Flowmeter - Low Flow Meter SPX for water applications FAQ

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Q. I want to connect an SPX flow meter to my (controller, PLC, counter, data aquisition card....) How do I do it?

A. The SPX has a square-wave (on/off) signal. The frequency is proportional to the flow rate, and each on/off "pulse" is equal to a unit of liquid volume. The K-factor, or pulses per gallon, is marked on the meter. If your control can count, and is set capable of seeing a current-sinking input (most PLC's and counters are) you can go direct with no other electronics. If you can only receive analog inputs, you will need an AO55 transmitter to convert from the pulse signal to 4-20 mA. For more information, see the tech bulletin "Connecting SeaMetrics Flowmeters to Programmable Logic Controllers". Most of the information is also relevant to other controls.

Q. Is the SPX compatible with (acid, caustic, ethylene glycol, etc.)?

A. The main material is polypropylene, the standard lens is acrylic. These are both good general chemically-resistant materials, but they can't handle many of the stronger chemicals. The rotor is PVDF, the shaft is a nickel-bonded tungsten carbide, similar to a stainless steel in resistance. We may be able to help determine compatibility, but if these materials are questionable, take a look at the SPT, which has an all-PTFE body and a zirconia ceramic shaft.

Q.	I want to connect an SPX flow meter to my (controller, PLC, counter, data aquisition card....) How do I do it?
A.	The SPX has a square-wave (on/off) signal. The frequency is proportional to the flow rate, and each on/off "pulse" is equal to a unit of liquid volume. The K-factor, or pulses per gallon, is marked on the meter. If your control can count, and is set capable of seeing a current-sinking input (most PLC's and counters are) you can go direct with no other electronics. If you can only receive analog inputs, you will need an AO55 transmitter to convert from the pulse signal to 4-20 mA. For more information, see the tech bulletin "Connecting SeaMetrics Flowmeters to Programmable Logic Controllers". Most of the information is also relevant to other controls.
Q.	Is the SPX compatible with (acid, caustic, ethylene glycol, etc.)?
A.	The main material is polypropylene, the standard lens is acrylic. These are both good general chemically-resistant materials, but they can't handle many of the stronger chemicals. The rotor is PVDF, the shaft is a nickel-bonded tungsten carbide, similar to a stainless steel in resistance. We may be able to help determine compatibility, but if these materials are questionable, take a look at the SPT, which has an all-PTFE body and a zirconia ceramic shaft.