Backer Hotwatt Cartridge Heaters

Cartridge Heaters / Immersion Heaters

Eagle Sensors & Controls is an authorized Backer Hotwatt distributor. Contact us with sales and application support.

Cartridge-and-Immersion

Electric Heater Special Features and Modifications

The following is an outline of Special Features and Modifications available with Backer Hotwatt Electric Heating Elements.It applies to all Standard, Superwatt, Square and Rectangular Cartridge Heaters and Immersion Heaters. Catalog Numbers have been assigned to all special features and modifications. Please provide an adequate description to avoid confusion when a special feature applies to more than one size or item. Special features for other heaters are covered in each specific section.

Lead Configurations

SF1: Flexible Leads for applications where leads can be bent close to end of unit.
See specific unit size for maximum allowable amperage

sf1

Standard on:

  • In-Stock Standard and Superwatt Cartridge
  • Standard Cartridge: 1/8″ to 3/4″ and 1.9″ and 2 3/8″ diameter
  • Superwatt Cartridge: 1/4″ to 3/4″ diameter
  • Square and Rectangular: all sizes
  • Immersion: 1/4″ to 3/4″ and 1.9″ and 2 3/8″ diameter

Available on:

  • Standard Cartridge: 15/16″ to 1 1/4″ diameter
  • Immersion: 1″ and 1 1/4″ diameter

SF2: Leads for application where repairable leads are desired or when unit amperage will not allow the use of Type SF-1 leads.

sf2

Standard on:

  • Superwatt Cartridge: 1″ diameter

Available on:

  • Standard Cartridge: 3/16″ to 3/4″ diameter
  • Immersion: 1/4″ to 3/4″ diameter

SF3: Post terminals.

sf3

Standard on:

  • Standard Cartridge: 15/16″ to 1 1/4″ diameter
  • Immersion: 1″ to 1 1/4″ diameter

Available on:

  • Standard Cartridge: 3/4″ diameter
  • Immersion: 3/4″ diameter

SF4: Leads for application where lead space is minimum and it is desirable to bring
leads out at right angles to sheath. Specify overall length of heater when ordering

Available on:

  • Standard Cartridge: 3/16″ to 3/4″ diameter
  • Superwatt Cartridge: 1/4″ to 3/4″ diameter
  • Square and Rectangular Cartridge: All sizes

SF5: Lead spring protector. Leads reinforced with steel spring for applications where excessive flexing is encountered. Standard spring length is 1″ on 1/4″ to 1/2″ diameters and 1 1/2″ on 5/8″ to 3/4″ diameters. Longer spring lengths are available. Consult factory

sf5

Catalog
Number		 Unit
Diameter		 A B
SF5A 1/4″ 1/4″ 1″
SF5B 3/8″ 1/4″ 1″
SF5C 1/2″ 1/4″ 1″
SF5D 5/8″ 1/2″ 1 1/2″
SF5E 3/4″ 1/2″ 1 1/2″

Available on:

  • Standard Cartridge: 1/4″ to 3/4″ diameter
  • Superwatt Cartridge: 1/4″ to 3/4″ diameter

SF6: Ground wire.
Available on:

  • All products

SF7: Fiberglass sleeving. Additional sleeving over leads for protection.
Leads are normally 2″ longer than sleeve.
SF7A: Common sleeve. Single sleeve over both leads.
SF7B: Individual sleeve. Single sleeve over each lead. Specify length of sleeve.
Available on:

  • All products with leads

SF8: Silicone rubber sleeving. Additional sleeving over leads for protection and moisture resistance.
SF8A: Common sleeve. Single sleeve over both leads.
SF8B: Individual sleeve. Single sleeve over each lead. Specify length of sleeve. Leads are normally 2″ longer than sleeve.
Available on:

  • All products with leads

SF9: Strain relief clip for leads subject to strain and pull.

sf9

Available on:

  • Standard Cartridge: 1/4″ to 3/4″ diameter with Type SF1 leads only
  • Superwatt Cartridge: 1/4″ to 3/4″ diameter with Type SF1 leads only

SF10: Ceramic bead insulation for leads subject to high temperatures up to 1000°F. Specify lengths of beads required when ordering.
Available on:

