Propane tank valves

[durk_2007]

I have a 500gal tank for my house and 3-100LB tanks for my shop. (The way my property is arranged I really don't have a good place to set a tank away from building) so multiple small tank it is.
They want $1 lb to fill the small ones at the service station or $.50 to deliver to my tank. So I want to fill my 100lbs from my main tank. I understand the process (used to run a fork lift) question is do I have a wet leg here?

 

[Raisedonadeere]

I am not familiar with fittings on a 500 gal tank but if you can get a connection to the liquid portion, you could hook that to your 100lb tank on a scale and let it fill to the proper weight. The 100 lb tank needs to be cooler than the 500 lb one for this to happen.
just pack ice around the 100lb tank or put a heating pad on the 500 gallon tank. the liquid will go to the cooler tank, but you must master how to monitor correct fill to avoid serious unsafe situations resulting from overfill.

You can do the same thing hooked to the vapor outlet, but it would take a long time which makes it difficult to monitor for correct fill.

the liquid migrates (flows) to the cooler tank always.

 

[Walkers]

this link might help, I know it is an ar15 forum, but it shows the parts. https://www.ar15.com/forums/outdoors/Filling_propane_tanks_from_big_tank_how_to_with_pics/17-686883/

 

[The Cobbler]

I've never been able to come close to a full tank , never mind overfilling one when doing a transfer .
I'm not sure overfilling is even possible . once the pressure builds up , it stops flowing

 

[dhally]

Another idea would be to run a pipeline from one of your bulk tanks to your usage point. No small tanks needed!

 

[Raisedonadeere]

I've never been able to come close to a full tank , never mind overfilling one when doing a transfer .
I'm not sure overfilling is even possible . once the pressure builds up , it stops flowing

I only mentioned overfilling because it would be possible if someone actually put the receiving tank in dry ice or something or got carried away and heated the supply tank excessively.

If one tank is cooler than the other and you leave them connected indefinitely, all the liquid will flow to the cooler tank until it is eventually all liquid, that is, unless the supply tank empties of liquid.

 

[durk_2007]

The fitting at the small tank (receiver) has a valve that can be used to purge pressure and vapor until it's full of liquid. The main thing I'm trying to figure out is do I even have the proper connection on my tank to do it before I spend the money on the hose kit.

 

[durk_2007]

Another idea would be to run a pipeline from one of your bulk tanks to your usage point. No small tanks needed!

I'd love to plumb it from the existing tank. it's just that it's over 200ft thru trees/sidewalk/driveway and buried electric. I just don't have the gumption for that. It's just for backup heat and hot water at a slop sink.

 

[toyotadriver]

I don’t see a liquid withdrawal port on your tank. Well the valve in the middle on the first picture might be one but uncertain. There should be a cap on it.

I do fill smaller propane bottles from my larger tank. Similar basic set up as the linked thread earlier.

I have an HVAC vacuum pump and I pull a vacuum on the small tank first. Once it’s vacuumed down I connect it to the 500 gallon tank and start filling. Once the pressure equalizes, I open the vent screw on the small tank and allow it to flow out. Vapor propane will slowly vent until your small tank is full. You will know it’s full when liquid propane starts venting out. You’ll waste a little propane and that’s why I wait till I have a few bottles to fill and do them all at once.

I have filled bottles as small as 5 lbs and as large as 100 lbs this way (along with every size in between) with zero issues. The vacuum really helps to fill the tank quickly with less waste. Once the pressures equalize and liquid propane stops flowing, you open the screw on the valve to vent some vapor propane. As the vapor vents, it drops the pressure in the small tank and then liquid propane starts to flow into the small tank again. You have to waste a little propane to keep it flowing but you can get a full fill with no issues doing it that way.

I don’t use a scale to weigh the propane bottles. I just fill till it vents liquid propane and that means it’s as full as I can get it.

 

[toyotadriver]

To the OP….can you tap the vapor line from your larger tank? Run a line to the shop and then put a low pressure regulator on the shop. Then you can run directly off the bigger tank.

 

[fitter30]

Try contacting this company that's selling lp liquid withdrawal fittings

Pardon Our Interruption...

northlandgasequipment

 

[86turbodsl]

When i put my 1000G tank in, i went to the trouble to put a wet leg in. The reality of owning it for 15 years is that it doesn't really work that good for transfer in my opinion. I rarely use it to fill my own tanks. IF you pump the empty tank down to a vacuum, maybe it would work better, but the transfer is really hard to get it going and you don't have a way to **** on it when you're starting the transfer.

