Ultrasonic flowmeter

Dear,

I need to measure flow on existing pipe 1.6m diameter, and it is not allowed to remove it, so I guess I will go for clamp on ultrasonic flowmeter, however, I only have 4D upstream available instead of the required 10D, do you think the accuracy will vary much in this case?

good day,

Charbel

is it a liquid or gas you are trying to measure?

it is a liquid

The real question is not, "will it vary much?", but, "how much will it vary?", because that's always the follow-up question.

And that's an unknown. You don't know because the magnitude of error due to upstream/down pipe geometry flow profile is rarely, if ever, researched and published. The error is acknowledged, but is not quantified.

For other flow technologies, there is some evidence. Siemens published the results of a flow stand test for magmeters with upstream anomalies like elbows in-line or out-of-line where the flow rate error was less than 2% (I was astounded to have finally found actual test results when I read that.) And some years ago, I found four or five references to orifice plate erosion-wear or installed-backwards error, with error rates reading from 10% to 25% low.

But I've never found any published comments on the magnitude of clamp-on error.

Siemens clamp-on flowmeters have a setting that claims to provide some correction for flow profile induced error, but no numbers for what the error reduction is:

The accuracy is not going to be good. It may be good enough depending on the process. More important in most cases is repeatability.

You may not be stuck with clamp-on technologies. There are hot tap systems for insertion type mag meters and insertion ultrasonics that may be applicable. Talk to your supplier.

https://youtu.be/0R_bw0qTf10