Last week the propane tank on my 1999 340 went empty for the first time. Until this year, my only experience with propane was with small, disposable tanks. I had no idea what to do about getting a full tank. A while ago someone told me I could buy a new tank at Kmart. So off I went to my local Kmart. Once there, I was told that it was no longer "propane season" (gas grill season) and that the tanks were no longer in stock. Thus began a wild goose chase to the local NJ strip malls to find the illusive tank. Home Depot had tanks, but they were much bigger than the one Hunter provided. The people at Home Depot did say that my tank could be REFILLED and that a local gas station could do it. (I had thought that tanks were like batteries ... you traded in the old one for a new one.) After much searching, I found the gas station, and the attendant refilled my tank. He determined it was "full" by weighing it. But he had never seen a tank this size before and basically guessed at the proper charge. I put the tank in the truck of my car and drove home. The next evening I went off to install the new tank in my boat. When I hooked up the hose to the tank and opened the valve on the top of the tank, my system pressure gauge read 150 psi. An hour later the pressure had dropped to 145 psi. It kept dropping through the night. By morning it was down to 120 psi. During this time, I kept the tank value closed, except for short intervals when I checked the pressure using the system gauge. Thus I concluded that the tank had a huge leak. The smell of propane in the locker and in the trunk of my car reinforced this conclusion. That afternoon, I took the tank home and immersed it in my water-filled kitchen sink looking for the telltale bubbles that would indicate a leak. But I didn't see any. Therefore I concluded that the leak was so bad that by now the tank was empty. The next day, I brought my sick tank to my Hunter dealer, Sandy Hook Yacht sales. Ed Mahon listened to my story and swabbed the tank with soapy water looking for leak-induced bubbles. Of course there were none. I told Ed I knew there was a leak because I saw the pressure drop down from 150 psi. When I told him this extra info, he explained all --- the tank has a safety valve to keep pressure below 100 psi. That valve was working. As a test, we connected my tank to the propane system of one of their stock boats. The gauge read 100 psi, just as it should. This episode made me feel very stupid. Perhaps there is some documentation that came with the boat that explains about refilling propane tanks, but I don't recall seeing it. When I looked through the binder that Hunter provided, I saw no info on this matter. It's possible that when I checked out the boat at commissioning time, this stuff was explained to me, but I don't remember. If I had gas grill experience, I probably would not have made this mistake. The scary thought is that the trunk of my car was probably filled with propane. I am lucky there was no sparks. Certainly the guy at the gas station who filled the tank was uninformed. I hope this note spares someone else from this experience. The more general scary thought about boats is how much owners need to know to keep their boats in good shape and safe. Unlike cars or houses, we have to rely much more on ourselves to fix things when they go wrong. Despite reading books, magazines, and sites like this, there are always gaps in our knowledge that can lead to unpleasant results.
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Dakota Jim Russell
Gas Dealer Negligent
This is one time that the owner of the tank should not have to know the proper amount of gas to put in the tank. The tank is filled to a specific weight. The dealer should clearly know what that weight is. In fact I found the weight spec stamped on the handle of the two tanks that I own for my 340. This is not much different than the filling of a propane tank for a propane char-grill, though the weight would be different. What should be learned is not to go to this propane dealer again as he will probably kill someone with his ignorance. You probably would do the community a favor by getting him some help via local authorities.
This is one time that the owner of the tank should not have to know the proper amount of gas to put in the tank. The tank is filled to a specific weight. The dealer should clearly know what that weight is. In fact I found the weight spec stamped on the handle of the two tanks that I own for my 340. This is not much different than the filling of a propane tank for a propane char-grill, though the weight would be different. What should be learned is not to go to this propane dealer again as he will probably kill someone with his ignorance. You probably would do the community a favor by getting him some help via local authorities.
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Rick webb
Proper Propane Proprietor
Check the yellow pages and go to a real propane dealer not a gas station that does it as an aside. As much as you seem to use you may want to get an adapter and use the disposable containers. That is probably a good thing to have anyway as the disposable cans are very readily available.
Check the yellow pages and go to a real propane dealer not a gas station that does it as an aside. As much as you seem to use you may want to get an adapter and use the disposable containers. That is probably a good thing to have anyway as the disposable cans are very readily available.
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George Lamb
Thanks Larry!
You may have felt dumb, but it was great of you to make this post. I had never really thought about the PSI when filling my propane tanks, but then again I have never had a problem with them. With a topic as potentially dangerous as propane tanks, I do not think that any of us can have too much information. This kind of post is what makes this web site so valuable.
You may have felt dumb, but it was great of you to make this post. I had never really thought about the PSI when filling my propane tanks, but then again I have never had a problem with them. With a topic as potentially dangerous as propane tanks, I do not think that any of us can have too much information. This kind of post is what makes this web site so valuable.
