Johnson water pump volume?

[eianm]

I installed a new Johnson WPS4- rated at 15 liters / minute, but i am actually achieving less than 5 L/Minute. My filter bowl is clear of any muck- sink is less than 5ft of 1/2 line from the pump- I also fitted a Johnson accumulator.
I have noticed that my filter bowl does not fill 100%- it has a small air pocket at the top representing maybe 10% of volume- is this normal- OR indication that i have an air leak somewhere? The pump does NOT cycle on and off when tap not turned on, so i am assuming i do NOT have an air leak??

 

[waternwaves]

The pump rating is for O ft. discharge pressure, and npsh (full water column no suction) condition. Depending on line size, filters, fittings and hose length to the pump, and the line size fittings and hose length on the discharge side you will see significant reductions.

Also, the pump curves I saw for that pump about 8 liters minute at cut in pressure and a little over 6 lpm at cutout.

So 5 liters a minute with line losses seems both normal and respectable for this application.