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Natural Gas to Propane conversion


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  #1  
Old 11-11-2011, 04:01 PM
jeffj13 jeffj13 is offline
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Default Natural Gas to Propane conversion

I was just given an old Kohler generator model number 6.5RMY62. It most recently ran on natural gas, but I need to convert it to propane. I have the generator and a 100lb propane tank, but nothing in between. While I don't know generators, I am very handy. What parts to I need to hook this up to propane. I assume I need some sort of regulator. Also, are there any adjustments (i.e. carburetor) that I need to do?

Also, I anyone knows where I can get a manual for this, I would appreciate it.

Thanks for your help.

jeff
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  #2  
Old 11-11-2011, 07:25 PM
LWB250 LWB250 is offline
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Default Re: Natural Gas to Propane conversion

Quote:
Originally Posted by jeffj13 View Post
I was just given an old Kohler generator model number 6.5RMY62. It most recently ran on natural gas, but I need to convert it to propane. I have the generator and a 100lb propane tank, but nothing in between. While I don't know generators, I am very handy. What parts to I need to hook this up to propane. I assume I need some sort of regulator. Also, are there any adjustments (i.e. carburetor) that I need to do?

Also, I anyone knows where I can get a manual for this, I would appreciate it.

Thanks for your help.

jeff

Jeff,

Depending on the fuel system used, you may not need anything in the way of parts.

Can you post some pictures of the fuel system components currently on the machine, like the regulator and mixer (carb)?

Dan
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Old 11-16-2012, 12:37 PM
rusteholic rusteholic is offline
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Default Re: Natural Gas to Propane conversion

Hi, I came across this post because I have an old Kohler nat gat generator that I'd need to run on propane. I was going to just going to comeo out of the propane regulator to the nat gat pipe on the generator and hope for the best, and of course do it outside. Thoughts? I don't have the model or control switch number right now, but the story I got with it is that is was used for emergency lighting at the Earle Theater in Philadelphia. THanks!
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Old 11-16-2012, 12:41 PM
rusteholic rusteholic is offline
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Default Re: Natural Gas to Propane conversion

And I should proofread my messages before hitting submit..... I really am literate,lol thx
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Old 11-16-2012, 08:10 PM
Jim Rankin Jim Rankin is offline
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Default Re: Natural Gas to Propane conversion

I'm not familiar enough with the regulator you have on your generator to know for sure, but it appears to be a demand regulator which should function with either LP vapor or natural gas as long as the inlet pressure limit is not exceeded. Most regulators have inlet pressure stamped on it somewhere, so check that.

Do you have an electric solenoid valve on it already? Same thing applies, do not exceed inlet pressure rating and always a good idea to check for leaks before you depend on it.
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Old 11-16-2012, 09:06 PM
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Default Re: Natural Gas to Propane conversion

I'm looking for the "inlet" fitting on the regulator and seeing nothing, so I am assuming that the small "flat bulge" on the top rear of said reg is where the original gaseous fuel was introduced to said regulator..I do NOT see an electric solenoid valve, as Jim Rankin (hey Jim I'm still alive ) has mentioned.
Do NOT, under any circumstances, install this, or any other gaseous fed device without such a solenoid valve to ,fed by the units 6V or 12V generator output ckt. prior to the regulator..
If you do and and the engine should fail for any reason you will still have LP flowing into the carb and out and DOWN to the garage floor or the ground...UNTIL it finds an ignition source. If that happens you will be looking for another generator and LORD forbid a new garage/house w/possible superficial surface burns to any expoced skin ...

Now ask me how I know that an LP flame is a yellowish white when you're inside and looking OUT of said flame..
Gene

PS; It's funny now that I look back at that day BUT it wasn't funny then!!!
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Old 11-16-2012, 11:03 PM
Jim Rankin Jim Rankin is offline
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Default Re: Natural Gas to Propane conversion

Gene, Glad to hear from you!

Yellow flame, yes, seen it myself! Always gets you where there's moisture on your skin.

