Safety Question - Forced Air Burner

[Lieblad]

LOL !!!
Massflow air sensor & Ardunio ! Can we quit making things so ’effin complicated ? Ok, maybe if we need to know CFM, but we dont. WTF ?
We only care if the blower is running right’n proper so the gas can switch on...

The HVAC business may call these switches what activate at very low pressures a ”differential switch”. Many are adjustable, many can operate as low as a fraction of inch Water Column.

An example, Your washing machine at home uses one to detect when its tub is filled.
Airflow detector is a paddle switch assembly whats inserted into ductwork. The forced airflow presses upon the paddle, pushing it aside. Thats what operates its switch.

All being said, at our shop, we dont monitor or interlock airflow to fuel delivery. Our forges, a blower failure is a minor startle, but not a high risk. Being us its only users & highly aware of forge operation, its a minor hazard we choose to live with & deal with whenever it happens.

Being the OP asked about safety, I will usually advise to the ’best’ method or practice usually based on how I would build something for industry despite knowing most homegamers omit all sorts of safety functions either by choice or just not knowing any better.

 

[Stacy E. Apelt - Bladesmith]

I think it is NFPA code, but probably also in state/local fire codes.
A call to the local fire marshal or code division would tell you what is required in your area. Counties may have fewer rules, or ignore some NFPA requirements. Those Rugged Individualist areas often go by, "If you burn down your own Gal Dang house that is your own stupidity ... as long as it don't burn down mine!" Cities can't work that way
I cities, all propane above 1 pound is supposed to be stored 20 feet from an occupied building. IIRC, propane over 100 pounds is supposed to be stored in a raised exterior tank on a concrete slab. Exterior tanks must have automatic safety shut off valve that stops all gas flow in case of fire/power failure.

For 20 and 100 pound cylinders, a main shutoff solenoid is just a good safety procedure. Many ( probably most) knifemakers have the propane tanks inside the forge building Sh!# happens in forges. If the power gets knocked out, a gas hose gets cut or burned through, or other calamity strikes, having a shutoff solenoid at the tank may prevent a bad situation from becoming a disaster. Optimally, one should place the propane tanks outside and use black iron gas piping to bring it into the shop. There ahold be a shut off valve, main regulator, and solenoid at the tank. Inside there should be a main ball valve and a propane quick connect to attach the propane hoses that go to the forges and other burners.

Now, do I have all this (right now), NO, do most knifemakers have all this - NO, should we do it if we run a shop more than a day a week - YES.
A shutoff solenoid adds only about $50-100 to your setup, and could save you tens of thousands in damage.