Tubular Heaters
Highly versatile and economical Durex tubular heating elements are applied in virtually every conceivable type of
heating application. These robust heaters are a reliable thermal source used to heat a multitude of liquids, gases,
and solids and can be applied straight or bent into complex formations. Tubular heaters are also used for radiant
heating in open air or in vacuum atmospheres. The elements can be cast into or clamped onto metal to form heated
parts. A wide selection of standard designs are available or they can be custom designed for your requirements.
Durex Industries’ application and design engineering team are available to assist in specifying the proper heater
configuration.
Terminal Pin
Tubular Heaters
INTRODUCTION
Nickel-Chromium
Resistance Wire
Threaded Stud
MgO Insulation
Metal Sheath
Design Features
Typical Applications
Precision helical wound nickel-chromium resistance wire
• Metal mold, die and platen heating
◦ Provides uniform thermal profile
Circumferential cold pin-to-wire fusion weld
◦ Ensures robust connection for long heater life
Compacted, high purity MgO dielectric insulation
◦ Extends resistance wire life at high temperatures
Recompacted bends
◦ Provides longer life by ensuring insulation integrity
UL & CSA recognized elements available
◦ Assures safe and reliable performance
• Medical and analytical device heating
• Cast into metal parts and platens
• Cut and seal heads on packaging equipment
• Tank wall and pipe heating
• Liquid immersion & circulation heaters
• Furnace & oven heating
• Comfort heating and freeze protection
• Process air and gas heating
• Thermoforming, curing, drying
1
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
TUBULAR HEATER SPECIFICATIONS
Sheath Diameter +-0.005” (+-0.13mm) 0.260” (6.60mm) 0.315” (8.00mm) 0.375” (9.52mm) 0.430” (10.92mm) 0.475” (12.07mm) 0.496” (12.60mm)
Sheath Length Max.
404” (10,260mm) 370” (9398mm) 337” (8560mm) 329” (8356mm) 281” (7137mm) 263” (6680mm)
Maximum Voltage
250
480
480
600
600
600
Maximum Amperage
15
30
30
40
40
40
Wattage Tolerance
Industry Standard +5% -10%
Resistance Tolerance
Industry Standard +10% -5%
Length Specifications
Overall Sheath Length
Sheath Length
Heated Length
Minimum Unheated
11-20”
± ³/₃₂”
± ¹/₄”
1”
21-50”
± ⅛”
± ¹/₂”
1 ¹/₄”
51-80”
± ⁵/₃₂”
± ⁷/₈”
1 ½”
81-110”
± ³/₁₆”
± 1 ¹/₈”
1 ⅝”
111-140”
± ⁷/₃₂”
± 1 ³/₈ “
1 ¾”
141-170”
± ¹/₄”
± 1 ⁵/₈”
2”
171-200”
± ³/₈”
± 1 ⁷/₈”
2 ¼”
201” & up
± ¹/₂”
± 2 ³/₈”
2 ½”
Tubular Heaters
Physical and Electrical Specifications
APPLICATION GUIDELINES
Heating Metal Parts
Below are the installation methods for heating metals in order of best to least effective.
FAIR - Clamp On
BEST - Cast In or Milled Groove Plates
GOOD - Milled Groove & Plate
Excellent contact along heater sheath
Air gaps reduce heat transfer
Very little heater-to-part contact
makes it difficult to transfer heat
Durex recommends to “press fit” the tubular element into milled groove plates for extended heater life. Ensure that
all heated portions of the heater are in contact with the part. Heat transfer cement should be used to promote heat
transfer. If clamps are used, they should be closely spaced and not over tightened to ensure good heater-to-part
contact. Allow for up to 10% length increase due to thermal expansion during heating.
Heating Liquids
To prevent overheating or fouling the heater element, ensure the heated portion of the
tubular heater is immersed in liquid AT ALL TIMES. For optimal results, properly match
the sheath material and heater watt density to the liquid application. Factory installed
fittings or field installed compression fittings are used to mount and seal the tubular
element against the tank wall. Refer to the Immersion, Circulation and Over-The-Side
Heater sections of the catalog for other liquid heating products.
Heating Air & Gases
Tubular elements are typically formed into a “U” hairpin or other formation,
installed through wall openings and secured with lock washers, clips,
threaded fittings, mounting bracket or flange. For optimal results, use an
Incoloy® sheath and ensure reasonable watt densities are used. Allow for
10% length increase due to thermal expansion. For horizontal installations,
provide supports at least every 18” of length to avoid element sagging due
to high temperatures. Refer to the Circulation and Duct Heater sections of
the catalog for forced air and gas heating products.
