Strip and Ring Heaters Selection and Installation Guidelines

COMPONENT - Strip & Ring Heaters

Installation Guidelines

Chromalox strip elements, in most cases, can be applied wth standard hardware. However, for firm contact and best heat transfer, stocked Chromalox clamps are recommended.

Note - Heat insulating material should not be placed against the sheath of the heating element.

Utility Clamps

Utility Clamps

Utility Clamps secure strip elements to flat surfaces or surfaces wth large radii such as large tanks. hreaded studs are welded to surface, heaters are positioned, then clamps are bolted down. Where more than one lamp is used, tighten nuts and then back off 1/2 turn to allow for expansion..

Milled Plates

Milled Plates

Milled Plates allow heaters to be held in position in platens and similar objects wth a steel plate recessed to heaters width, thickness and positions, then screwed to the working plate or surface. Clamping Bands Clamping Bands can be used to fi rmly fasten strips longitudinally to large diameter cylindrical surfaces. Connecting Lead Wires - Should be nickelplated copper, nickel or alloy. Copper will oxidize and loosen connections. Do not use copper terminal lugs. See Accessories in this section.

Clamping Bands

Clamping Bands

Milled Plates Clamping Bands can be used to firmly fasten strips longitudinally to large diameter cylindrical surfaces.

Oven Mounting

Oven Mounting

Oven Mounting - Application of strip elements to ovens may be made simply wth the use of welded-on studs and secondary insulation bushings. Mounting holes in tabs are slotted to allow for expansion. Refer to Modifi cations in this section.

Selection Guides

Product To Be Heated Temperature for Desired Products Sheathed Material Product Temp (°F) Allowable Watt Density (W/In2)
Molds, Platens, Dies, Pipes, Tanks Up to 1400°F Clamp-On Applications Rust-Resisting Iron 560 3
150 8
Chrome Steel 850 7
700 10
400 15
INCOLOY® 1 200 28
750 20
1100 8
1350 3
1400 2.5
Free Air Velocity- 1 ft/sec. Up to 1400°F Bracket Mounted Rust-Resisting Iron 500 3
100 8
Chrome Steel 950 7
800 10
500 15
INCOLOY® 1 1400 3
400 34
Rust-Resisting Iron 500 3
Free Air Velocity-4 ft/sec. Up to 1400°F Bracket Mounted 250 8
Chrome Steel 1000 7
850 10
550 15
INCOLOY® 1 1400 5
600 34
Note:1 CSA Only

Strip & Ring Heater Modifications

Lengthwise Bending

Lengthwise BendingLengthwise Bending for clamping around pipes or cylindrical vessels. Terminals may be located inside or outside of curvature for all types listed.

3" Min. Inside Radius — Type S, SE, OT PT, th, NH, SNH, SN and ST.

6" Min. Inside Radius — Type SSE, SSEM, SSNH and SSNHM.

4-3/4" Min. Inside Radius — Type WS.

Cross-Section Curving

Cross-Section Curving

Cross-Section Curving — Type SE only, for clamping strips to 2, 2-1/2, 3, 4, 6, 8 and 12" pipes. For larger size pipe, use flat strips. Radii available 1-3/16, 1-7/16, 1-3/4, 2-1/4, 3-5/16, 4-5/16 and 6-5/16" and 8-3/4”. Terminals outside only.

Special Lengths — Type PT, SE, SN and SNH only. Special lengths are made-to-order for instances in which the amount of heat applied to a surface is critical and standard lengths are not suitable.

Special Voltage and Wattage — All types. Certain highly specialized applications may require special ratings. However, most can be handled wth standard heaters or standard ratings applied on an alternate voltage. Contact your Local Chromalox Sales office.

Special Wattage Distribution — All types except td. When even temperatures are required and end losses may cause an unsatisfactory temperature drop near the edges, additional wattage can be provided at each end of the strip to make up for losses.

