Propane tank valve question

[BarbandBob]

Had propane tank off for 3 months and turned and opened the valve - had short blast of propane exit valve stem but quit when valve was fully opened. Is this normal? Has never happened to us during our 40 years of camping.

[mike.t]

Don't think anything should come out. I think the tank must be connected to something.

[Mr_D]

The newer tanks have a "high flow valve" in them. If there is no backpressure the valve assumes there's a broken line and shuts off the flow. It also happens if you open the valve too quickly.
So yes, there must be something attached to the tank or it shuts off the flow. It's a safety "feature",

[KIX]

If it were mine I would back seat the valve then use a bubble solution to verify that stem leak is sealed.

[jesilvas]

LP tank?

So this is on a motor home? Or is this a DOT cylinder? What service valve is on it, what were conditions, anything connected? There's a lot more to learn before we answer.

[KIX]

The OP said:

Originally Posted by BarbandBob

Had propane tank off for 3 months and turned and opened the valve - had short blast of propane exit valve stem but quit when valve was fully opened. Is this normal? Has never happened to us during our 40 years of camping.

[jesilvas]

Originally Posted by BarbandBob

Had propane tank off for 3 months and turned and opened the valve - had short blast of propane exit valve stem but quit when valve was fully opened. Is this normal? Has never happened to us during our 40 years of camping.

Originally Posted by KIX

The OP said:

I see that. What is valve stem on the LP "tank?"

[nothermark]

You had some Propane get past the packing around the valve stem. Packing in a valve is what prevents the line contents from blowing out past the stem.

Old valves were adjustable to squeeze the packing tighter by tightening the nut around the stem. There is a balancing point between a good seal and being able to turn the valve. You can try tightening the nut a bit. Maybe 1/8 of a turn.

Many newer valves use an O ring that cannot be tightened to change the packing pressure on the stem. They either work or do not.

You can use soapy water to look for leaks. With either style valve the best thing to do is run full open or full shut. With some designs it makes a difference and with some it does not but most folks will not know what they have.

[mel s]

Originally Posted by BarbandBob

Had propane tank off for 3 months and turned and opened the valve - had short blast of propane exit valve stem but quit when valve was fully opened. Is this normal? Has never happened to us during our 40 years of camping.

BarbandBob
That happened to me...... but only once in 14 years.

When I asked a LP dealer about it he said:
1.) That sometimes happens if/when the shut off valve seal/packing "drys out".
2.) Because of the "shut off valve design" no propane can escape when the valve is fully open or fully closed.
3.) Often the propane that escapes through "dried out packing" while opening, or closing, the valve "lubricates the packing", (aka: restores the seal).

Apparently the "short blast of propane" restored my seal/packing... (it has NOT happened again... 4 years later).

Mel
'96 Safari

[chief02]

Yes you opened the valve to quickly with no back pressure and tripped the "excess flow safety valve". Perfectly noramal. This can happen even when hooked up because the lines can be empty and when you open to fast the sudden volume of LPG going into the lines can be enough to mimic an open system that triggers the safety device in the tank valve.

[KIX]

Originally Posted by jesilvas

I see that. What is valve stem on the LP "tank?"

Post #8 gives a pretty good description. The stem is the round "rod" that turns the valve seat inside the valve body when you manually turn the hand wheel to open or close the valve.