Propane transfer system question

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angie_nrs

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This is a topic brought up in another thread. I have an attachment that I can fill the small green propane tanks from a 20# tank. However, I would like to find a solution to filling a 20 or 30# tank from a larger propane pig. I'm a complete novice in this area but I think if I had the supplies, hubs could figure it out. It's just not my forte'. Here is a pic from a different thread.

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It's post 77 from this thread
https://www.homesteadingforum.org/threads/you-have-12-hours-notice.11498/
If anyone could give any tips or suggestions on exactly what to buy, where to buy it, and how to do it, I would appreciate it!

Something like this could come in handy even if a person didn't have a full pig to draw from. If you had the abiltiy to do it, I'm sure lots of folks would be willing to trade some propane if you could put it in a smaller tank for them so that they could actually use it with their propane grills and such. Many people may have a full pig with no idea how to utilize the propane in it if the grid went down.
 
Here's what I could find.
I wanted to connect my motorhome to my 500 gallon home tank.
The propane company told me they would not do it and if I did and they wouldn't fill my 500 gallon tank.
  • At the very least, it is likely you will need your bulk propane tank retrofitted. Filling a grill tank (typically a 20 lb tank) requires liquid propane. While your bulk tank has liquid propane in it, the propane that comes from it for domestic use is the gaseous propane at the top of the tank. You would need a separate "liquid propane tap", which involves connecting to a different line attached to the tank that pulls from the bottom of the tank. It seems that while it is common for this line to be present, it normally is not configured to be usable by the homeowner. Your gas supplier would need to attach appropriate hardware to the tank to allow its use. Which brings us back to the point above.
 
As backlash said, you need a liquid port, how ever any big tank that I have ever seen has one on the under side, it looks like a drain plug, and has ORB threads, there is a special fitting but a short pipe nipple is close to the correct thread, I can take a picture if it will help, the way that the hoses are hooked in the photo will only transfer vapour, perhaps a bit of liquid if the pressure in the big tank is high enough. the tank in the photo may have a liquid dip tube , as it appears to have more than one port on top, not common, and not very safe unless you really know what you are doing that white spray is -40, and if your glove has any moisture on it you might not get it off quick enough to prevent fairly painful frost bite.
 
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Your supplier is not going to help with drawing liquid, I can tell you getting fittings isn't easy, I am only providing this information for in case of emergency. liquid propane boils at - 40, it is potentially dangerous. super cold steam.
 
Knowing almost nothing about the subject.....

Would it be possible to tip the tank on it's side to get the propane out instead of the vapor with the hookup above? Clearly, this would only be done in an emergent situation with someone skilled with heavy duty equipment. That said, could it work?

In the picture above, is the 20# tank only getting propane vapor and therefore not really getting filled?
 
When filling a propane tank its done using liquid not vapor. A gas grill tank only fills with about 3.75 gallons 30# tank around five gallons due to expansion, all tanks have a tare weight stamped on them and are weighed when filling with the exception of tanks with a percentage gauge on them, it’s very dangerous if you have no experience not proper hose, fitting and scales.
 
Knowing almost nothing about the subject.....

Would it be possible to tip the tank on it's side to get the propane out instead of the vapor with the hookup above? Clearly, this would only be done in an emergent situation with someone skilled with heavy duty equipment. That said, could it work?

In the picture above, is the 20# tank only getting propane vapor and therefore not really getting filled?
theoretical it could work but it would be slow, the vapor valve has a excess flow protection so that is will shut of at much flow. . it would be better to get a long low pressure hose to run what ever you are needing the BBQ tank for. tapping the liquid port would be easier and safer, the fittings are just regular ORB fittings, and in an emergency situation, there won't be inspectors around. hydraulic hose will also work in an emergency
In the picture, the OP did point out that his tank had a liquid dip tube port, so the tank was actually filling with liquid, that configuration is not very common, perhaps on fairly old tanks or specialty tanks.
 
now that Angie has started this thread, there is a potential source of fittings and "stuff" in a PAW world. Large rental propane construction heaters, often have tanks on wagons that are set up with liquid draw ports, most often at the bottom of the tank. I know that these are fairly common in colder climate area. the liquid is used because the boil off rate is not enough to keep up with the requirements of multiple large heaters, so a evaporator is used i before the heaters to make the system function. Again this can be dangerous, but better a risk than to freeze, not be able to boil water etc. really the risk is in the bleed down of liquid propane, if attention is paid it is easily dealt with.
 
