Thermal Accessories Options & Descriptions

Hookup Thermocouple & Hi Temp Wire, Platen Bolts, Threaded Wells, Protection Tubes, SSSC, SSR, Connectors, High Temperature Electrical Plugs & Receptacles, & Terminals

  • Platen Bolts


                                                        Platen Bolts

    IHE offers a wide selection of carriage bolts in various thread sizes to fasten and secure material.  We carry hard-to-find structural bolts, machine screws and must-haves like wedge anchors, washers and rivets.  We can provide custom bolts, nuts, and screws for mining, heavy machinery, military, and equipment applications.  We work with sizes from 1/4" to 4" in diameter and lengths of up to 72".  IHE has the ability to meet your unique fastener requirements, such as extra-large and extra-long sizes.  If you need to drill a hole through a part, fit an extra thread, add a special body diameter, or create a special pattern across the flats, we can do it for you.  Blanks can be modified according to your exact need and specifications.  We understand the requirements for specialized bolts that meet all chemical and physical certifications you require.  We can supply custom fasteners and even package them according to your size, weight, container as well as labeling requirements, facilitating integration with your inventory plus handling systems.

  • Threaded Wells








    Threaded Wells

    Threaded Wells are pressure-tight receptacles that extend the life of a thermocouple in environments where the sensor does not have the mechanical or chemical strength to withstand the process flow or pressure.  Threaded Wells facilitate removing, changing, checking and/or replacing thermocouples without draining the process system, and thus allowing for little or no downtime.  The use of standardized Threaded Wells throughout permits easy relocation of thermocouples.

  • Protection Tubes



    Protection Tubes

    Metal and Ceramic Protection Tubes are used to protect thermocouples from:

    • From corrosive fluids and gases

    • From extreme pressures in a pressurized vessel

    • Against mechanical damage

    Protecting tubes, or wells, are used to protect the thermocouple junction.  A wide variety of tube materials are available to accommodate many applications.  To ensure minimum maintenance, the thermocouples have absolutely no moving parts.  Thermocouples with Protecting Tubes demonstrate the fastest response to temperature changes and offer the most reliable, lowest cost, and simplest solution for thermocouple protection in harsh industrial environments.  The wide range of options and accessories add to their versatility, and the rugged design makes them easy to install and maintain.

  • Solid State Switching Controls & Relays




                                                         Solid State Switching Controls & Relays

    A solid-state relay (SSR) is an electronic switching device in which a small control signal controls a larger load current or voltage.  It consists of a sensor which responds to an appropriate input (control signal), a solid-state electronic switching device which switches power to the load circuitry, and some coupling mechanism to enable the control signal to activate this switch without mechanical parts.  The relay may be designed to switch either AC or DC to the load.  It serves the same function as an electromechanical relay, but has no moving parts.  The control signal must be coupled to the controlled circuit in a way which isolates the two circuits electrically.  Many SSR's use optical coupling.  The control voltage energizes an LED which illuminates and switches on a photo-sensitive diode (photo-voltaic); the diode current turns on a back-to-back thyristor, silicon controlled rectifier, or MOSFET to switch the load.  The optical coupling allows the control circuit to be electrically isolated from the load.   A SSR based on a single MOSFET, or multiple MOSFETs in a paralleled array, works well for DC loads.  MOSFETs have an inherent substrate diode that conducts in the reverse direction, so a single MOSFET cannot block current in both directions.  For AC (bi-directional) operation two MOSFETs are arranged back to back with their source pins tied together.  Their drain pins are connected to either side of the output.  The substrate diodes are alternately reverse biased to block current when the relay is off.  When the relay is on, the common source is always riding on the instantaneous signal level and both gates are biased positive relative to the source by the photo-diode.  It is common to provide access to the common source so that multiple MOSFETs can be wired in parallel if switching a DC load.  Usually a network is provided to speed the turn-off of the MOSFET when the control input is removed.

    One significant advantage of a solid-state SCR or TRIAC relay over an electromechanical (EMR) device is its natural tendency to open the AC circuit only at a point of zero load current.  Because SCR's and TRIAC's are thyristors, their inherent hysteresis maintains circuit continuity after the LED is de-energized until the AC current falls below a threshold value (the holding current).  In practical terms what this means is the circuit will never be interrupted in the middle of a sine wave peak.  Such untimely interruptions in a circuit containing substantial inductance would normally produce large voltage spikes due to the sudden magnetic field collapse around the inductance.  This will not happen in a circuit broken by an SCR or TRIAC. This feature is called zero-crossover switching.

    Advantages of SSR's

    • Lower (if any) minimum output current (latching current) required.

    • Output resistance remains constant regardless of amount of use.

    • Inherently smaller than a mechanical relay of similar specification.

    • Increased lifetime, particularly if activated many times, as there are no moving parts to wear.

    • Clean, bounceless operation.  Decreased electrical noise when switching.  Totally silent operation.

    • No sparking, allowing use in explosive environments where it is critical that no spark is generated during switching.

    • Much less sensitive to storage and operating environment factors such as mechanical shock, vibration, humidity, and external magnetic fields.

