Eaton BK/MDQ-9 Glass Cartridge Fuse – Equivalent & Substitute Parts

Part Overview

The Eaton BK/MDQ-9 is a 9 A, 32 V AC/DC slow-blow glass cartridge fuse designed for applications requiring reliable overcurrent protection in industrial and commercial equipment. This fuse operates within the 3AB and 3AG holder standards and measures 1/4" × 1-1/4" (6.35 mm × 31.75 mm). The part maintains Active product status with 673 units in current inventory stock.

Substitute parts are identified when equivalent electrical ratings, mechanical dimensions, and functional characteristics align with the original specification, enabling direct replacement without circuit redesign or holder modification.

Substiute Parts

BK/MDQ-9

Eaton - Electronics DivisionIn Stock: 740BK/MDQ-9 Datasheet

Current PartRFQ

BK/MDL-9-R

Eaton - Electronics DivisionIn Stock: 922BK/MDL-9-R Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BK/MDQ-9 is determined by strict alignment of the following parameters:

• Current Rating: Must equal 9 A
• Voltage Rating (AC): Must equal 32 V
• Fuse Type: Must be Cartridge, Glass
• Response Time: Must be Slow Blow
• Package / Case: Must be 3AB, 3AG, 1/4" × 1-1/4"
• Breaking Capacity @ Rated Voltage: Must equal 1 kA
• Physical Dimensions: Must be 0.250" Dia × 1.250" L (6.35 mm × 31.75 mm)

The Eaton BK/MDL-9-R meets all substitution criteria and is classified as a parametric equivalent. Both parts share identical electrical and mechanical specifications, enabling direct replacement within existing 3AB and 3AG holder assemblies.

Parameter Comparison

Engineering Selection Recommendations

BK/MDQ-9 Selection Criteria:

• Specified when RoHS non-compliant status is acceptable or required by legacy system design
• Maintains CSA and UL certifications for North American applications
• Current inventory of 673 units supports immediate procurement

BK/MDL-9-R Selection Criteria:

• Specified when ROHS3 compliance is required by design or regulatory mandate
• Provides expanded certification scope with CE approval in addition to CSA and UL
• Higher inventory availability (823 units) supports extended production runs
• Suitable for applications requiring REACH compliance documentation

Both parts satisfy identical electrical and mechanical requirements. Selection between them depends on regulatory compliance requirements and certification scope applicable to the end application.

Frequently Asked Questions (FAQ)

Q: Can the BK/MDL-9-R directly replace the BK/MDQ-9 in existing assemblies?

A: Yes. Both parts share identical current rating (9 A), voltage rating (32 V AC), fuse type (Cartridge, Glass), response time (Slow Blow), package designation (3AB, 3AG), and physical dimensions (0.250" Dia × 1.250" L). Direct installation in existing 3AB and 3AG holders is supported without modification.

Q: What is the difference in DC Cold Resistance between these parts?

A: The BK/MDQ-9 has a DC Cold Resistance of 0.00888 Ohms, while the BK/MDL-9-R measures 0.012 Ohms. Both values fall within acceptable operating parameters for slow-blow cartridge fuses at the 9 A rating and do not affect functional compatibility.

Q: Why does the BK/MDL-9-R have additional certifications?

A: The BK/MDL-9-R includes CE certification in addition to CSA and UL approvals, expanding its regulatory acceptance to European markets. This does not affect its use in North American applications where CSA and UL certifications are primary requirements.

Q: Is RoHS compliance a factor in selecting between these parts?

A: RoHS compliance becomes a selection factor only when the end application or customer specification explicitly requires it. The BK/MDQ-9 is RoHS non-compliant, while the BK/MDL-9-R is ROHS3 compliant. Verify application requirements before selection.

Q: Are both parts suitable for 32 V AC and DC applications?

A: Yes. Both the BK/MDQ-9 and BK/MDL-9-R are rated for 32 V AC/DC operation with a 1 kA breaking capacity at rated voltage, supporting both alternating and direct current circuit protection.

Q: What holder types are compatible with these fuses?

A: Both fuses require a holder and are compatible with 3AB and 3AG holder standards. The 1/4" × 1-1/4" (6.35 mm × 31.75 mm) physical dimensions ensure mechanical fit within these standardized holder assemblies.