Oven
Unheated
Length
Heated
Length
Tubular Element
Tank Wall
Duct Heating
Air
Flow
2
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
APPLICATION GUIDELINES
Tubular heaters used for radiant heating typically use reflectors to direct heat ener- REFLECTIVE RADIANT HEATER
gy toward the part being heated. This works well for warming, drying and curing
applications. However, when using heaters in a vacuum, the only heat transfer is
through radiation, so reduce watt density by 20% to 30% versus air heating. Aluminum sheath as well as Inconel® sheathed heaters are typically used with vacuum Heating
Polished reflector
feed through assemblies. Durex can test and measure vacuum leakage rates down element
to 8x10-8 SCCS He (3x10-6 Pa l/s).
General Temperature and Watt Density Guidelines
Tubular Heaters
Radiant Heating and Vacuums
Tubular Sheath & Watt Density Guidelines
Heated Medium
Clamp On to Metal
Milled Groove Molds, Etc.
Vacuum Platens
Clean, Potable Water
De-I Water
Process Water & Very Diluted Corrosives
Mild or Dilute Acids & Alkalies
Oils (Depends on Type & Use)
Ovens, Natural Convection
Flowing Air @ min. 500 fpm
Process Temperature
°F (°C)
Solids
To 500 (260)
To 1000 (540)
To 500 (260)
To 1000 (540)
To 650 (345)
To 1000 (540)
Liquids
To 212 (100)
To 500 (260)
To 212 (100)
To 200 (95)
To 200 (95)
50 - 600 (10 - 315)
Air
To 700 (370)
To 1200 (650)
To 800 (425)
To 1000 (650)
Sheath Material
Max. Watt Density
W/in2 (W/cm2)
Aluminum, SS
Incoloy® or Inconel®
20 (3)
10 (1.5)
60 (9)
30 (4.5)
40 (6)
20 (3)
Copper
Incoloy®
316SS
304SS or Incoloy®
Incoloy®, 316SS or Inconel®
Steel
60 - 90 (9 - 14)
30 - 40 (4.5 - 6)
60 (9)
48 (7.5)
15 - 23 (2.3 - 3.5)
6 - 23 (1 - 3.5)
Incoloy®
Incoloy®
Incoloy®
Incoloy®
30 (4.5)
10 (2.3)
30 (4.5)
23 (3.5)
Maximum Recommended Sheath Temperatures
Sheath Material
Copper
Aluminum
Steel
304 SS
316 SS
Incoloy® 840
Incoloy® 800
321 SS
Incoloy® 825
Inconel® 600
Maximum Temperature
in Air °F (°C)
Typical Applications
Standard Available Sheath Materials
350 (175)
Clean, potable water heating
750 (400)
Vacuum platens
750 (400)
Oils, glycol, molten salts, non-corrosives
1200 (650)
Improved corrosion resistance over steel
1200 (650)
De-ionized water and some corrosives
1600 (870)
Improved corrosion resistance over steel and 304SS
1600 (870)
Improved resistance to chloride attack, other corrosives
Other Available Sheath Materials
1200 (650)
Improved corrosion resistance over steel and 304SS
1600 (870)
Highly resistant to many acids, salts and other media
1800 (980)
Highly resistant to many acids, salts and other media
3
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
CONSTRUCTION OPTIONS
Unheated Length
The unheated length can be varied to suit application requirements. Longer unheated sections are often used to keep
the termination area cool or to focus heat generation in a specific area of the part or media being heated.
Durex tubular heaters can be tailor-made to vary the watt density along the length of the heater.
This aids in temperature uniformity in mold applications or to make up for heat losses close to the ends.
Sheath Treatment and Finish
For pharmaceutical and other “clean” applications, a bright anneal finish can be supplied. Also available, depending
on configuration, is sheath passivation which removes any free iron that may stain or rust the finish of the sheath.
Tubular Heaters
Distributed Wattage
TERMINATION OPTIONS
#6-32, #8-32, & #10-32 Hex Nut & Washer
Insulator
TYPE S
Threaded Stud
Terminal with
Ceramic Insulator
TYPE S1
Threaded Stud
Terminal with
Stacked Mica
½” min
#6-32, #8-32, & #10-32 Hex Nut & Washer
Stacked Mica
½” min
1” min
1” min
Screw Size
TYPE L
Screw Lug
Terminal
TYPE L1
Screw Lug
Terminal 90°
A
Screw Size
Screw Size
#8-32
#10-32
½”
W
Dia.
