What is the safe way to fill a propane tank?

JimK-NY wrote:
I have seen more and more places stop venting when filling propane tanks. The OPD valve is designed to prevent overfilling. In addition every fill station I have seen uses a scale as an additional check against overfilling due to OPD valve failure.

The OPD is intended as a backup device for a Fixed Liquid Level Gauge ("spitter/bleeder/vent") or weight based fill. It is not intended to be the primary full 80% measurement indicator. Weight or measured fill preferences vary from state to state, although measured fills do seem to be the most common. NY is generally a weight based state for DOT cylinders, although I don't know if that's a legal requirement or not.

I haven't seen weight used for filling a portable propane cylinder for over 20 years. EVERY supplier around here fills using (as required by State Law) a temperature compensated meter. The usual charge at the present time is $2.49 per gallon.
All the propane filling sites I have been to use the "spitter valve" method. They stop filling when the OPD shuts off the flow or the "spitter valve" shows liquid propane, whichever comes first.

I have seen more and more places stop venting when filling propane tanks. The OPD valve is designed to prevent overfilling. In addition every fill station I have seen uses a scale as an additional check against overfilling due to OPD valve failure.

CavemanCharlie wrote:
I fill my own tanks from the large tank at the farm. I open the bleed port and then I use a old bathroom scale to get to the proper weight. I try to err on the side of caution and not get them to full. Since I am not paying for the propane it is not a issue for me.

So How about filling the tanks by weight ?? The empty weight is stamped on to the side of the tank.

That's perfectly acceptable for DOT cylinders that you can get on a scale. It is not the least bit practical to fill a permanently mounted RV tank by weight, of course.

I fill my own tanks from the large tank at the farm. I open the bleed port and then I use a old bathroom scale to get to the proper weight. I try to err on the side of caution and not get them to full. Since I am not paying for the propane it is not a issue for me.

So How about filling the tanks by weight ?? The empty weight is stamped on to the side of the tank.

Re It takes more propane if you bleed the tank... True. but read on
As I said before the gas in the tank is not AIR it is propane. As the tank fills the gas is condensed (Due to pressure) back into liquid.. However I seriously doubt you would notice the difference. More likely the tank was more empty when the bleeder was opened in the first place.

Re: Training
Was present when a class was reviewing the final
The instructor would read the question,, then the proper answer after a short pause.

The quetion was "What happens if you mix air and propane in the proper ratio and there is a spark"

Before anyone could say anything I answered "You land two counties over"
After the laughter died the instructor said "Exactly".

Remember this when plying with propane folks .

switch them out at any store. Of course if you have the big ones, you gotta fill.

donn0128 wrote:
The right way is option two. Connect open valve, open bleeder, start pump, when propane comes out of the bleed valve, close vslve, stop pump, close bleed, disconnect. The bleed valve is what is called an 80% valve. It is intended to allow liquid propane out at 80% of tank capacity.

This.

Using the scale for weight on a bottle, adding tare weight to nominal capacity as shown by the WC ( water capacity) is the only absolute method of filling a bottle to its 80% safe level. Weight is the absolute regarless of temperature.
Propane is an expansive liquid between its boiling , which expands or contracts with temperature, unlike water, which does not change volume in its liquid state. Propane weight is 4.24# / gal. at 68 deg. F. Raise or lower the temp, volume changes, thats why the 80% fill rule.

# 2 is the correct filling method on mounted or dismounted tanks when weight cannot be measured absolutely as the 'spitter' tube is a static fluid level that vents liquid at that level. OPD valves should not be counted upon as a fail safe. They are mechanical float valves that can and do sometimes fail to shut off flow at the 80% level. They are meant as a fail safe, not as an absolute measure.

There is no air or any other gas to vent to refill a tank. As the liquid is pumped in, the vapor condenses back into liquid.

NFPA 1158 requires propane dispensers and their operators to undergo training, each fill operator must pass written and demonstrate practical knowledge tests to qualify in my state.
I 'm in my 60s . I teach younger staff not what we did, but what to do.

The Bleed valve as you call it is the "Visual Overfill Indicagtor Device"

I have seen all sorts of claims about that valve like "You can't fill the tank if you don't let the air out".. There is no "Air" in the tank, it's full of propane gas.

There is a float valve that is supposed to cut off the inlet when the tank is 80% full. however like all mechanical valves IT CAN FAIL.

The "Spitter" valve as I call it (Visual overfill indicator) will clearly show when you hit 80% so the operator can close the fill valve and shut off the pump manually.

Oh and you left off a step

CLOSE ALL OUTLET VALVES FIRST.