Flowmeters transmit pulses per revolution of the built in impeller which turns when fluid flows through the meter. The number of revolutions per Ml will vary depending on a number of factors including viscosity of the fluid, temperature and pressure of the fluid being delivered, mounting and orientation of the flowmeter and over time wear and tear on the flowmeter. As the variables change the flowmeter needs to be calibrated.


The calibration is used to correct the readings to ensure final readings which are as accurate as possible.


To Calibrate your taps please see the article on calibration


Considerations for calibrating flow meters & intervals of calibration:

  1. Flowmeter purpose: Is this a process-critical measurement where a change in meter characteristics would compromise the process in some way, or result in increased expenditure?
  2. Application: Is the fluid and the process benign or aggressive? Is the flow meter working at its operational limits? Could deposits or corrosion affect calibration?  Are there elements of the fluid that could compromise the measurement in some way e.g. particles in suspension?
  3. Flowmeter type: Is the meter a type which is likely to change performance for some reason? Is it mechanical, electronic or just a visual aid?
  4. Historic data: How accurate have previous re-calibrations been? Could/should the recalibration interval be reduced or increased with little risk to the overall process?
  5. Have there been any noticeable changes in measurements? Some modern flowmeters will monitor themselves and advise when something is not quite right. Most traditional types of flowmeter do not offer this facility but an astute operator may well notice a change and have it monitored for cause and effect.

Manufacturers will often try to dictate re-calibration periods. But as you can see from the tips above, the re-calibration period should be determined by the user – taking into account their unique conditions.  Advice should still be sought from the manufacturer, as they will know what the longer-term limitations of their flowmeters are likely to be. However, the final decision is likely to be a moving target, at least initially until the whole system operation and reliability is understood.