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Screw Plug Immersion Heaters

Industrial immersion heaters are medium capacity heating units designed to heat liquids, viscous fluids, forced air and gases inside tanks, vessels, and pipes. Bucan screw plug electrical immersion heaters are designed to be immersed directly into the gas or liquid being heated; since these heaters come into direct contact with the gas or liquid, heat-up times are very fast.

Immersion heaters manufactured at Bucan consist of a single or a set of tubular elements that are formed into hairpins and welded or brazed to a screw plug. The sheath material of the heating elements could be steel, copper, stainless steel or Incoloy.

The standard screw plug sizes utilized are 1”, 1 1/4, 2” and 2 1/2” and are made of steel, brass or stainless steel, depending on the application. Various types of electrical protective enclosures, built-in thermostats, thermocouples and high-limit switches can be incorporated into screw plug immersion heaters.

Immersion heaters may be used to heat up flammable liquids or gases in industrial applications. Contact us to inquire about our explosion proof housing units.

Screw Plug NPT size Plug material Standard element diameters Maximum voltage Phase Heating elements material Maximum number of elements
1" BRASS
STEEL
SS 304
SS 316
0.315" / 0.375" 300 V / 600 V 1 COPPER
STEEL
INCOLOY 800®
INCONEL 600®
SS 304
SS316
2 / 1
1 1/4" 0.315" / 0.375" 300 V / 600 V 1 / 3 3
2" 0.430"  600 V 3 3
2 1/2" 0.430" 600 V 3

3

  • PROCESS WATER HEATING
  • HEATING OILS, WAX, TAR, ASPHALT, PARAFFIN
  • MILD ALKALINE & ACID SOLUTIONS
  • FREEZE PROTECTION
  • EQUIPMENT WARM-UP
  • HEATING GASES
  • FOOD PROCESSING

MAXIMUM TEMPERATURE AND SHEATH MATERIAL SELECTION TABLE

Heater sheath Maximum sheath temperature Used to heat
Steel 750°F (400°C) oil, hydraulic oil
Copper 360°F (180°C) water, tap/municipal only
Incoloy 800® 1500°F (815°C) water, alkaline solutions, air, gases, radiant
Incoloy 840® 1400°F (760°C) air, radiant
Inconel 600® 1600°F (870°C) strong alkaline solutions, high temperature gases
Stainless steel 1200°F (650°C) de-ionized, de-mineralized, process water, some mild acids

 

  • NEMA 4 (MOISTURE PROOF) TERMINAL BOX
  • BUILT-IN THERMOWELL
  • BUILT-IN SINGLE OR DOUBLE POLE THERMOSTATS
  • PASSIVATION FOR STAINLESS STEEL AND INCOLOY HEATERS
  • BUILT-IN PROCESS OR HIGH LIMIT THERMOCOUPLES
  • SPECIAL PLUGS OR NON-STANDARD THREAD SIZES
  • NEMA 7 (EXPLOSION PROOF) TERMINAL BOX, PLEASE CONSULT THE FACTORY

Thermostats

Immersion heaters use the bulb and capillary style thermostats. These thermostats operate by the principle of expansion and contraction of a heat sensitive liquid found inside the bulb and capillary assembly, which controls the activation of an electrical switch inside the thermostat.

Thermostats in most cases open the electrical circuit when the desired temperature is attained (open on rise). The standard thermostat utilized is 25A Max, up to 240V, single-pole single-throw style with a temperature range of 10-120°C. The table below shows other ranges of thermostats that are available.

Thermostat Contact Operation Temperature Range Maximum Amps Maximum Voltage
T SPST 10 to 120 C 25A 277V
T1 SPST -18 to 40C 25A 277V
T2 SPST 70 to 280C 25A 277V
T3 SPST 160 to 370 C 25A 277V
T4 DPST 10 to 120 C 15A 600V
T5 DPST -18 to 40C 15A 600V
T6 DPST 70 to 280C 15A 600V
T7 DPST 160 to 370 C 15A 600V

Terminal Boxes for Screw Plug Immersion Heaters

Terminal Box Type Fig.# Dimension "A" Dimension "B" Dimension "C" Hole Size "E"
NEMA 1 Terminal box fig. 1 3 3/4" Dia. 2 3/4" N/A 7/8" knock-out
NEMA 1 Terminal box with built-in thermostat fig. 2 3 3/4" Dia. 3 3/4" N/A 7/8" knock-out
NEMA 4 / NEMA 7 Terminal box fig. 3 3 1/2" Dia. 3 1/8" 4 1/2" 1" NPT
NEMA 4 / NEMA 7 Terminal box with built-in thermostat fig. 4 4 1/4" Dia. 5 3/16" 5 1/4" 1 1/4" NPT