LP Gas Fill ASME Tank possible overfill?

[Missionstreet]

I have a 1998 F53 chassis with a 14 Gal Manchester tank. The sticker indicates it has some sort of overfill protection despite the shutoff handle being "pinwheel" shaped.

Recently filled up my tank with 9 gallons (before winter storage, gauge read below E and no flame on the stove leading me to believe it was truly "empty").

The guy didn't bother to open the 80 percent level "valve" (please correct me if I'm mistaken in naming this) but told me it's "automatic". I guess he was relying on the overfill device in my 24 year old tank.

I did open the 80 percent valve 2-3 seconds after he started filling and immediately heard a hiss followed by a spraying vapor. I then told him to stop just shy of 9 gallons. When h he disconnected there was a brief strong spray at the ACME connection as he removed the hose

My question is how easily can the liquid vs vapor state of be distinguished?

Also does this situation seem to indicate an overfill event? As mentioned I believe tank was completely empty but am cautious that air somehow entered the tank.

My greatest concern is some type of overpressurazation.

Thanks in advance,

[BFL13]

Agree just use some. You can release some if nervous.

Fill up today. New thing after half hour drive
got out and could smell propane. Fridge was beeping said No Fuel.

Reset fridge to LP went to yellow dot normal drove more next stop smell propane again outside

Checked tank opened closed big valve then found little valve above that was not all the way to the right. Turned it left and it hissed says it is the 80% thing. Hand turned it tight to the right seems to have fixed that.

He had a short rod tool for that as usual not sure what went wrong this time. Hope hand tight is ok.

[dougrainer]

Air cannot enter a tank that has been used and had LP in it. Doug

[dougrainer]

1. You cannot over pressurize the ASME tank.
2. It is normal for the fill nozzle to squirt/puff when removing the fill nozzle
3. The CORRECT procedure for filling all ASME tanks is to always open the 80% valve when filling. Your Tank DOES have a "80" percent liquid shut off valve. But they can still malfunction or allow slightly too much liquid into the tank
4. The small 80% valve is always opened and will spew vapor while filling. Its purpose during filling is to let you SEE if the tank has overfilled before the Auto shut off kicks in. When filling if you see liquid start to spew out that 80% valve you STOP the fill. Immediately. IF your filler stopped filling because the Auto shut off kicked off, you are OK. When full, it is normal for the 80% valve to then spew a little liquid.
5. I would leave the Shut off valve closed before driving and when you get home, open the valve and then run the Furnace or Water Heater for about 30 minutes. That will burn off any small excess liquid.
6. It is always not a good idea to travel with a freshly filled full ASME tank with the shut off valve open. The reason being when full and driving, the Liquid LP can slosh in the tank and then liquid can slosh out thru the cut off valve and get into the LP regulator which will cause the Rubber diaphragm to freeze and then the regulator will leak and have to be replaced. Doug

[Fisherman]

Next time you go get your BBQ tank filled, watch when the attendant unscrews the fill connector, there's about a 1 second puff of propane while it's disconnected. That's normal. How would air enter a tank when it's turned off.

[red31]

what type of gloves were you wearing when you opened the '80% valve'?

[bgum]

It is highly unlikely that it is over filled. It should have been easy to tell the difference between vapor and a full stream of liquid. Normally the internal valve will shut the in flow off. I guess the valve could get stuck open or closed.