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Or it in a bucket of water. Freezing makes liquid and keeps the pressure
low. It normally regulates itself by dumping to liquid if the pressure is
high.
A bucket of water - such that it doesn't freeze - will heat it enough and
build pressure.
Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/
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If you manifold the smaller tanks together they will act as one larger tank
in terms of pressure delivery. The amout of liquid surface area has a lot to
do with how quickly you can draw off vapor without freezeing. This combined
with the droplight or a water bath could save you the hassels of transfering
propane from one to the other. One other thing , the place I get my propane
charges me by the gallon so I only pay for what they put in the tank ie: no
waste.
Andrew
Mike Graf
Try two electric heating pads wrapped around the bottle and held in
place with bungee cords. We've used a similar technique for nitrous
tanks and it works very well. No risk of overheating either.
Propane Vapor Pressure vs Temperature
Temp °F Pressure,PSI gage
-40 3.6
-30 8
-20 13.5
-10 23.3
0 28
10 37
20 47
30 58
40 72
50 86
60 102
70 127
80 140
90 165
100 196
110 220
(I hope this table comes through okay. -40 degrees should read 3.6 psi
and 110 degrees should read 220 psi. I would have sent a graph, but I
don't think the newgroup can handle pictures.)
I use a rubber hog waterer with about 2 inches of water in the bottom
and put the tank in it. As long as that water doesn't freeze, you've
got at least 60 psi on the high side of the regulator.
Dont' try the thing with emptying one bottle into another. It probably
won't work anyway with OPD valves on today's tanks. I guarantee that
you WILL get all the liquid out of the tank if you keep the temp up.
The liquid keeps gassing off inside the tank at the pressures the chart
shows, so you will have a short period of time where you still have full
pressure for the temp as the last bit of liquid turns to a gas. Then
you get a rapid drop and you are "out".
Add a 250 psi gage to the input side of your regulator and you will see
all this happen.
I would get a second tank anyway, so I don't run out in the middle of a job.
Pete Stanaitis
------------------------
One thing to think about the problem. When the new tanks were sent out
there was some gas stored within. Sometimes liquid gets in and a customer
that I knew in CA several years ago - had some in there. The gas vendor
didn't put in a open hose and dump (up side down) the junk out of the tank
before filling.
So this might be the issue if heating the tank to get pressure doesn't work.
Cut the columns out below and put into a spreadsheet - highlight and go to charts...
Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/
Just talked at length to the propane service guy today since he was here
testing our whole system for leaks, proper valving, etc.. He drove up
the driveway as I was starting to reply to this post!!!
He says that new tanks have only air in them, if anything. It would
cost them extra to put anything in there. He said that, unless the new
tank is under an actual vacuum (not likely when you buy from cheap
places according to him) when you get it, you have to purge the air out
before filling. Quite a process, according to him. They have to add a
little propane, exhaust all pressure, then do that four more times, for
a total of 5 times before filling! Total surprise to me, and I doubt
that most fillers do it anyway.
Pete Stanaitis
------------------------------
Martin H. Eastburn wrote:
> Great chart.
>
> One thing to think about the problem. When the new tanks were sent out
> there was some gas stored within. Sometimes liquid gets in and a customer
> that I knew in CA several years ago - had some in there. The gas vendor
> didn't put in a open hose and dump (up side down) the junk out of the
> tank before filling.
>
> So this might be the issue if heating the tank to get pressure doesn't
> work.
> Cut the columns out below and put into a spreadsheet - highlight and go
> to charts...
>
> Martin
> Martin H. Eastburn
> @ home at Lions' Lair with our computer lionslair at consolidated dot net
> TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
> NRA Second Amendment Task Force Charter Founder
> IHMSA and NRA Metallic Silhouette maker & member.
> http://lufkinced.com/
>
>
> spaco wrote:
>
>> Here's what is going on:
>>
>> Propane Vapor Pressure vs Temperature Temp 蚌 Pressure,PSI gage
This was one of the new OPT or whatever they call them. First version.
> He says that new tanks have only air in them, if anything. It would
>cost them extra to put anything in there. He said that, unless the new
>tank is under an actual vacuum (not likely when you buy from cheap
>places according to him) when you get it, you have to purge the air out
>before filling. Quite a process, according to him. They have to add a
>little propane, exhaust all pressure, then do that four more times, for
>a total of 5 times before filling! Total surprise to me, and I doubt
>that most fillers do it anyway.
