharge service, less so at larger municipal sizes.

Foot valve

Not really a separate mechanism — a check valve (usually swing or spring-loaded inside) built into a strainer body and installed at the submerged end of a suction line. Its job is holding the suction line primed by stopping water from draining back to the source when the pump stops, with screen protection built in.

Reading the rating systems

One thing trips people up across all five types: pressure ratings aren't on one universal scale. WOG (water-oil-gas, a cold non-shock rating) isn't the same system as WSP (working steam pressure) or an ANSI pressure class. A "200 WOG" valve is not a Class 200 valve. Matching a spec written in one system against a product listed in another is a common source of the wrong-part-shipped problem — if your spec cites a system, match it, don't convert casually.

Maintenance and rebuild considerations

Serviceability varies by type, and it's worth weighing alongside the table above, especially where debris, hard water, or heavy cycling are in play.

Swing check: generally the most field-serviceable — larger AWWA sizes open for disc, seat, or hinge pin replacement without pulling the valve, given clearance on both sides.
Inline/spring check: smaller brass, stainless, and PVC units are usually replace-rather-than-rebuild — pulling the whole valve beats servicing the internal spring and poppet.
Wafer check: sits between two flanges, so servicing means breaking both connections rather than opening a bolted cover. Plan access at install time.
Ball check: small units are typically replaced whole; larger spring-assisted versions may support internal service depending on the design.
Foot valve: service usually means pulling the whole assembly from the source, since it lives submerged — and the strainer screen needs its own cleaning cycle.

None of this is a hard rule across every manufacturer's design — check the specific product's construction (bolted cover vs. sealed body) before planning a maintenance interval around it.

The honest tradeoff, in one line each

Swing: cheapest headloss, most orientation-restricted. Inline/spring: most orientation-flexible at small sizes, adds some resistance. Wafer: compact and fast-closing at larger sizes, costs a bit more than a comparable swing check. Ball: best with dirty or viscous flow, mostly a small-line player. Foot valve: solves suction priming specifically — not a substitute for an inline check elsewhere in the system.

Choosing between a swing check and a spring-loaded alternative specifically because of orientation? Our orientation and installation guide covers the vertical up-vs-down rule and pump-discharge placement in more depth than fits here.

More on check valves

Published performance data is general engineering reference, not a certification for your application. Confirm specifics against the manufacturer datasheet or ask us.

We'll recommend the correct valve — or tell you if you don't need one.

Send us the spec, the old part number, or just a photo of what you're replacing — request a quote and you'll have an answer from a person the same business day.

Technical data disclaimer: Specifications, dimensions, pressure/temperature ratings, and compatibility information on this page are compiled from manufacturer publications and are provided for reference only. Always verify suitability for your application against the manufacturer’s current documentation before purchase or installation. Apex Flow Solutions assumes no liability for errors, omissions, or misapplication of this information.