Optimizing power of jets

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Forcier
Posts: 2
Joined: Fri Mar 02, 2012 12:08 pm

Optimizing power of jets

Post by Forcier »

I have to remove caked dirt from inside unused septic leach line pipes. I want to use my existing water supply which ranges between 50 and 60 PSI. The total length of 1.5" nominal diameter pipe plus 1.5" inside diameter PolyFlex hose is 200 feet. I own a machine shop and will make a nozzle for the working end of the PolyFlex hose. It will have possibly twelve .125" dia jets - 3 pointing forward and 9 radially. What I would like help with is deciding what diameter and quantity of jets to optimize the POWER delivered by my water system to break up the accumulated dirt. The 3 forward pointing jets will hopefully puncture a hole thru the dirt (which is not extremely compacted or hard) and the 9 radial jets will clean the inside of the pipe and the perforations at the bottom of the leach lines. The leach lines are 4" inside diameter and about 80 feet long. The suggestion of twelve 1/8" diameter jets is just a guess on my part, but maybe a place to start from. My objective is to optimize the power directed at the dirt, with the idea that a high velocity of water may be more useful than merely supplying lots of volume. Of course, extremely tiny holes will optimize the velocity, but there would be little energy to do work. An actual rigorous calculation is un-needed, although it would be nice to get something more accurate than my guess. I think I would have the length of the orifice nozzles be about twice as long as their diameter in order to get some clear directionality to the exit stream.

I hope someone can help. I have used your orifice calculator as well as others to get a sense of the pressure drops, but the complexity of multiple nozzles and optimizing for energy transfer is pretty much beyond me.

Sincerely,
Jerry Forcier 3 AM PST - Friday, March 2, 2012
admin
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Re: Optimizing power of jets

Post by admin »

Try to help....
In order to have decent flow velocity, decent pressure in front of nozzle is required. If you would know how high velocity is required it would be very helpful. If I can suggest 10-20 m/s is good, but I can not give you guaranties.
I think number of nozzles should be selected based on the available area inside the pipe that you are cleaning. As much as you can place, it would be better. That geometry would than lead to the possible shape of nozzle, defining start and end diameter of nozzle - like D1 and D2. In that case when you have these two diameters (D1 is like 20 mm and D2 is like 4 mm), than you can easily calculate required pressure in front of nozzle to achieve wanted flow velocity with nozzle calculator and also flow rate of that one nozzle. Same pressure is required for all other nozzles - radial or straight, if all nozzles are with same geometry with same requirements for velocities.
With known flow rate for one nozzle total flow rate is the sum of all. Required pressure for the pump is than calculated based on the total flow rate, pipe length and diameter that you already know adding pressure required for nozzle.
Pipe flow calculations - since 2000
Forcier
Posts: 2
Joined: Fri Mar 02, 2012 12:08 pm

Re: Optimizing power of jets

Post by Forcier »

Thank you. That helped some. In the meantime, I have found that for the low flow of 4GPM my pump can put out, only three nozzles are recommended - two rear facing (to pull the nozzle forward) at .032" diam. and one forward facing at .018" diam.
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