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Correct. The pressure reg at the meter is the only "regulator". From there the volume is adjusted at the gen with a load block. See above post. That is a temporary install, nothing is permanently installed. It is also why I have the electric ball valve - if the gen were to quit that would kill the power to the valve and close it.

Direct line is left of the reg. The "load block" is the yellow ball valve in that instance.

The hose to the manifold can switch between the direct line and the demand reg up top. When I was working on it this day I had taken the load block out, but there is a load block that can go downstream of the demand reg to tune propane.

There is a gas manifold that sits ahead of the carb, under the air cleaner box. I don't have the "snorkel" set up to shoot in to the two intakes, just one manifold that mixes the fuel with the intake air going to both cylinders.

View attachment 10839
The demand regulators primary function is to be a safety valve where when engine vacuum disappears fuel flow stops. If you do not have enough NG volume from your demand regulator then you should look into a high flow rebuild kit for yours that uses a 1/2“ orifice.

Personally I’d consider using the engine oil pressure switch as a fail safe trigger for the MBV. Either use the existing one or tee off the port and add a second.

How stiff does that polyethylene gas pipe get when the temps drop?
 

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The demand regulators primary function is to be a safety valve where when engine vacuum disappears fuel flow stops. If you do not have enough NG volume from your demand regulator then you should look into a high flow rebuild kit for yours that uses a 1/2“ orifice.
I have 3 of these regs - put 2 on and have a third as a spare. However, that is a thought - I believe I can get higher flow regulators instead of modifying one.

I am also thinking the issue is overall low system pressure (from the service reg at the meter). When I was asking about the service there was an upgrade to 2psi, I believe. However, they would not adjust the pressure as-is (I want to say its 14in WC). If we did the 2psi upgrade there would have to be a step-down reg. We were told the proper way to do it would be a step-down reg at each appliance. That is too much work/too big of an upgrade.

We ran the numbers on the BTU's and if we max'ed out all the appliances we wouldn't have enough, looking at the numbers, for the big gen. However, we never max out the usage. The highest would be the furnace and water heater. And with a variable load on the gen - we're no where near max on that, either, at least for very long (start up on AC might be the only time). So we decided to try the port off the meter as-is.

Again, this would be a perfect question to answer with a manometer - if the pressure ahead of the demand reg is too low for the demand reg to work with the volume the engine is demanding then it doesn't matter what demand reg is used - unless there is a demand reg that can run at lower pressure, and supply adequate fuel volume, to the engine at lower pressure.

Personally I’d consider using the engine oil pressure switch as a fail safe trigger for the MBV. Either use the existing one or tee off the port and add a second.
That is certainly an idea. It may be a quicker acting trigger - the winding down of the alternator and the discharge of the filter caps in the AC to 12v adapter delay the power cut off to the valve, but its not terrible.

How stiff does that polyethylene gas pipe get when the temps drop?
Not sure off the top of my head what all the material is, but it is a metal pipe that is lined. I want to say it is aluminum. It is "stiff" - it is not a "hose". However, it does hold its shape when formed. If it was used all the time it would break. So a hose would be the better route. As to how flexible it is when it gets cold - I'm sure it stiffens up a bit, but its already stiff from the metal.
 

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The demand regulators primary function is to be a safety valve where when engine vacuum disappears fuel flow stops. If you do not have enough NG volume from your demand regulator then you should look into a high flow rebuild kit for yours that uses a 1/2“ orifice.

Personally I’d consider using the engine oil pressure switch as a fail safe trigger for the MBV. Either use the existing one or tee off the port and add a second.

How stiff does that polyethylene gas pipe get when the temps drop?
drmerdp, I've done some digging and can't find anything on a 1/2 inch outlet garretson regulator outside of several sites stating "This unit is also available in a new high flow model with 1/2 inch outlet" but nothing outside of that. You have a resource for those?
 

