Variable Heat

[Holeshot]

I am looking for a way to control the tempature of a stream of air. Right now I am using a industrial heat gun (because it is small) running through a contactor. That is fine for turning it off and on but I have no control over the heat level. Its a 110vac gun, I may have to go to a 3 phase if anyone makes one. I am flexible with voltage and I can send analog signals. I just cant find anything that will give me this kind of control. Maybe the key words I have been using on google are not the ideal ones, or maybe I am searching for something that dosent exist. Suggestions apreciated, and I can answer questions.

 

[Tom Jenkins]

Watlow and Chromalox make industrial heating elements. Omega Engineering makes an analog to duration conversion module specifically for controlling heaters, and also have heating equipment.

 

[azecraze]

Tom just mentioned Watlow, and that just happens to be the type of load controller I am using on my hydro plant.

I am using Watlow Din-a-Mite.
They have good analog input capabilities and the models I am using are rated at 80A single phase.

 

[Lancie1]

Well, if you really want to use a heat gun, you could :

( Rube Goldberg METHOD 1)

1. Install a thermocouple or RTD to meausre the temperature;

2. Feed the temperature signal to a 4- 20 mA output temperature controller;

3. Send the temperature controller output to a stepper motor or positioner motor;

4. Use the stepper motor to turn the shaft of an autotransformer (Variac is one brand), proportionally to the temperature.

5. Install the variable autotransformer between your contactor and the heat gun power supply to control the voltage, and thus the temperature.

OR METHOD 2: Do what Tom Jenkins said, get a temperature controller and a heating element.

 

[Ron Beaufort]

I'm probably missing something here ... but are you turning the whole heat gun (blower and all) off and on? ... if so, then you probably need to take the thing apart and separate out the wires for the heating element ... then leave the air blower running constantly and cycle just the heating element off and on ... a contactor may work for what you need to do ... but a solid state relay would probably be better in the long run ...

note: if this happens to be a cheaper type of heat gun, then you might not be able to do this "separate the heater from the blower" thing ... some cheaper types use the resistance of part of the heating coil to drop the voltage for the blower motor ...

one of the parts that Tom Jenkins referred to can be found at:

Omega Engineering

search for part number PCM1 (price tag = about $110) ... you'll also probably want to get one of their SSR (solid state relays) and a heat sink ... these parts will give you one neat little package ... you can feed a 4-20 mA signal to the pulse control module ... it will send time-proportional signals to the SSR ... the heating element will pulse off and on ... and you should be in business ... at least for the output side of things ... so how are you going to tell how hot the air stream is? ... or are you just manually dialing in an output signal? ...

finally ... if you tell us what you're building (and your budget), we can probably give you better advice about how to get the job done ... is this a "just for myself at home" type project ... or something for long term industrial use? ...

 

[Holeshot]

Thanks For the leads Tom, azercraze and Lancie!

Ron good questions and I will try to answer them all.

You are not missing anything, I am turning it all off and on. The only control I have for the temperature is the potentiometer on the heat gun.

if so, then you probably need to take the thing apart and separate out the wires for the heating element

Good idea there except it doesn’t give me control over the temperature output.

This is an industrial machine, we are using the heat gun to cut thin plastic of a large load of product. The plastic is similar to the saran wrap you use to cover your food. At different times the manufacturing facilities will be running different product, with different properties, that force us to change the "cutting" temperature. After a line of wrap is cut we remove it off the load.

I used a cheap industrial heat gun to test the theory. The life expectancy and reliability of these heat guns is not good enough for an industrial application. I dont necessarily have to know the temperature output as much as I need to be able to change it. Although knowing the temperature would be helpful.

I am going to check out the suggestion Ron made.

Thank you very much for your time and input. This is a great forum, usually I just view because you guys are more helpful than I can be. I’m glad there is a place that people can share ideas and thoughts like this.

Thanks again