I used to own a welding supply distributorship that also sold propane. I
still have the license.
That guy was jerking you around. Either he didn't know any better or he was
trying to set you up for an extra charge if you bring him a new tank to fill.
Almost all small tanks now come filled with dry nitrogen. Some come with
propane at atmospheric pressure in them. Those typically have a "purged"
sticker on the valve handle.
Purging a portable tank at the minimum requires nothing extra. Simply open
the 20% valve while filling. Air or nitrogen is non-condensable so it will be
discharged rapidly as the propane level rises. Some guys pressurize and purge
the tank once but my testing showed not even that to be necessary. Simply
letting the 20% valve spew while filling lets all the air out.
It's easy to check. Simply measure the tank's pressure and temperature and
compare it to a vapor pressure chart. Propane is a great refrigerant so vapor
pressure charts are widely available. Here's one
http://www.glacierbay.com/support/library_docs/ptchart-propane.html
Measure the tank's temperature, look up the equivalent pressure in the table
and compare it to the gauge's reading (a 200 psi gauge attached to a propane
nipple works fine.) If the pressure is HIGHER then there are non-condensables
in the vapor space. Easy enough to get rid of. Simply purge the tank for a
few seconds. People cursed with those infernal OPD valves will have to attach
a nipple to the valve to get any flow.
A little air in the tank doesn't hurt anything. It can't explode - it's far
too rich. It'll make the fire act like it is a little lean for a few minutes
until the air is purged.
If the pressure is a bit LOWER than the chart indicates, don't panic. That
just means that the LP has some butane in it. It's still perfectly good fuel
gas.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
What do you call 10 blondes standing in a row? Air line.
John, what can you tell us about the new propane tanks? :)
What's different?
Like... can you get liquid out of them by inverting them?
Alvin in AZ
You can until the tank is almost empty. When the tank is full and inverted,
the OPD float tries to float to the bottom of the tank and thus remains open.
When the level drops to about the 20% level, the float starts rising toward
the valve and eventually shuts off.
Assuming you own your tank and aren't swapping it at the local C-store, the
best thing you can do is, before it is ever filled the first time, unscrew the
valve from the tank and unscrew the OPD gadget from the bottom of the valve.
It simply screws into the bottom of the valve with about a 1/4" NPT thread.
That one step eliminates the cursed valve and the flow restriction.
Interestingly enough, I've yet to encounter an OPD valve that actually closes
off when the float rises. The flow is restricted but not turned off. Thus,
the supposed justification for the damned things - to keep the bored and
distracted filling attendant from over-filling the tank - isn't there. Worse,
it instills a false sense of security. I've had more than one attendant tell
me that he doesn't bother with scales or the 20% valve anymore. He just turns
the pump on and lets it pump away until it 'stops'. That is, until the tank
is solid with liquid.
Like most government meddling, the unintended consequences have negated any
alleged benefit that might have accrued. And again characteristic of
government meddling, they'd never in a million years admit to making a
mistake.
The easiest way to get around the flow restriction if you can handle the
weight is the 100 lb tank. It doesn't have to have an OPD and none do.
Another technique is to buy or have a gas company install a 250 or 500 gallon
tank with a "wet leg". This is a fitting on the tank that has a dip tube. It
is designed to empty tanks before moving them. With a few fittings, though,
it can be equipped with a valve and hose. One can feed a high BTU burner
directly from the wet leg or he can use it to fill smaller tanks.
Until I retired, I had a 500 gallon tank at my restaurant with a wet leg on
it. I filled my 20 and 30 lb bottles that I used for catering and I filled
the tank on my motorhome. I don't have a need for and wouldn't want to pay
for having that large a tank filled now so I use 100 lb tanks as my bulk
tanks. I fill my 20 and 30 lb tanks that still have the old style valves
using a simple siphon method. No pump is needed.
This my page on filling throw-away tanks
http://www.neon-john.com/RV/Propane/propane_refill.htm
I made the page when I still had my bulk tank. Nowadays a 100 lb tank
replaces the 30 pound one shown in the photo and 20 and 30 lb tanks fit the
same hose with an adapter. The gravity head really isn't necessary. If the
receiving tank's 20% valve is open, the difference in pressure will push the
liquid propane. It can even push it a little bit up hill.
The advantage of the 100 lb tank is that it is the smallest tank that most
dealers charge by the gallon instead of fixed fees. For the smaller tanks,
labor costs are such a large portion of the sale price that a fixed fee is
necessary even if the tank is only half empty. Generally, with a 100 lb tank,
they'll charge you their per-gallon price.