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Mark Johnson
10lb tanks
The tanks on my boat are 10lbs. They are also aluminum!, not steel like barbque tanks. Jim is right that the weight of the tank is stamped right on it. Your 10lb aluminum tank will weigh much less than the same size tank in steel. Any propane filling station that's worth anything should know to look for the tank weight before refilling. The pressure release valve is there for safety reasons. When the tank gets hot in the summer it releases gas so the tank does not explode! That's also the reason the propane tanks have their own separate lockers that vent overboard. Mark Johnson
The tanks on my boat are 10lbs. They are also aluminum!, not steel like barbque tanks. Jim is right that the weight of the tank is stamped right on it. Your 10lb aluminum tank will weigh much less than the same size tank in steel. Any propane filling station that's worth anything should know to look for the tank weight before refilling. The pressure release valve is there for safety reasons. When the tank gets hot in the summer it releases gas so the tank does not explode! That's also the reason the propane tanks have their own separate lockers that vent overboard. Mark Johnson
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Bob Miller
Propane!!!!!!!!!!
Please everybody ignore everything you have read on this posting. I have never seen so much mis-information. The propane level of the tank is NOT measured by pressure - it is measured by weight. But when filling the tank you do not determine that it is full by weighing it - you know it is full when the overspill valve starts to spit liquid. The pressure is determined by the outside air temperature. It is normal for the pressure to read as low as 80 psi on cold days and 170 psi on hot days (nothing to do with the amount of propane in the tank). The pressure relief valve should not be set at 100 degrees farenheit or it will release propane on a normal summer day (I think the previous writer was talking about 100 degrees celsius). The best advise in the previous articles is to go a propane dealer - not a gas station or discount supermarket.
Please everybody ignore everything you have read on this posting. I have never seen so much mis-information. The propane level of the tank is NOT measured by pressure - it is measured by weight. But when filling the tank you do not determine that it is full by weighing it - you know it is full when the overspill valve starts to spit liquid. The pressure is determined by the outside air temperature. It is normal for the pressure to read as low as 80 psi on cold days and 170 psi on hot days (nothing to do with the amount of propane in the tank). The pressure relief valve should not be set at 100 degrees farenheit or it will release propane on a normal summer day (I think the previous writer was talking about 100 degrees celsius). The best advise in the previous articles is to go a propane dealer - not a gas station or discount supermarket.
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Bob Miller
Furture Clarification!!!!!!!!!!!
According to my local propane dealer, the pressure relief valves are set at about 300 to 325 psi. The tanks are filled until liquid spits out the over flow valve like I said, but there is a tube inside the tank behind the over flow valve that detects when the tank is 80% full of liquid. When the tank is 80% full (maximum recommended) it will read about 100 psi on a normal day. But if the tank is a little over full, or it is a very hot day, the pressure can go up to 170 psi. A tank almost empty, or on a very cold day can read about 80 psi. Hope this helps.
According to my local propane dealer, the pressure relief valves are set at about 300 to 325 psi. The tanks are filled until liquid spits out the over flow valve like I said, but there is a tube inside the tank behind the over flow valve that detects when the tank is 80% full of liquid. When the tank is 80% full (maximum recommended) it will read about 100 psi on a normal day. But if the tank is a little over full, or it is a very hot day, the pressure can go up to 170 psi. A tank almost empty, or on a very cold day can read about 80 psi. Hope this helps.
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Ex 23 owner
Pressure doesn't vary with amount of liquid
For a given temperature, all liquids have a gas pressure at which they reach stasis between the liquid and gaseous state. At this pressure -- called a partial pressure because it does not depend on the pressure of the other gases -- evaporation and condensation are equal. It does NOT depend on the amount of liquid in the container, assuming that there is enough to generate the partial pressure. In other words, the pressure of propane gas in the tank will be the same, whether the container is "full" or one-eighth full. This pressure depends on the tanks temperature. The story changes if the tank is so full of liquid that there is no space for gas, or if the tank runs dry of liquid. It is also complicated a bit by the fact that there are some gases other than propane (air) contaminating the tank, and these will NOT condense.
For a given temperature, all liquids have a gas pressure at which they reach stasis between the liquid and gaseous state. At this pressure -- called a partial pressure because it does not depend on the pressure of the other gases -- evaporation and condensation are equal. It does NOT depend on the amount of liquid in the container, assuming that there is enough to generate the partial pressure. In other words, the pressure of propane gas in the tank will be the same, whether the container is "full" or one-eighth full. This pressure depends on the tanks temperature. The story changes if the tank is so full of liquid that there is no space for gas, or if the tank runs dry of liquid. It is also complicated a bit by the fact that there are some gases other than propane (air) contaminating the tank, and these will NOT condense.
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Dakota Jim Russell
Thanks for the Education, but one question . . .
Guess I learned a few things. However, I've observed the guy filling my tank watching the weight scale on which it is setting to determine how much to put in. I've never seen him fill the tank until the liquid was spilling out. I note that the pressure in my Aluminum 340 tank has not exceeded 150 #. This is in sharp contrast to a large propane tank (for heating a house, etc.)which is not weighed when it is filled. So why does he watch the scale with my small tank? And why is 10.5 lbs. stamped on the tank handle? Curious . . .