  • All products with leads
Lead End Termination

SF11: Lugs, rings, quick connect terminals attached to the end of lead wires. Specify terminal type and size when ordering. Special terminals are available.
Available on:

  • All products with leads

SF11A: Ring terminals. Specify size: #6, #8, #10.

sf11a

SF11B: Straight quick connect terminals. Specify male or female and size: 3/16″ or 1/4″

sf11b

SF11C: Flag quick connect terminals. Specify male or female and size: 3/16″ or 1/4″

sf11c

SF11D: Spade terminals. Specify size: #6, #8, #10

sf11d

SF12: Male dead front armored plug. May be mounted directly to heater.Available on:

  • Products with leads. Consult factory for availability.
  • Ground wire (SF6) should be specified when using any 3 prong plug.

sf12p1

SF12-P1: 2 prong/straight blade/2 pole/2 Wire/UL&CSA Listed/
NEMA 1-15P/125 volts/15 amps.

sf12p2

SF12-P2: 2 prong/twist lock/2 pole/2 wire/UL Listed/
NEMA L1-15P/125 volts/15 amps.

sf12p3

SF12-P3: 3 prong/twist lock/2 pole/3 wire/UL&CSA Listed/
NEMA L6-15P/250 volts/15 amps.

sf12p4

SF12-P4: 3 prong/twist lock/2 pole/3 wire/UL&CSA Listed/
NEMA L6-20/250 volts/20 amps.

sf12p5

SF12-P5: 3 prong/straight blade/2 pole/3 wire/UL&CSA Listed/
NEMA 5-15P/125 volts/15 amps.

SF13: Enclosures for protection of electrical connections.

SF13A: General purpose box, NEMA No. 1. 2 3/4″ x 1 1/2″ x 1 1/2″.

sf13a

Available on:

  • Standard Cartridge: 3/8″ to 1″ diameter.
  • Superwatt Cartridge: 3/8″ x 1″ diameter.

SF13B: Moisture resistant box. Mounted on NPT fitting.

sf13b

Available on:

  • Standard Cartridge: 3/8″ to 1 1/4″ diameter.
  • Superwatt Cartridge: 3/8″ to 1″ diameter.

SF13C: Explosion resistant box. Mounted on NPT fitting.

sf13c

Available on:

  • Standard Cartridge: 3/8″ to 1 1/4″ diameter.
  • Superwatt Cartridge: 3/8″ to 1″ diameter.

SF13D: General purpose box. NEMA No. 1. Rust resistant steel. 4″ octagonal.

sf13d

Available on:

  • Standard Cartridge: 1 1/4″ to 2 3/8″ diameter.
Lead Protection

SF14: Flexible, Stainless steel conduit for straight leads.

Available on:

  • All products with leads: 3/16″ to 1 1/4″ diameter.

SF15: Flexible, stainless steel conduit for right angle leads.

sf17

Unit Size Conduit O.D. Min.Bend Dia.
3/16″ – 1/4″ .244 nominal 1.31″ inside
3/8″ .350 nominal 1.93″ inside
1/2″ – 5/8″ .381 nominal 2.12″ inside
3/4″ & up .500 nominal 2.25″ inside

Available on:

  • Standard Cartridge: 3/16″ to 1 1/4″ diameter.
  • Superwatt Cartridge: 1/4″ to 1″ diameter.
  • Square Cartridge: 1/4″ to 1/2″ square.

SF16: Stainless steel, flexible braid for straight leads. Specify braid length.
Leads are supplied 6″ longer than braid.

sf16

Available on:

  • Standard Cartridge: 3/8″ to 3/4″ diameter.
  • Superwatt Cartridge: 3/8″ to 3/4″ diameter.
  • Square and Rectangular: 3/8″ and 1/2″ square (1/4″ x 5/8″ and 1/4″ x 1″ rectangular).

SF17: Convoluted bronze tubing. Flexible sealed tubing for waterproof leads.

sf17

Available on:

  • Standard Cartridge: 3/8″ to 1 1/4″ diameter.
  • Superwatt Cartridge: 3/8″ to 1″ diameter.
  • Square Cartridge: 3/8″ and 1/2″ square.
  • Immersion Heater: 3/8″ to 1 1/4″ diameter.

