Orifice Straight Run Requirements

Most of the flowmeter literature I've seen suggests 5d of straight piping before the meter and 10d after. But this is a rule of thumb, and it might not account for large numbers of fittings in either direction. Simple flow-restricting orifices would probably require less.

That ISO 5167-2 beta ratio stuff sounds like too much theory trying to chase too little practical knowledge. What does the orifice or flowmeter manufacturer's literature say?

To be really safe, how about 1 km before and 2 km after?* [The kramarat asterisk indicates facetiousness.]

If I cannot get the 5d upstream and 10d downstream then I always use a flow straightener before the orifice plate with good results.

What is a flow straightener? Is it real, or a joke?

I used to buy flow straighteners from ISA Controls, Shildon, County Durham, UK, I think they may be part of the Emerson group now. Its a plate about 30mm thick with holes drilled to a calculated pattern

Thank you. The concept is absolutely new to me, but it seems that it just might work. Thank you, again.

Try this link, I forgot that they were part of the Solartron group. www.solartronisa.com ,