Thursday, December 31, 2015

Replacing the Print Head on AH4000 Recorder

AH400 Recorder
AH400 Recorder
The AH4000 multi-channel recorder is used on HotfoilEHS power consoles to monitor and record pre weld, soak, and post weld heat treating. One of the most common questions asked is how to replace the print head.

The video below provides visual, step-by-step instructions.

10 Million BTU Burner for Custom Designed Heat Treating Furnace

Custom heat treating furnaces are designed for the tempering of metals. These furnaces can be electrically heated, or gas heated, depending on the energy source available. Tempering is defined as (from Wikipedia):

"Tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy. The reduction in hardness is usually accompanied by an increase in ductility, thereby decreasing the brittleness of the metal. Tempering is usually performed after quenching, which is rapid cooling of the metal to put it in its hardest state. Tempering is accomplished by controlled heating of the quenched work-piece to a temperature below its "lower critical temperature". "

The video below shows the testing of a 10 million BTU ratio air burner designed for a custom heat treating furnace used to pre-stress large metal components prior to welding. Hotfoil-EHS manufactures complete furnace systems using OEM burners and in-house developed control systems.

For more information, contact:

2960 East State Street Ext.
Hamilton, NJ 08619
Phone # 609.588.0900
Fax # 609.588.8333

Tuesday, December 15, 2015

Self Regulating Heating Cable

Self regulating heating cable
Self regulating heating cable
Self-regulating heating cables automatically adjust their power output to compensate for temperature changes. The outer jacket, braid, and inner jacket provide mechanical, chemical, and electrical protection. The magic happens in the conductive core that surrounds the two parallel conductors. As the ambient temperature drops, the core contracts microscopically, and the number of electrical paths through the core increases, more heat is produced. Conversely, as the ambient temperature rises, the core expands and has fewer electrical paths, and less heat is produced. At a certain temperature, almost all the electrical paths are disrupted and power output is close to zero. A self-regulating heating cable adjusts its power output along its entire length. That's what makes it a safe and reliable solution for many applications.

Self-regulating cable is flexible, and is much easier than constant wattage cable because it can be cut-to-length in the field, terminated, and (if needed) overlapped without fear of burnout. This is very valuable in areas where complex piping systems exist with many valves, tanks and vessels.

As with any heat tracing cable, proper wattage requirements need to be calculated. In order to properly calculate wattage, the following information must be known:
  • Pipe size and material
  • Insulation type and thickness
  • Maintain temperature
  • Minimum ambient temperature
  • Minimum start-up temperature
  • Service voltage
  • Chemical environment
  • Maximum intermittent exposure temperature
  • Electrical area classification
Once this information is known, most manufacturers will have wattage calculators where you can simply use the above data to calculate your requirements.

Sunday, December 13, 2015

An Introduction to Thermocouples

Schematic of Type K Thermocouple
(courtesy of Wikipedia)
A thermocouple is a temperature sensor that produces a micro-voltage from a phenomena called the Seebeck Effect. In simple terms, when the junction of two different (dissimilar) metals varies in temperature from a second junction (called the reference junction), a voltage is produced. When the reference junction temperature is known and maintained, the voltage produced by the sensing junction can be measured and directly applied to the change in the sensing junctions' temperature.

Thermocouples are widely used for industrial and commercial temperate control because they are inexpensive, fairly accurate, have a fairly linear temperature-to-signal output curve, come in many “types” (different metal alloys) for many different temperature ranges, and are easily interchangeable. They require no external power to work and can be used in continuous temperature measurement applications from -185 Deg. Celsius (Type T) up to 1700 Deg. Celsius (Type B).

thermocouple attachment unit
Thermocouple attachment unit
For pre-weld heat treatment, Type K thermocouples are generally used. Thermocouples can be directly attached to the workpiece by spot welding the junction of Type K thermocouple wire. The attachment is done with the help of a TAU, or thermocouple attachment devices. Thermocouples are attached so that there is firm contact between the sensing tip and the assembly being heat treated.