    • SSR's are fast (SSR's switching time is dependent on the time needed to power the LED on and off, of the order of microseconds to milliseconds.

  • Sensors




    The three most commonly used sensors are Thermistors, Resistance Temperature Detectors (RTDs) and Thermocouples.

    A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors.  The word is a portmanteau of thermal and resistor.  Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting over-current protectors, and self-regulating heating elements.  Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals.  The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range, typically -90°F to 266°F (−90 °C to 130°C).

    Resistance temperature detectors (RTDs), are sensors used to measure temperature by correlating the resistance of the RTD element with temperature.  Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core.  The element is usually quite fragile, so it is often placed inside a sheathed probe to protect it.  The RTD element is made from a pure material, typically platinum, nickel or copper.  The material has a predictable change in resistance as the temperature changes; it is this predictable change that is used to determine temperature.  They are slowly replacing the use of thermocouples in many industrial applications below 1112°F (600°C), due to higher accuracy and repeatability.  There are three main categories of RTD sensors; Thin Film, Wire-Wound, and Coiled Elements.  While these types are the ones most widely used in industry there are some places where other more exotic shapes are used, for example carbon resistors are used at ultra low temperatures -279°F to -459°F (-173°C to -273°C).  Resistance thermometers are constructed in a number of forms and offer greater stability, accuracy and repeatability in some cases than thermocouples.  While thermocouples use the Seebeck effect to generate a voltage, resistance thermometers use electrical resistance and require a power source to operate.  The resistance ideally varies nearly linearly with temperature per the Callendar-Van Dusen equation.  The platinum detecting wire needs to be kept free of contamination to remain stable.  A platinum wire or film is supported on a former in such a way that it gets minimal differential expansion or other strains from its former, yet is reasonably resistant to vibration.  RTD assemblies made from iron or copper are also used in some applications.

    The advantages of platinum resistance thermometers include:

    • High accuracy

    • Low drift

    • Wide operating range

    • Suitability for precision applications.


    RTDs in industrial applications are rarely used above 1220°F (660°C).  At temperatures above 1220°F (660°C) it becomes increasingly difficult to prevent the platinum from becoming contaminated by impurities from the metal sheath of the thermometer.  This is why laboratory standard thermometers replace the metal sheath with a glass construction.  At very low temperatures, say below -454°F {(-270°C) (or 3 K)}, because there are very few phonons, the resistance of an RTD is mainly determined by impurities and boundary scattering and thus basically independent of temperature.  As a result, the sensitivity of the RTD is essentially zero and therefore not useful.  Compared to thermistors, platinum RTDs are less sensitive to small temperature changes and have a slower response time.  However, thermistors have a smaller temperature range and stability.  Measurement of resistance requires a small current to be passed through the device under test.  This can cause resistive heating, causing significant loss of accuracy if manufacturers' limits are not respected, or the design does not properly consider the heat path.  Mechanical strain on the resistance thermometer can also cause inaccuracy.  Lead wire resistance can also be a factor; adopting three-wire and four-wire, instead of two-wire, connections can eliminate connection lead resistance effects from measurements.  Three-wire connection is sufficient for most purposes and almost universal industrial practice.  Four-wire connections are used for the most precise applications.


    The two most common ways of measuring industrial temperatures are with resistance temperature detectors (RTDs) and thermocouples.

    Choice between them is usually determined by four factors:

    Temperature: If process temperatures are between −328°F to 932°F (−200°C to 500°C), an industrial RTD is the preferred option.  Thermocouples have a range of −292°F to 4,208°F (−180°C to 2,320°C), so for temperatures above 932°F (500°C) they are the only contact temperature measurement device.

    Response Time: If the process requires a very fast response to temperature changes—fractions of a second as opposed to seconds (e.g. 2.5 to 10 s)—then a thermocouple is the best choice. Time response is measured by immersing the sensor in water moving at 1 m/s (3 ft/s) with a 63.2% step change.

    Size: A standard RTD sheath is 3.175 to 6.35 mm (0.1250 to 0.250 in) in diameter; sheath diameters for thermocouples can be less than 1.6 mm (0.063 in).

    Accuracy & Stability Requirements: If a tolerance of 35°F (2°C) is acceptable and the highest level of repeatability is not required, a thermocouple will serve. RTDs are capable of higher accuracy and can maintain stability for many years, while thermocouples can drift within the first few hours of use.

  • Connectors



    Quick Disconnect High Temperature Electrical Plugs and Receptacles provide a simple and safe method of applying power to heater installations.  The combination of a plug and cup assembly married to an armored cable covering the leads eliminates all live and exposed terminals and wiring, eliminating potential hazards.  Mini-connectors are color coded and can be used in ambient temperatures to 400°F (205°C) continuous and 500°F (260°C) intermittent.  Hi-Temp Mini connectors are colored red and can be used to 800°F (425°C) continuous and 1000°F (540°C) intermittent.  Connectors are available in a variety of materials and configurations.

