Program Calculation Problem

Hello Everyone



I have a system where there is resin and hardener being piped pumped in a hose (separate) to the nozzle where the chemicals are mixed. The system is existing and I have been asked to do some modifications.



The customer would like to know the quantity used but all I have is the speed of the VFD (controlled by 0 to 10 VDC analog) a prox for revolutions, and the specific gravity of the chemicals.



How can I build a formula to figure out the quantity of the product used.

Work through the math - USING THE UNITS! This is a middle-school math problem...

But with this, right now, I don't see that you have enough information. You know how many revolutions you're using. You know the specific gravity. But you don't know (or haven't shared with us) the volume of material per revolution. If you can come up with that information, the calculation is easy.

(Revolutions)(volume/revolution)(wt/volume) = usage (weight)

My volume would change based on the speed would it not?

Are the revolutions in reference to a positive displacement pump?

I don't know, but just a thought... Why not just simply use a flow meter and count pulses?

It just seems to me that the method you are wanting to use would not really be that accurate, only ball park.

We really need the answer to OkiePC's question: Is this a positive displacement pump? It makes all the difference in the world.

Even though I suspect it is positive displacement because its pumping viscous material - we need to know for sure, and also what the pump specs are. If you don't have the specs google the pump maker and model. Once you know that its a piece of cake.

Even with a positive displacement pump you would still need to be careful. PD pumps pumping viscous materials to nozzles will often have some kind of relief valve built in to recirculate material in the event of a blockage. Sometimes this is also used for pressure control. You need to know and understand the complete system before you can assume that volume is directly proportional to speed.

Andybr.

I agree that the using the information currently available will only be a ball park estimate. However, if you are not able to get the data on the pump, you could do a couple of trials, to determine about how much product per revolution.

Fill up a five gallon bucket with product, count how many revolutions were required to fill the bucket. Weigh the bucket, then divide the weight by the revs. should get an approx. weight per rev. Repeat at least one more time, to see if the value is repeatable.

If you want volume instead of weight, just divide the 5 gallons by the revs.