More gas oven questions and a few good links

[BikerBill]

Hello again,

I am near completion of my large oven. I am stuck on using a gas fired heater. I know eveyone says do not do it, but I really haven't found out why.

I understand the explosive factor while spraying.

There is a "SLIGHT" risk of a circulating fan moving some stray powder to the source of an ignition. That could easily be eliminated with proper filtering.

I did some searching and found that the powder itself will become flammable around 900 degrees.. far above the curing point.

The fumes given of during curing are definitely not flammable.

So what is the real problem with gas fired ovens ? Is it just a liability issue the suppliers are using to cover them selfs from some idiot who tries to spray inside a lit gas oven

Look at the following links I have found for information on ovens and tell me what I am missing ?

http://www.coatings.de/manual/kap5-5.pdf
look at the image on the bottom of the page of a gas fired burner with a built in filter.

Also look at http://www.coatings.de/manual/kap5-2.pdf
this burner box looks as though small amounts of dust could come into contact with an open flame.

Any reason why I could not incorporate these ideas into my oven. I have the parts and knowledge to assemble a safe burner and controls. My only concern is all the talk about not using gas fired ovens for PC.

Aside from that here is a good link for a lot PC info
http://www.coatings.de/pcmanual.cfm

Bill

[DALE]

There is nothing wrong with useing gas ovens. There are many oven companies offering gas or LP ovens.

[BikerBill]

Dale,

Then why all the talk about how dangerous they are for PC

I have seen that companys sell them for the industry, But do they use heat exchangers or are they an open flame as in the links I posted?

Real estate is tight in my shop, to build an efficient heat exhcanger would take up half as much room as the oven.

Bill

[DALE]

They use heat exchangers. But I see no reason why your way won't work.

[Woodfrag]

All of these gas oven posts have had me thinking.
Has anyone considered making a sealed oven with the burners being located below an uninsulated area and the other 5 sides being insulated.

Other then temperature control and cold spots it seems to be a good idea. We do something similar to this for our clam bake steamer just minus the insulation. My thoughts for fixinG the cold spots also would be heat tiles on the floor to spread the heat evenly.

I've been doodling up some drawings but I figured I would throw it out in front of the pros first.

[planebuilder]

I am planning to build an 8' x 8' x 24' gas oven. I have a container to insulate and plan on building burners or setaling them from old gas furnaces. I have looked at lots of pics and drawings on the net of gas ovens and am not convinced that a heat exchanger that completely isolates the flame from the interior is common. It seems the flame is shielded and the exause and heat enters the oven proper a little downstream, and then recirculates behind baffels and through the flame area again...Does anyone know for sure!

[planebuilder]

P.S. There seems to be some false security about electric heat. I have seen red hot elements cause disasterous ignition. Wheather gas or electric it seems critical to prevent a powder cloud from being blown of the part in the oven.

[planebuilder]

Here is a link to a page that shows the circulation schematic in a gas oven, sure looks like no "isolated" heat exchanger.
http://www.spraytechsys.com/powder/s..._air-flow.html

[pickleboy]

it is not isolated but is seperated from the part area by a bulkhead.(notice the dashed lines in gray). this will cut down on the possibility of powder cloud getting to the flame area.

[dbug10]

I agree with Pickle i have a Genrich batch oven and there is no "heat exchanger" there is a bulkhead to seperate the flame from the oven but i have seen them built with an exposed flame in the bake chamber im not saying its ok but if you use common sense any configuration would be fine