How do you graphically represent the performance of a diaphragm pump?

It is important to understand diaphragm pump performance, and be able to measure this performance as well. In order to show the performance of a diaphragm pump, we must create a graphical representation.

Typically, it involves two separate curves. They have to be done independently because of the way a diaphragm pump has both an inlet for vacuum and an outlet for pressure. 

These curves must be done one at a time. It's typically done with:

• flow on the vertical axis
• pressure on the horizontal axis to the right
• vacuum on the left

They can be independent curves, or they can be combined.

Typically, performance is measured with instrumentation. What you do is pick one side, run a tube out with a valve on it, and you have a valve that is used to shut the flow down while you monitor pressure and flow.

The interesting thing about diaphragm pumps is that they typically exhibit an inverted curve where the current starts off low, increases, and then decreases. This is where the motor's doing the most work and where the highest current is.

Something similar happens on the vacuum side. When looking at a diaphragm pump's specifications, what you will typically see listed is:

• max flow
• max vacuum
• max pressure
• max current

I hope this helps. Let us know if you have any questions.