What is listed for max flow and max pressure isn't really what you should look at when assessing the performance of a diaphragm pump. Why?
Max flow is generated at zero pressure, and the max pressure is generated at zero flow. The same is true with vacuum —the max vacuum is at zero flow.
For example, if you need 30 liters per minute at a few psi, you're not looking at a 30 liter per minute pump because it'll probably be something that's got a much higher flow to get you to 30 liters per minute with this kind of pressure.
The second thing to note is that when you're taking measurements on the pressure side, these curves are generated with no restrictions on the other side. For example, on the inlet side, and on the vacuum side of the curve, there is zero restriction.
If in your application and your actual product, you have an orifice or tubing or something like that, and let's say you have a pressure drop of 2 psi, the net effect of that is that every data point over here is shifted over by 2 psi. The net effect is that this whole thing has shifted down.
So, the second consideration when evaluating diaphragm pump performance is that when you're looking at these curves, you need to remember they are ideal curves, and you might be inside them. This is why it's essential to ensure that your performance will be covered when evaluating a pump.
At Dynaflo, we help you through all this to ensure you have the right pump for your application. I hope this helps!