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SMC Check Valves for Air or Liquid

These Poppet Check Valves offer precise, low-pressure backflow prevention in compact, high-flow designs. Available in a range of NPT sizes from 1/4” to 3/4”, each valve features a thin elastomer disc and poppet mechanism that opens at low cracking pressures for responsive performance. Offered in chemically resistant materials like glass-filled polypropylene and PVDF, and with multiple seal and spring options—including 302 stainless steel or Hastelloy®—these valves are ideal for applications requiring durability, compatibility, and a positive seal even under slight vacuum. All models support up to 125 psi and 140°F, making them versatile for air and fluid systems.

Polypropylene
EPDM, Buna, Aflas®, or FKM seals
Hastelloy or 302 stainless steel spring
High flow rate
Seat area open diameter: 0.438"
Positive seal at very low back pressure or slight vacuum
Maximum pressure: 125 psi
Maximum temperature: 140°F

Item #	Description	Catalog Pg.	Price
Item 22231	1/4" FNPT x 1/4" FNPT Series 694 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 10.09/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	10.09/Each In Stock
Item 22637	1/4" FNPT x 1/4" FNPT Series 694 Black Polypropylene Check Valve with EPDM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 9.64/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	9.64/Each In Stock
Item 22638	1/4" FNPT x 1/4" FNPT Series 694 Black Polypropylene Check Valve with Buna-N Seals, 1/3 psi Cracking Pressure & 302 SS Spring 9.64/Each Out of Stock (On Order) Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	9.64/Each Out of Stock (On Order)
Item 22639	1/4" FNPT x 1/4" FNPT Series 694 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & Hastelloy® Spring 13.83/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	13.83/Each In Stock
Item 22232	3/8" FNPT x 3/8" FNPT Series 693 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 10.38/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	10.38/Each In Stock
Item 22640	3/8" FNPT x 3/8" FNPT Series 693 Black Polypropylene Check Valve with Buna-N Seals, 1/3 psi Cracking Pressure & 302 SS Spring 9.91/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	9.91/Each In Stock
Item 22641	3/8" FNPT x 3/8" FNPT Series 693 Black Polypropylene Check Valve with EPDM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 9.91/Each Out of Stock (On Order) Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	9.91/Each Out of Stock (On Order)
Item 22642	3/8" FNPT x 3/8" FNPT Series 693 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & Hastelloy® Spring 14.11/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	14.11/Each In Stock
Item 22210	1/2" FNPT x 1/2" FNPT Series 685 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 11.07/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	11.07/Each In Stock
Item 22643	1/2" FNPT x 1/2" FNPT Series 685 Black Polypropylene Check Valve with Buna-N Seals, 1/3 psi Cracking Pressure & 302 SS Spring 10.53/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	10.53/Each In Stock
Item 22644	1/2" FNPT x 1/2" FNPT Series 685 Black Polypropylene Check Valve with EPDM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 10.53/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	10.53/Each In Stock
Item 22645	1/2" FNPT x 1/2" FNPT Series 685 Black Polypropylene Check Valve with EPDM Seals & No Spring 10.53/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	10.53/Each In Stock
Item 22352	1/2" FNPT x 1/2" FNPT Series 685 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & Hastelloy® Spring 14.98/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	14.98/Each In Stock
Item 22646	1/2" FNPT x 1/2" FNPT Series 685 Black Polypropylene Check Valve with FKM Seals, 3 psi Cracking Pressure & Hastelloy® Spring 15.61/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	15.61/Each In Stock
Item 22647	1/2" FNPT x 1/2" FNPT Series 685 White & Black Polypropylene Check Valve with EPDM Seals, 7 psi Cracking Pressure & Hastelloy® Spring 15.68/Each Out of Stock (On Order) Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	15.68/Each Out of Stock (On Order)
Item 22648	1/2" FNPT x 1/2" MNPT Series 685 White & Black Polypropylene Check Valve with EPDM Seals, 7 psi Cracking Pressure & Hastelloy® Spring 15.68/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	15.68/Each In Stock
Item 22649	1/2" FNPT x 1/2" FNPT Series 685 White Polypropylene Check Valve with Aflas® Seals, 3 psi Cracking Pressure & Hastelloy® Spring 22.59/Each Out of Stock (On Order) Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	22.59/Each Out of Stock (On Order)
Item 22650	1/2" FNPT x 1/2" FNPT Series 685 White Polypropylene Check Valve with EPDM Seals, 1/3 psi Cracking Pressure & Hastelloy® Spring 14.97/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	14.97/Each In Stock
Item 22211	3/4" FNPT x 3/4" FNPT Series 687 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 12.52/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	12.52/Each In Stock
Item 22651	3/4" FNPT x 3/4" FNPT Series 687 Black Polypropylene Check Valve with Buna-N Seals, 1/3 psi Cracking Pressure & 302 SS Spring 11.93/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	11.93/Each In Stock
Item 22652	3/4" FNPT x 3/4" FNPT Series 687 White Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 13.23/Each Out of Stock (On Order) Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	13.23/Each Out of Stock (On Order)
Item 22653	3/4" FNPT x 3/4" FNPT Series 687 Black Polypropylene Check Valve with Buna-N Seals, 1/3 psi Cracking Pressure & Hastelloy® Spring 15.68/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	15.68/Each In Stock
Item 22654	3/4" FNPT x 3/4" FNPT Series 687 Black Polypropylene Check Valve with Buna-N Seals & No Spring 11.93/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	11.93/Each In Stock
Item 22655	3/4" FNPT x 3/4" FNPT Series 687 Black Polypropylene Check Valve with Buna-N Seals, 1/2 psi Cracking Pressure & 302 SS Spring 17.96/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	17.96/Each In Stock
Item 22656	3/4" FNPT x 3/4" FNPT Series 687 Black Polypropylene Check Valve with EPDM Seals, 1/3 psi Cracking Pressure & 302 SS Spring 11.93/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	11.93/Each In Stock
Item 22657	3/4" FNPT x 3/4" FNPT Series 687 Black Polypropylene Check Valve with FKM Seals, 1/3 psi Cracking Pressure & Hastelloy® Spring 16.28/Each In Stock Save 5% when you buy 12+ Save 10% when you buy 24+ Save 15% when you buy 72+	P-561	16.28/Each In Stock

Note: Product testing for individual applications is recommended before use. U.S. Plastic Corp. cannot be held liable for individual application failures.

SMC Check Valves for Air or Liquid

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