Nozzle pressure?

[Geo-George]

What would be the required pressure to operate a 1 1/2 inch suction nozzle?
1 1/2 inch nozzle with a 1 inch water supply. ( Keene nozzle )
I want to activate a "Simple Simon" dredge system.
I have up to a 40' drop over about 200' to where I will be using the nozzle.
Geo-

[Gold Seeker]

Most smaller dredge pumps put out about a minimum of around 70 PSI and 90 to 100 GPM, bigger dredges will have higher PSI and especially higher GPM, I have seen homemade smaller dredges with pumps putting out 40 to 50 PSI and 90 to 100 GPM and work, but I would try to shoot for 60 to 70 PSI and at least 80 to 90 GPM. IMHO


Skip

[finegold]

Geo,

My memory serves me differently than the 70 psi comment.

D&B Custom dredge from the late seventies had a "killer" pump with amazing tolerances. Their dredge was untouchable for power. They used a "quad" jet in the style of the "crash box". The pump they created, had an operating max of 36 psi, 140 gpm through a tapered, smooth 7/8 oriface (not 4, just one 7/8" orifaces for performance testing).

The Precision pump/VW, operating in 25+ feet of water and with very good performance, was pushing 36 psi (and looking at the pictures I have of their typical precision jet feed size and lengths, they were likely getting about 32 psi at the orifaces - friction loss). Hoser John will remember the rig from the Middle fork of the American, in the Rucka Chuckies, where Fred Nelson was learning the ropes around 1984.

Fred in the 2000 - 2008 seasons, ran a Precision pump, with the Geo-Metro power plant on the South Fork of the American (an 8" reduced at the nozzle to a legal 6") from depths of 4' to maybe 18'(?) at 28 to 30 psi - mostly 28. His setup had all you could want, with power to spare (twin 1.5" oriface eductors) with a single 4" dia hose feed to twin "rams horn" to eductors). Hoser John was there to see that rig.

Last year (until August 6, of course), I ran my 8" with a Precision pump/VW, it a short 5" feed to a quad setup, and in 6 - 15' of water - anything higher than 28 psi was hairy and I like a nozzle with power! Most of the time the rig ran at 26 psi. There is quite a bit of the "unknown variables' in every set up and each has its own sweet spot.

If your eductors are sized and angled properly, and your straight tube length is correct (whether crashbox straight jet or a flare - and the flare angle and length are proper - did I mention there is more to a proper system than gpm and psi?) then 30 - 36 psi is about optimal in my experience for most setups. My 8" quad being the odd ball but I didn't get the chance to work it deep. Might have had to crank it up quite a bit - don't know.

Please note, this is only from my experience and observation and a just something to consider. I am not intending or suggesting that other opinions are wrong. Just because I have being doing this for many years, could just mean I have not been doing it very well for many years.

Hope this is of some value to consider.

[Geo-George]

What would be the required pressure to operate a 1 1/2 inch suction nozzle?
1 1/2 inch nozzle with a 1 inch water supply. ( Keene nozzle )
I want to activate a "Simple Simon" dredge system.
I have up to a 40' drop over about 200' to where I will be using the nozzle.
Geo-

BTW, I'm working a gravel bar with about 1' of overburden on a basalt bed.
Water depth of 3 to 12 inches. I'm figuring to use a 10' x 1 1/2" hose from the nozzle to the sluice.
Geo-

[finegold]

Geo,

You have about 17 psi available. Assuming (could be a bbbbbbbbig mistake) that the oriface is 13/32, the flow (theoretical) would be 19 gpm. It would require the feed pipe (cheap pvc - no hose, curves , or angles) to be 1.5" dia. for a loss of 0.54 psi per 100' friction loss.

End result: approx. 16 psi at a flow of 19 gpm through a 13/32 dia. oriface.

I have no experience with performance in the 1-1/2" nozzle size/ 13/32" oriface, therefore I do not know how well it would function (that being relative to your expectations and/or needs)

The number to convert feet of head to psi (for all practical purposes) is 0.434 40 X 0.434 = 17.34 psi

Hope this helps rather than crush your dreams!

[Geo-George]

Perhaps I should explain further,.....

50' @ 4"
50' @3"
100' @ 1 1/2"
40' drop overall
From the 1 1/2" I'm reducing to 1" for about 10' to power the nozzle.
I can add another 50' @ 4" to the upper end with around another 15' of drop. ( the terrain gets steeper as I go upstream )

No dreams crushed here, I can and will adapt if nessesary.

[finegold]

Geo,

It is not a function of the amount of water (as long as it is larger than 1.5" in dia. in your pipe In this case) Example; if you built a secure tower forty feet tall, holding a 1.5" pipe, a 4" pipe, a 6" pipe, a 1 foot pipe, a 2' dia pipe, and finally a 3' dia pipe, each with a cap on the bottom and a 1" pipe with a valve on them, coming out of the cap; then filled each pipe with water to the top; added a pressure gauge to each outlet; turned on the valve to read the pressure of each pipe from the 1.5" thru the 3' dia pipe; guess what? They all read 17.34 psi. It is not measuring the total weight water in each pipe, only the weight (pressure) pushing on that 1 square inch of water in the pipe coming out of the cap on the bottom. Poke a hole on the outside of a dam with a pipe 40' below the water level on the other side, and even thought the dam maybe holding back a lake 10 miles long and 2 miles wide, the gauge on the pipe coming out of the dam is only going to read 17.34 psi.

Increasing your pipe sizes above the last section before the nozzle only reduces the friction loss over the 200' a tiny bit. Only so much water can flow through the 13/32" oriface at 17 psi. If you had a small pump with say a 40 gpm capacity at 10 psi inline then you could boost the psi, flow, etc at the nozzle. If gravity is your only power source, then it is all up to physics.

[Geo-George]

My line of thinking is regarding the presure on a submarine in the ocean.
The deeper the sub goes the greater the pressure on the exterior.
It is the weight of the water above that causes the sub to crush.
I would think that pressure would be far above 17.34 psi.
So it reasons to me that the greater the weight above, the greater the pressure in the line.
No?

[finegold]

Geo,

The formula is on the internet for converting "feet of head" to psi, assuming you don't have a handy reference at home. But sometimes seeing is believing. Run 40 ' of 1.5" pipe up a tree with an elbow and a valve on the bottom. Take a garden hose and fill up the pipe till it over flows and splashes down on you. shut the valve, remove the hose, attach a pressure gauge, open the valve, and it is going to read 17.34 psi. Run up a large pipe. Do the same thing. Its going to say the same thing - in pounds per square inch. It is not measuring the weight of all the water in the tube only the force exerted on one square inch at 40' below the water level.

[Geo-George]

O.K., here's what I managed to find per your advice on finding a conversion table.

http://www.shipcopumps.com/mathwizard/m ... t-head.asp

It shows that 40' of head produces 17.3 psi
Now if I were to increase the head to say 60', the psi increases to 26.
The table also allows you to enter a psi and shows the required head.

A formula I found:
http://www.accontrols.com/documents/Wat ... etHead.pdf
Multiply the psi by 2.309 to get the feet of water, or......
divide the feet of water by 2.309 to get the psi. ( @ 62* F. )

I do thank you, finegold. You got me to thinkin' and pointed me in an great direction.