Check valve manufacturers can test check valves to generate check valve dynamic characteristics curves, which is check valve deceleration vs reverse velocity curve. In the HAMMER engine, reverse velocity and deceleration at a time step can be calculated. The calculated values can be compared with check valve deceleration vs reverse velocity curve to determine when the check valve will close instantaneously.

Check Valve Closure Type

In order to support check valve dynamic characteristics curve, there is a new property, Check Valve Closure Typewhich can be set to one of three options:

• Instantaneous Closure: When Instantaneous Closure is selected, the check valve will be closed when reverse flow is sensed.
• Slow Closure: When Slow Closure is selected, you need to specify a Closure Time, which is the time to close the valve from fully open position after reverse flow is sensed.
• Dynamic Characteristics Curve: When Dynamic Characteristics Curve is selected, the user needs to edit check valve dynamic curve and select the curve in Check Valve Dynamic Curve field.

Check Valve Dynamic Curve

Check valve dynamic curve is deceleration vs reverse velocity curve in the following graph:

To edit a check valve dynamic characteristics curve, click Components, More, then Check Valve Dynamic Curves.

The Check Valve Dynamic Curves dialog opens:

Check Valve Dynamic Curves can be referenced by multiple check valves.

How Check Valve Dynamic Curves Are Used

During HAMMER engine calculation, reverse flow velocity and deceleration are calculated. Reverse flow velocity and deceleration are compared with reverse velocity and deceleration data in the check valve dynamic characteristics curve. If calculated reverse velocity exceeds the reverse velocity in the curve at the calculated deceleration, the check valve will close instantaneously.