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Lt. Commander

[import] Flow run

>>Message imported from previous forum - Category:Realflo Electronic Flow Measurement<<
User: mchartrand, originally posted: 2018-10-17 17:31:30 Id:53
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.


I am really new to Realflo software and understand it is the software use to access the flow computer in a transmitter like a 4203 or a scadapack using a regular transmitter. What i don't understand is what really is a flow run? what is the difference between a liquid run and water run?**_


I haven't dealt with the specifics of RealFlo before, but I'll provide some information to hopefully fill in the blanks until someone hopefully provides some more information.

A flow run is typically a particular stream of flow passing through a particular set of metering devices (a flow meter, perhaps a pressure transmitter and/or temperature transmitter). It's something that you might care about current flow rate (in L/sec, as well as kg/hr perhaps), in addition to totalised values for.

Water is a particular kind of liquid, so I'd expect the water run to be a simplified liquid run. Temperature and pressure affect the mass flow differently for different materials. So water flowing at 100L/s will have a different mass flow at 10degC than it will at 40degC. Once you go to an arbitrary liquid (and not water) then you will have different magic values for the correlation between volume, mass, temperature and pressure.

If you are only dealing with water, then a water run should be sufficient for all your requirements. If you're dealing with non-water (with lots of impurities, or particular strong acting impurities.. or just not water... maybe alcohol, or oil) then if you need precise volume/mass rates and totalisers then you will need to enter the magic values for that particular liquid, and provide some additional sensors.

It's a similar story with fuel gases, which is where my experience with flow runs comes from. They are usually metered with an ultrasonic flow meter, which measures volumetric flow (well average velocity flow, which is correlatable to volumetric flow with known corrections for side wall friction, turbulence, etc etc). But they are billed as a totalised mass. So they need to be compensated with a pressure and temperature measurement also. Each particular gas composition has a set of parameters for the compensation (so ethane is a bit different than methane, which is different than propane..), usually a pretty consistent blend is provided which will have a known set of parameters. Sometimes online gas chromatography will be used to determine what is the ratiometric composition of the gas, and then the compensation parameters will be tweaked online for the measured composition.


As for specifics...
The SCADAPack 4203 includes a 'multivariable sensor'.
This normally means that it will include a temperature and a static pressure instrument, plus either an input for a dedicated flow signal, or a differential pressure instrument which will allow this to be used with Orifice Plate type (or similar DP-related) flow meters.
It can be hooked up to another 'multivariable sensor' to allow it to do two calculations for two flow runs. An ideal second transmitter would be the SCADAPack 4102, which is a 'Modbus multivariable transmitter'.

The SCADAPack 32/32P devices can do up to 10 of the these calculation loops...


Thanks. This information really gives me a good understanding.**_