Problem with propane tank

I would add one more possibility to Old-Biscuit's post.
The pigtail was not completely tightened. It may not have leaked but with a temperature change or due to vibration the pigtail allowed the stub to move away from the OPD valve causing it to close.

On our new to us unit, King Kong tightened the ACME nut and extruded the plastic to the point I could no longer tighten it enough for the internal stub to force the valve to open. New pigtails solved that issue.

(Not your issue....just FYI)
Propane Cylinders (not tanks) have a spring loaded shutoff valve in the OPD service valve.
If pigtail hose is not properly tightened it will NOT open the shutoff valve.


(Not your issue....just FYI)
The pigtail ACME Nut (Green) has the 'excess flow device'
IF OPD service valve is opened to quickly it will cause the ball bearing to move towards hose end and block flow thru hose.
Opening OPD service valve slowly allows pressure downstrean to equalize with upstream and ball bearing to move/remain centered allowing full flow thru hose


(Not your issue....just FYI)
The pigtail ACME Nut also has a 'thermal bushing' that will melt from high temp (fire). When bushing melts internal stub in ACME Nut moves away from OPD Service valve and it's spring loaded valve shuts stopping ANY flow out of cylinder

YOUR ISSUE
Because in service propane cylinder was NOT empty and you had NO leaks/excessive usage downstream....then problem is with regulator
Regulator either failed.......diaphragm cracked/leaked
OR
Regulator 'locked up' and would not allow propane to flow

If failed it will not properly function on either cylinder

If 'locked up' it will probably function just fine and be a 'fluke'

Replace regulator if you have another flow issue

Yes you might be right and I think it is a tank issue more than the regulator.
Also the pigtail connectors have a check valve that may have stuck somehow.
If you do replace the regulator or pigtails I recommend Cavagna brand.(amazon)

It is hard to tell what is what when the issue disappears just from fiddling with it.

smkettner wrote:

PaulJ2 wrote:
I turned it on very slowly like normal and everything in the trailer worked normally.
Looks like gauge is either worthless or defective.

No the gauge is actually correct indicating the tank was not producing propane.

The problem was the tank excess flow safety valve had shut off. When you closed the valve and reopened slowly this reset the valve in the tank.

BTW for the gauge to operate as designed both tanks should be open.

I agree the safty valve could have tripped. But if so it did it on it's own. I started out with both tanks full,gauge showing green, and several days later noticed it had switched to red indicating one tank empty. I removed that tank to refill and it had 2 gal still unused.
I do know about turning tanks on very slowly and have always done that.
I will give it another chance though before it goes in for warranty replacement.

PaulJ2 wrote:
I turned it on very slowly like normal and everything in the trailer worked normally.
Looks like gauge is either worthless or defective.

No the gauge is actually correct indicating the tank was not producing propane.

The problem was the tank excess flow safety valve had shut off. When you closed the valve and reopened slowly this reset the valve in the tank.

BTW for the gauge to operate as designed both tanks should be open.

~DJ~ wrote:
New TT with new tanks, first time out camping I ran out of propane in the first tank (7 1/2 gal). I thought it ran out pretty fast but went out and checked the tanks the switch valve was showing red. I turned that tank off and the other one on. Valve turned green again. When I got home I lifted the tank off the tongue to refill. It was way too heavy to be empty. Only took 2.3 gallons.

Is this tank bad or is there a fix? Thanks....DJ

Exact same thing with mine. New trailer with two full tanks (5 gal). Gauge showed green then after several days turned red. I then switched to the other tank which again showed green. I removed the empty tank that also was much too heavy and had it refilled. Took only 3 gal? What gives? A lousy defective gauge? I turned it on very slowly like normal and everything in the trailer worked normally.
Looks like gauge is either worthless or defective.

An abnormal flow rate will shut the flow off. Could that be caused by something you did.

I think bad tank is unlikely. Swapping the tanks would easily test that.

Are you sure you had properly tightened the collar to the tank?

I've had a bad pigtail.

Regulator could be bad.

Doug

Try opening the tank very, very slowly. It's the protection valve closing internal to the tank when you open these new tanks too quickly...