To 0.315”
0.375” and above
Maximum 240V
A
⅞”
1 ⅟₁₆”
W
⁵/₁₆”
⁷/₁₆”
W
TYPE D
Quick Connect
TYPE D1
Quick Connect 90°
¾”
½”
Maximum 240V
Insulated Lead Wire
(Specify Type & Gauge)
Fiberglass Insulated
Sleeving
TYPE W
Leadwire Terminal
Assembly
1 ½”
Type
WS
WF
WM
Insulation
Silicone
Fiberglass
Mica/Glass
Max. Temperature
390°F (200°C)
480°F (250°C)
840°F (450°C)
Volts
600V
600V
600V
Note: If protective armor cable (hose) is required, please consult factory.
Specify Length
4
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
MOUNTING OPTIONS
+
B
A
A
3/4”
5/8”
3/4”
3/4”
3/4”
B
Specify
Specify
Specify
Specify
Specify
D Dia. Mtg. Holes
F
TYPE F
Mounting Flange
+
+
TYPE K
Mounting Bracket
E
+
+
C
W/2
Tubular Heaters
Heater
Dia.
TYPE R
Locator Washers
Heater Dia.
0.260”
0.315”
0.375”
0.430”
0.475”
B A
B/2
T
+
D
Hex Nut
Threadsize
Gasket
TYPE B
Threaded Bulkhead
Fittings
Flat Washer
B
A
Dia.
Type
BB
BS
B4
E
+
Specify all required
dimensions and tolerances.
Specify all required
dimensions and tolerances.
W
BC
+
+
Material
Brass
Steel
304SS
Dia.
0.260”
0.315”
0.375”
0.430”
0.475”
C
+
A
+
C
H
B
Thread
1/2 - 20
1/2 - 20
5/8 - 18
5/8 - 18
3/4 - 20
A
3/4”
3/4”
15/16”
15/16”
1”
G Thickness
B
5/8”
5/8”
3/4”
3/4”
7/8”
C
3/4”
3/4”
7/8”
7/8”
1”
SEAL OPTIONS
TYPE G - Silicone Conformal Coating - General Protection, Porous
Max. temperature: 220°F (105°C)
End Seal
(Varies with Type)
TYPE E - Epoxy Seal - Moisture and Contamination Resistant
(better choice for long-term moisture resistance), Low porosity
Max. temperature: 450°F (230°C)
MgO Insulation
TYPE V - Silicone RTV - Moisture and Contamination Protection, Porous
Max. temperature: 400°F (200°C)
Insulated Wire
TYPE M
Silicone Rubber Overmold
Dia. A
Max. temperature: 300°F (150°C)
Specify
Length
2”
Fiberglass Insulated Lead Wire
TYPE PA
Potted Adapter
Heater Dia.
Specify Length
Potted Adapter
Dia.
0.260”
0.315”
0.430”
Potted protection tube ensures an integral bond between wire insulation,
the seal, and protective sleeving that may be required.
• Type PS is silicone RTV and silicone insulated lead wire
• Type PP is epoxy coating and Fiberglass insulated lead wire
• Type PT is epoxy coating and Teflon® insulated lead wire
Thread Size
TYPE HS
Ceramic to Metal Hermetic Terminals
Max. temperature: 1000°F (540°C)
Dia.
A
A
⁷/₁₆”
⁷/₁₆”
⅝”
Thread Size Dia.
W
#8-32
0.260” 1 ¾”
#10-32
0.315” 1 ⅞”
#¼-28
0.430” 2 ⅛”
5
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
BENDING OPTIONS
Tubular Heaters
Tubular elements can be formed into 2-D and 3-D shapes to better suit application requirements. Typical bend
configurations are shown across the following pages. Ensure to allow for up to 10% dimensional increase due to
thermal expansion and to provide adequate support to prevent element sagging due to high temperatures. If field
bending of straight elements is necessary, contact Durex for field bending guidelines prior to bending. Also specify
“full sheath anneal” on the order to allow for field bending.
Bend Tolerances for Incoloy® and Stainless Steel Sheath Elements
Bend Data Reference
0.260”
0.437”
0.375”
±1/8”
±1/16”
±0.005”
Minimum Bend Radius Standard
Minimum Bend Radius w/Repressed Bend
Standard Bend Tolerances
Special Bend Tolerances
Precision Bend Tolerances w/Tooling
0.315”
0.562”
0.50”
±1/8”
±1/16”
±0.005”
Heater Diameter
0.375”
0.430”
0.687”
0.75”
0.562”
0.625”
±1/8”
±1/8”
±1/16”
±1/16”
±0.005”
±0.005”
0.475”
0.812”
0.687”
±1/8”
±1/16”
±0.005”
0.490”
0.875”
0.75”
±1/8”
±1/16”
±0.005”
Note: Tighter bend radii possible for steel and copper sheath elements. Please consult Durex for more information.
