Author Topic: WI  (Read 9758 times)

BruceM

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Re: WI
« Reply #30 on: June 16, 2018, 07:04:32 PM »
Alas, those pulse diaphram pumps are run from pulsing vacuum- hooked up to the gas engine intake manifold I'd guess.

The CS intake manifold vacuum isn't likely strong enough to operate one. 

BruceM

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Re: WI
« Reply #31 on: June 17, 2018, 02:47:06 AM »
Is is likely to be able to draw up water 36 inches?  Sure looks like a sweet solution- didn't realize they existed for regular engines...I'd only used them for RC engines when I was a young man. 

BruceM

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Re: WI
« Reply #32 on: June 17, 2018, 05:27:21 AM »
I'll have get one and test it, it might be just the ticket.  Thanks for the great idea, Glort!

ajaffa1

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Re: WI
« Reply #33 on: June 17, 2018, 08:44:06 AM »
Good thinking guys, my ride on lawn mower uses one of those as a fuel pump, it ran faultlessly for 6 years until the engine head gasket failed and the crankcase pressure increased. Bloody thing vented hot sump all up my leg. Replaced the head gasket and flushed out the diaphragm pump, runs like new.

Not sure how much pressure there would be in a Lister crankcase because they already incorporate a spring steel diaphragm to release the pressure. If it works you could fit two one for WI and one to pump fuel rather than gravity feeding.

Very interesting.

Bob

ajaffa1

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Re: WI
« Reply #34 on: June 17, 2018, 10:58:37 PM »
Most small 2 stroke have a small diaphragm pump built into the bottom of the carburetor. They have a lift pipe and a return to the fuel tank. They shift a lot of fuel, as you will know if you have ever had the return pipe break or blow off.

Only trouble with a four stroke with this sort of WI is that you are going to get two injection pulses for every combustion stroke, doubt it would matter but you might want to experiment with a needle valve for correct dosing.

Bob

BruceM

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Re: WI
« Reply #35 on: June 18, 2018, 04:16:15 PM »
I've got a pulse pump on order; too interesting to not try out.  Bob raised an interesting point; with 2 diaphram actions per crankcase per intake gulp, you do get dribble into the bottom of the intake manifold unless you implement a little shallow dish to catch it.   That's the advantage of Mr X's vacuum fed approach- all water is entered into the peak intake airstream.

 I also ordered a kit of RO tubing, float valve and shut off valve for $13. so that I could do a gravity fed constant water level version of the intake manifold vacuum fed WI.  The diaphram pump could also feed a small constant level tank- by just having an overflow port to drain back to the supply bucket.  All quite cheap to implement so worth some dabbling to find a nice setup for CS WI.

BruceM

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Re: WI
« Reply #36 on: June 21, 2018, 04:12:24 AM »
I got the vacuum pulse type diaphram fuel pump today and tested it hooked to the 6/1 crankcase.  It works nicely but has a total lift of only about 13 inches of water (zero flow); intake and outlet combined, it matters not where the pump is between them.  At 10 inches it pumps a steady flow way more than needed, flow starts falling off rapidly from there. These pumps are direct single diaphram types so pumping lift can be no more than the vacuum in the crankcase.  I'm sure some CS engines with less hours may have better crankcase vacuum, but that's all I've got.  It's lower than typical gas lawnmower engines because the crankcase volume of air is so large relative to piston displacement volume, I think.

So I decided that gravity is pretty reliable and cheap and I've had enough pump fiddling. The float valve and plumbing kit came along with the diaphram pump. I've got the two tanks made up with fittings, float valve and plumbing mounted.  Tomorrow I'll do some flow rate adjustment testing and then will add my little solenoid valve for Picaxe control.  I sleeved down the 3/16 ID brass tube in intake manifold to 1/16 ID for starters. I'll have the top of the regulated water level in the float filled tank just below the brass intake manifold inlet blow the manifold, so I can see the static water level in the supply tubing. The intake manifold will pull it up the last 1.5 inches.  I used clear Sterilite storage containers (that I had on hand) for the two water tanks so monitoring them will be easy. The 5 gallon supply bin is intended to be filled to 3 gallons and low enough that I can fill it easily.  The big lid will allow me to fill it from a 5 gallon bucket.

