PSI Gauges for Propane Level ?

[SV Demeter]

Im just about finished converting my boat to propane from CNG and one of the things Im wondering about is if any of the gauges available that measure pressure are good at indicating how much fuel is left in the tank? Right now my system has one of these at the regulator:





But I have seen these:



I know when the tanks are filled it is typically done with a scale and is based on weight. Im just wondering if pressure measurements can give decent indications? If so can anyone advise on the PSI using a 20lb tank for full, 1/2, 1/4?

Thanks,

[captain58sailin]

I believe that pressure would be static with regards to the level in the tank until it was almost completely empty. The pressure would increase with the tempurature and go down with it getting colder, I am not sure how you would use pressure to determine level. I always pick the tank up and if it feels heavy, I have enough, if it feels light, I get some more, if I am not sure, I get some more.

[delmarrey]

Propane use to be measured by weight. Now were getting it by cu ft. from a pump that maybe bypassing.

But no, you can not go by pressure. The pressure could be regulated by temperature. When the pressure starts to drop fast your out of gas.

BTW there are some stickers one can put on the side of the tank. They measure the level when it being used, by temperature.

[Vasco]

Get a fiberglass tank, you can see the propane level. The gauges are useless for determining propane remaining.

[SV Demeter]

Thanks all. Pretty much what I was thinking that it had to be measured based on weight. Thats how my gas grill at home works. So it sounds like this thing is pretty much not worth wasting my money on? I like the idea of the fiberglass tank and will get one when the steel one I have now rusts out but for now Im going to use what I have, got too many other things left to buy.

[perchance]

Propane is a liquid under pressure so the guage won't tell you the remaining volume. most tanks used in commercial applications have some type of float guage to measure propane level but you already knew that. The tanks used to supply forklifts have them and would probably work on a boat if you could adapt the tank fitting.

[SV Demeter]

Originally Posted by delmarrey

Propane use to be measured by weight. Now were getting it by cu ft. from a pump that maybe bypassing.

But no, you can not go by pressure. The pressure could be regulated by temperature. When the pressure starts to drop fast your out of gas.

BTW there are some stickers one can put on the side of the tank. They measure the level when it being used, by temperature.

like this?

[colemj]

A gauge can be useful for indicating leaks in the system, but not so useful for amount of propane remaining. I always do a pressure leak check after changing tanks or reconnecting the stove.

Mark

[SV Demeter]

Originally Posted by colemj

A gauge can be useful for indicating leaks in the system, but not so useful for amount of propane remaining. I always do a pressure leak check after changing tanks or reconnecting the stove.

Mark

Most definitely Mark. Im just trying to figure out if any of these products on the market are worth buying. From what im reading here it sounds like best bet would be to get a fiberglass tank or in the mean time get used to picking up the cylinder from time to time and estimating weight. I know what a full one feels like. It doesnt sound like anyone is advocating that level gauge I posted earlier as being very useful.

[Vasco]

Originally Posted by SV Demeter

Most definitely Mark. Im just trying to figure out if any of these products on the market are worth buying. From what im reading here it sounds like best bet would be to get a fiberglass tank or in the mean time get used to picking up the cylinder from time to time and estimating weight. I know what a full one feels like. It doesnt sound like anyone is advocating that level gauge I posted earlier as being very useful.

If you're cruising you should definitely have 2 tanks. We have 2 ten pounders plus a little butane burner for emergencies or warming up stuff at parties on the beach.

[btrayfors]

I agree that weight or fiberglass tank are the only way to know how much propane is in the tank. But, it's sometimes VERY inconvenient to weigh the tank. In my case, I have a horizontal tank which is bolted down...4 bolts. A real pain to loosen them to check propane level.

Learned a little trick a few years ago, though. You can buy at West Marine a little brass adapter which will adapt your propane line to fit the small propane tanks which are used for camping or soldering or whatever. They are very inexpensive and available everywhere.

I built a little mount for two of them near my main propane tank. If it runs out, I just have to connect one of the little tanks using the brass adapter. The little tanks will provide enough propane to get me thru a few days (or even weeks, depending) until I can get the main tank refilled.

Bill

[bobofthenorth]

Poor man's gauge - pour a little boiling water down the side of the tank and you'll be able to see the level. None of the other methods suggested here work as well as this one.

[Bash]

Originally Posted by SV Demeter

Im just wondering if pressure measurements can give decent indications? If so can anyone advise on the PSI using a 20lb tank for full, 1/2, 1/4?

I have the same type of trident gauge you currently have. It will show around 100 psi when full, but for most of the life of the tank it sits around 90. If I see it dip to around 70, I know the tank only has another hour of propane left. When it drops below that, it's pretty much done.

[SV Demeter]

Originally Posted by btrayfors

I agree that weight or fiberglass tank are the only way to know how much propane is in the tank. But, it's sometimes VERY inconvenient to weigh the tank. In my case, I have a horizontal tank which is bolted down...4 bolts. A real pain to loosen them to check propane level.

Learned a little trick a few years ago, though. You can buy at West Marine a little brass adapter which will adapt your propane line to fit the small propane tanks which are used for camping or soldering or whatever. They are very inexpensive and available everywhere.

I built a little mount for two of them near my main propane tank. If it runs out, I just have to connect one of the little tanks using the brass adapter. The little tanks will provide enough propane to get me thru a few days (or even weeks, depending) until I can get the main tank refilled.

Bill

Im familiar Bill with this device and might get one. Im hoping to set up the grill we have with its own 6lb tank as it currently uses the canisters you are referring to. From what I hear those cans get expensive in the islands and they generate a lot of trash if you are gilling a lot which we like to do. My thought was to set up the grill with its own tank and that could also serve as a backup for the galley stove tank. I like the idea of carrying one or two of the small cylinders though for taking the grill to the beach and emergency back up.