If you find that you're filling the 100 lb tank more often than maybe once a
month then you'd be better off with a bulk tank. You can book a year's supply
in the summer when the price is the lowest. Last year the advanced booking
price from my local dealer was 50 cents a gallon lower than the winter price.
It was $2 a gallon advanced booking and $2.50 for winter fillings.
It's gonna be crazy this year, as they quoted the advanced booking price back
in July at $2.79/gal. Like last year, I'm going to lay in a bit more firewood
and leave the bulk tank empty. I have 2 100 lb tanks for emergency backup but
I'll not be using any propane on a regular basis this year.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
I don't speak Stupid so do speak slowly.
A supposed factoid is that the Compressed Gas and/or the NFPA people who
instituted the OPD requirement don't tell anyone that they left a
loophole: It's legal to fill a non-OPD tank of less than 40-pound
capacity as long as that tank is marked "Industrial Use Only."
Check with your favorite Propane supplier for the wording that he/she/it
prefers but the answer is a resounding "YES"!
Around here, "Cutting Gas" seems to be acceptable to most of the suppliers.
The other was a forklift bottle - but they are expensive to buy.
Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/
If you're talking about fork lift tanks then the answer is yes. That kind of
tank doesn't have a POL fitting, though. It uses an ACME threaded fitting
that is different from the OPD ACME thread. Fork lift tanks can be fitted for
either vapor or liquid withdrawal. Liquid is used on the larger machines and
in very cold climates. Engine coolant flows through the vaporizer/pressure
regulator to supply the heat of vaporization.
Once you get past the steep purchase price, fork lift tanks would be great to
supply high BTU burners. The ACME fitting is a high flow fitting and of
course, there is the option of liquid withdrawal. Just about every tank I've
ever seen has a built-in level indicator.
The way crap like this work is that NannyGov comes up with some horrible new
(NOT) risk that they have to protect the sheeple from. Then one of two things
happens, depending on whether the affected industries think that they can make
money on the new regs. If they can then they go all out with PR campaigns to
sell the new seizure of freedom and wealth as a benefit. Air Bombs in cars,
the hysteria about lead and mercury are examples.
If the major affected industries perceive the new NannyGov regulation as
harmful to their bottom line then they fight it equally vigorously but usually
not in public. Sometimes two different industries are pitted against each
others. Such was the case with OPD. The tank and valve manufacturers lobbied
strongly for it. The propane gas dealers, realizing what a hassle was being
created, lobbied strongly against it. In such an instance, the result isn't
pretty.
What is really funny is to watch the safety nazis on each side try to promote
their cause while not sounding too silly. Fer'instance. The safety nazis
will scream and shout and run about at the mere thought of bringing a portable
propane bottle inside. Yet, take that same amount of propane, change the
shape of the bottle a little and strap it on the back of a fork lift and
everything is hunky-dory, even though fork lifts fairly routinely run off
docks, exposing the tanks to much more of a crushing and puncture hazard than
running a heater off a 20 lb grill tank inside a house.
Ahh, the vagaries of the safety nazi!
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Sporadic E is the Earth's aluminum foil beanie for the 'global warming' sheep.
Thanks! Maybe I can still get some life out of all those old 20-pounders
yet. :)
Cool, thanks. :)
> Assuming you own your tank and aren't swapping it at the local
> C-store, the best thing you can do is, before it is ever filled
> the first time, unscrew the valve from the tank and unscrew the
> OPD gadget from the bottom of the valve. It simply screws into the
> bottom of the valve with about a 1/4" NPT thread.
>
> That one step eliminates the cursed valve and the flow restriction.
>
> Interestingly enough, I've yet to encounter an OPD valve that
> actually closes off when the float rises. The flow is restricted
> but not turned off. Thus, the supposed justification for the
> damned things - to keep the bored and distracted filling attendant
> from over-filling the tank - isn't there. Worse, it instills a
> false sense of security. I've had more than one attendant tell me
> that he doesn't bother with scales or the 20% valve anymore. He
> just turns the pump on and lets it pump away until it 'stops'.
> That is, until the tank is solid with liquid.
Thanks for the warning on that one! :)
I'll watch 'em. :)
> Like most government meddling, the unintended consequences have
> negated any alleged benefit that might have accrued. And again
> characteristic of government meddling, they'd never in a million
> years admit to making a mistake.
