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Heaters, Sensors, Controllers, Relays, Linear Displacement, and Leadwire

Tubular Heater Manufacturer & Distributor

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Information

MPI offers you the absolute best tubular element, available 0.260”, 0.315”, 0.375” & 0.430” sheath O.D. Tubular elements are the most versatile, dependable and rugged of any heat generating device. These qualities make it an ideal heat source for many applications. The Tubular Element is the core of the most common heating solutions found today.
MPI Tubular Elements are manufactured from the highest quality materials. This gives you the most dependable heat source for your specific needs.

****Metric Diameters also Available****

Applications

  • FORMING MACHINES
  • HEATING MOLDS & PLATENS
  • IMMERSION INTO LIQUIDS
  • RADIANT & CONVECTION HEATING
  • EMBEDDED OR CAST INTO METAL
Construction
Standard Specs & Tolerances
Overall length (inches)11-2021-4041-7071-100101-140141-170171-200201+
Tolerance in sheath length (+/- in)0.10.1250.160.190.220.250.3750.5
Tolerance in heated length (+/- in)0.250.50.91.1301.41.6522.38
Min. unheated length (inches)11.251.51.6251.752.252.252.5

 

Tubular diameter (inches)Maximum voltageMaximum ampsMinimum Ohms per heated length (inches)Maximum Ohms per heated length (inches)Minimum sheath length (inches)Maximum sheath length (inches)
0.260240150.11711240
0.315300300.062011240
0.375600300.052011240
0.430600400.052011240
0.475600400.052011240
Selection

The two most critical factors that affect the durability of a tubular heater are:

  • Sheath material
  • Watt density

The corrosivity of the medium and its operating temperature are critical in determining the sheath material type. The table below lists various sheath materials, maximum allowable temperatures and mediums within which they are recommended to operate.

The watt density determines the temperature that a heating element sheath will attain within specific application conditions.

Sheath MaterialMaximum Sheath TemperatureApplications
Copper350°FImmersion into water and non-corrosive low viscosity liquids
Steel750°FOil, wax, asphalt, cast in aluminum or iron
Stainless Steel 304-3161200°FCorrosive liquids, food industry, sterilizers
Incoloy1500°FAir, corrosive liquids, clamped to surfaces

 

THE WATT DENSITY IS DETERMINED WITH THE FOLLOWING FORMULA:

FACTORS TO BE CONSIDERED WHEN SELECTING WATT DENSITIES

  • Application temperature
  • Application conditions
  • The maximum recommended temperature for the selected sheath material (table shown above).
  • The maximum watt density recommended for the material being heated. The table below shows some popular materials with their maximum recommended operational temperatures and watt densities.
  • In the case of possible scale or sludge formation, heater elements should run at lower watt densities.
  • In clamp-on applications, graph 1 (see below) shows the relationship between the watt density of the heating elements, the required operating temperature, and the maximum targeted sheath temperature.
  • When heating gases, the speed of the incoming gas and its outlet temperature should be considered in watt density calculations. Graphs 2, 3, 4 and 5 (seen below) show the relationship between the flow rate of air, its outlet temperature, the sheath temperature of the heating element selected and its corresponding watt density.
  • When operating in vacuum, the watt density should be 20% to 30% lower. Because of the absence of air, heaters in vacuum mostly conduct heat through radiation.

MAXIMUM WATT DENSITY RATINGS FOR VARIOUS SOLUTIONS

SolutionMaximum Watts/in2Max Operating Temperature (°F)
Acetic acid40180
Chromic acid40180
Citric acid23180
Nitric acid20-25167
Phosphoric acid25-28180
Alkaline solutions40212
Asphalt, tar4-10200-500
Bunker C fuel oil10160
Caustic soda 2%45210
Caustic soda 10%25210
Caustic soda 75%10180
Ethylene glycol30300
Fuel oil pre-heating9180
Gasoline20300
Machine oil, SAE 3018250
Mineral oil16-26200-400
Molasses4-5100
Heat transfer oils12-20500-650
Vegetable oil30-50400
Degreasing solution23275
Hydraulic oil12-15100
Sodium phosphate40212
Trichlorethylene23150
Clean water55-80212
Deionized water60212
Demineralized water60212
Moisture Proofing

MOISTURE RESISTING SEALS

The MgO insulating medium inside a tubular heater is highly hygroscopic and can absorb moisture from its terminal ends. Moisture resisting seals are barriers that resist or stop moisture and contamination.

SILICONE RESIN

This seal is a silicone-based resin that is applied to tubular heater terminal ends. The seal penetrates a short length of the MgO insulation and transforms it into a moisture and contamination resistant medium suitable for temperatures below 390°F.

RTV SEAL

This is a silicone room temperature vulcanizing seal that can resist moisture and contamination for up to 450°F.

EPOXY SEAL

This is a liquid resin which is thermally cured to reach solid state. This moisture barrier is adequate for temperatures up to 250°F.



Bend Configurations (Fig 1-8)
Bend Configurations (Fig 9-16)
Bend Configurations (Fig 17-24)
Bend Configurations (Fig 25-31)
Bend Configurations (Fig 32-35)