Restriction Orifice Specifications 1

[Weegie]

I'm looking for standards/specification numbers that cover the calculations for, and manufacturing of, 'restriction orifices'(and not 'flow orifice plates').
Are they covered by the same standards/specifications for flow orifice plates e.g., ISO 5167, AGA Report No.3, API 14.3.2 or something else ?
I have searched through the above and they seem to be more 'flow orifice plate' specific and I cannot find any mention of restriction orifices.

Thanks in advance.

 

[JohnGP]

Weegie,

Why not design per flow orifice? After all, an RO will require the same strength considerations as a flow orifice when it does see flow - it's just that you are not trying to accurately measure the flow presumably.

See following for some manufactured ROs -

http://www.thermocouple.co.uk/Downloads/FM-OP_ROPA.pdf

Cheers,
John

 

[Weegie]

Appreciate the reply John.

The RO is in a pump recirc line and is there to limit the flow rate and not as a dp orifice for flow measurement.
I checked out your link and the RO's there are manufactured 'generally' to ISO 5167 which is for orifice plate manufacture/design.
I had read somewhere that the RO pressure drop was more of a concern as it is typically much higher (PSI) than an orifice plate pressure drop (usually sized for only 100" wc. The issue was about plate thickness/strength handling the higher (PSI) drop.

 

[JohnGP]

I have previously used Roark to confirm the strength of an orifice plate. I don't have the file with me but there must have been something unusual about the setup, to make me do that.

I realise that you are not trying to measure flow - the link that I gave provides recommended RO thicknesses for given pressure drop, so may help to put you in the right ball park. You just need to work out what size hole provides the pressure drop.

Cheers,
John

 

[Weegie]

John,
Your link did help and is greatly apreciated. My reason for wanting an RO specific spec (if there is such a thing) is that I'm doing instrument data sheets.
My flow orifice plate data sheets point potential vendors to specs like ISO 5167, AGA Report No. 3 and/or API 14.3.2

I want to reference similar (or the same ?)type specs on my RO data sheets for the vendors.
The vendor link you provided state that they manufacture 'generally' to ISO 5167. That to me suggests that possibly there is no real spec for RO's out there.

Thanks again for your help.

 

[casflo]

The restriction flow orifices have sharp edge and the flow orifices have rounded edge so the recovery pressure is bigger.
You can found the design of restriction orifices in the Crane Technical Paper No. 410.
Regards.
casflo

 

[JohnGP]

Weegie,
I suspect that you are right in that there are no specs covering ROs - but there probably doesn't need to be. They don't have to be designed with defined accuracy as an accurate flow element, and are not a pressure retaining device. They just require sufficient strength for the pressure drop you end up with for the flow, and be a reasonable fit between flanges. You can specify all the necessary operating parameters in your datasheet.

Cheers,
John

 

[sjrfc2]

There is a Steam Trap Handbook that provides info on orifice plates regarding orifice size and capacity curves versus differential pressure. Capacities are given for both steam and condensate. I think the author is McKelvey.

Data was developed to show relative loss if orifices vice traps are used for ridding condensate from lines. Regarding construction there is a spec MS18301 to use that type of plate in line betwen two flanges.

 

[stanier]

Download freeware

http://www.pumpsystemsmatter.org/content_detail.aspx?id=110

An orifice plate node is available. Connect to pump or pressure node and do the calculations.

This software is based on AFT's Fathom. if you wnt the full blown version invest.

http://www.aft.com.

Software is good and there are a few interesting modules such as slurry, goal seek etc.

 

[Weegie]

Gents, many thanks for all your input and expert advice.
It's greatly appreciated.

Has anybody ever seen or heard of ASME 3-31-3 Calculation for thickness of Restriction Orifices ?
I searched but, couldn't find it.

I found it listed on this web site.

http://www.e-m-f.co.uk/Flow Standards.htm