Here's what I could find.
I wanted to connect my motorhome to my 500 gallon home tank.
The propane company told me they would not do it and if I did and they wouldn't fill my 500 gallon tank.
  • At the very least, it is likely you will need your bulk propane tank retrofitted. Filling a grill tank (typically a 20 lb tank) requires liquid propane. While your bulk tank has liquid propane in it, the propane that comes from it for domestic use is the gaseous propane at the top of the tank. You would need a separate "liquid propane tap", which involves connecting to a different line attached to the tank that pulls from the bottom of the tank. It seems that while it is common for this line to be present, it normally is not configured to be usable by the homeowner. Your gas supplier would need to attach appropriate hardware to the tank to allow its use. Which brings us back to the point above.
We bought one of these to connect our camper to a bbq grill hook up on our old house. GasSaf 24 Feet 3/8 inch ID Natural Gas Grill Hose Quick Connect Propane Gas Hose Assembly - 3/8 Female Pipe Thread x 3/8Male Flare Quick Disconnect - CSA Certified




We are using the hose now to connect our camper to a 250 gallon tank while my daughter is here.
 
We had a tank with a wet valve. The tank started leaking so the propane company took it to fix it. When we got it back the wet valve was gone and they "can't find it". We never used it and don't really need it so we eventually quit bugging them for it but I've never used them again and let all the neighbors know they took it.
 
Depends a bit on your bulk tank. Some wet legs come in from the top. Some are on the bottom. Thetop of the tank is vapor,the bottom is liquid. The wet leg on top has drop pipe to the bottom.

Most wet legs have a seat that pushes in when a nipple is screwed into it. I use a valve and a nipple and leave it in. Once this is screwed in, a hose is attached to the valve. The other end of this hose has a POL. The POL is attached to the small tank. The small tank is in a upright position. I have a valve at the POL as well. There is a bleeder screw on the side of the small cylinder,this is a 80 percent bleed. Turn the valve on at the big tank. Then the valve by the POL. Open the small tank valve. You will hear the liquid entering the little tank.

Then using a screwdriver loosen but don't remove the bleeder screw. When liquid starts to spit out the bleeder. You are 80 percent full.
Close the bleeder and shut the valves off. I have one by the POL so I can shut off fast.

You are done..

Liquid propane can cause frostbite so maybe goggles and leather gloves are wise. Of course the obvious, no smoking.
 
Here is a few photos.

The top is the bleeder screw. This is on a hundred pound cylinder but same on smaller cylinders. Some bleeder are a nut.

The second is the hose. Imusy have robbed the pol and extra valve. I laid a pol down therefor visual

The last hose is for filling 1lb cylinders. A20 pounder is turned upside down. Then a small tank is attached. Then filled. A digital scale could be used, zeroed out. I have better luck if the tanks are chilled.
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20220221_193536.jpg
20220221_193557.jpg
 
Depends a bit on your bulk tank. Some wet legs come in from the top. Some are on the bottom. Thetop of the tank is vapor,the bottom is liquid. The wet leg on top has drop pipe to the bottom.

Most wet legs have a seat that pushes in when a nipple is screwed into it. I use a valve and a nipple and leave it in. Once this is screwed in, a hose is attached to the valve. The other end of this hose has a POL. The POL is attached to the small tank. The small tank is in a upright position. I have a valve at the POL as well. There is a bleeder screw on the side of the small cylinder,this is a 80 percent bleed. Turn the valve on at the big tank. Then the valve by the POL. Open the small tank valve. You will hear the liquid entering the little tank.

Then using a screwdriver loosen but don't remove the bleeder screw. When liquid starts to spit out the bleeder. You are 80 percent full.
Close the bleeder and shut the valves off. I have one by the POL so I can shut off fast.

You are done..

Liquid propane can cause frostbite so maybe goggles and leather gloves are wise. Of course the obvious, no smoking.
Just to be clear...

