Propane level indicators - types and how they work

[howson]

mpking and Cate&Rob -- then how does the screw on gauges work? There's no float and I can't envision how it would weigh the contents. Not doubting you guys, just can't connect what I've seen with what I'm reading. I know propane is great for BBQ grills and RV heaters...after that not too knowledgeable.

[Cate&Rob]

howson
Hi Howard,

Note that this gauge has a wide green “gas” section (corresponding to the vapor pressure range based on temperature) and a narrow yellow “low gas” section corresponding to reducing pressure after all the liquid propane has vaporized inside the tank.

There is no way to measure liquid propane volume by measuring its gas vapor pressure. (Despite what the pressure gauge manufacturers claim )

This is the same way that the auto switchover device works between tanks on our RVs. Pressure remains more-or-less constant until all the liquid propane has vaporized.

If we want to go one step deeper into this, what is in the tank is LPG (liquified petroleum gas) and is a blend of predominantly propane and butane. The blend varies based on expected temperature. Butane has a lower vapor pressure and is appropriate for high temperature locations. Propane has a higher vapor pressure and is appropriate for low temperature locations. This can cause problems when you fill at a hot location (mostly butane) and travel to a cold location where propane vapor pressure is required.

Rob

[260RD2Go]

Moderators if the title does not work please change

Good morning folks, or it could be afternoon.
How does everyone know or check the level of propane in their tanks? I did a search here and came up short. The other place had some. The third place, IR**, had more, but between the battering and naysayers I could not trust half the comments . I know folks here are straight forward and honest.

I have seen sensors you mount to the bottom of the tanks and use your smart phone or by a separate monitor. I have also seen pencil looking devices you run up the tank and it light up at the fluid level (probably what I want if it is any good). I have also seen the stick on tape that goes on the side of the tank. Even learned how to use the bathroom scale - not for me

So what actually works out there, and what do I stay away from as in seeing reviews of stuff that some are junk. I'm getting to the point I cant remember what tank I am on (yes look at the hard to see change over arrow) or which is empty as I keep forgetting to tie a piece of flagging on the empty one between trips.

Thanks
Keith

Being a retired tech I love my tech toys. I went with the Mopeka system as well. I wanted to be able to check the tanks without having to access the tanks directly. At first I was concerned that a sensor might fall off of the bottom of the LP tanks but that has not happened yet.

P.S. I got the LP tank rings also, based on feedback, that the included tank clips did not work very well.

[Cate&Rob]

howson
Hi Howard,

A good summary of propane vs butane vapour pressure. https://www.engineeringtoolbox.com/p...ix-d_1043.html

From the charts & graphs, you can see that pure propane is at risk of popping open the tank pressure relief valve at temps over 100F and pure butane loses all vapor pressure below 30F. The blends tailored to expected weather are somewhere in between.

Rob

[boyscout]

Note that this gauge has a wide green “gas” section (corresponding to the vapor pressure range based on temperature) and a narrow yellow “low gas” section corresponding to reducing pressure after all the liquid propane has vaporized inside the tank. There is no way to measure liquid propane volume by measuring its gas vapor pressure. (Despite what the pressure gauge manufacturers claim )

Rob, I *think* you're confirming what I've observed about these screw-on dial gauges.

The expensive ones I own now, like the less-expensive ones I used to own, have a large green area on the dial. However my experience is that one cannot judge how much propane remains in the tank by the needle's position within the green area on the dial. The needle can move down in the green area, and later be back up again, without any propane being used.

It sounds as though you're confirming that these gauges aren't so much gauges as they are stop lights. When the needle is anywhere in the green you have at least some liquid propane in your tank (but can't know how much by the needle position). When the needle is in the yellow you're running on fumes and will soon be out. When the needle is in the red the tank is empty.

Is that a fair characterization of what you're saying?

Since it's often useful to know how much propane is in the tank I use the Mopeka sensors and bought the screw-on gauges solely for their fast leak-stop feature.

[Cate&Rob]

When the needle is anywhere in the green you have at least some liquid propane in your tank (but can't know how much by the needle position). When the needle is in the yellow you're running on fumes and will soon be out. When the needle is in the red the tank is empty.

Hi Mark,

That is a correct summary of all that those gauges can tell you. Vapour pressure cannot indicate volume of liquid in the tank . . . just that there is at least some.

Rob

[d2reid]

Another naysayer here... I have Mopeka, sometimes it works sometimes it doesn't. User error for sure.

I've tried gauges, meh!!!

I tried the strip on the side, meh!!!

But what works time after time for me is the little red/green gauge on the regulator when a tank runs out. Tank runs out, gauge turns red, auto flips to the next tank. Get empty tank filled, flip lever on top, gauge turns green until the other tank runs out.

