BH25M 25-Pin Male Bulkhead Underwater Connector – SubConn Compatible Standard Circular Series

Product Overview

The HYSF SUBSEA BH25M 25-Pin Male Bulkhead Underwater Connector is a high-density, pressure-resistant subsea electrical connector designed to provide reliable multi-channel power, signal, and control connections through underwater equipment housings.As part of the HYSF Standard Circular Connector Series, the BH25M features twenty-five male electrical contacts, a corrosion-resistant 316L stainless steel housing, and a threaded bulkhead mounting arrangement designed for demanding marine environments.The connector provides a fixed electrical interface between the internal electronics of a sealed underwater enclosure and an external subsea cable assembly.The Standard Circular series is designed for underwater applications at depths of up to 6,000 meters (60 MPa), subject to the qualification of the complete connector installation.The BH25M belongs to the 25-pin Standard Circular configuration, which has a nominal rated current of 5A per contact and a series rated voltage of 550V AC/DC.Selected higher-current contact configurations may support up to 10A, depending on the approved connector design. These higher ratings should not be applied automatically to every contact.The standard BH25M features a 3/4-16 UNF-2A mounting thread, a nominal 25 mm thread length, and approximately 0.3 meters of internal wire leads for integration into subsea equipment.The BH25M is designed to mate with the IL25F 25-Pin Female Inline Underwater Connector.Its mating interface is designed for compatibility with corresponding SubConn and SEACON Standard Circular underwater connectors.Typical applications include remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), sonar systems, hydrophone arrays, oceanographic instruments, offshore monitoring equipment, subsea electronic modules, and marine scientific research platforms.

Key Features and Benefits

1. High-Density 25-Pin Male Electrical Interface

The BH25M incorporates twenty-five electrical contact positions within a single circular bulkhead connector.Its high-density configuration provides an efficient solution for underwater equipment requiring numerous independent electrical channels through one pressure housing penetration.The twenty-five contacts can be allocated to appropriately designed circuits involving:

• Underwater sensor signals
• Marine instrumentation
• Electrical control functions
• Low-power distribution
• Acoustic measurement circuits
• Environmental monitoring
• Auxiliary equipment connections
• Multi-channel data acquisition
• Subsea electronic systems

Compared with multiple low-pin-count bulkhead connectors, a single 25-pin interface may reduce the number of openings required in an underwater enclosure.This can simplify mechanical design, internal cable routing, external cable management, and equipment maintenance.The actual electrical circuit allocation must be determined using the approved pin assignment and wiring documentation.

2. Nominal Current Rating of 5A per Contact

The BH25M belongs to the HYSF Standard Circular 12/16/25 Pin connector family.The 25-pin configuration has a nominal current rating of 5A per contact.This differs from the Standard 12-pin and 16-pin configurations, which have a catalog current rating of 10A per contact.The manufacturer’s 25-pin series documentation also identifies selected higher-current configurations that may support up to 10A.However, the exact contact positions and conditions associated with these ratings must be verified against the approved connector specifications.The permissible electrical loading of a completed assembly depends on:

• Individual contact ratings
• Internal wire cross-sectional area
• Number of simultaneously energized circuits
• Cable termination quality
• Operating temperature
• Heat dissipation
• Voltage drop
• Installation conditions

For equipment requiring continuous operation near the maximum electrical rating, the complete connector and wiring system should be evaluated for thermal and electrical performance.

3. 550V AC/DC Rated Voltage

The HYSF Standard Circular connector family supports a rated voltage of 550V AC/DC.The BH25M can be integrated into suitable underwater electrical systems operating within the approved voltage limits of the connector and complete assembly.When designing a multi-channel subsea connection, engineers should consider conductor insulation, circuit separation, connected equipment, and environmental conditions.The permitted operating voltage must not exceed the rating of the lowest-rated component in the completed electrical system.

