Flow straighteners

Please describe the context in which the 17 tubes may be found. Why is straightening carried out at that place?

What does the manufacturer have to say about it?

the API flow standards say that if you use a 19 tube straighting vane system, all the equations and accuracy fiquires work. If you use anything else, then the manufacturer must supply data that supports that their design achieves the same accuracy as the 19 tube bundle.

It means that the formulas provided by API only apply to 19 tube bundels. If you use anything else, you'll need another, different set of formulas which should be provided by your supplier.

There shouldn't be a problem with measurement. It's just that the supplier should assure you that their 17 tube straightener will result in the same accuracy as the 19 tube straightener for your flow meter.

The problem is that the literature available only states the formulas and calculations with a 19-tube bundle. A whole experimentation process was done in order to consider that this type of straightener was useful to cut the swirl in the flow, making it possible to exclude this effect from the sources of uncertainty when measuring.

In my opinion, you should ask the manufacturer about the tests performed and the validation of the usage of a 17-tube bundle type of straightener in a measurement system.