orifice plate 1

[cam72]

For a orifice plate in pipe size 16" which type of taps are suitable? Flange taps or D,D/2 taps? is there any advantage of using D,D/2 taps in large pipe size? Thanks.

 

[hacksaw]

Of course not, it is driven by many factors related to your piping layout, fluid properties, plate style, service, accessibility, etc.

You basically work through all that with your design team, ten run a couple of sizing calcs and sort through what you are trying to accomplish.

The governing issue is what you are trying to accomplish, the taps are near the bottom of the list.

 

[ccfowler]

Hacksaw has provided excellent advice!

What type of fluid: gas, liquid, saturated vapor, ...?
What range of flow rates (turn-down ratio)?
What magnitude of accuracy or repeatability are of concern?
Is this for metering, control, or both?

When used for metering applications, orifice plates tend produce indications that understate the actual flow rate under most circumstances. Wear and distortions due to pressure differential loadings further tend to compromise accuracy in the direction of understating the actual flow rate.

Orifice plates are famous for being relatively cheap, but when all of the implications are fairly taken into consideration, they commonly do not fare well in overall costs compared to other metering options. Tap placement should be given full consideration, but the upstream and downstream piping configuration is most important. If particulates are involved in the flow, using an orifice for metering is almost certain to be a very poor choice.

Orifice meters, flow nozzles, etc. have been around for a long time and are very well documented in available literature. By taking all of the available information on installation considerations, correction factors, etc., it is possible for instrumentation and computation means to minimize errors in the flow rates indicated by the compete metering system.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[hacksaw]

well said...