Vacs are rated by the vac manufacturer at maximum cfm and maximum lift.
Not really. They give performance charts that state what to expect all along the range of their performance
At max cfm (flow) you have 0 lift. At max lift (pressure) you have 0 CFM.
Right
So, you have to restrict the flow to create the pressure, thus tapered heads and reduced orifices. (thats why a
glide works)
Partly, at any rate. Part of the "advantage" of a glide is smooth movement across the carpet.
It's the same with a water pump. They are rated at max flow and max pressure.
They have performance curves as well.
i
When jets are put in the system the flow is restricted and the pressure is increased.
Yes.
So all vacs or pumps really operate or perform best in the mid range, controlled by the sizing of the orifice.
In principle, "Yes". It's not quite that simple, though, because the RPM of the pump affects it's performance, and it does better at higher RPM than in the mid- range.
The ideal system is to maximize both cfm and pressure to get the most of these facets of performance in a balanced way.
It all depends upon your definition of the word, "balanced". It's not necessarily picking a mid- point for CFM and available lift to cross each other. There's also the airflow that a wand or hose will allow. The best thing to do is have a system that consumes as little available lift as possible before hoses are connected to it. And to have it capable of moving as much airflow as the things connected to it will allow.
depends how you define "it". Just joking. I think we are on the same page.
John
Thus machine manf. like Mytee, or whoever, should rate (and measure) their product with a given length and diameter of hose with a particular wand and glide and jets.
"Should" is a pretty strong word. It may be a neat idea, but too difficult to implement. For instance, especially for airflow, a hose with a curve in it will not perform as well as one that's straight. So, how do you account for that...?
This would be great, but how would we standardize that test for a fair comparison of a competing product?
t all depends upon your definition of the word, "balanced". It's not necessarily picking a mid- point for CFM and available lift to cross each other.
That's the "can of worms", so to speak. The best thing would be to scrap the idea of hoses and attachments from a system evaluation standpoint. And focus on the system itself, with nothing attached. Get enough detail in that regard, and you'll know all you need to know, regarding it performance.
