Jet Pump venturi/nozzle selection

**toolfool** · 09-17-2008, 06:23 PM

Hello pump guys - I have a new 3/4 horse Dayton convertible jet-pump. I have a Dayton ejector-kit which includes the cast iron ejector, four different sizes of plastic nozzle/venturis and a chart. The chart tells me to choose nozzle/venturi size that matches my motor hp. Choices are for 1/2, 3/4, 1, and 1-1/2 hp. Here is my question: If I want to maximum delivered water pressure, at the expense of some flow, can I choose an alternative nozzle/venturi size? The vertical lift from my cistern is just 10 feet. Horizontal run from cistern is 50 feet of 1-1/4 pipe. Thanks.

**speedbump** · 09-18-2008, 07:50 AM

I assume you have the shallow well ejector. Dayton is a motor name from Graingers. And there was a Rapidayton Pump years ago, but has long since been discontinued.

Anyhow, the answer is yes, you can substitute. Sta-Rite makes oodles of nozzle and venturi combinations. Betta Flo makes several. They always use a 1/4" nozzle and just change the venturi. This makes life so much simpler. So if you have a 1/4" nozzle, you can play with the venturi's to get the desired pressure. We do it a lot with our jet pumps when someone wants to use a jet pump with a cistern and a Cycle Stop Valve.

Since I don't know what pump you have I can't be much help with your exact combination.

We have done testing with our test bench for the 1 and 1.5 hp jet pumps with many venturi sizes from 9 to 21/32nds of an inch. The difference in pressure compared to volume is impressive.

bob...

**Porky** · 09-18-2008, 05:58 PM

Speedbump said it all in a few words!

**toolfool** · 09-19-2008, 10:47 AM

Thanks guys. Yes it is a Grainger 1D875, which is listed as a 'premium' pump. I have not put it in service yet. Am gunning for plenty of pressure to push through the filters I talked about in a previous thread. I imagine a smaller orifice will yield higher pressure. The sizes start at 0.480 and step evenly up to about 0.580. A 0.500 is recommended. Would be happy to see 65 psi static.