  • Hookup Wire / Thermocouple Wire




















    Hookup Wire/Thermocouple Wire

    High temperature lead wire as well as thermocouple wire is available in many different gages and classifications to match your specific needs no mater how complex.

    High Temperature Lead Wire is frequently used in scenarios where the application demands lead wire that can withstand between 302°F (150°C) and 842°F (450°C).  Conductors in high temperature cable can be either nickel coated copper, tinned copper, or pure nickel, while the insulation can range from rubber, PTFE tapes, and mica tapes to fiberglass and ceramic braids.  Thermocouple wire
    is flame retardant, resistant to chemicals, and excellent in high temperature applications.  Certain thermocouple wire types even have the capabilities to withstand environments up to 2200°F (1204°C).  Widely used in both science and industry, thermocouple wire continues to be a popular high temp wire because of its exceptional electrical and physical features.  Thermocouple grade wire is used to make the sensing point of the thermocouple.  Extension grade wire is used to extend a thermocouple signal from a probe back to the instrument reading the signal.  Both types of thermocouple wire are designed and constructed for continued, dependable, long term use.  Although thermocouple wire is a commonly used high temp cable, additional high temperature cable types are popular for various applications.

    Mineral-insulated copper-clad cable is a variety of electrical cable made from copper conductors inside a copper sheath, insulated by inorganic magnesium oxide powder (MgO).  Up to seven conductors are often found in an MI cable, with up to 19 available.  The inorganic construction of mineral insulated cable makes it extremely fire and heat resistant.  MI has an operating limit equal to the melting point of copper, 1982°F (1083°C).  Since MI cables use no organic material as insulation (except at the ends), they can easily withstand high temperatures and heavy current overloads. It emits no smoke or toxic substances and allows no flame propagation.  MI is more resistant to fires than plastic-insulated cables.  In process industries handling flammable fluids MI cable is used where small fires would otherwise cause damage to control or power cables.  MI cable is also highly resistant to ionizing radiation.  The metal tube surrounding the conductors effectively shields circuits in MI cable from electromagnetic interference.  The metal sheath provides protection against accidental contact with energized circuit conductors.  MI cables may be covered with a plastic sheath, colored for identification purposes.  The plastic sheath also provides additional corrosion protection for the copper sheath.  The metal sheath and solid filling of MI cable makes it mechanically robust and resistant to impact; an MI cable may be struck repeatedly and still provide adequate insulation resistance for a circuit. Copper sheathing is waterproof and resistant to ultraviolet light and many corrosive elements.  MI cable is approved by electrical codes for use in areas with hazardous concentrations of flammable gas in air.  MI cable will not allow propagation of an explosion inside the copper tube, and the cable is unlikely to initiate an explosion even during circuit fault conditions.  Metal sheathing will not contribute fuel or hazardous combustion products to a fire, and cannot propagate a fire along a cable tray or within a building.  The cable is inherently fire-rated without additional coatings, and will survive designated fire tests representative of actual fire conditions longer than the enclosing structure.  Although made from solid copper elements, the finished cable assembly is still pliable due to the malleability of copper.  The cable can be bent to follow shapes of buildings or bent around obstacles, allowing for a neat appearance when exposed.  Since the inorganic insulation does not degrade with (moderate) heating, the finished cable assembly can be allowed to rise to higher temperatures than plastic-insulated cables.

Thermocouples are perishable items and the controller where they connect to may be many feet away. To safe on maintenance costs, use jacks and panels to connect the lead wires from the thermocouples to the extension THERMOCOUPLE WIRE (which the are connected to a control panel). Correctly chosen thermocouple extension wires and properly fitted connections will allow for an extension of up to 100ft without affecting the thermoelectric characteristics.  When ordering thermocouple wire, we need to know: desired wire gauge, solid or stranded, wire insulation and anything else about your application or process that you can share.


In the industrial heating industry, most standard wire can withstand continuous temperatures up to 450°F. These wires may have a PVC, Teflon or Silicone insulation and may have metallic armor to protect the conductors insulation material.


High temperature wire can withstand continuous temperatures up to 1200°F at a maximum of 600 continuous Volts. To withstand these temperatures, high temp wires have different coatings than standard wires. Common features of high temperature wire is that it is often insulated with MICA tapes and a fiberglass braided jacket which is sometimes the chemically treated For extra mechanical protection, high temperature wire can be ordered with a stainless steel jacket.



Our specialty is Industrial Heating Applications and Processes all the way up to 2200˚F.


IHE is The Premier Location to find all of the Industrial Heaters, Thermocouples, Temperature Controllers, Metals Alloys, Platens Dies & Tooling, and Thermal Accessories you need.  We provide essential Thermal Application and Process services for any size project, such as Thermal Design & Engineering, Thermal Consultation and Thermal Supply.



Need the accessories to go with your latest Thermal Project?  Need to retrofit or replace older parts and pieces on your existing systems?  No problem, we supply all of the Platen Bolts, SSR's, Hookup Wire, High Temp Wire, Connectors and anything else you could think up or possibly need, to help your project stay operational and avoid costly down time.



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