My propane fired oven build

[bigtoy302]

Originally Posted by chromo

Looks like a great job and really nice.

I notice the elbow on the heater going into the oven though. Is that Galvanized and if so how hot does that get? Be careful of toxic fumes if galvanized duct gets too hot.

On dialup here and not seen all the pics load yet. Are you using a baffle to spread the airflow from the heater somehow?

Yes it galvanized. It does get really hot but no hot enough to burn the galvanized off. You definitely do not want to touch the elbow. It just blows straight into the oven. I am thinking about putting a baffle on it so it does not blow directly on large parts.

[russ_hillis]

I've been following this thread with some interest. Have you figured out how to light the heater automatically yet? I was thinking a thermo-coupler and a peizo would be part of the puzzle but I'm not sure how that would all tie together.

[ed_denu]

According to the AGA(American Galvanizers Association) galvanized steel can begin to have problems starting at temperatures of 390 degrees. Here is an excerpt from their web site:

"Very high temperature environments can have an affect on galvanized steel. These effects depend on the time exposed and the severity of the environment. When considering long-term exposure, the recommended maximum service temperature is approximately 390 F (200 C). Problems that could occur from long-term exposure to temperatures above this level include peeling. Peeling is caused by closely spaced voids that expand and form a gap, it causes the outer free zinc layer to split-off from the underlying zinc-iron alloy layers. However, the remaining zinc-iron alloy layers will still provide a high level of corrosion protection for many years.

At temperatures ranging between 390 F (200 C) and 480 F (250 C), the zinc-iron alloy layers will continue to protect the steel from corrosion. High temperatures above 480 F (250 C) will accelerate peeling and continued exposure can result in the zinc-iron alloy layers cracking and separating from the steel. Temperature applications of hot-dip galvanized steel above 480 F (250 C) are not recommended.

When considering short-term usage, that is, periods of less than two hours at a time or onetime temperature excursions for less than twenty-four hours, the recommended maximum service temperature for galvanized steel is approximately 660 F (350 C)".

[bigtoy302]

Originally Posted by russ_hillis

I've been following this thread with some interest. Have you figured out how to light the heater automatically yet? I was thinking a thermo-coupler and a peizo would be part of the puzzle but I'm not sure how that would all tie together.

Read the thread again. It is automatically fired by the pid with a 110V solenoid valve.

[bigtoy302]

Originally Posted by ed_denu

According to the AGA(American Galvanizers Association) galvanized steel can begin to have problems starting at temperatures of 390 degrees. Here is an excerpt from their web site:

"Very high temperature environments can have an affect on galvanized steel. These effects depend on the time exposed and the severity of the environment. When considering long-term exposure, the recommended maximum service temperature is approximately 390 F (200 C). Problems that could occur from long-term exposure to temperatures above this level include peeling. Peeling is caused by closely spaced voids that expand and form a gap, it causes the outer free zinc layer to split-off from the underlying zinc-iron alloy layers. However, the remaining zinc-iron alloy layers will still provide a high level of corrosion protection for many years.

At temperatures ranging between 390 F (200 C) and 480 F (250 C), the zinc-iron alloy layers will continue to protect the steel from corrosion. High temperatures above 480 F (250 C) will accelerate peeling and continued exposure can result in the zinc-iron alloy layers cracking and separating from the steel. Temperature applications of hot-dip galvanized steel above 480 F (250 C) are not recommended.

When considering short-term usage, that is, periods of less than two hours at a time or onetime temperature excursions for less than twenty-four hours, the recommended maximum service temperature for galvanized steel is approximately 660 F (350 C)".

So what your saying is that everybody's oven is going to start to fail? Most people's oven are sheeted with galvanized and I have never heard of issues with it failing or giving of noxious gasses.

[ed_denu]

Originally Posted by bigtoy302

So what your saying is that everybody's oven is going to start to fail? Most people's oven are sheeted with galvanized and I have never heard of issues with it failing or giving of noxious gasses.

I'm not saying anything. I'm just pointing out that according to the manufacturers, galvanized coatings can begin to fail at 390 degrees with prolonged use, or sooner with higher temperatures. The quote I referenced from the AGA site discusses the corrosion protection properties and how long HDG will last under certain conditions.

As for fumes, my understanding is that zinc melts around 900 degrees and vaporizes around 1650 degrees. These temperatures are much higher than most PC ovens would encounter. Zinc fumes are more of a concern when welding galvanized steel and proper protection, including the use of an appropriate welding mask should always be used.

[Cronox]

Hi big toy I have two questions about the oven. This oven can reach 700f temperature, it's to strong the air in the oven please let me know. Great Oven. thanks

Milton

[bigtoy302]

Originally Posted by Cronox

Hi big toy I have two questions about the oven. This oven can reach 700f temperature, it's to strong the air in the oven please let me know. Great Oven. thanks

Milton

I have not taken it over 400 yet. Why would you want to go to 700?

[SCOTTRODS]

Originally Posted by Cronox

Hi big toy I have two questions about the oven. This oven can reach 700f temperature, it's to strong the air in the oven please let me know. Great Oven. thanks

Milton

DUDE! if you're gonna powder coat, you need to change your signature to "Milton the Toaster". ! ! !

[SCOTTRODS]

Originally Posted by bigtoy302

I have not taken it over 400 yet. Why would you want to go to 700?

I think for Ceramics. They cure at around 600-650 I think....