Propane tank fill questions

[Llittle54]

Originally Posted by mikeinca

I've looked at that in the past. Some folks were very happy with it but some not insignificant percentage of people had issues with various aspects of the system so I passed. Have you had personal experience with it?

I won’t buy Moepka again. I’ve replaced them a few times when they unexpectedly quit working. They also scream through the batteries.
Last time one died after what I consider little use, I contacted Moepka. Had a few back and forth emails. The last one, I was informed they would get back to me. That was about 2 years ago, no response despite my follow ups.
When they work they are great just don’t expect any customer service if you have problems.

[Gulliver72]

Get a pair of Mopeka propane sensors which mount beneath your tanks, look at your phone, and you will know the exact amount remaining any time you wish. It will also notify you with a gentle alarm when a tank is approaching empty.

[lemley]

If you keep your Airstream at home, I recommend keeping the cylinders full in the winter. I’m quite thankful mine were full during the February freeze when we were without power and water for close to 3 days with temps never getting above freezing. The Airstream was our only place for a hot meal and a warm shower.

Texan

[Ultraclassic]

Originally Posted by mikeinca

So I know that the twin 30lb tanks on my 2020 Globetrotter will theoretically hold around 7 gallons of propane. But when you take them to a propane seller, how much propane do they actually fill the tanks with? Isn't there an 80% fill requirement which allows for expansion of the propane in hot weather? Also, how much does an Airstream 30lb steel tank weigh empty? I've found different numbers for different manufacturers and I don't know who makes the tanks that Airstream supplies with their trailer. Has anyone actually weighed one?

The reason for all this is that, absent an accurate gauge to measure the propane remaining in a tank, if I knew the weight of an empty tank, how much propane it actually contained when "full", and knowing the weight of propane is 4.24lbs/gallon I could figure out how much propane was in a tank at any given time by weighing it.

I think the tare weight (empty) is stamped on the tank?

30lb steel empty 24-28

My Aluminum 30lb are 17.4 lbs tare weight

[uncle_bob]

Originally Posted by jeffmc306

Thanks David. I’m not sure why both tanks were low because I would open them one at a time and watch to make sure the regulator arrow was pointing to the same tank each time, not in the middle. Not wanting to take a chance at running both empty (and not knowing so), my work-around was to keep one in reserve. Might have to invest in the Mopeka someday.

This last trip I did open both valves if we left the trailer and checked to see if the arrow had switched when we returned (it hadn’t). Now that we’re home I’ll pull both and weigh them to verify.

I appreciate the explanation though!
-Jeff

Hi

Simple answer: don't trust the magic switch over gizmo. Use the valve on the top of the tank.

Bob

[mikeinca]

Originally Posted by Ultraclassic

I think the tare weight (empty) is stamped on the tank?

30lb steel empty 24-28

Yeah, thanks, I subsequently found the stamping: TW = 23.2

[fander]

Another reason not to fill to 100% is you would have liquid propane coming out of your gas line. All 20 pounders have a float now that keeps the bottle from overfilling. Also many places such as convenience stores that exchange cylinders don't fill them to 80%. They are usually short around a gallon.

[Mollysdad]

another vote for the lo-tech hot water measure.
The water doesn't have to be boiling, just tap water hot.
Pour a cup over the tank and slide your hand down the tank. You'll be amazed how accurate the line is. I'd bet you get within an inch.
The liquid absorbs the heat faster than the empty top section so there is a line you can easily feel.

[robertwarren]

I have been very satisfied with the Mopeka Propane Tank Sensors sold on Amazon. Very accurate and dependable. Data is sent directly to my iPhone. Be sure to use the rubber tank spacers, sold separately on Amazon. Safe travels!

[SouthForkAS]

"I've never seen a scale used to measure the amount of propane sold here in California"
2 things surprised me recently:
They're filling propane with scales (along with gallon meter) in San Berdoo (on and off the mountain) and U Haul is currently the cheapest (Alabama Street)

[Native143]

I keep one tank open and one closed. When one runs out I switch over, obviously. Then take empty to a Tractor Supply, Camping World or someone who charges by the gallon. And even if I feel I just to top off still go there. Why pay for a full tank when you only need a few gallons?

