Flo Control 2"" Union Check Valve 1750-20 has union connections on both ends, slip socket 2"" PVC, and has an internal adjustable Spring Tension, factory set at 5 lbs, but adjustable within the range of 1 to 14 lbs.
For spas and hot tubs, most blowers use a 1/4 lb spring, and most water lines use only a 1/2 lb spring. This 2"" adjustable check valve has broader uses, for use in pool or spa solar systems or for pool equipment located far below the pool water level. It also has many industrial and commercial uses. Unions allow for removal or reversal of check valve, to change spring tension or to inspect for damage or debris, or for winterization purposes.