LP Tank 3/4 Limit?

[Zapnod]

I have a Thor Omni and the LP tank will not show filled over 3/4 of a tank. So the LP tank never shows 100% full even when it is filled all the way. I had Camperworld look at it and they told me it is a state law (UT, even though I purchased it in NV) that the LP tank can not be filled over 3/4 of a tank for safety. Has anyone heard of this or is this BS?

[lwmcguir]

Originally Posted by Zapnod

I have a Thor Omni and the LP tank will not show filled over 3/4 of a tank. So the LP tank never shows 100% full even when it is filled all the way. I had Camperworld look at it and they told me it is a state law (UT, even though I purchased it in NV) that the LP tank can not be filled over 3/4 of a tank for safety. Has anyone heard of this or is this BS?

80% is max on most ASME tanks

[Travelin' Texans]

80% in all LP tanks is the law.

[taylorbob1]

I really miss the removable two - 5 gal (4 gal each filled) set-up I had on a previous travel trailer.
I believe that there still are Class A & C rigs out there with the two tank feature.

It had the auto switch-over so when the one emptied, the second one became active.
Then I could remove the empty one and get it filled at a local business without driving my entire rig.

The single tank I now have holds 8 gals when filled to 80%, but is a challenge to monitor actual remaining propane once it gets below half.

[JimOIB]

This a good article about RV propane tanks.

https://rvlifestyle.com/innards-rv-propane-tank/

[16ACE27]

Originally Posted by lwmcguir

80% is max on most ASME tanks

Originally Posted by Travelin' Texans

80% in all LP tanks is the law.

Originally Posted by EA37TS

Camping World is correct. 80 percent is the maximum fill for LPG nationwide.

But the tank indicator inside the MH should indicated FULL at 80%.

[Beau388]

Originally Posted by 16ACE27

But the tank indicator inside the MH should indicated FULL at 80%.

In a Manchester ASME RV tank (not a DOT bottle), the gauge on the tank is adjustable. The outside gauge is magnetically coupled the inside the tank float mechanism. The coach's inside gauge is just a repeater of the tank's gauge.

[Bob Nodine]

Originally Posted by Zapnod

I have a Thor Omni and the LP tank will not show filled over 3/4 of a tank. So the LP tank never shows 100% full even when it is filled all the way. I had Camperworld look at it and they told me it is a state law (UT, even though I purchased it in NV) that the LP tank can not be filled over 3/4 of a tank for safety. Has anyone heard of this or is this BS?

Not sure which tank you have but a 12 gallon horizontal propane tank will not hold more than 9.6 gallons before the OPV (overflow protection valve) will shut off the propane. Usually they don't even get to 9.6 gallons because the OPV is not set at exactly 80%. Theoretically you should be able to fill until the bleed valve emits propane but on the tank we have the OPV valve shuts off the propane before the liquid gets to the bleed valve. Turns out we can only get 8.2 gallons of propane in our tank before the OPV shuts down the fill.

The sight gauge on the tank can be very inaccurate and the indicator inside the RV is controlled by a variable resistor attached to that sight gauge. These devices are almost as bad as the old idiot oil pressure lights on automobiles. We came from a diesel pusher with a 39 gallon propane tank and were surprised at how fast we used up our small quantity of onboard propane with the furnace, water heater, etc. When we suddenly were without heat in 22 degree weather last winter because of low propane I decided to improve on the tank level indicator.

I installed the Mopeka tank level sensor that is connected to an app on my phone by Bluetooth. With this app you can fill your tank to the maximum it will hold and then set the visual display to indicate full. As the propane is used the pseudo tank will deplete and give you a percentage of how much propane you have left. I usually try to fill up at 50%. This method of sensing the propane level is more accurate and consistent than the float/resistive method. I attached both sensors, one at each end of the horizontal tank. As you can see from the screenshot one of the batteries is low and the sensor stop transmitting about a week ago. We are now at the tail end of a seven week trip and I will replace the battery when we get home.

https://tinyurl.com/2f9bhduf

[Judge]

Originally Posted by Zapnod

I have a Thor Omni and the LP tank will not show filled over 3/4 of a tank. So the LP tank never shows 100% full even when it is filled all the way. I had Camperworld look at it and they told me it is a state law (UT, even though I purchased it in NV) that the LP tank can not be filled over 3/4 of a tank for safety. Has anyone heard of this or is this BS?

I have a Magnitude and as ACE said it should read 100%.


The sensor is nothing fancy. You will see a plastic analog gauge with two wires coming out of it on the front of the tank.

