PID Controller & thremocouples

[Dixieblade57]

Clueless
I have been looking at some of the PID controllers on EBay but, I really do not have a clue what I am looking for.
Here is what I will be using it for. In its infancy the PID controller, working with a K type thermocouple, (at least that is what I think I need).
The PID will just be used to measure the given temperature of my propane forge while operating.

However in the future I intend to rework the forge and install gas solenoids. Then the PID will have to be able to turn off and on the solenoids to maintain a set temperature. That way I can let the unit bring me up to temp and maintain it. I would also like to if I decide at a later date to use a blower that the controller can also turn it on and off if necessary.
I think being able to program it to use my forge to HT would be a great feature also. You know like being able to bring to a certain temp and maintain that and the either go up or down for a certain period of time, etc., etc.!

So what the heck am I looking for?
Is there a certain model number I need to be looking for?
If not please at least make me a list of the features that I need to looking for in the specs!

I just don't want to buy one that is not going to work for my needs wheter it be for the present or later when I upgrade it doesn't have the capabilities to handle the additional tasks.

 

[Dixieblade57]

NO replies!

Is the question that stupid or is it worded incorrectly/poorly. I am not going to make anyone sign anything in blood.

I just need some advice on how to get the right PID!!!!!!!!! They can't all be the same but, I am unsure of which I need

 

[Ed Caffrey]

Maybe I can help....I use PID controllers for both controller functions and for pyrometers in my shop.

First, let me give you my opinion on building a forge that uses solenoid/PID controllers. It might seem like a great idea, but in reality, I would discourage it. Changing the set-point on the PID is not as quick and easy as you might think, and unless your planning on using the same temp all the time in a forge, it becomes a hindrance. You are also putting more parts into a forge, which just gives you more things to go wrong. I just don't like them, nor think they are a good idea.

OK, that being said, you basically have two options with a PID controller.... A single line readout, and a dual line readout. I use the single line readout models for pyrometers in my forges, and use the dual line readout models for controllers for my salt pot, and my quench tank.

Heres an example of the single line readout model:
http://cgi.ebay.com/UNIVERSAL-PID-T...emQQptZLH_DefaultDomain_0?hash=item2ea8ece00b

Heres an example of the dual line readout model:
http://cgi.ebay.com/PID-SSR-TEMPERA...emQQptZLH_DefaultDomain_0?hash=item35a4570f74

I generally use thermocouples from Omega.com:
http://www.omega.com/ppt/pptsc.asp?ref=JTIN&Nav=tema07

The main difference between the two PID controllers is that the single line does not display the set point....only the temp read from the thermocouple. The dual line readout shows the set point on the lower line, and the temp read from the thermocouple on the top line.

Both have the same setting parameters and capabilities.