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SYSTEM DESIGN
Meter Selection
The flow meter must be carefully chosen using the information in the Meter Selection Factors
section above. The meter must be selected based on the operating system and product
characteristics. System variables include flow rate, temperature and pressure. The product
characteristics include the material compatibility, lubricity, viscosity, suspensions, pH, and other
factors. Failure to select the correct flow meter may result in serious injury, system failure or
reduced system performance.
Air Elimination
In any system I which the supply tank may be completely drained or where multiple products
manifold into one metering system, there is a risk of air being present in the fluid stream. The
solution is an air or vapor eliminator located before the flow meter to vent the air or vapor from
the system before it can be measured. Air or vapor elimination is required for all weights and
measures regulatory approvals in custody transfer applications.
Control Valves
Safety and isolation valves should be used throughout the metering system. In any pumping
system where there is one pump and multiple flow meters, a digital or hydro-mechanical Rate-
of-Flow control valve must be used at each flow meter to prevent the meter from operating above
its maximum flow rating.
Best Plumbing Configuration
1) Flow meter must have secure mounting to a riser stand or the foundation.
2) The inlet and outlet piping must be securely supported, in a manner that does not allow pipe
stress on the flow meter. The meter must also be supported and must not hang from the pipe
fittings.
3) System must be designed to keep the flow meter full of liquid at all times. Meter inlet and
outlet should be lower than the associated system plumbing (in the SUMP POSITION).
4) System piping must be of at least 1-1/2” or larger thoughout the entire metering system. This
will allow for minimal pressure loss.
5) The pipe should be laid out as straight as possible to reduce pressure loss from flow
restrictions.
6) It is not necessary for the air eliminator to be installed directly to the meter. It may be
installed upstream from the meter. For effective operation of the air eliminator, it should be
mounted between the meter and any valves, pipe tees or any other potential places where air
may enter the system.
7) The metering system must include a means for calibration.
