Natural gas carb?

[Henry W]

Henry - do you know how to determine the "size" (in gas flow terms) of a propane demand valve? Our next door neighbours here have an ancient nissan-powered fork-lift truck, and something's gone wrong with the propane feed side, so it won't work any more. I reckon they need to replace the demand valve (because you can get it running with a squirt of "Start ya bastard" (ether)), but no gas is fed through. The valve is very similar to the one Bill showed a picture of.

If I could tell how big a demand valve is needed, I could replace it & get lots of free welding off them for moving what is, at the moment, a total deadweight.

Here are some things that need to be checked:

Is the propane tank sized so it can meet the demand?

Is thee first stage regulator sized and meeting the demand for the length of gas line run?

Is the second stage regulator sized properly for the engines demand?

Is the line from the second stage regulator to the engine sized properly to meet the demand?

Is the gas shut off valve sized properly to meet the demand?

I don't want to go any further than this. I shure hate to be liable if somthing goes wrong.

If you know someone that worked on gas furnaces or water heaters and you can trust them ask and see if they can test W.C. on the regulator near the engine. They will know what to do. I recommend a tube type Manometer. They are the simplest and don't need recalibrating.

Henry

[wrightkiller]

Timsr2:  in my pictures you will see a propane regulator for propane ,with hoses and fittings ,,,,,,,,,,,,,,

for nat gas you pipe direct to the vac/demand valve, with the right rubber hose.... sized for the job... size ...and  shutoff valve, befor the hose     no orifices or springs  to change  
   The propane regulator drops the pressure to the right level for the the vac/demand valve

            and yes you need to know what you are doing  ...If you don't just ask some one who does


Billswan: Just trying to give good info out......    no bust intended  

http://www.propane-generators.com/     is a good site to learn from    http://www.propane-generators.com/natural-gas-chart.htm

[Henry W]

Regulator housing looks the same for both fuels, but the spring settings and orifices differ. LPG is supplied at a higher pressure than NG. There is no cheap way around this, you need to buy the correct equipment for your application from a reputable company.

You are correct TimSR2,
One of the most common mistakes that people do is install the wrong equipment.

Yes the W.C. (pressure) is differant on LPG and N.G.

Do not cut costs on an install.

Henry

[vdubnut62]

Henry - do you know how to determine the "size" (in gas flow terms) of a propane demand valve? Our next door neighbours here have an ancient nissan-powered fork-lift truck, and something's gone wrong with the propane feed side, so it won't work any more. I reckon they need to replace the demand valve (because you can get it running with a squirt of "Start ya bastard" (ether)), but no gas is fed through. The valve is very similar to the one Bill showed a picture of.

If I could tell how big a demand valve is needed, I could replace it & get lots of free welding off them for moving what is, at the moment, a total deadweight.

Take the darn thing apart and free it up with WD-40 and/or replace the diaphragm if it's dry rotted.
Bob will be your uncle.
Ron

[AdeV]

Henry - don't worry about liability - you're on a different continent to me, the rules don't apply.... Besides, this isn't a new installation, all I need to do is replace the demand valve with the same size that's already there, and it should (in theory) work. The truck worked fine on propane for the last 15 years, it's just the last 2 years it hasn't.

Ron - I'm pretty sure that you're right that it's the diaphragm that's failed - but finding a spare part has proved impossible. It would seem to be easier to replace the whole valve, than to try to repair this one.

[Crofter]

Henry - don't worry about liability - you're on a different continent to me, the rules don't apply.... Besides, this isn't a new installation, all I need to do is replace the demand valve with the same size that's already there, and it should (in theory) work. The truck worked fine on propane for the last 15 years, it's just the last 2 years it hasn't.

Ron - I'm pretty sure that you're right that it's the diaphragm that's failed - but finding a spare part has proved impossible. It would seem to be easier to replace the whole valve, than to try to repair this one.

AdeV; As ron says, the most common failure is diaphragm or corrosion that jams the inlet valve. It might be possible to source diaphragm material from a larger diameter regulator as long as it is relatively the same thickness. It might be doable but you may run into a riveted attachment of the parts.

I could chase down the name of a person who sourced new material for rebuilding old collectable chainsaw fuel pump diaphragms. My curiosity would make me need to see the innards of that animal!

As mentioned it is totally forbidden territory and there are life threatening consequences to screwing up. Knowing the original WC settings would be a real plus. The tautness of the diaphram also affects the fuel mixture curve as well.

[Henry W]

My apolagies guy's, I was thinking a new install at the time. I have been spending most of my time thinking about my new build and what parts are needed. Also how much I am willing to accept on output and how fast I need to spin the engine to echeve it.

Henry

[wrightkiller]

Try this site.......http://411lift.com/quoteform.html?gclid=CPrWx7G2waYCFQY65QodXV6cIw

or this one  http://www.pngtechnologies.com/Products_GenericImpco.html

[BioHazard]

Try this site.......or this one  http://www.pngtechnologies.com/Products_GenericImpco.html

That's a great link...
What are these "governors" they sell?
http://www.pngtechnologies.com/Governors.html
How does that govern the engine? What is it controlled by? It looks like a throttle body...

[billswan]

Try this site.......or this one  http://www.pngtechnologies.com/Products_GenericImpco.html

That's a great link...
What are these "governors" they sell?
http://www.pngtechnologies.com/Governors.html
How does that govern the engine? What is it controlled by? It looks like a throttle body...

Just guessing those are replacement parts for governors on spark ignition engines. You are looking at only part of the system.

Years ago gasoline truck engine governors started with a parts in the distributor. Those parts when up to a preset max speed would send a signal through a vacuum line back to the parts in or in this case under the carb. The butterfly valve would limit he engines max speed.
The ones I remember seamed to work well but I am not to sure they weren't just meant to stop a ignorant driver from busting up an engine in the lower gears. Not something that could govern an engine continually on a gen.  Just to protect engine from over speed. I could be wrong though been may years since I worked on en engine with one.

Billswan


Billswan

[Crofter]

Billswan, that is correct. The governors shown are likely a simple overspeed vacuum actuated throttle body that goes below the mixture control carb. I am not sure how the controlling vacuum is modulated on the ones pictured, but some old gas engine trucks had a weight and spring controlling a sleeve on the distributor shaft below the timing advance mechanism in the ignition distributor.  It would not act as a governor like for a generator.

[vdubnut62]

Some of the old BD144 diesel engines in the International B-275 tractors had a pneumatic governor. It did have a butterfly valve.
Also had a Datsun pickup /w the same setup on an SD-22 diesel.  But although they shared the same type of components, they did not work the same.
I guess this is a long winded way of saying that it is possible for it to operate as a speed control setup.
Ron