4. SubConn and SEACON Compatible Standard Circular Interface

The HYSF BH25M is designed for mating compatibility with corresponding SubConn and SEACON Standard Circular 25-pin connector interfaces.This makes the BH25M suitable for consideration in compatible replacement projects and newly developed subsea equipment.Applications may include:

• Replacement underwater bulkhead connectors
• ROV electrical system upgrades
• Marine instrumentation maintenance
• Offshore subsea equipment
• OEM underwater electrical systems
• Custom subsea cable integration

The primary corresponding cable connector is the IL25F female inline underwater connector.Before using a BH25M with another manufacturer’s connector, verify the exact product series, contact arrangement, mating geometry, retention system, and installation requirements.Matching contact count alone does not guarantee compatibility.

5. Deep-Sea Design Capability up to 6,000 Meters

The HYSF Standard Circular connector family is designed for subsea environments involving high external hydrostatic pressure.The series supports a design depth capability of up to 6,000 meters, equivalent to approximately 60 MPa.This makes the BH25M suitable for consideration in:

• Deep-sea exploration
• Seabed scientific research
• Offshore underwater monitoring
• Subsea robotic systems
• Oceanographic instruments
• Deep-water sensor networks
• Underwater electronic enclosures

The BH25M provides a sealed electrical passage through an equipment housing when installed using the approved mounting and sealing arrangement.Actual operating depth depends on the complete installation, including:

• Connector housing
• Bulkhead mounting interface
• O-ring sealing system
• Equipment enclosure
• Internal electrical terminations
• External mating cable connector
• Complete assembly qualification

For critical deep-water applications, the installed connector assembly should be verified for the intended operating pressure.

6. Marine-Grade 316L Stainless Steel Housing

The standard BH25M uses a 316L stainless steel housing.316L stainless steel is widely used in marine engineering because of its combination of corrosion resistance and mechanical strength.The material provides a durable housing for the electrical contacts and threaded bulkhead mounting arrangement.Its advantages include:

• Good corrosion resistance in marine environments
• Mechanical strength
• Dimensional stability
• Durable threaded mounting
• Resistance to routine equipment handling
• Suitability for demanding subsea installations

Alternative housing materials may be considered for specific engineering projects.When stainless steel connectors are installed in aluminum pressure housings, the potential for galvanic corrosion should be evaluated.Appropriate material selection, protective coatings, and electrical isolation may be necessary.

7. Precision 3/4-16 UNF-2A Bulkhead Mounting Thread

The BH25M is designed for threaded installation through underwater equipment enclosures.The Standard Circular 12/16/25 Pin technical documentation specifies:

• Mounting Thread: 3/4-16 UNF-2A
• Nominal Thread Length: 25 mm
• Base Mounting Radius: 32.4 mm
• Recommended Mounting Surface Roughness: Ra 1.6
• Mounting Type: Threaded Bulkhead

The threaded design allows the connector to be secured through a compatible pressure housing wall.The standard mounting arrangement includes the specified locking nut, with POM as the standard nut material and 316L stainless steel available as an alternative.Before machining the equipment enclosure, the exact installation dimensions should be checked against the approved BH25M mechanical drawing.Thread size alone is not sufficient to determine the required hole geometry, sealing dimensions, and panel thickness.

8. Watertight O-Ring Sealing System

The BH25M uses an O-ring sealing arrangement designed to help prevent seawater ingress through the bulkhead mounting interface.The sealing performance depends on several installation factors:

• Correct O-ring dimensions
• Suitable elastomer material
• Accurate mounting geometry
• Proper sealing surface finish
• Appropriate O-ring compression
• Correct installation procedure
• Housing wall thickness
• Mechanical loading conditions

The sealing components should be inspected before installation.For equipment operating at high hydrostatic pressure, the complete bulkhead installation should be included in the pressure qualification process.

9. Standard 0.3-Meter Internal Wire Leads

The BH25M is normally supplied with approximately 0.3 meters of internal wire leads.These leads extend from the rear of the connector into the underwater equipment housing.They provide electrical integration with:

• Electronic control boards
• Sensor electronics
• Power distribution terminals
• Marine instrumentation
• Internal wiring harnesses
• Data acquisition systems
• Subsea monitoring modules

Custom lead lengths and specialized termination configurations can be specified according to project requirements.The actual wire identification and pin-to-wire assignment must be verified using the approved production drawing.

