Are 3 3/4" burners too much for one tank of propane?🤔

S

Sammy T

Joined
Jan 6, 2022
Messages
6
So my problem is that I am unable to reach high PSI with all three of my burners open. Only 7 psi wide open on the high pressure regulator with three running. If I close off one burner, my regulator Guage will show higher PSI. With two closed the PSI grows to 17 only. They are 3/4" Frosty T burner.
Too much on one line?
Too much for 5 gallon propane tank to push?
Bad HP regulator?
Please help me get my forge running strong.
 
For a moment, I was thinking you meant to join BBQForums.com .

I'm sorry I can't help with your forge question.
 
Post this in the knifemakers section to get more (and better) answers.

What’s your ambient temp there? My vertical tank produces a noticeably lower volume of gas vapor when it’s cold, like below freezing.

Parker
 
It's about 7 degrees here on Colorado. You totally saved my day catspa! Makes perfect sense. Today way the christening of the forge so I'm back to feeling pretty good about the day. Right on man.
 
How fast are the pressures changing when you open and close the valve (if that's all you need to do to cycle the third burner off and on)?

The 2 "obvious" possibilities are 1/ that the cylinder is not getting enough heat input from its surroundings to maintain the take-off rate for 3 burners, or 2/ that there is a restriction in the system that will not allow the take-off rate for 3 burners.

Possibility 1/ will show a fairly slow response to switching the 3rd burner: probably minutes, maybe even tens of minutes, for the pressure to stabilize at the new value. Possibility 2/ will show an immediate response: within a couple of seconds.

If you don't know from the testing you've already done, it's worth spending a few minutes checking to see which of the possible explanations seems to apply in your case. You don't even need the forge up to temperature for this.

The restriction could be a safety restrictor in the Propane cylinder, intended to limit the flow, or a too-small regulator, or something else. First thing to do is see whether there's a restriction, then, if there is, to track it down and eliminate it.

If it's "just" ambient temperature, a bigger cylinder, manifolding 2 cylinders together, or increasing the heat transfer to the cylinder are potential fixes.
 
I will try to give it a little more time tonight to see if the pressure will stabilize. I wondered if there was something up with the regulator as well. It's 30 psi high pressure regulator but was fairly inexpensive. My burner manifold is in row from the tank 1st is 1st and, etc, 3rd is 3rd in the line up. I will try to figure out how to post some photos if that will help troubleshoot this problem. Thank you so much!!
 
Modern 20-40 lb tanks are safety rated for around 120k BTU output, same with regulators. These are automatic valves built in to the connections. Any more output and they think it's a leak. .035 MIG tip burners are around 80k BTU, so three of them it double the rated capacity. There is also the factor of how much liquid propane can evaporate in a standard tank, and that's slightly higher, around 150k BTU. That's the reason your PSI is dropping so severely. A tank manifold kit, which connects two tanks to a single regulator, will help with this issue.

Tank Manifold kit on Amazon

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That makes sense. I think that even if it is warm enough, the 3 burners with .035 mig tips just send out too much. Thank you for the tip! I will try it our this weekend and report my results.
 
Save your $ and buy a 100# tank (about 21 gallons).
 
weo said:
Save your $ and buy a 100# tank (about 21 gallons).
Click to expand...
100# tanks don't have that built in restriction that 20# tanks have. 100# tanks also use the older style connector (POL I think), and not the newer ACME type fitting that have the restriction.
 
So a 100 lb tank should be able to push enough propane to keep all 3 burners at higher psi? I'm down to try it, its just a little more than I'm ready to fork out right now. But if it is the solution, I'm doing it. Thank you for the new insight and info about the different possibilities with propane tank sizes.
 
I'll defer to the guys with experience and local knowledge on the cylinders over there: I'm in the UK.

Mig tips are sized on the nominal size of the mig wire they are intended to work with. The actual hole diameter tends to be .006" to .007" bigger than the nominal size when I've measured them, so a .035" mig tip will "usually" have a bore of .041" to .042". I measured a few different brands and sizes for my .006" to .007" value, but they were all Metric-threaded and I certainly will not have tried the Inch-threaded, tapered Tweco .035" tips. If you need to be sure, please measure your own.

The mig tips have a nice smooth tapered lead-in, intended to help the wire find the hole, but incidentally very good for flow. A mig tip should give a discharge coefficient between 0.75 and 0.8, probably nearer 0.8.

There is a "BTU Calculator" spreadsheet link from Ron Reil's site. You can plug in the numbers there to find the BTU consumption and/or lb/hr consumption of your burners. I'd advise doing it.
 
4# to 40# tanks have an OPD valve.

If you take the tanks to a propane dealer (gas supplier, not the filling place) you can get the OPD valve replaced with a regular valve. Explain the use and needed flow rate and they will do it.

A 100# tank is very reasonably priced at Home Depot/Lowe's and easily filled at any propane filling location (I use U-Haul) Your old regulator will work fine with the 100# tank.
 
100-pound tanks used to be very cheap. I spent $75 at Home Depot twenty years ago. Now they ate $200. The Worthington Pro tanks they sell now are a better grade and have double valves (for filling and output).

I never heard of anyone regretting getting a 100# tank.

BTW, some propane supply companies will come out and fill your 100# tank. U-Haul is just around the corner from my shop, so I just toss it in the back of the Benz and get it filled. A 100# tank takes 23 gallons of propane.
 
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