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paulz
Member
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# Posted: 17 Dec 2019 09:03am
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Is it ok/good to open the bleed screw and drain prior to getting them refilled? The local gas station guys sometimes don't mess with it.
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Nobadays
Member
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# Posted: 17 Dec 2019 09:14am
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I think the bleed screw is primarily to bleed air from the tank as the fill it.... and yeah I got one filled the other day and they didn't open it, kinda wondering myself if I got a full time. The machine stopped pumping propane, I assume because of back pressure but was it full?
I do know at altitude you need to bleed air from the tank or it just won't fill. Ran into that problem up in Montana one time.
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silverwaterlady
Member
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# Posted: 17 Dec 2019 09:25am
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I thought propane tanks were purged of air before purchasing or if in the case of the Amazon purchased tanks we got that were not purged, they did it a Uhaul for us before they were filled for the first time.
Many places won’t do this for you. Also, Uhaul only changes for the amount of propane you buy. They don’t rip you off like the place by our cabin. We have to make sure the tank is totally empty before we take it there.
After all that, is there going to be air even in a purged propane tank? If so, how do I get rid of it before I take the tank in for refills?
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Brettny
Member
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# Posted: 17 Dec 2019 09:50am
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You can purge it some but there filled by weight so if the tank stops accepting propane at 15lbs then it should be purged.
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ICC
Member
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# Posted: 17 Dec 2019 10:22am - Edited by: ICC
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Bleeding air, or purging a NEW tank is necessary when filling the first time to get rid of the air in the tank. Air in a tank may contain moisture and cause problems. Also if air is in the tank it will be at the top as propane is heavier. That air will then cause problems as it ravels down the propane pipe to the appliance.
If you run a tank down to completely empty there is the small chance that air could have entered the tank by reverse flow. Not too likely, but when filling a tank that is completely empty the technician should use he bleed off screw to be sure there is no air in the tank. If there is a small amount of propane left in the tank there is no need to bleed.
A good propane store will use a scale to tell when the tank is full and whether or not it is empty when you bring it in. Tanks are all stamped with the tare weight as well as the date of certification.
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NorthRick
Member
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# Posted: 17 Dec 2019 05:01pm
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Don't the places that fill your tanks have a gauge similar to a gas pump? Ours do. The guy resets it to zero, fills your tank to full and looks at the gauge to see how many gallons it took. Walk inside and tell the cashier how many gallons you got, pay your bill and go.
As for opening the bleed screw before you take it in. There's no need to.
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Fanman
Member
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# Posted: 17 Dec 2019 05:44pm
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A portable tank with a bleed screw? I've never heard of one, most portable tanks have an "overfill prevention device".
The bleed screw is usually found on RV tanks; on those the bleed screw is opened just before filling. The tank is filled only until liquid starts coming out the bleed.
Both insure that there is some gas space above the liquid in the tank to allow for expansion after filling.
Most new tanks are vacuum purged at manufacture so there should be no air inside before filling.
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ICC
Member
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# Posted: 17 Dec 2019 06:15pm - Edited by: ICC
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a picture says a thousand words
Most new tanks I have seen come with a sticker on the valve knob that states the tank must be purged when being filled.
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Brettny
Member
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# Posted: 17 Dec 2019 06:49pm
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I have quite a few 20lb tanks (about 24) dates all the way back to the early 90s. They all have a bleeder screw.
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toyota_mdt_tech
Member
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# Posted: 17 Dec 2019 08:54pm
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I think new tanks are filled with nitrogen to prevent corrosion. Purge remove nitrogen, maybe pull it into a vacuum, that would certainly purge it, get more propane.
The new tanks, you have to have something screwed in to open the valve, just winding the hand valve open wont do it.
