Backer Hotwatt Cartridge Heaters
Eagle Sensors & Controls is an authorized Backer Hotwatt distributor. Contact us with sales and application support.
Cartridge-and-Immersion- Standard Cartridge Heaters
- Superwatt High Watt Cartride Heaters High Watt Density
- Metric Cartridge Heaters
- Square Rectangle Cartridge Heaters Milled Slots
- Immersion Heaters
- Miniature Circulation Heater
- Cartridge Heaters Special Features
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
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.
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.
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
| 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.
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.
SF11B: Straight quick connect terminals. Specify male or female and size: 3/16″ or 1/4″
SF11C: Flag quick connect terminals. Specify male or female and size: 3/16″ or 1/4″
SF11D: Spade terminals. Specify size: #6, #8, #10
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.
SF12-P1: 2 prong/straight blade/2 pole/2 Wire/UL&CSA Listed/
NEMA 1-15P/125 volts/15 amps.
SF12-P2: 2 prong/twist lock/2 pole/2 wire/UL Listed/
NEMA L1-15P/125 volts/15 amps.
SF12-P3: 3 prong/twist lock/2 pole/3 wire/UL&CSA Listed/
NEMA L6-15P/250 volts/15 amps.
SF12-P4: 3 prong/twist lock/2 pole/3 wire/UL&CSA Listed/
NEMA L6-20/250 volts/20 amps.
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″.
Available on:
- Standard Cartridge: 3/8″ to 1″ diameter.
- Superwatt Cartridge: 3/8″ x 1″ diameter.
SF13B: Moisture resistant box. Mounted on NPT fitting.
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.
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.
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.
| 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.
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.
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.
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.
SF23: Table Of Dimensions
| 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.