Advice on Regulator Selection for Foundry Furnace

[vtcnc]

I put a fan speed control on the blower. The 20psi regulator, hose and ball valve came in the other day. Was going to get a box store grill regulator but they were asking $39.99 and up and that seems like a steep price for zero flow control. I didn't want to get into dis-assembling to add the ball valve volume control so I ordered a complete assembly from Tejas Smokers out of Texas. The connector to the tank supposedly has a safety feature in it as well. We will see if that screws things up or not.

I'll post some photos in a separate thread once I get things fired up. I think @pontiac428 had mentioned melting beer cans. Nope. Not interested in dinking around with that. I have lots of quality, clean, cast aluminum scrap and a source for more so I'm excited to learn how to make quality castings. I think at this stage my favorite channel on YouTube for learning about all of this is OlFoundryman.

 

[pontiac428]

The smelting beer cans thing was tongue-in-cheek, because we both know you're not that sort of shop bumpkin.

I'm curious, why did you and @Cadillac choose ball valves for volume control? Needle valves make a critical orifice which is insensitive to supply side pressure changes (withing a range), so pressure fluctuations (which may really happen using a regulator made for a different gas- acetylene goes up to 225 psi, vs propane which sits just above 100 psi) won't affect output volume. Just asking. A legitimate reason would be the ball valve gives more total volume than an equivalent pipe diameter needle valve, if you don't want to go up in piping size.

 

[den-den]

If this was designed for natural gas, it likely has a large fuel orifice and runs with very low fuel pressure. Many propane furnaces use higher fuel pressure to pull in enough air. When a blower supplys the air, lower fuel pressure and a larger orifice gets similar results.

 

[Cadillac]

I used ball valves because that’s what I had on hand and I figure it was better for the volume going through it.
I e been looking into changing over to a waste oil burner. I have endless amounts of used oil.

 

[DevinSS]

I use a acetylene regulator I had and the line from a O/A setup. I had some old ones. Then at the business end I have another ball valve for volume control. Instead of a blower I use a airline from the compressor. The air line also has a regulator on it which if I remember I inject about 5-10 psi of air. I’m sure theirs better ways but it was all material on hand. Works good.

My father scored a free foundry furnace, blower and tube from a friend. Well, o.k., not free - he traded a couple of game skulls for it.

Anyhoo...the prior owner claims it was hooked up to a LNG line from his shop. I plan to fire on LP. I have the steel jacketed flex line that tees into the blower tube. There is no nozzle or regulator for the atomization and control of propane.

There is plenty out there on nozzles, blower tube, etc., but I'm having a hard time nailing down the type of regulator I should purchase. One thing I have learned is that a grill regulator will not work, the pressure is too low. Please correct me if I have drawn the wrong conclusion on that point.

I found this one from a link source on backyard foundry:

Amazon.com : GasSaf 5FT 0-10PSI High Pressure Propane Adjustable Regulator with Hose or QCC1/Type1 Propane Tank Cylinder Fits for Turkey Fryer,BBQ Grill, Heater, Stove and More Appliances -Safety Certified … : Patio, Lawn & Garden

Amazon.com : GasSaf 5FT 0-10PSI High Pressure Propane Adjustable Regulator with Hose or QCC1/Type1 Propane Tank Cylinder Fits for Turkey Fryer,BBQ Grill, Heater, Stove and More Appliances -Safety Certified … : Patio, Lawn & Garden

www.amazon.com

This claims to be high pressure, but as I inevitably shop around, I see other regulators for upto 20, 30 and 60! psi.

So, the furnace will only be suitable for small crucibles, maybe no more than 3# of aluminum. Any advice on what size and type of regulator I should be looking at?

Thanks

I have a small furnace with out a blower and have run around 13 psi pressure on propane .
The burner was made from plans of the internet.I dont recall the actual hole size for the jet but remember volume through a orfice depends on pressure.

 

[vtcnc]

The smelting beer cans thing was tongue-in-cheek, because we both know you're not that sort of shop bumpkin.

I'm curious, why did you and @Cadillac choose ball valves for volume control? Needle valves make a critical orifice which is insensitive to supply side pressure changes (withing a range), so pressure fluctuations (which may really happen using a regulator made for a different gas- acetylene goes up to 225 psi, vs propane which sits just above 100 psi) won't affect output volume. Just asking. A legitimate reason would be the ball valve gives more total volume than an equivalent pipe diameter needle valve, if you don't want to go up in piping size.

LOL. Oh, I can bumpkin! I am from Vermont!

I went with the ball valve - mostly from the perspective of getting up and running quickly. I just want to get this thing running and not dink around with nozzles and orifices. So, I've got blower control from zero (ambient) to forced (some reasonable amount of CFM), then I have regulator control from 0-20psi and then ball valve control for gas volume. I figure between the three I should be able to dial into something reasonable with the gross controls I have in place. We will see.

 

[vtcnc]

If this was designed for natural gas, it likely has a large fuel orifice and runs with very low fuel pressure. Many propane furnaces use higher fuel pressure to pull in enough air. When a blower supplys the air, lower fuel pressure and a larger orifice gets similar results.

I think this was hooked up to NG. It came with a reinforced steel jacketed line which made me think NG. I'm hoping you are right about the blower + large orifice combination.

 

[pontiac428]

I dont recall the actual hole size for the jet but remember volume through a orfice depends on pressure.

Not really, the relationship looks something like Q=diameter(^2) x sqrt(dP), so the diameter factor is far dominant and the pressure drop factor is minor. That's what make critical orifices so useful in practice, the jet delivers the volume fairly consistently with fluctuating input pressure.

The reason I brought it up is we often optimize our projects to the Nth degree and strive for precision, whether it's necessary or not. It's part of the shop fun, and none of us are strangers to waxing esoteric on the details around here!

 

[rwm]

Did you try this yet?