I have an odd request from a customer (those are usually the most interesting though)

I need a heating element to heat air flow in a 3 in tube to 250 deg F. My guess is approx 50 CFM.
Now the tricky part. It needs to be waterproof, and I may actually see the tube filled with fluids frequently. Also needs to be sanitary and cleanable.
Any suggestions? I'm sure I wouldn't have enough surface area by just heating the tube wall (unless I have a long run) which would get expensive then.

Think BIG hair dryer that doesn't care about being dropped in a bathtub.

Not asking for much are they

The only "good" solution would be to heat the outside of the tube ( or add a second inner tube for additional surface area. )

There are heating elements that will take the fluid contact, but I don't think they would hold up to being heated to several hundred degrees to heat the air and then getting hit with a cool fluid!

_________________
Nick Hahn
Lornic Design

Specializing in pork harvesting equipment.

"The Standard Deviation of the Sampling Distribution of the Sample Mean ! " ( My wife's favorite statistics phrase! )

with a little more discussion with the customer, they want a few more "options" with this little project. Timers, auto temp control etc. I can justify a small PLC and will be able to "lock out" a couple valves and keep the heating element dry (all the time).

That should make it much easier to generate clean hot air.

Try these guys

http://www.ogdenmfg.com

We use their immersion heaters for water and they also have some duct heaters we use to create a "modified environment", basically its just a more controlled temperature and humidity chamber from proofing dough.

Hope this helps.

_________________
"24 hours in a day, 24 beers in a case. Coincidence? I think not."
~ Stephen Wright

An old co-worker EE sent me a link to the perfect thing. Ostram Sylvania makes exactly what I needed. It doesn't handle being flooded very well, but looks like it will do the trick.

http://www.sylvania.com/BusinessProduct ... AirHeaters

Very cool, we may have the need for such a thing also.

_________________
"24 hours in a day, 24 beers in a case. Coincidence? I think not."
~ Stephen Wright