Guess I learned a few things. However, I've observed the guy filling my tank watching the weight scale on which it is setting to determine how much to put in. I've never seen him fill the tank until the liquid was spilling out. I note that the pressure in my Aluminum 340 tank has not exceeded 150 #. This is in sharp contrast to a large propane tank (for heating a house, etc.)which is not weighed when it is filled. So why does he watch the scale with my small tank? And why is 10.5 lbs. stamped on the tank handle? Curious . . .
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Larry Jackel
A glimmering of knowledge
Now I understand what must have been going on in my tank (Mostly thanks to Bob Miller). I got in trouble because I had the wrong mental model for the propane behavior. I thought it was just an "ideal gas" under pressure. WRONG! As Bob pointed out, in the typical pressures of a propane tank, the propane separates into a liquid and a gaseous phase. Doing some searching on the web, I found that the partial pressure above liquid propane is 127 psi at 70 degrees F, and 172 psi at 100 degrees F. (The vapor pressure is probably close to an exponential of temperature, but I don't know that as a fact.) Right now it's about 60F in NJ, which should extrapolate to about 100 psi. So what went on in my tank the other night? The tank had been sitting in the trunk of my car all day long in the sun. Let's say the temperature got to 100F. So the tank pressure should have been ~170 psi. By the time I got it to my boat in the evening it must have cooled to around 90F for a pressure of about 150psi. I observed the pressure drop during the coarse of the evening because the air temperature was dropping, cooling the tank. When I got the tank to Sandy Hook Yacht Sales the temperature of the propane must have been around 60F which would give me a measured pressure of about 100 psi. I went sailing late this afternoon. It was a beautiful day in NJ with temperature of around 70F. Guess what? The tank pressure had gone up to about 110 psi. Conclusions: 1) I never had a leak. The "propane smell" in my trunk must have been the remnants of the odorant that is added to the propane so that you can smell it. The smell probably got in my truck when I put the just-filled tank in my car. 2) The safety valve must be set to a pressure of 200 psi or higher. Otherwise the propane will be discharged on a typical summer day.
Now I understand what must have been going on in my tank (Mostly thanks to Bob Miller). I got in trouble because I had the wrong mental model for the propane behavior. I thought it was just an "ideal gas" under pressure. WRONG! As Bob pointed out, in the typical pressures of a propane tank, the propane separates into a liquid and a gaseous phase. Doing some searching on the web, I found that the partial pressure above liquid propane is 127 psi at 70 degrees F, and 172 psi at 100 degrees F. (The vapor pressure is probably close to an exponential of temperature, but I don't know that as a fact.) Right now it's about 60F in NJ, which should extrapolate to about 100 psi. So what went on in my tank the other night? The tank had been sitting in the trunk of my car all day long in the sun. Let's say the temperature got to 100F. So the tank pressure should have been ~170 psi. By the time I got it to my boat in the evening it must have cooled to around 90F for a pressure of about 150psi. I observed the pressure drop during the coarse of the evening because the air temperature was dropping, cooling the tank. When I got the tank to Sandy Hook Yacht Sales the temperature of the propane must have been around 60F which would give me a measured pressure of about 100 psi. I went sailing late this afternoon. It was a beautiful day in NJ with temperature of around 70F. Guess what? The tank pressure had gone up to about 110 psi. Conclusions: 1) I never had a leak. The "propane smell" in my trunk must have been the remnants of the odorant that is added to the propane so that you can smell it. The smell probably got in my truck when I put the just-filled tank in my car. 2) The safety valve must be set to a pressure of 200 psi or higher. Otherwise the propane will be discharged on a typical summer day.
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Mike Alge
propane tanks
The man filling your tank is filling by weight . The 10.5 lbs is the weight of the tank . That weight is put on the scale first and it is called the tare wgt. If that wgt. is on a 20lb bottle, then he will fill the bottle till it reads 20lbs. The total wgt will then be 30.5 lbs . Also you should know that 20lbs. of propane is about 5 gallons. Most home heating tanks have a meter on them to show how much has been used so they are filled by the gallon
The man filling your tank is filling by weight . The 10.5 lbs is the weight of the tank . That weight is put on the scale first and it is called the tare wgt. If that wgt. is on a 20lb bottle, then he will fill the bottle till it reads 20lbs. The total wgt will then be 30.5 lbs . Also you should know that 20lbs. of propane is about 5 gallons. Most home heating tanks have a meter on them to show how much has been used so they are filled by the gallon
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Richard Owen
Fill by weight or ???
A propane tank can be filled 2 ways - by weight as mentioned, and by observing liquid vaporizing when it leaves a"spit valve". On these small tanks, the weight method is usually used since it is easy to do. The weight indicated is the weight of the tank plus an 80% fill - so you get the same thing either way.
A propane tank can be filled 2 ways - by weight as mentioned, and by observing liquid vaporizing when it leaves a"spit valve". On these small tanks, the weight method is usually used since it is easy to do. The weight indicated is the weight of the tank plus an 80% fill - so you get the same thing either way.
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