Over time you get to know about how much propane you use in any given situation. I have three tanks because I winter at ski resorts. I need fills about twice a week during single digit temps, about once a month in summer. I just check the gauge as needed, fill, done.

[Canyonlight]

But what works time after time for me is the little red/green gauge on the regulator when a tank runs out. Tank runs out, gauge turns red, auto flips to the next tank. Get empty tank filled, flip lever on top, gauge turns green until the other tank runs out.

X2 Dalls ! Checking and staying on top of propane usage is pretty darn simple. Guess we are getting old not needing an app or some device for even simple things ! By the way, I need an app to tell me when I am using too many apps for things that I do not need an app for.

Dan

[ncitro]

For what it’s worth my Mopeka used to be a bit flaky, but when I hardwired them to a power supply connected to the RV batteries they got a lot happier. Also a good gob off ultrasound gel between the transmitter and the tanks improved them quite a bit. I run my generator on propane only so when I’m using it a lot we go through a lot of it.

[Schiefswret]

Keith,

I use the device linked below and I know several other owners that use them also. The device has proven to be very accurate for me. But a couple of lessons learned.

They are inaccurate moments after filling. I guess that the tank contents have to settle first.
You must place on hand on the tank while using the device in the other hand. The instuctions state to do this, but many folks don't read the instructions and become frustrated.

It has some really bad reviews on Amazon, but I believe Cate&Rob and Paul & Deb are also using them with good success.


https://smile.amazon.com/product-rev...ews-filter-bar

Jim

hmmm... 42% of reviews are 3 stars and below, not a great indicator in my book. I use the hand-held scale (think hand held fish weighing) it’s a bit of a BITB but it is an accurate and inexpensive method. Search Amazon for “Grill gauge propane tank scale”

[Cate&Rob]

hmmm... 42% of reviews are 3 stars and below, not a great indicator in my book. I use the hand-held scale (think hand held fish weighing) it’s a bit of a BITB but it is an accurate and inexpensive method. Search Amazon for “Grill gauge propane tank scale”

Hi Dave,

I suspect that most of those having problems with this gauge are not placing their other hand directly on the tank when using the device. This makes a big difference to the stability of the sensor signal. TucsonJim had to prove this to me (at a Rally) . . . but, he was right, LOL! The other cause of inaccurate sensing is a weak battery in the device . . . easy to replace.

Just to reiterate the earlier discussion on this thread, WRT the comment in post 25 . . .the Dozyant "gauge" can NOT measure the volume of liquid propane in the tank.

Rob

[Schiefswret]

Hi Dave,

I suspect that most of those having problems with this gauge are not placing their other hand directly on the tank when using the device. This makes a big difference to the stability of the sensor signal. TucsonJim had to prove this to me (at a Rally) . . . but, he was right, LOL! The other cause of inaccurate sensing is a weak battery in the device . . . easy to replace.

Just to reiterate the earlier discussion on this thread, WRT the comment in post 25 . . .the Dozyant "gauge" can NOT measure the volume of liquid propane in the tank.

Rob

Gotcha👍🏻, for my purposes, as long as I know the ‘about’ level, I’m ok with that. When my pass side tank gets to about 1/4, by whatever method of measure, I’m ok with getting it refilled at that time. Worse case, it will shift over to the drivers side tank. I check them often enough to know pretty much where I stand. Been using this not-so-scientific method for about two years now with success. I appreciate (as usual) your input and many highly valuable tips.

[Schiefswret]

mpking and Cate&Rob -- then how does the screw on gauges work? There's no float and I can't envision how it would weigh the contents. Not doubting you guys, just can't connect what I've seen with what I'm reading. I know propane is great for BBQ grills and RV heaters...after that not too knowledgeable.

I’ve tried this type twice without success. May work well for others.

[Johnww]

We used the Mopeka products and they crapped out after 1 1/2 years of use. Had problems with the magnets coming off, battery life lasted about one year. When they worked they were great but I'm not sure if I will replace them

[howson]

We used the Mopeka products and they crapped out after 1 1/2 years of use. Had problems with the magnets coming off, battery life lasted about one year. When they worked they were great but I'm not sure if I will replace them

I had the same experience. They were great when they worked...but then they didn't. I now have Flame King bottles (with built-in gauge). So far, no issues.

Drawback, obviously, is not being able to swap bottles at a Blue Rhino (or equivalent bottle swap retailer). I must find a bottle refiller, but I haven't had an issue so far.
Howard

P.S. Yes, I use 20lb instead of the 30lb size that came with the trailer. I don't use much propane and it was an easy way to save some weight on the tongue.