Water Treaters ask, “How much chemical did our pumps feed yesterday?”
The feed rate for water treatment is extremely important. You want to determine if you have fed the correct volume of chemicals to ensure that concentrations are correct so that the water is properly treated. This also keeps usage costs within budget, because you can verify how much water-based chemical is being used.
Various methods used to monitor feed. One is to set the pump to turn on/off, based on a process measurement like pH, ORP or conductivity. The volume is assumed.
Another method is to use a timer to pump and a preset flow rate for a given interval. This is better. Still, you won’t know precisely how much chemical has been pumped.
What if the feed rate needs to be proportional, based on process measurement? A sure way is to put the feed tank (or whole tank and feed system) on a scale and weigh it as the volume comes down. The set-up on this is involved, but the results are conclusive, and often the best way.
There is another, simpler solution: Use a discharge volume Flow Checker. This device is is an oval gear positive-displacement flowmeter that gives a pulse output based on chemical feed volume. One pulse is generated for milliliter of chemical that moves through the feed tubing. It is available with FNPT or tube fittings.
Flow Checker Set-Up
Wire the Flow Checker to a flowmeter display, and the signal can be read as flow rate and total amount of chemical fed. The flow signal can also be re-transmitted to any other data logging device. Use a programmable display such as Precision Digital Model LS6200 that will accept the pulse signal from the flow checker and convert it into a flow rate measurement and totalize volume. This model will also re-transmit a 4-20mA signal for flow rate. It is programmable for display GPM, mL/min, etc. An optional NEMA 4X enclosure is available.
Flow Checker with NPT Connections
This low-cost solution costs less than a magnetic flowmeter and is more accurate for low flows up to 6.5 gph, 200 psi. Flow Checker is available for any metering pump.