Check Valves — Swing, In-Line & Dual Plate Backflow Protection

Check valves stop reverse flow before it damages pumps, heaters, and systems. PVFPro stocks swing, in-line spring, and dual plate check valves from Legend and Red-White in brass, bronze, carbon steel, and iron, with fast shipping from multiple U.S. warehouses.

What Is a Check Valve?

A check valve is a one-way valve: flow lifts or swings the closure member open, and reverse flow slams it shut. No handle, no operator — the media itself does the work. Check valves protect equipment from reverse flow damage: pumps from backspin, water heaters from thermal expansion push-back, and systems from cross-contamination. PVFPro stocks check valves from Legend Valve and Red-White Valve in swing, in-line, and dual plate designs, in brass, bronze, carbon steel, and iron.

Check Valve Types Stocked

Swing check — A hinged disc swings open on flow and drops shut on reversal. Simple, reliable, low pressure drop; the commercial standard on horizontal water lines.
In-line / spring check — A spring-loaded disc closes the moment forward flow stops, working in any orientation and stopping reverse flow fast — the right choice at pumps, equipment inlets, and vertical runs.
Dual plate check — Two spring-loaded half-discs on a single hinge pin close quickly with a short stroke. Compact wafer bodies fit between flanges, and the soft-close action limits slam and water hammer on larger lines.

Applications

Pump discharge — preventing backspin and reverse rotation on stop
Water heater and boiler inlets — blocking reverse flow and thermal migration
Boosted and re-pressure systems — retaining pressure when the pump stops
Commercial plumbing — preventing cross-connection backflow at branch takeoffs
HVAC chilled and heating water loops — enforcing loop direction
Irrigation and site water systems — keeping lines charged against drainback

How to Choose the Right Check Valve

Pick the style for the line orientation. Swing checks need horizontal (or designed vertical) runs; in-line spring checks work in any position; dual plate wafer checks mount between flanges.
Consider closing speed. Fast-closing spring and dual plate designs limit slam and hammer on systems with frequent pump starts and stops.
Match the material to the media. Brass and bronze for potable water; carbon steel and iron for larger utility and process lines; verify chemical compatibility for anything beyond water service.
Check the pressure class and temperature. Confirm the rating on each product page against system conditions.
Size for flow, not just pipe. An oversized check never fully opens and chatters; match the valve to the line size and design flow.

Technical Specifications Overview

Types stocked: Swing check, in-line spring check, dual plate wafer check.
Materials stocked: Brass, bronze, carbon steel, and iron by series.
Connections stocked: Threaded FNPT, solder, and flange/wafer mounting depending on series.
Standards: NPT threads to ASME B1.20.1; lead-free certified series carry NSF/ANSI 61 and 372 listings. Confirm listings per product page.
Brands stocked: Legend Valve and Red-White Valve Corp.

Water Hammer and Slam Prevention

Check valve slam is a system problem, not just a valve problem. When a pump stops, the column of water reverses and a slow-closing check lets it run before it slams the disc into the seat — the bang that shakes pipe anchors. Three fixes, in order of preference: use a faster-closing check (spring-loaded in-line or dual plate), slow the pump or valve closure that causes the reversal, or add engineered surge protection on long runs. Also respect the straight-run rule: spring checks and swing checks both measure and seat more predictably with a few pipe diameters of straight run on each side, not bolted straight into an elbow. And never install a swing check backwards — flow direction is cast into the body for a reason.

Frequently Asked Questions

Why is my swing check valve slamming? Slam happens when flow reverses before the disc closes — undersized or oversized valves make it worse. Dual plate and spring checks close faster and limit hammer.
Can a check valve be installed vertically? Spring-loaded in-line checks work in any orientation. Swing checks depend on the series — many are horizontal-run only; check the product page.
Is a check valve a backflow preventer? No. A check valve is single protection against reverse flow; code-designated backflow prevention requires listed assemblies. See our backflow collection or ask us.
Do check valves need maintenance? They have no operator, but discs, seats, and springs wear — especially on hard-water lines with frequent cycling. Flapper and spring replacement is routine on serviceable models.