Dual Contact Surface — Type SE only. 53-7/8" maximum A dimension. Flush-top construction gives good contact for all surfaces of the strip heater. Ideal for use in machined slots and installing between two smooth metal surfaces.

Without Mounting Tabs

Without Mounting Tabs

Without Mounting Tabs — All types. Permits installing more heat in a given confined space.

Specify “wthout mounting tabs” when ordering this feature.

Extra Strong Mounting Tabs — All types except WS. Recommended when strips are bent lengthwise and tabs are used for bolting.

Monel® Sheath — Type S, SE, OT, PT, HSP and WS.

Stainless Steel Sheath — All types.

Cover for Seamless Strips, Factory Welded

Cover for Seamless Strips Factory Welded

Cover for Seamless Strips wth threaded Opening for Conduit — Cover is welded to heater. Specify position of threaded opening ether on top of cover, or as shown. Type SSE, SSEM and SSNHM.

Fahnestock® Terminals

Fahnestock Terminals

Fahnestock® Terminals — Type S only. For quick temporary connections where ambient temperatures do not exceed 150°C. Maximum recommended amperage is 7.5 Amps.

Special Length Terminals — All types. Where a shorter or longer terminal bolt than standard shown in drawing is needed, indicate length needed.

Rubber-Molded Terminals

Rubber-Molded Terminals

Rubber-Molded Terminals — Type NS only. Used generally in low temperature applications where moisture, condensation and high humidity are considerations. Available in neoprene-rubber (to 190°F). Longer cold end or lower wattage is required to assure temperature limit of molding material is not exceeded. End opposite terminal is welded closed.

Special Lead Wire Terminal Construction

Special Lead Wire Terminal Construction

Special Lead Wire Terminal Construction

— All types. Specified most often when clearance is unavailable for standard terminals and when lead wires are more suitable for wiring to nearby components.

Secondary Insulation Bushing

Secondary Insulation Bushing

Secondary Insulation Bushings — All Types except NS. Must be used when strips are mounted for air heating only or when connected in series on line voltages 480V or above.

Note — To accommodate bushings, a 17/32 x 11/16" diameter mounting hole in tabs should be specified for heaters. To Order

— Specify PCN 255716 (includes bushing and hardware for one strip) and quantity.

Strip & Ring Heaters Accessories

Protective Terminal Covers

— Types OT, PT, SE, WS and Seamless Types SSE, SSEM, SSNH and SSNHM. Helps guard terminals from spillovers, dripping. Removable sheet-metal cover, wth Bx fitting, is shipped separately.

OT-AC-1 (PCN 129242)

A-2 B- 21/2 C- 21/2

OT-AC-1 (PCN 129242)

PT-AC-1 (PCN 255724)

A-17/8 B- 11/8 C- 13/4

PT-AC-1 (PCN 255724)

SE-AC-1 (PCN 255724)

A-21/16 B-11/2 C- 2

SE-AC-1 (PCN 255724)


— Types OT, PT, S, SE and th. Provide same advantage as flush-top construction and can be used wth stock heaters. Shims are 0.031" thick, 29/32" wide and lengths to fit heater.


Ceramic Post Terminal Insulators

Ceramic Post Terminal Insulators — All types except NS and SN. Use wth insulated wire to help protect against electrical shock. Wires can leave terminal at any angle.

Ceramic Post Terminal Insulators

PCN 259805 (Nickel plated steel hardware)

PCN 255732 (Stainless steel hardware)

PCN 255732 (Stainless steel hardware)

Porcelain Hi-Temp Insulation

Porcelain Hi-Temp Insulation —

For insulating buss bars spec. 51 porcelain insulators 1/2 L x 13/16" W wth 1/8 x 9/16" slot. 95 pieces per lb.

Porcelain Hi-Temp Insulation

To Order — Specify pounds, PCN 269780 and porcelain insulators.

  1. For Insulating Bare Wires — Two types available:
  2. 1. Porcelain Tubing — 3/8" O.D. x 1/8" I.D. x 6" L (may be broken for shorter lengths). Suitable for 10-gauge or smaller; 8-gauge takes No. 6 porcelain bead.

