Mechanical Water Flow Meter

"Best" depends on the application.
Best for 250mL/minute isn't the same as Best for 30L/minute.
Give us some spec's and you may get some advice.

Generally I'd think the mechanical ones are all paddle wheels of one type or another, just gotta spec' it to suit the application, flow variation, accuracy, installation etc.
Del

Did you read our rules for posting a question? From rule #14:

• Provide as much information as possible. The most frustrating questions on CR4 are like this one: "I need a sensor to test water flow - which is the best one." What are you testing for and what are you trying to determine? Is it in a stream, a pipe, or an aquifer? Are you looking to measure velocity or mass? Are you testing for particulates, mineral concentration, or pollution? Is it wastewater, potable water, slurry, etc.? The more you let us know, the better the chance that someone on the site will be able to help you find an answer.

The best technical specification will be the one written by the process or instrumentation engineer who is working of the project and who knows the process and requirements for the meter.

If you just want to copy one, go to:

Flow meters- Directory of manufacturers of flowmeters pick one that looks good and copy it.

No one can read your mind.

Rate or total? Accuracy? Application?

accuracy

You do not communicate well with others. You only chose one of the five words in a three part question. You did not even answer the question containing that word.

Good Luck

You, Guv. After all, no-one else here knows what you mean by "best".