The demand regulator should............should...........stop the flow of gas when the engine stops. but I don't even like to depend on it on a tractor or other outdoor engine unless it's an emergency. The solenoid valve is usually tied into the engine's ignition circuit.
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Old 11-19-2012, 10:20 PM
rusteholic rusteholic is offline
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Default Re: Natural Gas to Propane conversion

Gen & Jim, thanks for your reply. Yes, that bulge on the back of the regulator is the half of the union where the inlet pipe was attached (trap). I checked the regulator but I don't see any pressure rating stamped or a tag, but the solenoid valve has a pressure rating of 80# (24V) according to the tag. I would think that's WAY more than what you'd want at the carb. I never really messed with natural gas to know how much pressure there is inside the building after the street regulator, but I always assumed about 1 or 2 psi. I guess I can google that to find out, but figured a regulator from a gas grill should be about the same and flow plenty of gas for that engine.

The armored cable jacket you see in the pic runs between the carb and the electric solenoid valve. There also appears to be another in the base of the carb, and they are wired in series. At first I assumed the solenoid valve right after the regulator was an add on, but just looking at it I'd say it's always been there. So I guess even way back then they had some redundancy built in.

But yeah, I won't mess with this indoors or rely on it for backup power, it's only 2K 120VDC so it's really just another heavy conversation piece. I just want to see it run again (bad valves/little compression for starters), and I'm really interested in the control switch which is of the type I think where as soon as the 120V circuit is closed, the unit automatically starts on the 24VDC and will run until the 120V circuit is opened, and the generator will automatically shut down. (generator model KE2 32742, Control K-173-W-A-1). I'd love to find a schematic for the control, I assume the wiring diagram was on the cover which is missing. Still easier to understand that the board on a modern generator.

And speaking of things exploding lol, ask me why it's not a good idea to choke your old JD B with a kerosene manifold in your basement workshop to shut it down. WHen I saw all that white vaporized gasoline coming out of the exhaust I knew it was going to end badly. That flashed with a pretty blue flame! Luckily both me and my house survived Lesson learned.

THanks again for your input!
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Old 11-22-2012, 03:24 PM
dkamp dkamp is offline
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Default Re: Natural Gas to Propane conversion

A gaseous fuel system works in either one of two ways-

A valve (referred to as a 'Fuel Controller") sensing engine demand, feeds fuel into the intake stream under positive pressure (like a fuel injection system on a car)

or...

A valve, sensing engine demand, feeds fuel into the intake stream under NEGATIVE pressure (like the venturi principle of a liquid fuel carbeurator).

MOST fit the second description, using a device either referred to as a "Zero Governor", or a "Zero Regulator", or a "Negative Regulator". All the same principle... engine develops vacuum through a venturi, where the vacuum is directly related to the amount of LOAD that the engine is under. This means... not MANIFOLD vacuum... it's VENTURI vacuum. Frequently, this is referred to as 'ported' vacuum, but very specifically, it's in the venturi portion, between the choke and throttle plates, where there's a 'narrow' portion that airflow must pass through en route to the manifold and cylinders.

This vacuum signal is either

1) presented against the back side of a regulator diaghram... which controls fuel flow out through a pipe to some fuel distribution point, either in the intake manifold, or the intake throat...

or..

2) presented against the back side of a regulator diaphram which controls fuel flow AND... passes it down the SAME vacuum line, INTO the venturi.

IF your fuel controller has TWO lines coming out of it, one will go to the control sensing point (in the venturi) while the other will go to the fuel distribution point (manifold, intake throat, etc).

IF your fuel controller has ONE line (like an IMPCO J, or a BEAM 500, or a Garretson KN), then the single line will go to a venturi, where it not only senses pressure, but also injects the gaseous fuel.

This negative-pressure-regulator thing seems complicated, but is actually pretty simple. A common air-pressure regulator, like what you use on a shop air compressor, takes some unknown, higher pressure (like 100-150psi) and knocks it down to 95psi. Does it by applying OUTPUT pressure side to a diaphram, which is connected to a valve, and the valve is held closed by a spring. When the output-side pressure falls, the spring forces the valve open, allowing more high pressure air in, until the diaphram defeats the spring, and closes off the valve. Pressure is therefore, regulated by spring tension, working against diaphram surface area.

To compare it to a Fuel Controller, dial that thing all the way down to ZERO PSI... so there's NO output flow. Now dial it down just a little farther. In order for that governor to FLOW ANY FUEL, you'll actually need to apply NEGATIVE pressure to the diaphram... at which point, the regulator will flow whatever fuel necessary to maintain output pressure at that negative level. Voila- vous-avez a negative-pressure regulator!

As noted, the darned thing HAS to shut off... so that negative cutoff point has to be sensitive, and secure.