10. Gold-Plated Electrical Contacts

The BH25M incorporates gold-plated electrical contact surfaces.Gold plating provides a stable conductive surface and helps reduce oxidation that can affect electrical contact performance.This is especially important for underwater instruments and monitoring systems requiring dependable electrical continuity.Before mating the connector, the contact interface should be inspected for contamination, foreign particles, or visible mechanical damage.Correct handling and appropriate maintenance can help preserve reliable connector performance.

11. Wet-Mateable Underwater Connector Design

The BH25M belongs to HYSF SUBSEA’s wet-mateable Standard Circular connector family.The mating interface is designed to support underwater connection and disconnection according to the applicable operating procedures.Wet-mateable technology is useful for underwater systems requiring:

• Periodic sensor replacement
• Modular instrument installation
• Underwater cable servicing
• Equipment maintenance
• Subsea component reconfiguration

Important: Wet-mateable does not automatically mean live-mateable.Electrical power should be isolated before mating or unmating unless the complete connector assembly has been specifically qualified for energized operation.

BH25M Technical Specifications

Parameter	Specification
Brand	HYSF SUBSEA
Model Number	BH25M
Product Series	Standard Circular
Connector Type	Male Bulkhead Underwater Connector
Number of Contacts	25
Contact Gender	Male
Contact Finish	Gold-Plated
Standard Housing Material	316L Stainless Steel
Optional Housing Materials	Subject to Engineering Configuration
Rated Voltage	550V AC/DC
Nominal Rated Current	5A per Contact
Selected Higher-Current Configurations	Up to 10A, Subject to Confirmation
Design Depth Capability	Up to 6,000 Meters
Pressure Capability	Up to 60 MPa
Mating Type	Wet-Mateable
Mounting Type	Threaded Bulkhead
Mounting Thread	3/4-16 UNF-2A
Nominal Thread Length	25 mm
Base Mounting Radius	32.4 mm
Mounting Surface Roughness	Ra 1.6
Standard Internal Wire Length	0.3 Meter
Sealing System	O-Ring Sealing
Primary Mating Connector	IL25F
Protective Dummy Plug	DC25F
Compatibility	Corresponding SubConn and SEACON Standard Circular Interfaces
Warranty	12 Months

Engineering Note: The nominal current rating is 5A per contact. Higher-current configurations require verification of the specific contact arrangement, internal wiring, and complete assembly.

25-Pin Wiring and Conductor Identification

The BH25M provides twenty-five contact positions for multiple electrical circuits.Depending on the selected configuration, the rear wire leads may use different conductor colors, numbered sleeves, or customized identification systems.The Standard Circular 25-pin inline cable family includes wiring arrangements that use individual conductors and twisted-pair constructions.However, the inline cable color sequence should not automatically be applied to the BH25M internal leads.The actual bulkhead wiring depends on the approved production configuration.

Recommended Wiring Verification

Before connecting the BH25M to internal electronics:

1. Confirm the connector contact numbering using the correct mating-face view.
2. Identify every internal conductor.
3. Review the approved pin-to-wire drawing.
4. Verify each circuit using electrical continuity testing.
5. Confirm the required power, ground, signal, and control assignments.
6. Record customized wiring arrangements for future maintenance.

The actual conductor color mapping should be verified against the wiring documentation supplied with the completed connector.

Compatible Connectors and Accessories

IL25F – 25-Pin Female Inline Underwater Connector

The IL25F is the primary female cable connector designed to mate with the BH25M male bulkhead.The IL25F features twenty-five female electrical contacts and an integrated underwater cable.The standard IL25F is normally supplied with approximately one meter of cable.Normal electrical configuration:BH25M Male Bulkhead + IL25F Female Inline ConnectorThis combination provides a detachable electrical connection between the equipment’s internal electronics and an external underwater cable assembly.

DC25F – 25-Pin Female Dummy Plug

The DC25F is the corresponding female protective dummy plug for the BH25M male bulkhead.When the operational IL25F cable connector is disconnected, the DC25F can be installed to help protect the exposed male connector interface.Protective configuration:BH25M Male Bulkhead + DC25F Female Dummy PlugThe dummy plug is a protective accessory and does not transmit electrical power or signals.Its pressure suitability must be verified for the complete capped connector assembly.

BH25F – 25-Pin Female Bulkhead Underwater Connector

The BH25F is the corresponding female bulkhead model within the same Standard Circular 25-pin family.Its primary mating cable connector is the IL25M male inline connector.The corresponding protective accessory is the DC25M male dummy plug.