To Order — Specify quantity and PCN 263863.

Porcelain Tubing

2. Porcelain Beads — Listed in table below. Can be used when wiring does not permit straight tubing.

Porcelain Beads

When selecting porcelain beads for stranded wire, use next larger gauge wire and use bead for that size (i.e., 10 gauge stranded wire requires a No. 6 bead).

Ambient Temperature Corrections for Insulated Wires

— Multiply ampacity values, in tables below, by the following correction factors to determine current-carrying capacity at higher ambient temperatures.

Ambient Temp. Nickel-Plated



°C °F Silicon



30 86 1.36
50 122 0.98 0.97 0.98
60 140 0.95 0.94 0.95
70 158 0.93 0.9 0.93
80 176 0.9 0.87 0.9
90 194 0.87 0.83 0.87
100 212 0.85 0.79 0.85 1.22
120 248 0.79 0.71 0.79
140 284 0.72 0.61 0.72
149 300 0.65 0.5 0.65 1.12
177 350 0.58 0.35 0.58
204 400 0.49 0.49 1
232 450 0.35 0.35
260 500 0.87
269 550
300 572 0.7
Note — After exposure to high temperatures,

all wire insulation becomes brittle and will not wthstand repeated flexing.

Wire & Buss Bar

High-temperature wire and buss bar are recommended for connections to heater terminals and for runs in heated zones. When ambient temperature exceeds maximum allowed for insulated wire, use bare wire or buss bar wth porcelain insulators. Current-carrying capacities should be carefully noted.

Buss bar is solid or perforated to facilitate wiring, especially when terminals are in line. Perforated buss bar, has 11/32 x 7/32" slots on 7/16" centers. When connecting elements wth buss bar, provide expansion loops between elements. Buss bars may be used in multiples for higher ampacity (approx. 33-1/2% per buss bar) than listed above, center.

High Temperature (Bare) Wire
Size AWG Solid/S



Model PCN

550°F Max. Wire Temp. Nickel-plated Copper, Uninsulated

14 S


.064 CSB-14 263839
10 S 70 .102 CSB-10 263812
8 S 93 .128 CSB-8 263804
1000°F Max. Wire Temp. Manganese-nickel, Uninsulated
14 F 12 .075 AFB-14 269317
14 S 12 .064 AFB-14


12 F 15 .097 AFB-12 269296
12 S 15 .081 AFB-12 269288
10 F 20 .12 AFB-10 269270
10 S 20 .102 AFB-10 269261
To Order — Specify PCN and quantity.

Insulated Wire

Size AWG Solid/S



Model PCN

392°F Max. Wire Temp. Type A Nickel Wire

Silicone Rubber Treated Glass Braid Insulated 600V UL Listed
16 F 27 .224 3-CFI-16 263759
16 S 27 .224 3-CFI-16 263740
14 F 36 .237 3-CFI-14 263732
14 S 36 .237 3-CFI-14 263724
12 F 45 .263. 3-CFI-12 263716
12 S 45 .263 3-CFI-12 263708
10 F 60 .29 3-CFI-10 263695
10 S 60 .29 3-CFI-10 263687
482°F Max. Wire Temp. Type TGT,

Nickel-plated Copper, Tefl on® Impregnated

Glass Braid Insulated 600V UL Listed
14 F 39 .121 6-CFI-14 263791
14 S 39 .112 6-CFI-14 295398
12 F 54 .141 6-CFI-12 263783
12 S 54 .13 6-CFI-12 295400
10 F 73 .17 6-CFI-10 263775
10 S 73 .145 6-CFI-10 295419
8 F 93 .212 6-CFI-8 263767
482°F Max. Wire Temp. Tefl on® Tape and

Silicone Impregnated Glass Braid Insulated 600V UL Listed
14 F 39 .121 3-AFI-14 269253
12 F 54 .141 3-AFI-12 269237
10 F 73 .17 3-AFI-10 269210
842°F Max. Wire Temp. Nickel-clad

Copper, MGS-Mica Glass Insulated 600V
16 F 33 .065 6-CFIM-16 295355
14 F 44 .102 6-CFIM-14 295363
12 F 55 .118 6-CFIM-12 295371
To Order — Specify PCN and quantity.

