Interesting results with a calibration test on flow meters - HELP

[T8er]

I'm currently gauging and calibrating two flow meters for an experiment later on. And am having some interesting results.

I have attached a picture to show you my current set up.

Why am I doing this? I have them hooked up directly inline to make sure that they are getting accurate and repeatable results.

The meters themselves are ER-500's from Badger Meter. The rotors attached to the meters are a oval gear setup with a 1/4" NPT tap on either side. I have a pump that is hooked directly up to the rotors. I have ran a test on the meters 6 separate times and let the pump run for a few minutes to stabilize. And each time the Right Meter inline always has a higher readout of GPM. Why would this be? I would think that the first meter would have the larger readout due to that being the first one affected by the pressure from the pump. Could it be a hardware issue? Pump Issue? Rotor Issue?


My results from tests are as follows (All answers in GPM):

Test# 1:

Left Meter: 2.93​

Right Meter: 3.54​

Test #2:

Left Meter: 3.70​

Right Meter: 3.85​

Test #3:

Left Meter: 3.53​

Right Meter: 3.80​

Test #4:

Left Meter: 3.18​

Right Meter: 3.67​

Test #5:

Left Meter: 3.22​

Right Meter: 3.68​

Test #6:

Left Meter: 3.37​

Right Meter: 3.75​

Sorry for the formatting, wrighting this hastily before I leave the office for the day. I might need an adult beverage. Also the Red Wings play tonight, that'll cheer me up.

Thanks for all your help in advance!




The joy of engineering is to find a straight line on a double logarithmic diagram.

 

[1gibson]

Swap them and see if the higher reading stays with the meter, or the location. I'd suggest the first meter is conditioning the flow somehow that causes the second meter to read high.

 

[LittleInch]

No clear reason. Time to swap things. Try swapping readers and keep same meters.

Swap meters in the first instance.

Check setup in the readers

Keep records.

Check wires. That wiring looks a bit dubious and very thin wires. You can get broken wires very easily which gives random errors.

Lots of error checking to do.....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[cvg]

suggest only one at a time, not both. never heard of testing two meters on the same test bench at the same time. are you sure either one is working correctly? how are you actually calibrating them?

 

[danw2]

The Badger ER-500 is an electronic display that takes signals from any flowmeter.

Your unspecified model of oval gear flowmeters appear to have the red Badger logo.

The current Badger spec sheet shows the max flow rate for a 1/4" oval gear flow meter to be 2.2 GPM,

yet you're pushing over 3 GPM through them.

Badger's manual does not specifically advise against over running its max flow rate nor does it warn against pressure drops exceeding 1 bar, but a lot other oval gear brands do.

You need a flow meter with a higher capacity flow rating.

 

[bimr]

Agree with Danw2, you are operating the flow meter outside of it's capacity range. See the attached chart.'

Accuracy is only valid when you are operating within the devices flow range.