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Cascading TRV
- Thread starter HunterJ
- Start date
MikeHalloran
Mechanical
What do you mean by 'cascading'?
Like a series of plugs made of Cerrobend or other low-melting-point alloys with different melting temperatures?
Mike Halloran
Pembroke Pines, FL, USA
Like a series of plugs made of Cerrobend or other low-melting-point alloys with different melting temperatures?
Mike Halloran
Pembroke Pines, FL, USA
LittleInch
Petroleum
I don't think there is one. It's just a matter of piping system system design. All you need to do is ensure you use the correct type of TRV, which isn't affected by back pressure and you always relieve into the same or high rated systems.
It's not too common to have more than one cascade and most times now people don't like the cross connection. Far simpler to include a closed drain system.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
It's not too common to have more than one cascade and most times now people don't like the cross connection. Far simpler to include a closed drain system.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
georgeverghese
Chemical
Tricky topic
A few tips:
a) Actual set pressure on a conventional RVs' is affected by backpressure. For example, a 10% increase in backpressure increases the SP by 10%.
b) Actual set press on a balanced bellows RV is unaffected by backpressure for backpressures up to about 70-80% of set pressure.
You can find this this nugget in the API 521.
Good luck
A few tips:
a) Actual set pressure on a conventional RVs' is affected by backpressure. For example, a 10% increase in backpressure increases the SP by 10%.
b) Actual set press on a balanced bellows RV is unaffected by backpressure for backpressures up to about 70-80% of set pressure.
You can find this this nugget in the API 521.
Good luck
- Thread starter
- #5
Thanks for the replies.
I’m looking at using the C series fixed cracking pressure check valve [10 psi] Swagelok check valve that will vent/relieve pressure back into a vented above ground storage tank. Max pressure in the tank based off fluid height would be 11 psig.
So I guess in a perfect world if the tank were full this would start to relieve once the pressure in the closed pipe reached 21 psi.
I’m looking at using the C series fixed cracking pressure check valve [10 psi] Swagelok check valve that will vent/relieve pressure back into a vented above ground storage tank. Max pressure in the tank based off fluid height would be 11 psig.
So I guess in a perfect world if the tank were full this would start to relieve once the pressure in the closed pipe reached 21 psi.
georgeverghese
Chemical
Doesnt look like these Swagelok C series press diff valves could be called "safety relief valves".
They are just plain pressure differential valves.
They are just plain pressure differential valves.
LittleInch
Petroleum
HunterJ,
I believe you are correct.
This is not really what most people think of as a "cascading relief, nor is a "fixed pressure check valve" seen as a safety valve. the margin on setting pressure is likely to be much higher than a proper spring relief, possibly -50%, + 25%
If the tank level is low, then any pressure >10 psi will flow fluid back to the tank.
Is this what you want?
10 psi is very low - why so low?
This system as described does not make any sense.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I believe you are correct.
This is not really what most people think of as a "cascading relief, nor is a "fixed pressure check valve" seen as a safety valve. the margin on setting pressure is likely to be much higher than a proper spring relief, possibly -50%, + 25%
If the tank level is low, then any pressure >10 psi will flow fluid back to the tank.
Is this what you want?
10 psi is very low - why so low?
This system as described does not make any sense.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
- Status