[ewhitney45]

I have tried to use mopeka, found it to be very unreliable. Technically it can work after you jump thru hoops to sync up the blue tooth. Battery life is poor and batteries are difficult to change. plus the monitor is placed on the bottom of the tank held there by magnet in the sensor. Must use standoffs on the bottom of the tank. They too are unreliable. all in all difficult to set up, and maintain. My approach is to start with 2 full tanks, run one till empty, switch over to full tank, and than refill empty, start process all over. Works for me.

[jcanavera]

Also if any of you use 20 lb tanks and you do tank exchanges at the local grocery or big box hardware store be aware those tanks do not contain 20 lbs of propane. In most cases those tanks are only filled with 15 lbs of propane. That's the price you pay for the convenience of not having to refill your tank or having to have it recertified after it reaches its certification date stamped on the tank.

Jack

[DAllerton]

On the collar of your cylinder you should be able to find, among other things, two figures. These figures are given in pounds although some tanks and cylinders also have the metric equivalent given as well. The first is TW or Tare Weight. This is the weight of the cylinder when it is empty. For a 30# steel cylinder it should be around 23 or so pounds I think depending on the manufacturer; obviously, aluminum will be lighter. The second figure is WC or Water Capacity. This is the weight (in pounds) of the amount of water the cylinder is capable of holding. If you multiply the Water Capacity by .42 it will give you the propane capacity in pounds when filled to the appropriate 80%, which in fact does allow for outage. By using this formula a 30 pound cylinder for example should weigh between approximately 23 pounds and 53 pounds depending on how much propane is in it. In this manner you can determine how much propane is actually in a cylinder. You can then in fact convert this figure to gallons by dividing it by 4.24, which is the weight in pounds of 1 gallon of propane. Consequently, each gallon of propane will provide approximately 91,500 BTUs per hour for whatever intended purposes.

[JCWDCW]

Pour hot water over the side of the tank and run your hand down the side till you feel the cold interface of the propane liquid. It doesn’t always sweat a condensation line
JCW

[Peterf]

Hi. I know that our tanks weigh 23.2 lbs, add 30 lbs of propane and a full tank will weigh about 53 lbs. if I’m concerned, I will weigh the tanks and know that if one weighs say about 38 lbs it is about half full.

[Boston Gary]

Buy a two tank Mopeka. It reliably tells me if each tanks is 100%, 75, 50, 25, or near empty.

[Boston Gary]

Originally Posted by ewhitney45

I have tried to use mopeka, found it to be very unreliable. Technically it can work after you jump thru hoops to sync up the blue tooth. Battery life is poor and batteries are difficult to change. plus the monitor is placed on the bottom of the tank held there by magnet in the sensor. Must use standoffs on the bottom of the tank. They too are unreliable. all in all difficult to set up, and maintain. My approach is to start with 2 full tanks, run one till empty, switch over to full tank, and than refill empty, start process all over. Works for me.

I’ve had the two tank Mopeka for about 1.5 years. Other than both sensors were the same ‘color’, mine has worked reliably. I change the batteries the same day I change the batteries in smoke detector and LevelMatePRO pro

[ChuckieB]

Empty 30 lb tank weighs 25-28 lbs. full tank is 55 lbs.

[Ultraclassic]

Originally Posted by mikeinca

So I know that the twin 30lb tanks on my 2020 Globetrotter will theoretically hold around 7 gallons of propane. But when you take them to a propane seller, how much propane do they actually fill the tanks with? Isn't there an 80% fill requirement which allows for expansion of the propane in hot weather? Also, how much does an Airstream 30lb steel tank weigh empty? I've found different numbers for different manufacturers and I don't know who makes the tanks that Airstream supplies with their trailer. Has anyone actually weighed one?

The reason for all this is that, absent an accurate gauge to measure the propane remaining in a tank, if I knew the weight of an empty tank, how much propane it actually contained when "full", and knowing the weight of propane is 4.24lbs/gallon I could figure out how much propane was in a tank at any given time by weighing it.

It should be stamped on the tank, but I think it is 24-26 lbs dry.
My 30lb aluminum tanks are 17.6lbs dry and 5 always freakout a Newby at the filling station because they fill and clunk the nozzle before there circa 1903 weight scale changes to indicate it's full.