1. See note 1 in Buss Bar Table.

2. These wiring recommendations are general in nature.

Confirm actual wire size and selection in accordance with

NEC (National Electrical Code).

Buss Bar

Buss Bar Model DIM (In.) Amp-acity1 PCN
Width Thick
700°F Max. Wire Temp.
  0.5 .032 18 346124
  0.5 .064 28 346132
Perforated Slot Size = 7/32 Dia.
0.5 .032 9 346140
0.5 .064 16 346159
To Order — Specify PCN and number of feet.

1. these current values will cause the conductor to operate at 100°F

above surrounding ambient. Values may also be used for bare wire

wth porcelain tubes or bead insulation. Monel max. limit is 800°F.

SBK — the silicone boot termination kit provides electrical insulation for strip heater terminals and leads with ring type insulated connector on one end for bringing power to the strip heaters.

Silicone Boot Termination Kit with thermostat

Model PCN Temperature (F)
Closes Opens
SBKT-1 386011 38 53
SBKT-2 386020 60 75
SBKT-3 386038 105 120
SBK 121890 N/A N/A

Silicone Boot Termination Kit

SBKT — the silicone boot termination kit with thermostat used with strip heaters provides an inexpensive way to maintain temperature in control cabinets, panels and other small enclosures. In this application, strip heaters are used to prevent freezing and corrosion, and to control humidity in enclosures with humidity sensitive electronic components.

Silicone Boot Termination Kit

Element Clamps

Cast-iron clamps, for use with Chromalox strip and ring elements, retain their strength at elevated temperatures to assure maximum sheath-to-surface contact. Resulting uniform efficient heat transfer from internal resistance wire to the heated material minimize hot spots on the element, contributing to long service life.

Clamp 6018 — Usually used in sets of two or more to clamp ring elements to flat surfaces. 5/16" flathead machine screws are normally used with head brazed or welded to work surface (PCN 263978).

Clamp 6018

Clamp 5971 — Use to clamp two strip heaters on 2" centers using 5/16" studs spaced 5" apart (PCN 263636). Clamp 5971

Clamp 6933 — Use to clamp two strip heaters on 3" centers using 3/8" studs at 5" intervals (PCN 263644).

Clamp 6933

Clamp 5970 — Use to clamp three strip heaters on 2" centers using 5/16" studs at 5" intervals (PCN 263652).

Clamp 5970

Clamping Bands

Type SC Clamping Bands — Provide permanently tight fit on cylinders, nozzles, pipes and other round surfaces. Stainless steel band with alloy screw. For small pipe diameters, strip elements should have cross-section curving (see Modifications in the Components section).

Type SC Clamping Bands

For Most Satisfactory Results, bands should be spaced about 5 inches apart and should be drawn up tight to assure good contact between heater or thermostat bulb and surface.

Mounting Studs

Mounting Studs — For use with Chromalox clamps. For all clamps except No. 6933, studs are 5/16 — 18 x 1-1/2" Monel® (PCN 127845), steel washer (PCN 127853), Monel® nut (PCN 127861). For No. 6993 clamp; studs are 5/16" — 18 x 2" Monel® (PCN 127837).

Installation — Fasten studs to the work surface by welding, brazing or threading. Use correct size stud to fit clamp. See Selection & Installation Guidelines in the Components section. For temperatures over 750°F, stainless steel studs are recommended.

Note — When tightening nuts, torsion should not exceed 10 foot pounds maximum. Heaters must be allowed to expand. One center clamp should hold heater. Nuts on other clamps should be backed off approximately 1/2 turn to allow for heater expansion.

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