Liquid Relief Thrust force.

Hi everyone,

It has been my practiced to neglect the reaction load for pressure safety valves of liquid lines. But in this case, I have a rupture disk that is high pressure lines working around 25mPa.

I was searching for the correct formula of thrust load for rupture disk with liquid services but sad to say I found nothing. Even here I didn´t find any.

As I understand, The reaction equation and/or condition should be similar to the equation of the http://www.cheresources.com/reliefvalve.pdf posted by our dear forum member.

I don’t believe that the reaction load for rupture disk is equal to Pressure*Area for the liquid service. My reason is, liquid is nearly incompressible and with a slight volume change, my pressure drop rapidly.

The process would like to calculate this stuff using the Pressure heads and I feel that this is outrageous. Having in mind with the mass balance.

If my idea is incorrect, please correct it. Also I need references to support this information.

Thank you and regards

Theoretically, for a "free jet", the reactive force has two components, derived from Fluid mechanics:
Reactive_Force= [mass flow-rate]*[jet_velocity]+ [p_jet]*[area_jet]

In page 6 of your reference, there is the dynamic component, i.e.
[mass flow-rate]*[jet_velocity]= [vol flow-rate]* [density]*[jet_velocity]=
=[vol flow-rate]*[density]*[vol flow-rate]/[PI/4*D^2]=
=[4/PI]*[1000*SG]*[vol flow-rate]^2/[D^2]=
=1273*SG*[vol flow-rate]^2/[D^2]

Note that in Cheresources doc the numerical coefficient is 1268...

For other applications it is more convenient to evaluate by Bernoulli
jet_velocity=SQRT(2*dP/Density), etc

Best regards.

mariog,

Thank you for your reply.

I will review your procedure.

Thank you and regards,