When filling smaller tanks we want to use the wet leg i.e. that is in the liquid propane to draw from the larger.
???

I have seen Youtube videos were they turned the source tanks upside down.

Ben
 
The way the 80.percent bleeder screw works is due to a small drop tube off the screw tap. It drops down maybe 6 inches on a 20 pound cylinder. When the liquid propane gets to the bottom of the small drop tube, the liquid takes the path of least resistance and starts to spit out the screw. Shut screw, shut the valve. Now there is liquid to the bottom of the tube and vapor above the liquid. The drop tube length is set up to 80 percent liquid.
 
For a number of years the smaller propane tanks have been required to have float valves in them to prevent overfilling, often they can be a PITA because some of them only allow 3.5 gallons per fill. I was used to the bleed valve being slightly open to give an indication of the tank being full, the float valve was basically put in to protect you from yourself, kind of a Ralph Nader action, you may know him from writing about the Corvair car in his book, "Unsafe At Any Speed".
 
Having worked with propane powered industrial trucks I can tell you that the only difference between a vapor draw and a liquid draw tank is that the liquid draw tank has a tube that runs to within about an inch of the bottom of the fuel tank. These tanks are refueled from larger tanks with the liquid withdrawal valve. They go to a fuel pump - either a gear or rotor type pump and the fuel is pumped into the smaller tank. This is done for speed. As long as your storage tank is higher than the tank you want to fill you really don't need a pump. With the valve closed you connect the storage tank to the empty tank, open the bleed valve then the valve to the tank to be filled and then the storage tank. Let it fill until the vent starts spurting liquid. Turn off the storage tank and then the tank you are filling. NOTE: The hose is still full of liquid fuel!!! If the hose has a valve on it close the valve and disconnect it from the filled tank. You can discharge the liquid in the hose into another small tank or leave it connected to the storage tank. At the refueling station the hose is commonly left full and coiled on the storage tank until it is needed again. You can't use this tank as a source of fuel for any appliances - it is a refueling tank only.

It is strongly recommended that you wear an apron, gloves and a full face shield for personal protective gear when refilling a tank.
Use only approved LPG hose, fittings and valves. Any propane supply company will set you up with liquid withdrawal tank if you are using it to fill smaller, 5 to 30 gallon, tanks for your personal use. They probably have some training available with the setup of the large tank. You can buy the safety attire at most any safety supply store.

I have trained folks how to use the refueling system for industrial trucks in a half hour. It is not particularly dangerous as long as you remember that it is flammable and not ignition sources should be close. LPG is heavier than air and will sit at any low spot for a very long time - unless it is ignited.
Remember that, like gasoline, 1/4 cup evaporated into an area that is 8 by 8 by 8 feet is similar to a stick of dynamite if it is ignited. Don't store tanks indoors or in dropped areas. A covered, fenced area above the surrounding area with wind exposure is the best place to store pressurized tanks. The cover should prevent exposure to sun that can heat the tank, raising pressure, causing the over pressure valve to vent. At best it is a waste of fuel and at worst it will ignite if an ignition source is present.
 
Depends a bit on your bulk tank. Some wet legs come in from the top. Some are on the bottom. Thetop of the tank is vapor,the bottom is liquid. The wet leg on top has drop pipe to the bottom.

Most wet legs have a seat that pushes in when a nipple is screwed into it. I use a valve and a nipple and leave it in. Once this is screwed in, a hose is attached to the valve. The other end of this hose has a POL. The POL is attached to the small tank. The small tank is in a upright position. I have a valve at the POL as well. There is a bleeder screw on the side of the small cylinder,this is a 80 percent bleed. Turn the valve on at the big tank. Then the valve by the POL. Open the small tank valve. You will hear the liquid entering the little tank.

Then using a screwdriver loosen but don't remove the bleeder screw. When liquid starts to spit out the bleeder. You are 80 percent full.
Close the bleeder and shut the valves off. I have one by the POL so I can shut off fast.

You are done..

Liquid propane can cause frostbite so maybe goggles and leather gloves are wise. Of course the obvious, no smoking.

Yep, thats what we had.
 
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