Which gives me the biggest bang for the buck in the winter, a 5lb propane tank refilled five times, or a single 25lb propane tank filled once?
My guess is it would be determined by the price. Can you get 5, 5lb refills for less than one 25lb refill?
IANHankHill, but I would think the 25lb bottle would be the best deal if only from a labor point of view.
One trip instead of five.
What’s the cost for each?
The refill per lb price difference between 5 lb and 25 lb refills will be minor. It’s really more of a labor (and possibly safety) issue. If you’re a smaller or older person lifting and carrying the 25 lb cylinder + gas might be more than you want to handle.
Price is by the pound, so my first inclination is that pay the same for 5x5lb or 1x25lb. But the colder it gets, the lower the pressure in the tank, and once pressure is down too far, I have to get a refill. In this respect, do I still have to make five refill trips with the little tank to equal one refill trip with the big tank, or does that somehow change as we go into the deep freeze in the next few months?
I live a few floors up, so it is more convenient to stop on the way home from work five times for refills, than to lug up a single large tank. If there was a significant difference in how much I pay, then I might go over to a big tank.
Other than a camp stove, what can you run on a 5# (# = pound) tank? Even a 25# tank like what’s under nearly every gas grill can’t quite cope with the flow demands of a full-size residential range.
Perhaps you’re confusing pounds and gallons? The standard 25# gas grill tank holds 5 gallons.
What are you using propane for inside that you have to lug the tank several flights upstairs?
I’m curious too, but I was scared to ask.
The OP did refer to wanting the most “bang for the buck”… :dubious:
Very small BBQ (does a terrific job of two burgers at a time). The hatch to my deck is at waist level, beside my kitchen table, so I set up the bbq just outside the hatch. This sumer I have refilled every two or three weeks. The folks that fill it call it 5lb, and it is advertised as 4.9lb when I bought it – it is about the size of a curled up house cat. It is embossed with 5.28l which I suppose means the capacity is 5.28 litres, but that is just a WAG on my part.
The vapor pressure of propane is soley dependant on the temperature of the liquid propane. A 25 pound bottle puts out the same pressure as a 5 pound bottle if they’re at the same temperature. The difference is how much gas it can put out before the flow stops. If it’s really cold out, the already cold propane will continue to drop in temperature as the heat of evaporation is removed from the liquid, until it hits -43 C and stops evaporating completely.
But you still don’t need to refill it at that point. If you just leave the tank sitting around for a day, or bring it inside to warm up, the propane will heat back up and the vapor pressure will return to normal.
You can make the tank last longer before getting too cold by painting it black. It will then absorb more IR and last a bit longer, as well as having a higher starting temperature. That trick is used in an odd type of jet engine called a Gluhareff Pressure jet, which is a pulse jet that uses propane pressure to supercharge the intake.
I’m assuming you’re running a gas grill on a balcony?
You’re not supposed to fill the propane bottle over about 80% full and the new (and basically only ones now legal to fill) have an OPD, or overflow prevention device to keep the person filling the tank from overfilling it. Propane goes in as a liquid (normally a gas, this stuff is under high enough pressure and can give you instant frostbite) and the 80% limit is to allow for vaporization in the tank without putting too much pressure on the tank. The difference would depend on the physical properties of liquid propane at various temperatures, and although I don’t have a CRC handy, I’m guessing that any difference is negligible. My guess is that the five little trips is effectively exactly the same as one trip with the larger one even in winter.
Should have previewed. Whoops.
5.28 liters is 6.77 lbs of propane. Its density as a liquid is 0.582 ×10[sup]3[/sup] kg/m[sup]3[/sup] according to Wikipedia.
I meant to say -42 C.
As I just said, the vapor pressure of propane solely depends on the temperature of the propane. A 3/4 full tank and a 1/4 full tank will put out exactly the same flow if they’re both at ambient temperature.
The OPD is to prevent liquid propane from coming out of a tank. If the tank is overfilled, you end up with liquid flow, which vaporizes rapidly outside the tank and presents risk of explosion. If a tank is filled mostly full on a cold day, then warms up, the liquid propane will expand. The extra space given by an OPD allows it to expand without causing liquid flow.
It also smells really bad, because the ethyl mercaptan is deposited where the propane boils, rather than being burned in the gas. I have an engine that I was trying to fuel on liquid propane, and it smells horrible.
I’m assuming the mercaptan is added for its odor to tell you if you have a gas leak, correct?
Thanks, Wikkit, your answer is very helpful! (Yes, it is a gas grill on a balcony).
I take it that my problem in the winter will not hinge on the size of the tank, but on the temperature, particularly when it gets down to -42c.
In that case, I’ll stay with the wee tank and bring it inside to warm prior to use, rather than struggle with a bigger tank.
Yep, it is the smelliest substance on earth, according to some sources. But in normal usage, it is burned with the propane, so it doesn’t smell. If liquid propane is allowed to evaporate outside the tank or is just let out as a gas without burning, not all of the mercaptan evaporates with it, and everything smells. There is a story you can read online somewhere about unmanned Antarctic monitoring stations that were powered by large propane tanks. If the pilot light of the heater or generator went out, all of the propane would leak into the little building, depositing the mercaptan. The scientists would come back at some point to find a frozen station that smelled absolutely horrid.
I’m glad I could help, Muffin.