Hurt Hot and the tool to achieve it

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c_j
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homebrew failure 1

Post by c_j » Fri Nov 01, 2013 1:39 am

Apologies to the OP, I hope the homebrew ideas aren't too OT for this thread, but here's my first failure:
failure_1a.JPG
The parts list (as configured in the last two pics):
  1. Adapter - garden hose-female X 1/2" NPT-female
  2. Bushing - 1/2" NPT-male X 1/4" NPT-female (Weatherhead 3220-8-4)
  3. Adapter - 1/4" NPT-male X 1/4" compression (Weatherhead 68-4)
  4. Tubing - 1/4" O.D. copper
  5. Adapter - 1/4" compression X 1/4" NPT-male (Weatherhead 68-4)
  6. Street tee - 1/4" NPT-female X 1/4" NPT-male X 1/4" NPT-female (Weatherhead 3750-4)
  7. Street elbow - 1/4" NPT-male X 1/4" NPT-female (Weatherhead 3400-4)
  8. Air regulator - 1/4" BSP-male X 1/4" BSP-female *close enough to NPT thread (G. Hjukstrom SV-9609)
  9. Nipple - 1/4" NPT-male X 1/4" CEJN-style (Greenline CP61)
  10. Reducing coupling (galvanized) - 1/4" NPT-female X 3/8" NPT-female
  11. Nipple (galvanized) - 3/8" NPT-male X 4" long
[/size]
failure_1b.JPG
I drilled out the one compression fitting so the copper tubing could be shoved all the way through the tee to help create the venturi effect.
failure_1c.JPG
Close-up of venturi area.
failure_1d.JPG
The assembled rig
failure_1e.JPG
Hoses connected
failure_1f.JPG
Spraying water quite well, but no water hammering action at all. :(

Without having to add a pressure chamber, my ideas are to try:
  • A restrictor in the garden hose fitting,
  • moving the copper tubing further back into the tee,
  • increasing the size of the tee from 1/4" NPT to 3/8" NPT, and the nozzle from 3/8" NPT to 1/2" NPT, or
  • a special reversed check-valve with a ball bearing and a spring in the garden hose fitting.
Last edited by c_j on Fri Nov 01, 2013 12:28 pm, edited 2 times in total.

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Petros
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Re: Hurt Hot and the tool to achieve it

Post by Petros » Fri Nov 01, 2013 2:27 am

I actually have a device like that that I bought at a garage sale made by Sears. It is a big black plastic gun-like cannon that was intended to just spray water at high speed assited by compressed air hose. It really does not do much, you get water mist blasting out the end. My daughter uses it now as a prop for going to steam punk conventions.

looks something like this:
Image

I think one of the things that makes it work, after studying the patent drawings, is not the chamber but it appears to have a rotating disk in the path of the compressed air with a hole that runs thorough the disk, so every 180 deg of rotation you get a blast of high pressure air interrupting the water stream creating the water hammer.
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c_j
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homebrew failure 2 & 3

Post by c_j » Fri Nov 01, 2013 12:27 pm

Here are a couple of mods I tried and failed with on my homebrew (not-)pulsator:
failure_2a.JPG
Moved the copper tubing back further in the tee. (Plus shaped the end a bit, but I don't think that really mattered.)
I hoped to make the venturi suction stronger by doing this (which I think it did by the distance it would shoot). Result: No pulsation :(
failure_3a.JPG
I ground down the outside of a 3/16" (#10) stainless fender washer to use as a restrictor for the garden hose connection.
failure_3b.JPG
Restrictor installed. Result: No pulsation :(

I would really like to get this working with no chamber and no moving parts, so I'll try a couple of other things first.

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splatterdog
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Re: homebrew failure 1

Post by splatterdog » Fri Nov 01, 2013 1:43 pm

c_j wrote:Apologies to the OP, I hope the homebrew ideas aren't too OT for this thread, but here's my first failure:
[*][/list]
No sweat, still on topic here.

I'm pretty sure the air pressure reg is set at 60-70 psi

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Petros
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Re: Hurt Hot and the tool to achieve it

Post by Petros » Fri Nov 01, 2013 5:39 pm

If you are going to home brew it, you need to know how the original works. In their patent they have a diagram of the nozzle that looks like this (below), so you might start there:

Image

and a device that looks like this:

Image

look at the whole patent here: https://www.google.com/patents/US561569 ... CDcQ6AEwAA
'87 Tercel 4wd SR5 (current engine swap project)
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c_j
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homebrew failure 4

Post by c_j » Sat Nov 02, 2013 5:41 am

Holy diagrams Petros! I'm not sure where the first one came from, but I do recognize the second one from your link to the patent.

So here's my 4th failure:
failure_4a.JPG
This is an upgraded rig to better simulate the sizes on the Hecat model. The tee fitting is now 3/8" NPT and the nozzle is now a quick coupler (pressure-washer type) with a 5/8" hose barb.
Note there is no venturi, but I decided to try a poppet valve (moving part). And I did get it to oscillate, albeit too slowly, plus it was very finicky.

I used a 1/4"-20 X 1&1/4" flat head machine screw with a nylon locknut, with a return spring as a flow-check valve. This was sandwiched between the 3/8" hex nipple and the street tee. Although this can be made to hammer, I don't think I would recommend this type as it is too hard to tune.
Last edited by c_j on Sat Nov 02, 2013 2:10 pm, edited 2 times in total.