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This unit is also available in a new high flow model with 1/2 inch outlet
It is confusing that they say "with 1/2 inch outlet" because they don't list any such animal on their website. The model 039-31173-1 is their high flow regulator (with primer. remove -1 for unit w/o primer). You can compare the 039-31173-1 and the 039-122 and see that the big difference is the spring.
 

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It is confusing that they say "with 1/2 inch outlet" because they don't list any such animal on their website. The model 039-31173-1 is their high flow regulator (with primer. remove -1 for unit w/o primer). You can compare the 039-31173-1 and the 039-122 and see that the big difference is the spring.
Thanks, both of those models show 3/8 inch outlet.
 

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drmerdp, I've done some digging and can't find anything on a 1/2 inch outlet garretson regulator outside of several sites stating "This unit is also available in a new high flow model with 1/2 inch outlet" but nothing outside of that. You have a resource for those?
The high capacity KN has a 1/2 inlet orifice. Basically a brass piece that’s deep inside the 3/4 inlet port.The outlet port appears to be the same across all the models. I would be nice if they had larger outlets that would accommodate a larger diameter hose from the load block to carb inlet. The hose on my EU7000 is longer then I would like but nessesary to properly fish it’s way through the enclosure. Shorter is always better for this hose.

The exploded parts view show the orifice as item 5. It might be a simple swap without the need for replacing the spring loaded sealing washer on the inside of the unit. Impco may be able to shed some light on that.

It also looks like the high flow KN may not be availible with a primer button. Hmmm.


I wonder what’s the orifice size on @Bulldoggers KN regulator.
 

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I wonder if you drilled the orifice to 1/2 in (or bought one) and changed the spring to red, if that would essentially give you the high flow model?
 

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I wonder if you drilled the orifice to 1/2 in (or bought one) and changed the spring to red, if that would essentially give you the high flow model?
Yeah, I’m thinking converting to high flow is just a matter of 2 or 3 parts. Impco would need to confirm it.
 

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That assumption being - by "throttle adjustment" you mean the load block to throttle the fuel. In that case, yes.

Also countering my own assumption in an effort to be thorough - there was some discussion somewhere a while ago about the physical "throttle"/governor on a generator.

I'm in the same boat on a manometer - as of now I don't have one. I have been able to get around the issues I've had thus far. That having been said - it would have been really helpful to have one. I may go the route of making a water based one this season then see how things go.

On a bit of an off-topic - I wonder if the fuel volume through the demand reg on the small gen on ng (it uses it on both fuels) is why it cuts off with much load. That wouldn't surprise me at all - and if I had a manometer it would be pretty easy to determine that - the gas pressure ahead of the demand reg would drop too low.
I meant just that, the throttle on the generator itself, not the load block. The adjustment of the load block seems to not be much of a factor with what is going on. I am certain of that.

I stopped at the local propane shop and was given some things to try. He suggested I pick up a "pigtail" or whatever it's called to join both of my 100 pound tanks. The idea was to make sure the vaporization rate of a single 100 pound tank that may not be able to keep up with the fuel demands of such a large engine and heavy load was not the culprit. It made sense to try.

As for as the manometer, he scoffed at that idea.
 

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Discussion Starter · #213 ·
the digital manometer is cool to look at the draw or suction on the line to the carb plate as well as look at the low pressure on the gas feed.
pm if you need links to good hand held units.
 

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Not sure off the top of my head what all the material is, but it is a metal pipe that is lined. I want to say it is aluminum. It is "stiff" - it is not a "hose". However, it does hold its shape when formed. If it was used all the time it would break. So a hose would be the better route. As to how flexible it is when it gets cold - I'm sure it stiffens up a bit, but its already stiff from the metal.
Gotcha, I thought it was underground polyethylene gas pipe.

Sounds like you got gasflex. Interesting, Inside and outside Polyethylene coated aluminum. Ive never heard of it before today. It installs similar to CSST but does not require bonding and is 1/3 the price. It might be a good fit for a project I want to do.
 

