Hi-Density Cartridge Heater Specifications and Tolerances

Performance Ratings

Maximum Temperature: 1400°F (760°C)

Maximum Watt Density: 100-300 W/in2 (15.5-46.5 W/cm2) depending on heater size & operating temperature.

Note: The maximum operating temperature and the life expectancy of a cartridge heater is dependent on two main factors:

1. The maximum recommended sheath temperature (1200°F for a standard heater)

2. The maximum ambient temperature for the termination selected. Consult Tempco if you require a recommendation for your application.

Dimensional Specifications

Nominal Diameter1/4″5/16″3/8″1/2″5/8″3/4″1″
in(mm)in(mm)in(mm)in(mm)in(mm)in(mm)in(mm)
Actual Diameter0.2466.250.3087.820.3719.420.49612.60.62115.770.74618.950.99625.3
Diameter Tolerance±.0020.051±.0020.051±.0020.051±.0020.051±.0020.051±.0030.076±.0030.076
Minimum Length125.4125.4125.4125.4125.41 1/431.751 3/444.45
Maximum Length3691436914481219601524721829721829721829
Length Tolerance±3/32(2.4)±3/32(2.4)±3/32(2.4)±3/32(2.4)±3/32(2.4)±1/8(3.2)±1/8(3.2)
Heaters up to 5″ (127 mm)
±2% of Sheath Length Heaters over 5″ (127 mm)
Camber Tolerance Heaters up to 12″ (305 mm) long0.010″ (0.254 mm) per foot of length
Camber Tolerance Heaters over 12″ (305 mm) long0.020″ (0.508 mm) per foot of length

Scroll table to view all

A certain amount of Camber is unavoidable. With a slight force, Hi-Density Cartridge Heaters will flex enough to fit into a straight reamed hole.

Electrical Specifications

Nominal Diameter1/4″5/16″3/8″1/2″5/8″3/4″1″
Maximum Voltage240240240240480*480*480*
Maximum Amperage4.44.56.710.5232323
Maximum Amperage for Types C1C, C1D, C2C, C2D, CS, F, M3, R1B, S1, S2, SA, W & W3 Terminations335.57.69.79.79.7
Minimum Wattage at 120V on a 1″ long Heater5045455050
Minimum Wattage at 120V on a 2″ long Heater20202020202020
Maximum Wattage at 120V5255408001260276027602760
Maximum Wattage at 240V1050108016002520552055205520
Maximum Wattage at 480V11,00011,00011,000
Wattage TolerancePlus 5%, Minus 10%
Resistance TolerancePlus 10%, Minus 5%

† Current carrying capacities are for ambient temperatures up to 482°F (250°C) with mica insulated lead wires.

*480V when applicable. Consult Tempco.

Length TOLERANCE for:
— Lead Wires
— Wire Braid Leads
— Armor Cable Leads

  • Up to 36″: -1/2″, +1″ (-12.7 mm, +25.4 mm)
  • 36″ to 72″: -1″, +2″ (25.4 mm, +50.8 mm)
  • Above 72″: ±4″ (101.6 mm)

Note: Specifications detailed on this page are standard. Consult Tempco if your application requires tighter tolerances or has other special requirements.

Temperature Coefficient of Resistance

The electrical resistance (ohms) of the heater resistance wire increases with temperature rise.

Tempco standard Hi-Density Cartridge Heaters are manufactured with ohms (cold ohms) 3.3% lower than the actual calculated ohms (hot ohms) to compensate for this increase.

Available Electrical Features

DiameterDual Volts3-PhaseDual CircuitsMultiple Heat Zones
(maximum 3 zones)
1/4″NoNoNoNo
5/16″NoNoNoNo
3/8″Yes*NoNoYes*
1/2″Yes*YesYesYes*
5/8″YesYesYesYes
3/4″YesYesYesYes
1″YesYesYesYes

Consult factory for maximum wattages and voltages.

* Heaters may require a larger diameter transition area at lead end.