I'll do photos and/or video once I get the bugs worked out,







EdDee

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Re: WI
« Reply #37 on: June 21, 2018, 10:29:07 AM »
Hi Bruce,

I am using a gravity/float bowl type setup....has worked flawlessly for me in the past... (I didn't want additional pumps and things that could go wrong....)

I have a 3mm copper pipe that sits center of airflow in the air intake, coaxial to the intake manifold. The copper pipe stops slightly inside the intake port on the head (1/2" or so).... There is no constriction at the end of the pipe, free flowing...

The float bowl can be height adjusted so the level of the float bowl is around 4 to 6" below the level of the intake center (This will vary according to the length of water feed pipe you use, your air filter, and of course the air intake plumbing... also, be careful to prevent multiple dips in the water feed pipe, cumulative head is a bugger on a low pressure system) .... Adjust this height to change water flow. As soon as you restrict the pipe and put a nozzle on it, it gets prone to blocking... There is little difference in effect from mist to droplet, but droplets do work better.

With the above arrangement, there is no chance of flooding the engine, as intake draft is required to induce water...set and forget.... Oh yes, one small addition was a small valve on the water line to allow for water shutoff, seldom used, only when the tube was withdrawn to prevent spillage ultimately...

In the beginning, I shut the water off before shutting down and turned it on after warm up, ultimately, I ended up simply leaving the valve open, there was no ill effect on my system either...

Cheers
Ed
12/1 750RPM/9HP Roid 5kVA- WMO Disposal/Electricity & Hot Water Gen
12/1 650RPM/8HP Roid 4.5kVa - Demon Dino
Chinese Yanmar - Silent Runner with AutoStart
Classic Komatsu 1963 Dozer/Fergusson 35 Gold Belly ...
Bikes,Cars,Gunsmithing & Paintball...Oh yes, a 5Ha open air Workshop to play in!

BruceM

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Re: WI
« Reply #38 on: June 21, 2018, 03:43:17 PM »
Ed, Thanks for the info on your successful gravity-float valve-vacuum WI setup.  I'm intrigued that you had about 5 inches of water vacuum; I'm guessing the engine in question isn't a CS type? Perhaps you were thinking 4 cm which is just what I measured.  I measured my 6/1 Listeroid running intake vacuum at about 1.75" in the middle of the intake manifold and airstream.  Your coaxial tube projecting into the head inlet (good idea and easy to implement ) might be that much more effective but it intuitively seems unlikely to me. I'd really like to know if this 4-6" of water vacuum at inlet is on a CS type engine!

I did note that my engine didn't complain a bit about modest rate WI when cold, but I didn't try starting cold with water. Like you I like things as simple as practical. 



« Last Edit: June 21, 2018, 06:02:09 PM by BruceM »

BruceM

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Re: WI
« Reply #39 on: June 21, 2018, 05:56:53 PM »
All these fuel diaphram pumps are vacuum pulse driven. You'd have to change the design to run off pressure- the spring would have to be on the opposite side of the diaphram, where presently there are check valves, and the diaphram material would have to be stiffer to allow higher head. 

Didn't sleep much last night so I'm not sure how much progress I can make today.
 

BruceM

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Re: WI
« Reply #40 on: June 22, 2018, 12:05:18 AM »
I got it working and the flow rate set.  I ended up removing the flow restriction at the intake manifold, back to 3/16 ID brass tube as shown before in this thread.  With 1/16 inch ID at the intake manifold, I was only getting 1 ml/minute.  I kept removing the sleeved tubing one at a time until they were all gone.  My tiny pneumatic solenoid valve is pretty restrictive for water, cuts the flow in half at any giving water level height, but it's free so I'll use it for now.  The long 1/4 OD (RO type) tubing did restrict flow also compared to my prior test with a short loop of larger ID tubing. For a larger than 20 ml/min flow, I'd suggest larger tubing.