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Went digging through the thread a bit. 7/16 orifice. Hmm

I wonder if @Texas T ever got his unit dialed in under heavy load. He never gave any feedback after his install. I think he was running natural gas. And going through his posted pics also has a 7/16 orifice regulator.
 

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The engine on the 18kw is a pretty big engine - probably bigger than the 15kw we have (Honda GX690 v-twin). If you have a "demand regulator" on there with a load block it is entirely possible that your draw on that gas circuit through the demand reg is too much.

Truth be told - on NG with the 15kw I am running I have taken the demand reg out and replaced it with a powered ball valve as the "safety shut off"*. Then there is another manual ball valve that is the "load block". On Propane the demand reg I have works, on NG I think our pressure is too low.
I am using the same demand regulator that you were using. I noticed it in your pics. It was fine with propane, but not natural gas, with your engine. The question is it fine on propane with mine? I may need the larger model?
 

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Discussion Starter · #218 ·
Gotcha, I thought it was underground polyethylene gas pipe.

Sounds like you got gasflex. Interesting, Inside and outside Polyethylene coated aluminum. Ive never heard of it before today. It installs similar to CSST but does not require bonding and is 1/3 the price. It might be a good fit for a project I want to do.
yea lightning is hard on that stuff...
in some areas of the country it will not pass local and state fire code and fails gas code as a result.
they do not like it here in Iowa except on the main trunks...
then to black pipe at the service riser just before the service meter on the outside of the house.
 

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Discussion Starter · #219 ·
I am using the same demand regulator that you were using. I noticed it in your pics. It was fine with propane, but not natural gas, with your engine. The question is it fine on propane with mine? I may need the larger model?
it has to do with the sensitivity....
the smaller the orifice the better it is with small demand changes...
BUT
with that said the high part of the flow needs to be at below75% of the rated of the demand regulator...
there is a bunch of math for doing this by the number of cyls on the engine and the rpm and the CC'S of the engine.
if i had all of those numbers i can run the math.
you need the cfm numbers at low speed and full load speed...
the those numbers can be plugged in to another bunch of math for the demand regulator.

lol
love the math!
then go an extra bit for wiggle room on the numbers...

OH yeh!
there is a BIG thing on LP quality as well as NG quality...
both are a mix of gasses so.... the blend can be off like on gasoline!
not sure beyond a lab if they have a handheld meter yet that shows the exact mix....

(air fuel ratio)
that would be a cool thing to see is an afr meter just after the carby or just before the valves!
see the exact mix before it is burned in the engine...
right now they do the afr by the exhaust gasses ...
so a bunch of math and just a bit of magic to get a close number... not exact on the afr...
at least on the pre burn mix!

and there is different math depending on the fuel used.
 

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OH yeh!
there is a BIG thing on LP quality as well as NG quality...
both are a mix of gasses so.... the blend can be off like on gasoline!
not sure beyond a lab if they have a handheld meter yet that shows the exact mix....

(air fuel ratio)
that would be a cool thing to see is an afr meter just after the carby or just before the valves!
see the exact mix before it is burned in the engine...
right now they do the afr by the exhaust gasses ...
so a bunch of math and just a bit of magic to get a close number... not exact on the afr...
at least on the pre burn mix!
My home is about 3500 sq feet with a lot of devices and appliances that are always on. The btu required at startup of my 2006 model 4 ton or 3.5 ton central air along with the other devices and appliances in my home has to be relatively high. I ran the generator for about an hour. Gentleman at propane shop ask me if the tank sweat at all. When I said yes, he replied that I for certain had a tank size issue. It is also partly why he scoffed at the idea of measuring regulator pressure. The first and second stage regulators are from reputable companies that he believes are almost certainly delivering the correct pressures. There he felt was not the place to start. Manifolding two tanks hasn't solved the issue.

Wouldn't just opening the bleeder screw on the almost full vertical propane tanks let the "air" out since it's likely sitting on top of the propane? If not, how do you fix an almost full propane tank that may have not been properly purged? Any ideas?
 
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