Tubular Heaters Straight and Formed Standard Sizes and Materials
Cold Ends
The sheath materials available are stainless steel, steel, copper, and incoloy. Standard diameters are: .260", .315", .375", .440"and .475". Diameter tolerance is ±.010". Max. Temp. Max. Sheath Allowed Length Max. Cold Material on Sheath of Sheath Lengths
When not specified, cold ends will be the minimum length as shown in the table below. Longer cold lengths may be specified. Optional cold ends of unequal lengths are available.
Steel Copper St. Steel Incoloy
750ºF 350ºF 1200ºF 1600ºF
252" 252" 324" 324"
96" 96" 96" 96"
Sheath Length
Minimum Cold Ends
Up to 20" 20" to 100" 100" to 200"
1" 11⁄2" 4"
Mounting Fittings
Sheath Materials and Watt Densities Application Clamped to Surfaces
Still Air (Sheath Temp.) Clamped into Machined Grooves
Approx. Operating Temp.
Rec. Sheath Material
Watts/sq. in. Of Element Surface
up to 300ºF 500ºF 800ºF 1000ºF 1200ºF 1400ºF
Steel Steel Incoloy Incoloy Incoloy Incoloy
30 20 15 10 7 2.5
800ºF 1000ºF 1200ºF 1400ºF
Incoloy Incoloy Incoloy Incoloy
7 11 14 30
500ºF 800ºF 900ºF
Steel St. Steel Incoloy
25 15 15
Fittings are available with light jam nuts (plated steel), plain washers (plated steel), and/or copper gaskets. Brass bushings are used with copper and steel sheaths. Silver brazed stainless steel bushings are used with stainless steel and Incoloy sheaths. Welded stainless steel bushings are available at additional cost.
Formula for Determination of Unit Wattage
Catalog Number
Unit Wattage = Diameter x 3.142 x Heated Length x Allowable watts/sq. in.
Electrical Tolerances and Limits Min. OHMS/in. Max. OHMS/in. Max. Voltage Max. Amperes
.15 80 250 20
.315"
.375"
.440"
.475"
.05 50 300 30
.05 50 480 40
.05 50 600 40
.05 50 600 40
Wattage tolerance is +5%, -10% at rated volts.
Standard Length Tolerances Sheath Length Up to 20" 20" to 100" 100" to 200"
Thread Size B"
.260" .315" .375" .440" .475"
⁄2"-20 ⁄2"-20 5 ⁄8"-18 3 ⁄4"-16 3 ⁄4"-16
EF-12 EF-13 EF-16 EF-17 EF-17
1 1
Forming If you plan to do the bending required, observe the minimum bend limits in the table, and do not plan any bend within 1" of a cold end junction.
TUBULAR
Sheath Diameter .260"
Sheath Diameter A"
Annealing for bending must be specified.
Length
Heated Length
±1⁄16" ±1⁄8" ±1⁄4"
±2% ±2% ±2%
Web: www.hotwatt.com
If Hotwatt is to do the bending, submit a sketch showing clearly the form the bent unit is to take. Minimum Bend Radius Diameter
.260"
Formed By Factory
1
⁄4"
Formed By Customer
3
⁄4"
.315" ⁄16"
5
1"
Email: sales@hotwatt.com
.375" ⁄8"
3
11⁄4"
.440" ⁄16"
.475" ⁄16"
7
7
11⁄2"
11⁄2"
77