Ex C-Sapn junky here. :)
I just plain ol' had to stop watching the crap it was too dangged
irritating. :/
> The easiest way to get around the flow restriction if you can
> handle the weight is the 100 lb tank. It doesn't have to have an
> OPD and none do.
Thanks for the well thought out and well written answers! :)
> This my page on filling throw-away tanks
> http://www.neon-john.com/RV/Propane/propane_refill.htm
> John De Armond
Cool page, I already have a bottle filler, just haven't used it
in years. :) And I have one old tank and one new OPD tank so I'm
setup pretty good for my limited use of propane.
Alvin in AZ (libertarian)
Was re-reading you instructions and wanted to share my method of
refilling the "throw-aways"...
Instead of weighing them, I use the "slosh method". :) When the
bottle feels like it's a little over half full I call it good. :)
Plumb-full bottles are a pain to use with one of those solid
screw-on torch-heads (most of the time, IME) so why bother filling
it more than 2/3s full? :)
Alvin in AZ
Yep, that'll work for that kind of use. My use is a little different and I
need every cc of fluid. One of my major uses is to replace refillable tanks.
This notion popped into my head when I took a year off to see the country and
get paid for it, that is, driving a semi rig over the road. Here's what got
me started on this gig
http://www.neon-john.com/RV/Propane/dual_tank.htm
Before hitting the road I'd been in the restaurant business for about 10
years. I realized that for years I'd dragged out 20 and 30 lb propane bottles
to power portable steam tables and the like, only to drag back home most of
the propane. As trustworthy employees became harder and harder to find, I
found yours truly doing more and more of the grunt work. That's the major
reason that I sold out.
Anyway, I love food service so after I retired, I continued doing occasional
catering jobs. Now I'd be lugging out ALL the equipment by myself. I did a
time and motion study. One major heavy item that I eliminated was the
refillable propane tank. Initially I bought some 5 lb mini-tanks but I
quickly realized that if the tank ran empty, I'd have no recourse unless I
happened to have thought to toss in another tank. Plus they're more expensive
than 20 lb tanks.
My solution was to make up a tank "spider" to use disposable tanks. I used
one of the 6-way aluminum air line multi-outlet devices made out of a disc of
billet aluminum that Northern Tool sells. Visualize this assembly
http://www.neon-john.com/RV/Propane/Two_Tank_Adapter.jpg
With the ell screwed into the disc and the valve on the vertical side of the
ell, connected to the disposable cylinder adapter. There are provisions for 5
cylinders. The female POL fitting (so I can screw in a standard regulator)
screws into the 6th hole. Five cylinders will power my gas steam table for
most of a day and will power a high BTU burner for shrimp boils and turkey
fries for quite some time if the assembly is put in a bucket of water to
supply more heat of vaporization.
I package disposable cylinders in boxes that hold 5. They're light weight and
easy to handle. I usually toss 3 or 4 boxes in the truck, though I've never
used more than 2 sets of cylinders.
I save up batches of empty cylinders and refill them all at once. They go in
a chest freezer until they're nice and frigid. I learned that, using the hose
assembly shown on my refiller page, if I hold the cylinder upside down, liquid
directly fills the tank without vaporizing in the gas space which quickly
raises the temperature and slows the filling.
With a freezer-chilled cylinder, especially if it still has a little liquid in
it, I can fill a tank in under a minute. I no longer need to weight the
cylinder. I can listen and tell when the liquid is near the top (actual
bottom) of the tank. I do check-weigh each one afterward and occasionally I
have to blow off a little liquid using my tank drainer. I keep a chilled
cylinder nearby for that purpose.
The only downside is that purchasing all the parts at retail makes the
assembly quite expensive. I'm thinking about having a larger disc made at
e-machineshop or a local shop that is large enough in diameter that the elbow
won't be necessary. The threaded holes would be on the face of the disc
around the periphery instead of on the rim. If I can figure out how to fit a
check-valve in each hole, I can dispense with the valves. This might turn
into a product :-)
This same approach might be handy for 'smiths doing demos using small propane
forges. Especially if you're like me and have a back problem that precludes
lifting more than about 20 lbs. If you don't use a full 20 lb tank during the
demo then you're a candidate for this approach.
Oh, the other benefit. If I manage to forget spare tanks or I use more than I
planned, I can run out to almost any store and buy more cylinders. It'll be
expensive but at least I can get the job done. Probably no more expensive
than those C-store cylinder exchanges.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Ever stop to think, and forget to start again?