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Filling a Propane Tank From a Propane Tank Questions

dalmatiangirl61

Subscriber
Last Subscription Date
07/10/2019
I got tired of driving into town once a week to fill the propane bottles, so last week the propane dealer dropped off a 250 gallon tank with a wet line setup so I can fill my own bottles. The guy that dropped it off said to just hook hose to bottle and open valves, I tried that today and although some propane is transferring, its not filling the bottle. I think I need to open the little valve on side of the bottle valve assembly, but I'm not 100% sure, so before I try that I need verification that that is proper procedure, or I need proper procedure explained.

I am also not happy that 250 gallon tank has no method of locking the propane fill hose or valves, I am wondering if there are any quick connect fittings suitable for propane? If so, that would allow me to remove the hose when not in use, and with hose removed if someone opened valve no(little) propane could escape.

Snow is coming, I need to fill bottles asap!
 

DaveRW

Subscriber
Last Subscription Date
12/10/2019
When I worked at an RV Dealer I refilled propane bottles. All bottles had to be certified. A re-certification involved installing a new OPD valve on the bottle before filling A number stamped and a visual inspection of the bottle. They were switching to the OPD (over fill protection device) at that time. All bottles were filled by scale weight, and only to 80%,and by opening the bleeder valve on the main valve, (when liquid propane started to come out of the valve usually on bottles with the older valves), or scale weight was reached on the bottles with the newer valves)shut off the supply and shut the bleeder valve.
 

slip knot

Subscriber
Last Subscription Date
12/27/2019
Its been a lot of years since I filled a bottle from a nurse tank. but if I remember correctly the little valve on the tank is a dip tube to tell you its full. You would crack the valve open and when it started spitting liquid it was full. I'm not sure how the OPD tanks are built now.
 

Odin

Subscriber
Last Subscription Date
07/13/2019
Propane fill stations usually have a sealed pump that transfers the liquid from one vessel to another. Without this pump, the propane will only flow until the tanks are of equal vapor pressure. Which will happen long before the liquid level has actually reached where it should be.

To fill a tank correctly, it should be filled by weight using the data stamped into the tank's collar. OPD equipped tanks will shut off if you try to overfill one, but do not trust this- the devices can fail.
 

slip knot

Subscriber
Last Subscription Date
12/27/2019
I do recall that as the nurse tank went empty it didn't fill the bottle as much. Thanks to Odin for that reminder.
 

Dan H

Registered
In Ontario it is illegal to fill one tank from another. But, If I was going to do it, I would use a hanging type scale and weigh the empty tank. I would then hook my wet line up and turn it on. With the empty tank hanging in the air, I would then wet the hanging tank continuously with cold water until the scale reads tank weight + propane weight for that size of tank. The temperature differential between the two is what fills the tank. Without the cold water, the empty tank will only fill 1/2 way, which is not all bad . To do this is wrong, dangerous and illegal. Others in Ontario will rig a old piston auto ac compressor up with a belt to electric drive or a gas motor. I have seen that done as well but never attempted it myself. Dan
 

dalmatiangirl61

Subscriber
Last Subscription Date
07/10/2019
My bottles have current inspections, and the modern OPD valves. The propane dealer setup the large tank with the wet line valve and fill hose, and delivered to my place full of propane, so I'm guessing its not illegal. It would be illegal for me to fill/sell other peoples bottles.

There is no pump, just a hose with filler attachment. I left bottle connected today for about half an hour and it is maybe half full. Without a pump I don't think I could over fill a bottle, but may be wrong.

Dan, its below freezing outside, I'm failing to understand how wetting bottle is going to get it colder?
 

Capt...John

Registered
You may try this. Paint the big tank flat black so it warms up in the sunny part of the day. Place the small tank in a freezer to get it cold. Then fill your small tank. Let us know how that works. :O
 

pegasuspinto

Registered
IF you have two tanks, both with liquid in them (at least a little but any amount) if they are at the same temp, they will have the same pressure, and there will be no flow. If the little tank is just a little hotter, the liquid will try to backflow into the big tank! You have to crack that bleeder to releave some pressure so the flow can happen. Most tanks should have a dip tube on the bleeder, so when it spits any amount of liquid, it's full.
 

