The Double Check Valve Device Assembly – Check Valve Springs and Design Standards
In this exploded view of the DCVA, you can see the locations of the springs and each spring shall be at a minimum of at least 1 PSI or greater. The spring loading of the check valves provided the ability to “bite” through small debris that may be lodged on the check valve seat or disk and still seal drip tight. Unloaded check valve do not have this feature. The check valve loading is a critical part of the design of the DCVA. The DCVA is predominately used on fire protection systems and it is important to keep the pressure losses to a minimum. A spring loaded at 5 PSI would provide more closing force but would also create a greater pressure loss. The maximum pressure loss through a DCVA according to the American Water Association Standards cannot exceed 10 PSI. For this reason, manufacturers try to keep the spring load force to a minimum tolerance of 1.5 PIS per spring. On an average, a DCVA may reduce the pressure by approximately 3 to 4 PSI. The maximum operating pressure is 175 PSI and the operating temperature is 34 degrees to 180 degrees Fahrenheit.