I now have water level marks for about 10 and 20 ml/minute flow rates; the float arm is adjustable and I just change that for the desired flow rate.  Photos when it cools down.  It was tedious to keep fiddling and using a 60 ml syringe body for the water supply to see water consumption- timing 2ml drop. 

I'd like to add an inline filter to catch any crud in the water- any suggestions for a small inline fuel filter that won't clog when used for water and water/methanol?







EdDee

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Re: WI
« Reply #41 on: June 22, 2018, 01:32:03 PM »
Hi Bruce,

In reply to a previous question, it IS a CS style roid, 12Hp at 1000rpm, now running at 9-10hp at 750rpm...

The inlet manifold is 1 1/2" or so galv pipe, leading to a large truck type air cleaner with little input restriction... 4.5" of water is what it pulls on the pipe, but, my error, that is to the bottom of the float bowl, the water level is about 2" above the bottom, so around 2.5" actual pull.... my apologies!

Regds
Ed
12/1 750RPM/9HP Roid 5kVA- WMO Disposal/Electricity & Hot Water Gen
12/1 650RPM/8HP Roid 4.5kVa - Demon Dino
Chinese Yanmar - Silent Runner with AutoStart
Classic Komatsu 1963 Dozer/Fergusson 35 Gold Belly ...
Bikes,Cars,Gunsmithing & Paintball...Oh yes, a 5Ha open air Workshop to play in!

BruceM

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Re: WI
« Reply #42 on: June 22, 2018, 03:20:03 PM »
Thanks, Ed.  That's consistent with my measurements given your increased RPM. You were right on the mark with adjusting water level to achieve the desired flow rate, thank you.

I'm not thrilled with the float valve I'm using.  Instead of a sharp cutoff I get dribbling, then dripping, with half an inch of rise in water level beyond dribbling to a full shut off.  About 3/4" difference total between initial and later running water level.  That's more variation than I want as it represents a doubling in flow rate.  Not a show stopper, but annoying.  I'm going look into it further.  For now I'll adjust so it starts at 25 ml/min and tapers down to 15.












EdDee

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Re: WI
« Reply #43 on: June 22, 2018, 05:10:12 PM »
Hey Bruce...

Dont stress re the dribble... thats a progressive thing with the float valve scenario...

Run it, see where it averages and set level accordingly....

Regds
Ed
12/1 750RPM/9HP Roid 5kVA- WMO Disposal/Electricity & Hot Water Gen
12/1 650RPM/8HP Roid 4.5kVa - Demon Dino
Chinese Yanmar - Silent Runner with AutoStart
Classic Komatsu 1963 Dozer/Fergusson 35 Gold Belly ...
Bikes,Cars,Gunsmithing & Paintball...Oh yes, a 5Ha open air Workshop to play in!

BruceM

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Re: WI
« Reply #44 on: June 22, 2018, 05:32:25 PM »
Thanks Ed.  I am going to add an overflow pipe to the float tank- so that float valve failure doesn't flood the floor and intake manifold. 

It's right on the wall, so a 1/2" tube through the wall is a snap.

I've written to tech support at CDI- they have bought up all the float valve companies in the US so hopefully can make a good suggestion as to what might work best for my low pressure feed, low flow rate application. 

The consolidation of small companies in the US is alarming.  I've seen this in electronics as well-  6 good filter companies all bought out by the same company, product lines slashed, prices more than doubled with lead times of 4 months, no stocking of the formerly stocked products.  The purchasing company is awful, no decent engineers, no good tech support, a bunch of bullshit artists.
« Last Edit: June 22, 2018, 05:38:42 PM by BruceM »