SF18: Right angle convoluted bronze tubing.

sf18

Available on:

  • Standard Cartridge: 3/8″ to 3/4″ diameter.
  • Superwatt Cartridge: 3/8″ to 3/4″ diameter.
  • Square Cartridge: 3/8″ and 1/2″ square.

SF19: Straight solid copper extension. Specify length when ordering. Leads are 6″ longer than tubing.
Available on:

  • Standard Cartridge: 1/4″ to 3/4″ diameter.
  • Superwatt Cartridge: 1/4″ to 3/4″ diameter.
Sealing and Potting Lead End for Adverse Environmental Conditions

SF20: Silicon rubber potting for moisture proof application to 400° F (204ºC) in potting area.
Silicon rubber sleeving must be used in conjunction with potting. See Special Feature SF-8.

Available on:

  • Standard Cartridge: 3/16″ to 2 3/8″ diameter.
  • Superwatt Cartridge: 1/4″ to 1″ diameter.
  • Square and Rectangular: All sizes except 1/8″ square.
  • Immersion Heater: All sizes.

SF21: Epoxy potting for moisture proof applications to 265° F (129ºC) in potting area.

Available on:

  • Standard Cartridge: 1/4″ to 2 3/8″ diameter.
  • Superwatt Cartridge: 1/4″ to 1″ diameter.
  • Square and Rectangular: All sizes except 1/8″ square.
  • Immersion Heater: All sizes.

SF22: Teflon end seal for moisture applications to 400° F.

Available on:

  • Standard Cartridge: 1/8″ to 3/4″ diameter.
  • Superwatt Cartridge: 1/4″ to 3/4″ diameter.

SF23: Ceramic to metal seals for hermetic sealing and vacuum applications to 1000° F.

Specify Sheath Length | See Table

Available on:

  • Standard Cartridge: 3/8″ to 3/4″ diameter.
  • Superwatt Cartridge: 3/8″ to 3/4″ diameter.
  • Immersion Heater: 3/8″ to 3/4″ diameter.

special12

SF23: Table Of Dimensions

Table description
Catalog No. Unit Diameter
A B C D
SF23-A 3/8″  .148″ 1/2″ 1″
SF23-B 1/2″ .180″ 17/32″ 1 5/32″
SF23-C 5/8″ .238″ 9/16″ 1 3/16″
SF23-D 3/4″ .304″ 19/32″ 1 7/32″
Attach Fittings

SF25: Units with pipe bushing.

Heater
O.D.		 Pipe Thread NPT Size A B C D AF
1/4″ 1/8″ 1/8″ 1/2″ 3/16″ 15/16″ 7/16″
3/8″ 1/4″ 1/8″ 9/16″ 3/16″ 1 1/16″ 5/8″
1/2″ 3/8″ 3/16″ 5/8″ 1/4″ 1 1/8″ 11/16″
5/8″ 1/2″ 3/16″ 3/4″ 1/4″ 1 3/8″ 7/8″
3/4″ 3/4″ 1/4″ 7/8″ 3/8″ 1 5/8″ 1 1/8″
15/16 & 1″ 1″ 1/4″ 15/16″ 1/2″ 1 7/8″ 1 1/2″
1 1/4″ 1 1/4″ 5/16″ 1 1/32″ 1/2″ 1 15/16″ 1 3/4″
1.9″ 2″ 9/16″ 1 7/16″ NA NA 2 1/2″
2 3/8″ 2 1/2″ 5/8″ 1 3/4″ NA NA 3″
Brass Bushings

SF25A: Single Brass.
SF25B: Coupling Brass.

Stainless Steel Bushings

SF25C: Single Stainless Steel.
SF25D: Coupling Stainless Steel.
Available on:

  • Standard Cartridge: 1/4″ to 2 3/8″ diameter.
  • Superwatt Cartridge: 1/4″ to 1″ diameter.

SF26: Units with flanges. Mounting hole centers for 1/4″ to 5/8″ diameter is 1 1/8″ and for 3/4″ diameter is 1 5/32″. Special flange sizes available upon request.

Available on:

  • Standard Cartridge: 1/4″ to 3/4″ diameter.
  • Superwatt Cartridge: 1/4″ to 3/4″ diameter.

SF27: Stainless steel riser and support feet for over the side immersion heaters.

