Conterc 212 BTU meter have too much fluctuating flow

[syed1989]

Dears,
we have been using conterc 212 from last 15 years, suddenly last week flow started fluctuating with very higher values, I have changed the k-factor from 0000.100 P/Gal to 0005.250 P/Gal then flow came back to normal readings but fluctuating in +/- 300 values with actual flow meter values.
Kindly any one advice me how to stop these fluctuation and match the values between flow meter and BTU meter.

 

[danw2]

That energy meter uses a pulsed digital flow meter input signal and temperature probe input(s) to calculate BTU.

1. How do you know that it is not reporting reality, that the energy is, in fact much higher than previously?

2. config change
There's a checking setup parameters function described in the manual. Have you confirmed that the meter setup has not been changed, other than the K factor change you've made?

3. Error in the flow rate or the temperature inputs

Either flow rate error or temperature input error could contribute to a energy total error after 15 years. Typically RTD's only fail from vibration or water intrusion into the sheath. But if the upstream RTD drifts low so the delta T dereases, then the energy value decreases. Or the downstream RTD drifts high. A loose or missing reference wire on a 4-wire RTD will create an error. An increase in resistance (junction block terminals) in the downstream RTD circuit will appear as an increase in downstream temp with a delta T error on the low side.

Electrical noise is known to 'add' pulses to a pulse stream. But added pulses would increase the flow rate resulting in a false high flow rate error, not a false low flow rate error.

I can't recall any pulse output flowmeters I've dealt with that have added pulses to the pulse stream output. I have encountered those that have failed to send pulses for a time period which would manifest as a low energy total. One recently faulted to no-pulses about once a minute for 10-15 seconds.

4. Error in Contrec or the input signal sources?

The Contrec manual provides no troubleshooting technique for checking the pulse input or the temperature inputs. Substituting a calibration grade frequency source within the meter's configured frequency range and checking the total over some time period with what it should be by manual arithmetic would be one way of checking. A high end RTD calibration check (my handheld RTD simulator is not accurate enough, not does it offer 4-wire output) would prove or disprove the meter's RTD input accuracy.

If you're messing with the K factor to increase the reported energy value, it could be that the output from flow meter is either incorrect or is being corrupted by missing pulses. Checking the output signal with an accurate unit that can totalize could confirm that the signal is either accurate or not.