Problem

How can I model a Non-slam vs. slam type check valve for a transient simulation in HAMMER?

Solution

"Non-slam" check valves are modeling with a closure delay of zero. This is the default assumption for the check valve built into a pump, and the check valve option for a pipe. Meaning, the check valve closes instantly upon first detection of reverse flow. This is considered "non-slam" because reverse velocity has not had a chance to build up. In other words, the water column is essentially at rest (zero momentum) when the check valve closes, so there is little or no change in momentum to cause a "slam" (pressure surge) See the below check valve modeling reference article for details on the three different ways to model an instantly-closing check valve.

Conversely, a "slam" check valve can be modeled by introducing a closure delay. This can be modeled with the check valve node element, as explained in the below check valve modeling reference article.

See Also

Modeling Reference - Check Valves in HAMMER