TYPICAL BEND FORMATIONS
Style 1
Style 2
Style 3
A
H
R1
H
+
D
R
H
F
G
D
R2
L
Style 4
A
D
Style 5
Style 6
H
C
D
R
G
R1
A (angle)
A
Style 7
Style 8
R1
L
D
L
D
C
H
R
RR22 G
F
A
Specify R.H. or L.H.
Style 9
Style 10
R. Hand
Formation
R1
D
W
H
H
R1
D
H
R1
W
L
H
R2
D
R1
D
A
R2
R2
R2
L
K
A
R3
K
A
L
Style 11
L. Hand
Formation
Style 12
R1
Style 13
D
C
A
A
D
R1
H
R1
G
R3
X Hair pins R 2
W
H
R2
K
A
R4
R1
Dia.
H
R2
B
R3
+
K
R1
K
K
B
C
L
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190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
TYPICAL BEND FORMATIONS
Style 15
D
Style 16
R1
D R1
G
W
H
R1
F
L
A
A
Style 18
A
Style 19
Dia.
Dia.
Dia.
H
R1
R1
R3
H
(Angle)
H
K
R3
View A
F
R2
B
B
(Angle)
A
F
(Angle)
R3
L
A
Style 17
H
R2
B
R1
D
W
H
K
R1
R1
B
R2
Tubular Heaters
Style 14
R3
C
R2
R2
R3
A
Style 20
Style 21
Style 22
A
H
Dia.
Dia.
L
G
R1
H
R2
+
R2
R2
K
R2
A
Dia.
R1
B
R1
C
K
A
H
Style 23
L
Style 24
A
Style 25
H
L
C
Dia.
R1
R1
W
B
H
Dia.
R1
A
W
R2
R3
C
K
R3
K
C
L
B
R1
R1
R3
E
C
R2
X Hairpins
R2
L
H
R1
A
Style 26
A
A
Dia.
R1
X Hairpins
X Hairpins
R2
R2
R2
R5
R1
H
R1
R3
R1
L
Dia.
R1
R4
R2
Style 27
K
H
VI EW A
R2
Dia.
R1
R1
R3
K
L
7
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
TYPICAL BEND FORMATIONS
Style 29
A
Style 30
L
K
Dia.
R1
View A
R1
X Hair pins
R2
R4
R1
K
H
R2
R3
R1
R3
B
Dia.
H
R2
K
A
R3
R1
R3
H
R2
B
View B
K
L
Tubular Heaters
Style 28
R4
R1
Dia.
L
B
R3
A
Style 32
Style 31
A
Style 33
Dia.
K
L
R1
B
R1
H
Dia.
H
H
R2
R1
R4
R3
R1
R
Dia.
K
A
R3
Style 35
Style 34
L
B
A
K
F2
R1
L
R2
F2
R
A
H
B
+
R2
A
G
+
Dia.
Dia.
Style 36
Style 37
Style 38
M
A
L
L
H
C
Dia.
F
L
X Hairpins
R1 (2) Places
R1
R2 (4) Places
R2 (2) Places
G
Dia.
F
K
H
C
A
Dia.
A
8
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468
Tubular Heaters
TYPICAL BEND FORMATIONS
Style 40
C
Style 41
H
K
C
X Hairpins
K
R2 (2) Places
H
R1
X Hairpins
Dia.
R2 (4) Places
L
L
M
Dia.
R1
B
R1
B
A
R2 (4) Places
A
Style 42
A
Style 43
Style 44
B
H
H
R2 (2) Places
H
K
Dia.
L
Tubular Heaters
Style 39
K
R2 (2) Places
R2 (4) Places
H
K
B
B
G
R1 (2) Places
Dia.
A
Dia.
L
G
Dia.
R1
X Hairpins
Style 45
Style 46
Style 47
Dia.
H
K
R3 (2) Places
A
Dia.
H
R2 (2) Places
B
B
R3 (2) Places
C
R3 (1) Places
B
K
R1 (1) Place
L
H
R1 (4) Places
A
L
Dia.
A
X Hairpins
R1
9
190 Detroit Street, Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468