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splatterdog
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Re: Hurt Hot and the tool to achieve it

Post by splatterdog » Sat Nov 02, 2013 10:59 am

Just realized your missing one piece. Don't know if it's part of the hammer process or just for the safety of the plumbing/hose, but there's a backflow preventer at the water inlet.

c_j
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homebrew failure 5 & 6

Post by c_j » Sat Nov 02, 2013 9:19 pm

splatterdog wrote:Just realized your missing one piece. Don't know if it's part of the hammer process or just for the safety of the plumbing/hose, but there's a backflow preventer at the water inlet.
I don't think it should be required for operation of the real deal, but it really is in line with the design... interesting. Also interesting that the backflow preventer is not shown in most of the pictures on the net either. Hmm.

For the record, (and be warned that,) I did backflow a whole bunch of air into the garden hose, and I also ended up with an air compressor tank full of water.

Carrying on with today's results:
Failure 5 was putting a flow check-valve in the air side (leaving full flow for the water, and no venturi). I couldn't get it to oscillate. (no pics)

Failure 6 is really a partial success, and it uses the pressure chamber principle. This is using the original venturi again and a restricted garden hose inlet. It does pulsate when you tune it right, but when the air or water pressure changes, it stops pulsating. Since there are two pressure sources, (air and water,) it makes the tuning very unstable - especially with a tiny air compressor tank and a well water pump that cuts in and out with 20psi differential.

You can see in the pics that there are leaks all over. I was just winding things together hand-tight for speed.
failure_6a.JPG
failure_6b.JPG
failure_6c.JPG
You can see the slugs of water/air/water/air in the pic above.
Last edited by c_j on Sat Nov 02, 2013 9:47 pm, edited 2 times in total.

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dlb
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Re: Hurt Hot and the tool to achieve it

Post by dlb » Sat Nov 02, 2013 9:29 pm

this is hilarious. you're like a mad scientist working on this thing day and night, it seems. great creativity and determination.

c_j
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Re: Hurt Hot and the tool to achieve it

Post by c_j » Sat Nov 02, 2013 9:36 pm

dlb wrote:this is hilarious. you're like a mad scientist working on this thing day and night, it seems. great creativity and determination.
The device will be replicated. It will only cost $4000 in R&D. A mere pittance at 10x the cost of buying the real one.

...and I just noticed in the pics above that I assembled the venturi setup all wrong in the last mock up. doh!

c_j
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homebrew failure 7 & 8

Post by c_j » Sat Nov 02, 2013 11:50 pm

Failure 7 is where I took #6 and oriented the venturi the correct way. I thought that was going to be the winner, but doing that made it worse. I'm still scratching my head on that one. (no pics)

Failure 8 is similar. No garden hose restriction, expansion chamber, venturi, plus a home made backflow preventer (check valve). Didn't do a darn thing except shoot a nice stream of heavy mist.
failure_8a.JPG
Here are some of the internal bits that I have been trying:
moving_parts.JPG

c_j
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homebrew failure 11

Post by c_j » Mon Nov 11, 2013 11:01 pm

I'm skipping version 9 and 10, but here's 11:
failure_11a.JPG
We've got a ball & spring check valve on the water input again, and this time a looong spring and a valve which is a close fit up inside the brass fitting. Also a 1/8" restrictor plate at the other end of the long nipple by the tee (sorry - not shown).
failure_11b.JPG
failure_11c.JPG
There is definite pulsation going on here at around 20psi air pressure (the reg is set to 35psi, but it doesn't flow enough volume so 35psi static setting ends up being 20 psi when operating). You can hear the distinct rattle of the air valve and see the pressure gauge needle bounce. Also the spray pulses a bit (not enough though), and shoots at least 20 feet straight up. I know it only looks like 2 feet in the picture, but you just can't see beyond that.
failure_11d.JPG
I'm kind of done with this style device. The principle works, but it is too hard to tune. It needs to oscillate slower and have a more positive pulse. I think to keep things compact, one needs to choose a new design. Maybe one with a shuttle valve that slams back and forth powered by a feedback loop.

c_j
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Re: Hurt Hot and the tool to achieve it

Post by c_j » Wed Nov 13, 2013 12:47 am

This is what I was thinking for an air shuttle valve. Possible downsides to this design are that it may get stuck in the middle, or it may settle into the middle after a short time. It may just want to hammer away wildly too. Who knows.
shuttle_valve.png
After looking at this, it might be better to go for a pair of simpler shuttle valves plumbed together rather than this one-piece design. There would probably be more 'dead' time in between oscillations which would make for a stronger pulse.

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ARCHINSTL
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Re: Hurt Hot and the tool to achieve it

Post by ARCHINSTL » Wed Nov 13, 2013 9:26 am

Yes...
#-o
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c_j
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Re: Hurt Hot and the tool to achieve it

Post by c_j » Wed Nov 13, 2013 4:59 pm

And here's dual shuttle valves. It's not a working diagram, but at least I know I won't be bothering to continue down this path:
dual_shuttle_valve_not_finished.png
dual_shuttle_valve_not_finished.png (6.85 KiB) Viewed 1901 times
No, I'm not trying to make a bowl of spaghetti here, and don't be confusing this with the vacuum diagram of your terc. ...wait a minute, "If I took 2 TVSV valves, and ran some lines...."

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