The OSI model for digital communication popularized the use of seven layers for a model. That is why the S88 physical model does not have an eighth level.
Q: I want to know the effect of not following the straight pipe/meter run requirements for the following flowmeters: orifice, magnetic, vortex, turbine, ultrasonic and PD meters.
Furthermore, I wanted to know if there is any general rule for Meter run requirements and whose flowmeter has the least meter run requirement?
A: Please refer to the flow meter selection table, which is reproduced from my handbook. The table lists the straight run requirements and other features of all the volumetric and mass flowmeters.
A: I would like to remind readers that there are research based consensus standards. ASME-3M and IEC 5167 address orifice meter installations. Straight-run requirements for orifice meters depend on several parameters. Most vendors of flowmeter products provide instructions for installation of their meters. Hopefully, these are based on research data.
Sometimes we wonder about claims of wonderful accuracy.
A: Probably the swirlmeter, or vortex precession meter, has the least required straight run because it is itself a flow straightener.
A: Check the ASME codes and/or those of the API. They have long ago solved this problem.
A: The only thing I might add is a brief description of why you need a meter run. The meter run requirements for a flowmeter is specified so that the flow profile passing through the meter is repeatable. This repeatable profile allows the meter manufacturer to make certain assumptions about the flow characteristic when they are converting the data from the sensors into flow. A meter can be installed with meter runs that are less than specified, but the accuracy of the reading will be impacted. The effect of some pipe upstream pipe configurations has been studied and can be compensated in some meters. However it is obviously better to install the meter correctly in the first place.