PULSAR MEASUREMENT
75
COMMON QUESTIONS AND ANSWERS
The pipe vibrates. Will it affect the flow meter?
Common vibration frequencies are far lower than the sonic frequencies used by the flow meter, and will not
normally affect accuracy or performance. However, applications where very weak Transit Time signal is present
(when sensitivity is adjusted to maximum and signal strength is low), accuracy may be affected by pipe vibration,
or the flow meter may show readings under no-flow conditions. Attempt to relocate the sensor on a pipe section
where vibration is reduced, or arrange pipe mounting brackets to reduce vibration at the sensor mounting
location.
The flow meter must be installed in a high noise environment. Will this affect operation?
Our flow meters are designed to discriminate between environmental noise and the Transit Time signal. High
noise environments may affect the flow meter’s performance where low signal strength and/or low flow velocities
are being measured. Relocate the sensor in a quieter environment if possible.
Will pipe corrosion affect accuracy of the flow meter?
Yes. Rust, loose paint etc. must be removed from the outside of the pipe to provide a clean mounting position
when installing a Transit Time sensor. Severe corrosion/oxidation on the inside of the pipe may prevent the Transit
Time signal from penetrating into the flow. If the pipe cannot be cleaned, a spool piece (PVC recommended)
should be installed for sensor mounting.
What effect do pipe liners have on the flow meter?
The air gap between loose insertion liners and the pipe wall prevent the Transit Time signal from entering the
flow. Better results can be expected with bonded liners such as cement, epoxy or tar, however an on site test is
recommended to determine if the application is suitable for a Transit Time flow meter.
Why is Transit Time recommended for clean liquids?
The Transit Time sensor transmits sound across the flow stream in order to measure the time it takes to arrive at
the other sensor, and therefore requires a fluid medium that is relatively transparent to the acoustic signal. The
Transit Time system will not function when there is high volume of solids or aeration. As a guideline, Transit Time
flow meters are recommended for clean liquids with solids or bubbles content less than 2% by volume.
Can the sensor be submerged in water?
Yes, for short periods of time or by accident, but it is not recommended for continuous operation. The sensor is
constructed to withstand submersion to 10 psi (0.7 Bar) without damage provided the protective rubber boot is
filled with Super Lube®.
