A Specialty Temperature Sensor Specifically for Improving Heat Tracing Applications

Heat Tracing RTD (courtesy of
Applied Sensor Technologies)

A temperature sensor is key to any heat tracing application as it provides temperature feedback about the pipe temperature, which in turn, is used turn on or off the heating system (electric pipe tracing or steam control valve).

The temperature sensor is critical for both categories of heat tracing - process temperature maintenance and freeze protection.  Failure to maintain process temperature in a pipe or vessel could significantly effect product quality, or cause failure of ancillary equipment such as pumps, valves, and compressors. Properly protecting against freezing keeps pipes from bursting or product from blocking the flow. For both situations, product maintenance and freeze protection, accurate and reliable temperature sensing is critical.

There’s a new and very innovative line of RTD temperature assemblies specifically designed for heat tracing applications. The unique, replaceable element concept can save customers both time and money, plus increase overall system reliability and up-time.

A major refining company determined that they save over $1,000 in labor each time they have to replace a sensor and have reduced their repair time from two days to less than one hour.

The design consists of a terminal head and right-angle shaped outer sheath, with a curved weld-pad at the end. The replaceable RTD element assembly is contained in the outer tube and, when installed, presses against the pipe. Heat transfer is excellent and heat conduction away from the element is minimal. Should the element ever need to be replaced, it's a five-minute job to open the terminal head, unwire the sensor, slide it out and slide a new one in.

For more information, contact:

Ives Equipment
(877) 768-1600

www.ivesequipment.com

Basics of Self-Regulating Heat Trace Cable

Self-regulating Heat Tracing Layout

Self-regulating heater cable is a parallel circuit electric heater strip. An irradiation cross- linked conductive polymer core material is extruded over the multi-stranded, tin-plated, 18-gauge copper bus wires. The conductive core material increases or decreases its heat output in response to temperature changes. A thermoplastic elastomer dielectric jacket is then extruded over the conductive core. A copper braid is installed over this jacket providing a continuous ground path. A UV stabilized thermoplastic elastomer overjacket is provided to cover the braid for wet applications and exposure to the sun.

Principle of Operation:

The parallel bus wires apply voltage along the entire length of the heater cable. The conductive core provides an infinite number of parallel conductive paths permitting the cable to be cut to any length in the field with no dead or cold zones developing. The heater cable derives its self- regulating characteristic from the inherent properties of the conductive core material. As the core material temperature increases, the number of conductive paths in the core material decreases, automatically decreasing the heat output. As the temperature decreases, the number of conductive paths increases, causing the heat output to increase. This occurs at every point along the length of the cable, adjusting the power output to the varying conditions along the pipe. The self-regulating effect allows the cable to be overlapped without creating hot spots or burnout. As the cable self-regulates it heat output, it provides for the efficient use of electric power, producing heat only when and where it is needed, and also limiting the maximum surface temperature.

Application:

Self-regulating heater cable is ideal for use in maintaining fluid flow under low ambient conditions. Freeze protection and low watt density process temperature systems such as pipelines, fire protection, process water, dust suppression systems, hot water and structure anti-icing are typical applications for this product. For other than metal pipe heating, see appropriate application guide. The base product is supplied with a copper metal braid with a thermoplastic elastomer overjacket for wet applications, exposure to the sun, and where mechanical abuse is a problem. Cables are UL Listed and CSA Certified for use in non-hazardous locations and can be used on branch sprinkler systems.

For more information see the following Nelson Electric product sheet.

Self-Regulating Heat Trace Cable Application and Operating Principles from Ives Equipment