 

[toyotadriver]

When i put my 1000G tank in, i went to the trouble to put a wet leg in. The reality of owning it for 15 years is that it doesn't really work that good for transfer in my opinion. I rarely use it to fill my own tanks. IF you pump the empty tank down to a vacuum, maybe it would work better, but the transfer is really hard to get it going and you don't have a way to **** on it when you're starting the transfer.

Pulling a vacuum on the tank makes a big difference only in how fast it fills and in how much propane you will waste. If you don't pull a vacuum on it, you can still fill it without a problem but you'll waste a little more propane. You just open the vent valve on the small tank. It'll vent vapor propane out and that will enable the large tank's pressure to flow liquid propane into the smaller tank. Haven't had a single problem filling my smaller tanks. The pump on a propane fill place's fill station enables the tank to fill much quicker but that's the only real benefit.

 

[86turbodsl]

Pulling a vacuum on the tank makes a big difference only in how fast it fills and in how much propane you will waste. If you don't pull a vacuum on it, you can still fill it without a problem but you'll waste a little more propane. You just open the vent valve on the small tank. It'll vent vapor propane out and that will enable the large tank's pressure to flow liquid propane into the smaller tank. Haven't had a single problem filling my smaller tanks. The pump on a propane fill place's fill station enables the tank to fill much quicker but that's the only real benefit.

I'm usually trying to fill a BBQ tank, and they only have the one valve, so there's no vent.

 

[FredWanaker]

Just have the service guy top them all off when he does the big tank at 50 cents a pound.

 

[The Cobbler]

I'm usually trying to fill a BBQ tank, and they only have the one valve, so there's no vent.

disposable tanks?
refillable tanks as in 20 lb etc , have a port on the valve that will allow filling by volume. open it with a slotted screwdriver and it will vent as it fills

 

[Firebrick43]

I have a 500gal tank for my house and 3-100LB tanks for my shop. (The way my property is arranged I really don't have a good place to set a tank away from building) so multiple small tank it is.
They want $1 lb to fill the small ones at the service station or $.50 to deliver to my tank. So I want to fill my 100lbs from my main tank. I understand the process (used to run a fork lift) question is do I have a wet leg here?

Take the Fisher rubber caps off and take a pic of them. They are probably both relief. Sort of odd to have two relief valves unless that is a 1000 gallon tank which they did on old tanks instead of a single larger one on late 60 and up tanks. It would be also crazy to not have the brass cap on the liquid port as they dont always seal completely with the valve removed/slugged. But I have seen stupid **** before

But I highly doubt it. From looking at it, that is a 50's or early 60's tank. They almost always have the liquid withdrawal on those old tanks on the bottom, not the top like modern tanks. ***** as you have to lift them up with a crane to pump them out and sometimes they are plugged with **** that has settled out over the last 70 years.

 

[Firebrick43]

I'm usually trying to fill a BBQ tank, and they only have the one valve, so there's no vent.

He shouldn't have called it a vent. Its a spitter and all 20lbs OPD BBQ tanks have them. They are full when the liquid level reaches the dip tube at 80% and liquid, not gas comes out the little hole. Careful, the liquid is -44 degrees F and will cold burn very bad and cause terrible blisters.

 

[Firebrick43]

Sort of hard to see but the red arrow is point to the hole where the liquid propane will come out if the liquid level is up to the bottom of the dip tube.

The Blue arrow is the dip tube.

The Green arrow is the OPD overfill prevention device, that shouldn't actually be used to fill with as they can fail.

The black arrow is the pressure relief valve/vent that will release propane if it gets above 375 psi in the tank because its overfilled or severely overheated.

 

[toyotadriver]

I'm usually trying to fill a BBQ tank, and they only have the one valve, so there's no vent.

The post above mine explains it well with pics. It's used to vent pressure so liquid can flow into the smaller tank from the larger tank. Yes you are venting a little propane but it's normal. That the benefit to pulling a vacuum on the tank. You don't have to vacuum it to get it full but it is easier and quicker so I do it every time I fill a smaller tank. When they fill a tank at an actual propane fill place, they start pumping the propane into the tank and after the propane begins to flow, they open the vent/spitter whatever it's called and vent out a little propane while the pump fills it.

You can get it full much quicker with the pump which is why propane companies use the pump vs my non pump method. I can get mine just as full as a propane fill station but it'll just take a little longer.

 

[pcmeiners]

You really want to use one of those ports after they have been painted, left open to the weather, no less with seals which are decades old ?