Stand-by generator

Tom_Veatch · Jan 28, 2007

BobRip said:
I just thought of a couple of other factors with propane. When it is cold outside, there will be a lower vapor pressure and if there is not enough surface area of the tank to evaporate the propane, then the pressure will drop and the engine will be starved of fuel. I don't know the conditions where this occurs, but it should be checked. You may find it runs OK for a while, but as the propane evaporates it will get colder inside the tank and pressure will drop. There will not be enough surface are on the outside of the tank to let enough heat in to keep the propane warm enough to maintain adequate pressure.

Here is a chart showing maximum draw at various temperatures. You'll have to do some unit conversions but it may help determine whether there is a problem or not.

BobRip · Jan 28, 2007

Olmike said:
Yep,Thats what I was thinkin.Wrap the bottle with 1/2" copper or 5/8" heater hose & it would also help cool the motor.I have the heater lines routed through the vaporizer now so would'nt be a big job to heat the bottle.
Mike

This is a good head source.
If you get it too hot, the pressure in the bottle could go too high. Does somebody know the limit.

You can also parallel bottles to give more flow. You will probably need more that a 20 pound bottle to run it anyway.

Olmike · Jan 29, 2007

I have a 100# bottle for standby,the 20's are easyer to tote.

86turbodsl · Jan 31, 2007

I seriously doubt you'll have a problem with cold weather and the propane. The vapor / liquid temp point for propane is about -44C. If it's that cold, he's got other problems too...

BobRip · Jan 31, 2007

86turbodsl said:
I seriously doubt you'll have a problem with cold weather and the propane. The vapor / liquid temp point for propane is about -44C. If it's that cold, he's got other problems too...

You may be right, but the outside temperature does not have to be -44F to have it not run a generator. As the gas expands its temperature will drop. The smaller the internal surface area and the smaller the volume in the tank, the quicker it will drop. At -44F it has zero pressure. No gas would flow out of the tank. I don't know the pressure requirements for a generator, but obviously greater than 0 PSI. I am out of my area here so I will let others comment.

Highbeam · Jan 31, 2007

I have no problem freezing my BBQ sized propane tank to the ground when using the weed burner to start a slash fire in 40-50 degree weather. When this happens the output rate of gas to the burner is greatly diminished.

But, there is still enough gas flow to use the weedburner to heat the propane tank and then get more gas to boil off.

Tom_Veatch · Jan 31, 2007

Highbeam said:
...
But, there is still enough gas flow to use the weedburner to heat the propane tank and then get more gas to boil off.

Ouch! The picture I have of applying that torch flame to the propane bottle really increases the old pucker factor for me

BayouMan · Feb 3, 2007

I'm with you Tom!!!

Olmike · Feb 4, 2007

A follow-up on the gen project.I haven't tried to power the house yet,but since nobody offered any advice on wheather I could weld with ,it I did what any self respectin DIYer would do.I hooked A welder lead to the dc output & grounded to the frame of the gen & it run a very nice bead on 1/2" at about 2200rpm.Now I need install plugs for welder leads & figure out how to adjust the governer for welding & generatin.