BH25M vs. BH25F

Feature	BH25M	BH25F
Product Type	Male Bulkhead	Female Bulkhead
Contact Count	25	25
Contact Gender	Male	Female
Standard Housing	316L Stainless Steel	316L Stainless Steel
Rated Voltage	550V AC/DC	550V AC/DC
Nominal Current	5A per Contact	5A per Contact
Standard Wire Leads	0.3 m	0.3 m
Mounting Thread	3/4-16 UNF-2A	3/4-16 UNF-2A
Primary Mating Connector	IL25F	IL25M
Protective Dummy Plug	DC25F	DC25M

The two bulkhead connectors have opposite contact genders and should be selected according to the required mating cable configuration.

Typical Applications of BH25M Underwater Connectors

1. Remotely Operated Vehicles (ROVs)

ROVs often require multiple electrical connections between sealed pressure housings and external underwater equipment.The BH25M can provide a high-density interface for appropriate ROV sensor, instrumentation, and control circuits.Its twenty-five-contact arrangement may reduce the number of separate enclosure penetrations required.

2. Autonomous Underwater Vehicles (AUVs)

AUVs frequently use modular electronic equipment and external scientific instruments.The BH25M can provide a fixed bulkhead electrical connection for appropriate AUV sensor and monitoring systems.The detachable mating configuration supports equipment maintenance and cable replacement.

3. Sonar and Hydrophone Systems

Underwater acoustic systems may require numerous electrical channels for measurement, sensor excitation, control, and monitoring.The BH25M offers twenty-five contact positions for suitable acoustic instrumentation.For low-level analog signals, appropriate shielding, grounding, and electromagnetic interference control should be considered.

4. Oceanographic Research Instruments

Marine scientific instruments often require high-density electrical connections through watertight enclosures.The BH25M can be integrated into suitable:

• Oceanographic data acquisition systems
• Environmental monitoring equipment
• Marine sensor arrays
• Underwater acoustic instruments
• Seabed observation systems
• Deep-water scientific instrumentation

5. Underwater Cameras and Imaging Equipment

Subsea imaging systems may require multiple electrical circuits for camera power, control, and auxiliary sensors.The BH25M provides a fixed electrical interface through a properly designed underwater housing.High-speed data compatibility must be verified based on the complete cable design and signal requirements.

6. Offshore Monitoring Equipment

Offshore subsea monitoring systems frequently operate under high hydrostatic pressure and prolonged seawater exposure.The BH25M can provide a durable high-density electrical connection for suitably designed instrumentation and monitoring equipment.

7. Marine Research and Testing Systems

Underwater equipment manufacturers and research laboratories may require customizable electrical interfaces for specialized instruments.The BH25M provides a Standard Circular bulkhead configuration for appropriate prototype, testing, and scientific equipment.

BH25M Installation Guidelines

Step 1: Verify the Installation Drawing

Confirm the 3/4-16 UNF-2A mounting thread, nominal 25 mm thread length, and all sealing dimensions.Use the approved BH25M drawing before machining the enclosure.

Step 2: Inspect the Connector

Check the stainless steel housing, mounting thread, electrical contacts, and sealing surfaces for damage.

Step 3: Prepare the Equipment Housing

Machine the installation opening according to the approved drawing.Ensure the sealing surface is clean and free from burrs, scratches, and contamination.

Step 4: Inspect and Install the O-Ring

Verify the correct O-ring specification.Inspect it for damage and follow the approved installation procedure.

Step 5: Mount the BH25M

Position the connector through the enclosure wall.Secure it using the specified mounting hardware and tightening procedure.

Step 6: Connect the Internal Wires

Route the standard internal wire leads to the equipment electronics.Verify the actual contact assignments before making the electrical connections.

Step 7: Mate the IL25F Connector

Check both connector mating interfaces for contamination or damage.Align the IL25F correctly and complete the mating operation using the appropriate retention arrangement.

Step 8: Verify Electrical and Sealing Performance

Perform the required electrical tests and verify the completed enclosure sealing system.For critical subsea equipment, the complete installation should meet the required pressure qualification.

