Check Valves | Brass, Stainless Steel & PVC | Apex Flow Solutions

Check valves allow flow in one direction and close automatically when flow reverses, protecting pumps, gauges, and equipment from backflow damage. Apex Flow Solutions stocks brass, stainless steel, and PVC check valves from Midland Industries — spring-loaded inline designs, Y-pattern, swing, and hose-barb anti-siphon styles for water, chemical, and process lines.

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How to Choose the Right Check Valve

Material is the primary selection factor. Brass check valves cover the majority of industrial applications — water supply, compressed air, oil, and gas lines where temperatures are moderate and media is not corrosive. For saltwater, aggressive chemicals, food processing, or pharmaceutical applications, specify 316 stainless steel for its superior corrosion resistance and cleanability. PVC check valves are the right call for chemical feed, pool and spa systems, and water treatment where metal corrosion would be a long-term problem and operating pressures stay under 150 PSI.

Check valve style affects cracking pressure and orientation. Spring-loaded inline check valves work in any orientation — horizontal, vertical up, or vertical down — because the spring closes the disc regardless of gravity. Swing check valves rely on gravity to close and must be installed in horizontal lines or vertical flow-up configurations. For low-flow or low-pressure applications, verify the cracking pressure (the minimum pressure required to open the valve) against your system's minimum operating pressure. A check valve with a cracking pressure higher than your system pressure will restrict flow at all times.

Seal material matters for chemical compatibility. NBR (Buna-N) seals handle water, air, oil, and many hydrocarbons. Viton (FKM) seals are the choice for fuels, aromatic chemicals, and elevated temperatures. For aggressive acids and oxidizers in PVC valves, EPDM provides broad chemical resistance in water and mild chemical service.