Most fuel controllers operate at a very low inlet pressure... 8-11" of WATER COLUMN (inches WC)... like... 1/4psi. Measure these pressures with a manometer.

Municipal natural gas supply pressures are pretty high... but the residential meter knocks 'em down, and they vary a bit, but fall pretty close to 11" WC.

Propane tanks can vary from basically NO pressure (at -40F) to about 250 on a really, really hot day. There's a first-stage regulator (frequently red color) located AT the tank, which knocks it down to 10PSI. From that, it goes through a distribution line to a second-stage regulator, that drops it from 10psi, down to 11" WC. You HAVE to make sure you've got the right regulators, and you HAVE to make sure that the regulators TURN OFF properly, lest you experince the incoming yellow flame the gents have described.

Finally, you HAVE to make sure that the regulators you have, are INTENDED for the flow volumes that your generator will demand (typically expressed in BTU, or Cubic Feet per Hour), as some regulators, tanks, and valving have emergency cutoff features which shut off flow if it exceeds a certain setpoint... this feature protects lives and property by responding to things like ruptured fuel lines.

A generator that's setup for NG, frequently adapts to Propane, simply by making adjustments to suit incoming pressure, and then, fuel energy density. Natural Gas does not have the same amount of fuel energy density as propane- Propane is much more potent, so the propane-powered engine will need to have the mixture leaned-out a bit.

If you have a suitable propane tank, and first and second stage regulators, hooked to the inlet of the fuel controller, start it up, adjust the mixture, make sure the controller is going into fuel cutoff when you shut it down, and you'll have propane-power on tap.

PUT SHUTOFFS ON THE FUEL!

Don't trust anything, because errors in judgement here result in large flying objects as a result in rapid changes in atmospheric pressure and local ambient temperatures... i.e. explosions.
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Old 11-22-2012, 07:16 PM
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Gene O. Carpenter Gene O. Carpenter is online now
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Default Re: Natural Gas to Propane conversion

For what it's worth!! Most everyone who works with Nat, Lp or petrolieum will know that little tidbit that "decamp" provided in his last post about using a Manometer to adjust regulator output pressure. ie 8-11" of WATER COLUMN (inches WC)...
BUT not many of us happen to have a Mano or access to one.. I have one but haven't used it since I was forced ro retire back in 92.. So a quick way to obtain this useful tool is to fabricate one from items that most of you have availble in your "bucket O Goodies"

1st- fill that bucket, assuming it has no holes in it and will hold water,to the top, install a 1/4" "barb" fitting" in the outlet of regulator being tested, attach a 3'--4'X1/4" hose to said "barb" tape other end of hose to a ruler or yard stick, even with the end.. turn on gas supply and plunge the end of your measuring stick, whatever it may be, to the bottom of said bucket.Now slowly raise the measuring stick til the bubbles start to come out of the hose..When they do start to rise STOP and adjust hose end up or down til a bubble forms AND stays there.
The water mark on said measuring device will be your regulator output pressure.. This little tip can be used to test or set the low pressure on just about anything that requires a lower pressure ...
Gotta go,, just got the signal that "the Bird" is on the table....
Gene
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Old 11-22-2012, 07:43 PM
dkamp dkamp is offline
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Default Re: Natural Gas to Propane conversion

Yep, and I didn't suggest where one could BUY a manometer... because I haven't seen one for sale anywhere in a long time.

Another way to make a manometer, is to take a piece of clear plastic tube about four feet long, stick one end into the bucket'a'water, and suck in about two feet of water, then lift the end out, temporarily plug the ends, and then zip-tie it to a piece of plywood in a U shape. The water will fall to the bottom of the U.

Mark the level of the U, and then thumbtack a wooden ruler to the U, with the bottom of the ruler at the 0 mark. Connect a barb fitting and shutoff valve to the end of the tube opposite the ruler, and connect this to the pressure source.

When pressure is sufficient to raise the water level to the 11" mark, you've got 11" WC. Adding some food coloring to the water makes it easier to see.
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Old 11-22-2012, 08:39 PM
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Gene O. Carpenter Gene O. Carpenter is online now
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Default Re: Natural Gas to Propane conversion

That just goes to prove that "There's more than one way to skin a cat"!

Gene, in warm and sunny(today anyway) Brookville Pa..Looks like this may be my permanent address after all..
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