It is very likely Thor installed it so that it is not reading properly...... I had that issue with mine.

All you need to do is pull it off and rotate it counter-clockwise (if I recall correctly) by one position. It clips over a metal pentagon fitting that houses the float inside the tank.

[Jimmers]

When filled to the legal tank capacity which is regulated by an automated bleeder valve, the MONITOR PANEL should read 100%.

[lwmcguir]

Back in the farm and ranch day we had a lot of propane equipment and propane heaters. Some we added on electric gauges as the original just had the visible magnetic needle.

I set all the electronic gauges to read zero when the tank was empty. I was way more concerned with when the tank was empty rather than if it was 75 or 80% full

Many of the tank floats were off a bit and over time pulled them and adjusted them as needed.

Everyone has their own way and then can make it work.

In the Landmark I used the blue tooth remote type with the sensors under the 40-pound bottles. That worked pretty well other than poor battery life.

[dkoldman]

Looks like all know or agree about the 3/4 (80% actually) Full is max allowed. I think for OP he needs to know it is safety factor as the gas can expands with temperatures.

But I don't follow why any don't believe the inside gauge shows 100% full when outside is at 80%?

Mine does, works to a Tee. I go by gauge inside and let the gas installer do his job on outside. I pay when my inside says Full

@Judge,

Here is my gauge. It spells it out so if OP had gauge like this it would tell him 80% is Full.

It is also noteworthy that the gauge on the tank is actually NOT used for filling.

[dkoldman]

Thought I would add a picture of inside when Propane LPG is at the tank level of 75%, inside shows Full

[taylorbob1]

My inside manual gauge like dkoldman’s shows Full when the gauge on the tank reads 75%

But like I previously said, once the outside tank gauge gets down to 1/3 - 1/4, I have “range anxiety” on actual amount available.

[dkoldman]

We don't use that much propane and we start every trip with LPG propane full.

On the road I only look to get more propane if it is really cold or freezing outside and the inside gauge is at 1/3 tank. I don't ever bother to go outside to see what outside tanks says.

My filling up each trip sounds like I may use a lot, but I don't. I am just topping off. I am surprised they don't charge more when you get just a few gallons of LPG

When I added our Norcold Propane fridge to our inverter circuit, our Propane usage really went down ( it was low to begin with). I have to run the Propane Heater 3 plus days to put a dent in that gauge (inside or outside). To mitigate that we carry 1500W electric heater so if we have shorepower or if genny is running; we don't need the propane heater although one night it was so cold we had both 1500W heater & propane. Since the Propane Heater was on thermostat, the Electric heater still reduce the demand required for propane


Believe it or not, since we have owned are RV ( 3 years), we have only bought LPG at a U - Haul facility. That just means it was a planned purchase with no urgency.

[Jimmers]

Originally Posted by dkoldman

Thought I would add a picture of inside when Propane LPG is at the tank level of 75%, inside shows Full

As DK says, ours is the same.
Tank reads 75%+
Panel reads 100%
We fill in spring regardless and use maybe 35% even with late season camping.
Will be camping this next weekend and snow is predicted tomorrow thru next week on and off.
Gotta love Michigan.

[Judge]

Originally Posted by dkoldman

Looks like all know or agree about the 3/4 (80% actually) Full is max allowed. I think for OP he needs to know it is safety factor as the gas can expands with temperatures.

But I don't follow why any don't believe the inside gauge shows 100% full when outside is at 80%?

Mine does, works to a Tee. I go by gauge inside and let the gas installer do his job on outside. I pay when my inside says Full

@Judge,

Here is my gauge. It spells it out so if OP had gauge like this it would tell him 80% is Full.

It is also noteworthy that the gauge on the tank is actually NOT used for filling.

Your gauge / sensor looks slightly different than mine. I could easily roate my gauge / sensor so when the tank wasfl filled to “full” the digital gauge on my FireFly Display reads 100%.

I believe it is magnetic and it is reading the position of the float inside the tank.

[williamprunty]

Same thing here, have never been able to get past75% and always a slow fill. Had it serviced and verified fully functional. I guess it is what it is. I will say if you fill in a cold environment it will show 100% when you move into a warmer environment. At least that’s what happens with me. You may even get no indication (error) inside on the tablet when outside reads 3/4 tank.

[williamprunty]

Originally Posted by Judge

Your gauge / sensor looks slightly different than mine. I could easily roate my gauge / sensor so when the tank wasfl filled to “full” the digital gauge on my FireFly Display reads 100%.

I believe it is magnetic and it is reading the position of the float inside the tank.

New info, love it.