Dwyer Series PUB - Manual (Page 24)

3: Operating Procedures
20
3.5.3 Adjusting the calibration factor
With the system running:
1. Stop ( Stall) the PUB’s totalizer facility and zero it (Paragraph 3.6.1).
2. Run the PUB’s totalizer to measure the total flow over a 30 to 60 minute period, and note the total flow
indicated by the reference flow meter over the same period.
3. Calculate the % error between the PUB and reference meters. If the error is greater than ±1% calibrate the
PUB as detailed below.
3. Press the Options key to access the FLOW
READING OPTION screen shown.
4. Select Set zero flow (m/s) and press the
ENTER key.
5. Press the ENTER key on the subsequent screen
to accept the change, which will return you to
the screen shown.
6. Scroll down to select Exit and press the ENTER
key to return to the FLOW READING screen.
FLOW READING OPTION DD-MM-YY HH:MM:SS
Data review
Zero Cutoff (m/s) : 0.00
Set zero flow (m/s) : 0.00
Damping (secs) : 10
Totalizer : Run
Reset +Total
Key Point: In order to cancel any applied offset, you must either read the flow via
Quick Start or switch the PUB instrument OFF & ON. Any value that you trim-out using
the offset adjustment will be added/subtracted from the flow reading across the whole
range.
Key Point: USE THIS FACILITY WITH CARE & ONLY WHERE NECESSARY
The PUB instrument is fully calibrated before leaving the factory and under normal cir-
cumstances does not require further calibration when used on site.
This facility can be used to correct the flow indication where unavoidable errors occur
due to the lack of a straight pipe or where the sensors are forced to be fitted close to the
pipe-end, valve, junction etc.
Any adjustment must be made using a reference flowmeter fitted in the system.