Booster Pump discharge pressure not adding up

If I read your picture right( and I had to turn my head sideways to do it), the pressure going into the pump is as you put it -4 psig(minus 4), or 10.5 psia. With a discharge pressure of 15 psig (29.5 psia) your pump is developing 19 psi across it, in line with the pump curve.

The vertical line on the pump curve is not written properly, it should say Total DEVELOPED head, i.e. the difference from inlet to outlet. If the inlet is at 0 psig (14.5 psia), the the discharge head will be as the graph. If it's say 15m head (21 psig) on the suction side then the discharge head will be 15 + inlet head.

In your case the inlet pressure is less than atmospheric, hence the minus figure on the reading. At dead head ( no flow) the inlet pressure/head should be approx. 1.5m (5 ft), hence you will get a discharge head of approx. 18m or 25 psig.

So the pump is doing more or less exactly what it should be doing.

If you want to increase it either make the pump go faster or make your inlet system much bigger or raise the tank a few metres off the ground , but I suspect a lot of your losses are coming from the filter.

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LittleInch,

Thankyou for your clarification. Sorry about the photo. I will see what I can do with the inlet pipe work then work from there. Thanks again.

Lukas

LittleInch, try control-ALT-left arrow to rotate your screen view.

I'll give that a go. I can rotate pdfs ok, but not screens.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Larger inlet line and much larger screen.
Since you tank only offers 5' of head, you need the resistance low enough to get your desired flow through the strainer just with gravity.
If you do that, and run the pump at 1600rpm then you should have your 25psi at the discharge.
If you just speed the pump up now the pressure drop through the strainer will increase, you may start cavitating.

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P.E. Metallurgy, Plymouth Tube