(Note: The burner design is described fully in another equipment section called Oil Burner)
The oil tank is now pressurized to force oil into the furnace. A needle valve is used to adjust the flow. This system will easily melt approximately 8 pounds of aluminum in 30 minutes. A full crucible of brass is ready in about an hour. (Update 6/1/10 - I modified my furnace and I'm now melting a crucible full of aluminum in less than 15 minutes! See Swirling Fire under equipment.)
I inverted the propane tank, cut a hole in the bottom and welded a 1-1/2"x1" bushing into it. I fill the tank through this hole and then using common plumbing fittings to connect to an air compressor. I used the original 3/4" hole in the top of the tank (now on the bottom) to connect an oil filter and then a reinforced plastic oil supply line. Other changes in this system include the addition of a flexible 2" vacuum hose to connect the blower to the furnace and modification of the gate valve to regulate air flow.
I used a quick connect fitting, ball valve shut-off, and air gauge. I maintain the air pressure at 40lbs to force the oil into the furnace.
I installed an automotive oil filter to the oil line to help prevent clogging of the oil orifice in the burner. A ball valve shut-off provides a way to stop the oil flow in case of emergency.
Having built all that, I ran across this abrasive blaster from Harbor Freight. All it needs is the in-line oil filter. I need to look at the real thing in the store sometime
to see if it can be adapted to my needs, but for $100 it may well be my next oil supply system. It even comes with the wheeled stand built-in.
I can still make a gate valve cheaper than I can buy one. I slightly modified the original version of the wooden slide gate to regulate air flow. It is a lot more compact now and has stops at each end. The air passage was re-designed.
When lighting the furnace, I use just a little air and light the propane. Once
that's going good, I open the oil valve and gradually increase the air flow
until the oil gets burning. Too much air at first will blow out the propane flame.
A needle valve was inserted ahead of the ball valve shut-off to make adjusting the oil flow more precise. Once the oil flow is set with the needle valve, the ball valve allows for full cut-off of the oil to check the furnace and then re-start to the previous setting when turned back on.
I use the quick connect on the side of the burner to inject propane for a few minutes to help ignite the oil when lighting the furnace. After the furnace is lit, I remove the propane line for safety reasons. The propane line is not shown in this photo but you can see the quick connect fitting on the left side of the assembly.
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