Thaumaturge

In Memory Of
Age
68
Last Subscription Date
07/12/2019
Hook up main line, open aux taink main and screw driver bleeder. Open main. When gas from bleeder becomes visible close bleeder, close main tank valve then aux tank main valve. Refill stations have big diameter hand tighten collars with either internal (left hand) thread or outside (right hand thread) mounts. Small tanks have detent check valve. Fill station usually has 1/4 turn ball valve shut off mounted just behind tank fill connection. Pumped return bleeder line connects to main feed just behind ball valve. As noted, without pump can only fill aux tank to same pressure as main.
Doc
 

Heins

Subscriber
Last Subscription Date
01/02/2020
When farmers ran propane tractors in the summer time, they would fill them in the field from a larger propane tank. They didn't have a pump, they would hook a hose from the wet leg on the supply tank and open the vent on the tractor tank until liquid propane started to come out. That would drop the pressure in the tractor tank and liquid propane would flow into the tractor tank.

They would do the same thing with NH3 tanks.
 

autosparkii

Registered
I do this in nz, cannot find filling stations for 2 and 4 kilo bottles in winter so a 9kg bottle is inverted, smaller bottle connected to bigger and bleeder cracked open until liquid appears.

Your bottle is full now.

Another way I tried as I have a vacuum pump was to evacuate the empty bottle to 25 inches and they would draw in liquid to about 80% capacity.

Having cylinder temps about equal works well for me.
 

oldtractors

Registered
Age
50
Last Subscription Date
12/22/2015
It isn't that complicated. crack the bleeder on the BBQ tank to let vapor escape. When liquid starts coming out, shut the valves. On some tanks the overfill protection will shut off the flow before it is full. I have that problem with a couple of my horizontal 20 lb tanks. If the BBQ tank is warmer than the big tank, it won't work. You can fill the tanks to full capacity without a pump or any other tricks mentioned above.
Remember that propane is a boiling liquid and not a gas. No matter how full the tanks are, the pressure is the same at a particular temperature.
 

Lonnie Grissom

Registered
Being an old tow motor operator in a paper mill we had to do a lot tank filling. You can get some lp in smaller tank but you need a pump to fill tank full. There is asafety issue. Always use face shield and proper gloves.
 

Renny

Registered
If you can, try filling at the end of the day, as it is cooling off. The small empty tank will cool quicker than the large full tank, dropping the pressure in the small tank, allowing it to fill, but it will take a while. i use to do this to fill a truck tank. You have to watch, as if left too long, it will fill past 80%.
 

LCJudge

Subscriber
Age
60
Last Subscription Date
12/14/2019
I've never had any trouble filling my 1 gallon propane tanks that I use on engines. I have a 500 gal propane tank outside my building that is the "mother" tank and have a line and cut off plumbed inside the building. I simply connect the one gallon tank to the line, open the bleeder valve on the small tank and open the main line. If the small tank is empty, which mine always are, doing it this way is the same as dumping liquid propane into a bucket. No pressure equalization issues, etc. Once the liquid in the small tank reaches the bleeder valve level and liquid starts to spurt out, I shut everything off and its full. Has worked for me for the last few years. Your tanks have the certification date on them. They are OK to fill until they reach that date and then have to be recertified or tossed according to law although a lot of folks used them well beyond that date.
 

beezerbill

Subscriber
Last Subscription Date
01/10/2019
Google "filling barbeque propane tanks." Here's one hit that looks about right. https://www.youtube.com/watch?v=tUm3F_PUYJ0 He have might have slightly overfilled it, and don't forget that you lose a hose full of liquid propane on each fill. Wear insulated gloves - that stuff comes out cold! And be real vigilant about ANY ignition sources.

I think the problem you are having is not opening the vent so that gas can escape as liquid fills the tank.
 

dalmatiangirl61

Subscriber
Last Subscription Date
07/10/2019
I filled, um partially filled 2 more bottles today, opened the bleed valve, waited about 5 minutes and still maybe just half full:shrug:. Not sure what I might be doing wrong, or maybe just need to wait longer, idk. It was spitting snow today, just did not feel like waiting longer.

Bill, this setup has a valve right behind the fill nozzle so I don't lose the hose full of propane.
 
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