Restriction orifice Standards for liquid or gas-liquid services

[sukanta60]

Hi All,

What are the standards for sizing of restriction orifices? Needed for liquid and gas-liquid flow. Does AGA 3, ISO 5167-2, ASME MFC 3M really highlight this issue? I went through them but not satisfactory and specific.
The calculation can be done but the thing is the CONSIDERATIONS. For example, the upstream pressure and downstream pressure of a RO is 1000 psig and 80 psig accordingly. Is it possible doing this DP using single RO? When to use multiple RO? How to measure cavitation after RO? IF RO is after control valve, then what should be the upstream pressure of RO? what is the allowable/suitable range of beta ratio for RO? etc ,,,,
Is there any standards or guidelines which is specific for RO (for liquid services), not for in-general orifice plate?

Thanks in advance.

 

[hacksaw]

The flow meter standards should not be used for restriction "orifices" they are strictly for low d/p and single orifice, thin plate restrictions.

High d/p restrictions such as you describe are custom designed to take the pressure drop mechanically, and control the noise developed.

several of the valve manufacturers offer shuch restrictions.

restriction devices commonly used in BFW services are "gun barrel" types, or use properly sized control valves.

 

[danw2]

Guy who wrote an article for Piping Engineering didn't know of a code or standard that directly addresses RO's

[URL unfurl="true"]http://www.piping-engineering.com/restriction-orifice-ro-flow-control-instrument.html[/url]

It's got a couple of good illustrations of the various styles.

 

[sukanta60]

Thank you very much to all. I concluded to check the noise level, cavitation and plate thickness for the RO. This post is also enough helpful

http://www.eng-tips.com/viewthread.cfm?qid=305795

where the practical experience was shared nicely with remedy.

Sukanta Mondal.

 

[MortenA]

For a restriction orifice i would use the same equation as for a PSV in API 520

 

[sukanta60]

Dear MortenA, did you calculate only the orifice area/size?

Is there any noise calculation procedure for the restriction orifice plates for liquid services?

Sukanta Mondal.

 

[MortenA]

@sukanta60,

I dont understand your question - what else is there to calculate? The tricky part would be to determine the coefficient of discharge, for liquid i would follow the common .65 for a sharp orifice.

I dont know if the noise would also follow the API formula for a PSV - i would doubt that.

 

[sukanta60]

@Mortena,
Yes, the orifice plate bore size calculation is the main task. But with the size cavitation analysis, noise calculation and plate thickness needed to check also. I was asking for the checklist.

Sukanta Mondal.