High Viscosity Relief valve sizing

[iqmarco]

We are to size a relief valve for a fluid with viscosity >50000 cp using API 520 but,
we calculate a REynolds number too low (1). What can I do if the graph Re vs Kv starts in a Reynolds number = 34.

 

[don1980]

I would assess whether or not this is a system that can be protected by common relief devices. There are systems in which common relief devices are incapable of providing the protection needed. That's why, for example, ASME and API allow the alternative of using HIPPS.

A high viscosity polymer solution is a good example of a system that often can't be protected using relief devices. The risk is plugging of the inlet and/or outlet line.

I can't answer your specific question because I haven't experienced a case like yours which justified proceeding with a relief device. Possibly there are some high viscosity streams which don't have a risk of plugging. If there are, I don't have any experience with them.

 

[iqmarco]

Thanks for your answer. The material I'm dealing with is very viscous (65,000 cP). So, when I use the iterative process to adjust for viscous flow, the value of Reynold's number quickly decreases. (R=(2800*G*Q)/(mu*sqrt(A)) So, each time I calculate an orifice size, then choose the next closest standard size valve, and recalculate. I end up getting an even larger area and this continues and the area increases to ridiculus areas. Does anyone have some advice on this? I'm using API 520

 

[Latexman]

I am not familiar with the reference linked here:

thread1203-287187

But, it is on topic.

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.