Has anyone simulated a Cla-Val surge anticipator (Model 52-03) or surge relief valve (Model 50-01) in Water Hammer? The surge anticipator valve seems straight forward, but I'm not sure what kind of variables to use for time to open, time stays open, or time to close. These are all adjustable settings I believe, so is it trial and error in the model to specify these parameters and then field adjust and recheck in the model? Are there min. values for the valve to open and close?
And the surge relief valve in Hammer doesn't seem to apply to a Cla-Val. The Cla-Vals are hydraulically controlled so I don't believe they specify a spring constant...
Thx
-BWhite
Hello BWhite,
I do not have experience with those exact valve models, but I can provide some tips.
The settings for a surge valve are indeed adjustable, to allow you to customize the valve to match the characteristics of the actual valve you need to use. They are required because they can potentially have a significant affect on the transient response.
There isn't really any rule of thumb as to what values to use, as every surge valve is different. I would recommend asking the manufacturer for details on the response time of the valves. If the HAMMER run shows that those settings do not provide adequate protection, you may need to adjust based on the specifications of a different model. Or, you could try some values in the model until the transient is mitigated to your satisfaction, then select a surge valve that matches that size and response time. For more details on the meaning of each input field, check the below technote:
Modeling Reference - Surge Valves
If you're still unsure of exact values, I would recommend a sensitivity analysis. Meaning, try a range of values and check if they have a significant affect on the transient response in your system. if not, you may not need to worry about getting exact values.
If your surge relief valve is not controlled by a spring, I would recommend using a discharge to atmosphere (D2A) node instead. Set the Discharge Element Type to Valve, then use trial and error to find the time when the pressure rises above the threshold value. Meaning, run the model with the D2A closed, check when the pressure hits your threshold, then adjust the "time to start operating" accordingly, and so on.
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Thanks Jesse, I didn't even consider the D2A option. I'll test that out with some other sensitivity analyses. You've been very helpful!