Juramentado
We assume that the temperature of a blade in the forge is that same as the temperature of the inside of the forge itself.
Yes of course you are right. Any standard thermometers, including a bimetal thermometer cannot stand forge environment temperatures.
As Stacey suggested, a thermocouple is the normal system used. It is convenient, easy to setup and read, and inexpensive
The problems with using the infrared thermometers on steel can be seen a few links into the product that Carl Anderson posted.
Emissivity
It is important to understand that there are factors that can affect the accuracy of infrared thermometers. One important principle to understand is the concept of emissivity. Some forms of matter emit infrared radiation differently at the same temperature compared to a different form of matter. This property is influenced by the reflectance of the substance. Metal, glass, and wood all have different emissivity ratings between 0 - 1.0 this is one of the key technology differences you will see in different models of infrared thermometers. Most commons substances such as wood, rock, rubber and organic substances have an emissivity rating around 0.8 - 0.95. Therefore, many lower grade infrared models are designed fixed for this emissivity. . This is because it covers the vast majority of items you will be testing. It is important to understand that things with higher reflectance like shinny metal or tin foil are going to have an emissivity ratting closer to 0.1 -therefore, a lower model with a fixed emissivity at 0.95 will not be as accurate when measuring a shinny metal substance. Therefore, if you feel you may potentially use you device for shinny metal testing, we strongly recommend buying a unit with an adjustable emissivity between 0.1-0.95
A thermocouple (or some makers install more than 1 in a forge) reads constantly and consistently, not changing depending on how you point it.
You can watch for a rising or dropping heat - important to some forging processes
The company that I refer to for this kind of product is
http://www.omega.com/
If you are the reading sort, you can read all their literature and figure it out for yourself.
If you prefer, use the online product selector to order online or, call customer service and they can figure it out for you.
In a quick search this is what I find that may suit your needs
Assuming a K type thermocouple for a high temperature limit of 2440 degrees F
(Celsius readouts are available if you prefer)
High heat environment
Armored or high temperature cable sheathing
Long Life at High Temperatures
Readout
http://www.omega.com/ppt/pptsc.asp?ref=DP7000
$55
AND
Thermocouple
http://www.omega.com/ppt/pptsc.asp?ref=KQXL_NQXL
$26
Hookups are simple
1- Power to the unit
2- Wire from thermocouple to the unit.
Plus you need to put it into a little steel box enclosure.
Depending on your needs, you can choose compatibility with different power sources.
110 VAC, 220 VAC, 24VDC
I have seen many people buy stuff on E-Bay which comes without any tech info or support and then post here looking for advice on how to hook it up.
Although these are relatively simple devices, save a headache and use the customer service in a reputable company to help you match your purchase to your needs.
Or take this info and buy it locally to you.
(Where are you Manila in the Philippines?)
Im assuming if you knew any of this you wouldnt have posted your question so I hope this helps
Oh any for those who want to build their own electric furnaces
Electric controllers
http://www.omega.com/pptst/CN7500.html
$90
http://www.omega.com/ppt/pptsc.asp?ref=CN7800
$100
I know someone will now list 15 places where I can get it cheaper
(
.so any tips-where can I get it cheaper?)
Steve
