Error in DP Level Measurement

Out from my eye I caught a mistake in your calculation.

if the tank is 637 cm then the pressure should surely be 6.37 mH2O.

What else could possibly be wrong?

How about you try adding 1 bar to the measurement as in atmospheric pressure minus possibly the real level in the tank which we dont know what it is but I would think it is EMPTY!

Any combination of these:

• Transmitter mounted up to 3.66m lower than the bottom of the tank
• Something other than the expected fluid is in the tank
• Something other than liquid is in the connection to the transmitter
• The transmitter is incorrectly set up
• The measurements given in the post are incorrect
• The transmitter is malfunctioning
• There is an additional feed of power onto the transmitter circuit somewhere
• The input receiving information from the transmitter is incorrectly scaled
• The temperature is other than 4degC
• The non-tank side of the transmitter is conencted to something at a lower pressure than atmospheric
• There is an applied pressure over the top of the liquid in the tank caused by
• Blanket inerting gas
• Blocked vent valve
• The pressure tapping on the tank is too close to a pump discharge
• The pressure tapping is blocked, having previously been subject to that pressure
• The instrument isolation valves are closed, it having previously been subject to that pressure
• The pressure tapping is frozen-up
• The operative reading the transmitter should have gone to Specsavers (usual disclaimer)
• Etc.

The guy who configured it probably has dealt with how data is displayed in an HMI.

When looking at a recorded graph of tank level over time, no one wants the scale on the graph to be 0 to 6.34m. The major and minor division wouldn't be even numbers.

So that guy set the URV (Upper range value) to 10m so that scaling in the HMI/controller/SCADA/receiver would have major divisions at 1m, minor divisions every 10cm.

Or, as PWSlack points out, the transmitter could be mounted below the bottom of the tank, but you don't tell us what the LRV is.

By the way, all smart transmitters have engineering units in inches of water column, as well as metric mm or meters. If you're more comfortable using inches, change the eng units to inches.

If a higher-than-the-tank 10m URV bothers you so much, change it to some lower value, but make sure that whatever receives the signal gets re-rescaled accordingly.

...or re-scale it so that it displays 0-100% level, perhaps.

Friend,

What liquid are you measuring?

If the HRV is 10 mh2O maybe you are measuring some liquid heavier than water, I mention this by the HRV value, other possible reason could be you are having the transmitter 3,63 mts below the nozzle, It is necessary more information friend for your case

A drawing for your situation will be a lot useful in order to check all the system

Does both legs connected to the tank?

Best regards

JP

Check the calibration of your instrument,