Special Electrical Features

SF28: Three phase heaters.

Available on:

  • Standard Cartridge: 3/8″ to 2 3/8″ diameter.
  • Superwatt Cartridge: 3/8″ to 1″ diameter.
  • Immersion Heater: 3/8″ to 2 3/8″ diameter.
  • Square Cartridge: 3/8″ to 1/2″ square.

SF29: Multiple heat; when a single unit with multiple wattages is necessary.Some uses of these units include: quick heat-up with a standby circuit for maintenance of low temperature; providing different wattages when there is a wide variation in thermal loads; and replacing more expensive rheostats or powerstats for wattage control.

Available on:

  • Standard Cartridge: 3/8″ to 2 3/8″ diameter.
  • Superwatt Cartridge: 3/8″ to 1″ diameter.
  • Immersion Heater: 3/8″ to 2 3/8″ diameter.
  • Square Cartridge: 3/8″ to 1/2″ square.

SF30: Special wattage distribution for units requiring different concentrations of wattage over their heated length. Distribution should be specified as a percentage of wattage over a percentage of length, i.e. 36/25.

Available on:

  • All units over 3″ long.

SF31: Built in thermocouple. Junction at bottom of heater.
Ungrounded thermocouple:

  • SF31-JU – Iron/Constantan – Type J
  • SF31-KU – Chromel/Alumel – Type K

Grounded thermocouple:

  • SF31-JG – Iron/Constantan – Type J
  • SF31-KG – Chromel/Alumel – Type K

Available on:

  • Standard Cartridge: 3/8″ to 2 3/8″ diameter.
  • Superwatt Cartridge: 1/4″ to 1″ diameter.
  • Square Cartridge: 3/8″ to 1/2″ square.
  • Rectangular Cartridge: 1/4″ by 1″ rectangular.
  • Immersion Heater: 3/8″ to 2 3/8″ diameter.

SF32: High voltage heaters from 300V to 600V. Consult factory for availability on items.

Maximum Voltage/Unit Size

Diameter 5/8″ 3/4″ 1″ 1 1/4″ 1.90″ 2 3/8″
Std.Cart. 480V 480V 480V 600V 600V 600V
Superwatt 480V 480V 480V NA NA NA
Immersion 480V 480V 480V 600V 600V 600V
Features Ohter Physical Features

SF33: Double end units. One terminal at end. Especially suitable for heating: warming closets, ovens, press heads, drying cabinets, platens and plates. Double end units (post type terminals at each end) can be installed in reamed holes or in machined grooves. The standard sheath material is stainless steel and cannot be bent or formed. Available with SF1 or SF3 terminations.

Available on:

  • Standard Cartridge: 3/8″ to 3/4″ and 1 1/4″ diameter.
  • Square Cartridge: 1/2″ square only.

SF34: Odd sizes: 7/16″, 9/16″, 11/16″, 13/16″, and 7/8″ diameter. Stainless steel sheath.
Available on:

  • Standard Cartridge construction only.

SF36: Centerless ground on diameter for precision fit. Termination must be Type SF2 or SF3. Tolerance on diameter ±.0005.
Available on:

  • Standard Cartridge: 1/4″ and 1 1/4″ diameter.
  • Superwatt Cartridge: 1/4″ to 1″ diameter.
Finished diameters after grinding will be:
1/4″ = .2450 3/4″ = .7430
3/8″ = .3700 15/16″ = .9300
1/2″ = .4950 1″ = .9930
5/8″ = .6200 1 1/4″ = 1.240

SF37: Special alloy sheathing. Consult factory for availability before ordering.
SF37A: 347 Stainless steel.
SF37B: 321 Stainless steel.
SF37C: Inconel.
SF37D: Titanium.
Available on:

  • Standard Cartridge: 1/4″ and 1 1/4″ diameter.
  • Immersion Heater: All sizes.

SF38: Passivated finish for corrosion resistance.
Available on:

  • All Immersion Heaters.

SF39: Teflon coating for corrosive conditions. Termination must be type SF2 or SF3.
Available on:

  • Standard Cartridge: 3/16″ and 1 1/4″ diameter.
  • Square or Rectangular: All sizes (except 1/8″ square).
  • Immersion Heater: All sizes.