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beachman
Member
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# Posted: 19 Dec 2019 10:34am
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I wouldn't mess with the bleed screw if I were you. You might void some warranty or liability issue. I've used propane in winter-summer over 40 years and never messed with this screw. The whole tap is replaced every ten years so let them deal with it. I think Brettny is correct, they fill by weight or volume and propane stays a liquid under pressure until released.
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Brettny
Member
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# Posted: 19 Dec 2019 01:54pm
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It stays as a liquid until it vaporizes and turns into a gas. You can actually have a cup full of propane liquid...until it vaporizes. The colder it is the less it can vaporize.
I'm not aware of many if any 20-40lb propane tank warrentys. My propane filler will open the bleeder up almost every tank I fill and I could fill 10+ in one trip.
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ICC
Member
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# Posted: 19 Dec 2019 02:55pm
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If you open the bleed screw when the cylinder is NOT being filled two things might happen. 1- if there is propane in the cylinder you will release it. That's a waste and could be dangerous. 2- if the cylinder is empty and is colder than when it was last used air may enter the cylinder thus contaminating the inside.
There is no need to ever touch that screw unless you are filling the cylinder.
Many times the person doing the refill will tweak the bleed screw while filling to ensure that there is no air in the cylinder. They are doing a very careful and concientious refill. The dealer I use will vent every tank that weighs empty when brought in unless they know he person bringing it in like my case when I tell them it came from my hookup with the auto change over. Then they know there will not be any air that seeped into the cylinder.
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paulz
Member
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# Posted: 19 Dec 2019 05:14pm
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Just had my tanks filled, two 30 pounders and a 40. All 3 had run down to empty on my wall heater until the pilot went out. He cracked the bleed on each one while they were filling. Air came out until they were full, then propane, at which point he closed them. Took 23.2 gallons total.
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silverwaterlady
Member
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# Posted: 20 Dec 2019 11:38pm - Edited by: silverwaterlady
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No they don’t weigh it not at the place we go to. They charge you the same price no matter how much is left in the tank.
So because we are making sure they are completely empty we have air in the tanks? They are 30 pounds.
There is no other place for us to refill our tanks. I actually despise going there because they ripped us off. Even admitted the tank was half full at checkout but we had to pay the same price as a empty!
Once we widen our road we will be able to have a torpedo tank installed and be able to buy in bulk.
I live for the day I won’t have to deal with the rip off propane place.
I love being at my cabin but some of the bs in town really gets to me. That’s why I try to stay at camp and only venture out when absolutely necessary.
One more thing about that place, they never give a receipt unless you ask for one.
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toyota_mdt_tech
Member
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# Posted: 22 Dec 2019 09:13pm
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SWL, an ASME certified tank (torpedo tank) are now installed underground and filled via a small access cover in the ground. Crazy stuff and because its ASME certified, never needs testing, if its DOT, every 12 years. You are in Canada??? So things are probably different. Just had a buddy have one installed and they buried it. Crazy! Makes for cleaner look.
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ICC
Member
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# Posted: 22 Dec 2019 09:42pm - Edited by: ICC
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That is what I have. 1000 gallons. The tanks have special protective coatings and use a cathodic system to further protect the tank as there are no perfectly applied surface coatings.
ASME tanks are used in RV's too. Any tank that is permanently attached to the RV is an ASME type. They are referred to as a chassis mount tank.
 They are usually found hidden behind a panel or door used to access the shutoff and filler. ASME tanks can be mounted on a trailer and hauled to a dealer for refilling, whereas the DOT tanks like you see outside most homes and cabins, cannot be moved when they have content. If you can find an old ASME from a salvaged RV you can mount it on a trailer and pull to back and forth to the propane dealer. That can be handy if your cabin is off the beaten track and the big propane trucks won't travel to you. I have a friend who has done that. A 100 lb ASME on a Northern Tool utility trailer.
But be warned ASME tanks are not cheap.
To be technically correct the commonplace 20, 30, 40 and 100 lb. DOT approved containers are called cylinders and the ASME type are called tanks.
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