Non-Slam Style Check Valve 2

[sshep]

My Friends,

Is there a rule of thumb for when a non-slam type check valve should be considered?

I just saw an incident notification where water hammer shattered the body of a 16" cooling water check valve (see attached picture). My project's big pumps for cooling water, fire water, ect are all specified to have non-slam check valves, but it isn't clear what size and pressure this starts to be a concern.

best wishes,
SShep

 

[bimr]

Systems should be designed so that non-slam check valves are not required. These incidents are usually associated with water hammer.

For larger systems such as you describe, measures such as slowing the time for valves to close will eliminate some of the potential for water hammer.

Where long straight lengths of piping and elevation changes are constructed, the possibility of water hammer and flow reversal are much more likely and these scenarios should be evaluated more thoroughly.

One cause of water hammer is the sudden shutdown of pumps from power failure.

 

[EmmanuelTop]

See the discussion at

http://www.eng-tips.com/viewthread.cfm?qid=336042

2nd post contains attachment on selection of check valves for pumped systems.

See also

http://www.valmatic.com/pdfs/DesignSelectCriteriaCV.pdf

Dejan IVANOVIC
Process Engineer, MSChE

 

[bimr]

See the attachment regarding valve slam and check valves.

 

[sshep]

Thanks My Friends,

This was good info. The Val-matic literature had some quantitative guidance which was cool.

bimr, what was the source of your extract in case I need to make a citation.

best wishes,
Sean