Quality Control and Testing

HYSF SUBSEA manufactures underwater electrical connectors and customized subsea interconnection assemblies.Depending on the product configuration and project requirements, quality-control procedures may include:

• Hydrostatic pressure testing
• Electrical continuity testing
• Insulation resistance measurement
• Dielectric withstand testing
• Contact inspection
• Dimensional verification
• O-ring sealing inspection
• Internal wiring verification
• Mechanical integrity evaluation

Testing requirements and acceptance criteria should be defined according to the approved product configuration.

Frequently Asked Questions

Q1: What is the BH25M underwater connector?

The BH25M is a 25-pin male bulkhead underwater electrical connector belonging to the HYSF Standard Circular Series.It is designed to provide multiple electrical connections through sealed subsea equipment housings.

Q2: Which connector mates with BH25M?

The primary mating connector is the IL25F 25-Pin Female Inline Underwater Connector.

Q3: Is BH25M compatible with SubConn?

The BH25M is designed for compatibility with corresponding SubConn Standard Circular 25-pin interfaces.Exact mechanical compatibility should be verified against the relevant product drawings.

Q4: What is the rated current?

The nominal current rating is 5A per contact.Selected higher-current configurations may support up to 10A, subject to confirmation of the approved contact arrangement.

Q5: What is the rated voltage?

The Standard Circular series is rated for 550V AC/DC.

Q6: What is the maximum operating depth?

The connector family is designed for applications up to 6,000 meters (60 MPa), subject to the qualification of the complete installed assembly.

Q7: What is the mounting thread?

The standard BH25M mounting thread is 3/4-16 UNF-2A.

Q8: What is the standard thread length?

The nominal mounting thread length is 25 mm.

Q9: What is the standard housing material?

The standard BH25M housing is manufactured from 316L stainless steel.

Q10: What is the standard internal wire length?

The standard BH25M is normally supplied with approximately 0.3 meters of internal wire leads.

Q11: Can the internal wire length be customized?

Yes. Customized internal wire lengths and termination arrangements can be specified according to project requirements.

Q12: Is BH25M wet-mateable?

Yes. The BH25M belongs to the wet-mateable Standard Circular connector family.Electrical power should be isolated before mating or unmating unless energized operation has been specifically qualified.

Q13: Which dummy plug protects BH25M?

The corresponding protective accessory is the DC25F 25-Pin Female Dummy Plug.

Q14: What is the difference between BH25M and BH25F?

BH25M has twenty-five male contacts and primarily mates with IL25F.BH25F has twenty-five female contacts and primarily mates with IL25M.

Q15: Can BH25M be installed in an aluminum housing?

Installation may be possible when the mechanical dimensions and sealing requirements are suitable.Potential galvanic corrosion between stainless steel and aluminum should be evaluated.

Q16: Can BH25M be used for Ethernet?

The BH25M provides twenty-five electrical contacts, but contact count alone does not guarantee Ethernet compatibility.The complete cable construction, shielding, conductor pairing, impedance, and signal integrity must be verified.

Why Choose HYSF SUBSEA BH25M?

The HYSF SUBSEA BH25M 25-Pin Male Bulkhead Underwater Connector provides a durable high-density electrical interface for marine and subsea equipment.Its main advantages include:

• Twenty-five male electrical contacts
• SubConn-compatible Standard Circular mating interface
• Wet-mateable connector design
• Nominal 5A per contact rating
• Selected higher-current options subject to verification
• 550V AC/DC rated voltage
• Design depth capability up to 6,000 meters
• Corrosion-resistant 316L stainless steel housing
• 3/4-16 UNF-2A mounting thread
• Standard 0.3-meter internal wire leads
• O-ring bulkhead sealing
• Compatible IL25F female inline connector
• Corresponding DC25F protective dummy plug
• Customized wiring and material configurations
• 12-month product warranty

For underwater robotic vehicles, sonar systems, oceanographic instruments, offshore monitoring equipment, and deep-sea research platforms, the BH25M provides a practical solution for routing multiple electrical circuits through a single sealed equipment housing penetration.Its high-density contact configuration, durable metal housing, and compatibility with established Standard Circular connector interfaces make the BH25M suitable for demanding subsea electrical integration applications.