Flow meters in scada

The only things needed to be considered are:

• The method of measurement of flow
• The line size
• The method of attachment to/insertion in the line
• The accuracy required
• The wetted materials, if any
• The output signal type and its compatibility with SCADA inputs
• The process fluid, its temperature and pressure
• The meter's robustness against fouling with that fluid
• Reliability
• Compatibility with spares stockholdings across the facility
• Training of instrument service technicians in cleaning and repair
• The isolation from the process, if any, for checks/calibration
• The hazardous area rating and the EEx- code, together with the correctness of the electrical installation to that code
• The IP rating
• The power supply voltage, whether AC/DC, and compatibility with available power sources
• The distance from any flying lead to any user-provided junction box
• The cable glanding and thread(s)
• Whether or not it needs any HART or similar protocol, FieldBus, etc.
• The orientation of the connection terminals relative to the pipeline
• Its weight and whether any lifting gear would be needed to install it
• The process down-time involved in installing it.

I don't think the flow meters care if you use scada, dcs or PC or PL control. Just buy good ones. And hire a controls guy to implement them.

You want to control a temperature since it is a cooling system. In such a case you have to measure TEMPERATURE not flow, the flow will be regulated according to the differences between the measured and set temperatures. You could use a flow meter only to know how much water was needed this can help you to determine the evolution of your system. With time convection can be modified due to dirt so that you will need higher flow (higher velocity to compensate lower coefficients) for same power requirements.

Thank you all........

PWSlack's list is excellent.

I would add that the installation of a flow meter is a huge contributor to minimizing the uncertainty of the meter's readings. A poor installation cannot be corrected by configuring a parameter or two. One is generally stuck with the results.

Very serious consideration should be given to where a flow meter will be mounted and whether that location conforms to the requirements of the technology under consideration.

The installation requirements for a given technology are generally similar between manufacturers, and include things like
- meter run distance: straight run piping distances upstream and downstream of the meter
- a location which will maintain a full pipe - an assumption of all single phase flow meters
- minimum flow velocity required to maintain the required accuracy spec
- those installation factors unique to a technology - like
- clamp-on ultrasonics cannot 'shoot through' heavy rust, corrosion or sea shells.
- grounding of magnetic flowmeters in plastic pipe

The installation recommendations in most product manuals are 8 - 20 pages in length, and generally illustrated with graphics. It pays to read that part of the manual to see how the installation requirements line up with reality.