BH25F 25-Pin Female Bulkhead Underwater Connector – SubConn Compatible Standard Circular Series

Product Overview

The HYSF SUBSEA BH25F 25-Pin Female 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 BH25F features twenty-five gold-plated female electrical contacts, a corrosion-resistant 316L stainless steel housing, and a threaded bulkhead mounting arrangement for demanding marine applications.The BH25F provides a fixed electrical interface between internal equipment electronics and external subsea cable assemblies. Its twenty-five-contact configuration is particularly useful for systems requiring multiple electrical circuits through a single underwater pressure housing penetration.The Standard Circular series is designed for underwater applications at depths of up to 6,000 meters (60 MPa), subject to qualification of the complete connector installation.The BH25F belongs to the 25-pin Standard Circular configuration, which has a nominal current rating 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 automatically be assigned to every contact.The standard BH25F configuration 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 electrical integration inside underwater equipment.The BH25F is primarily designed to mate with the IL25M 25-Pin Male Inline Underwater Connector.Its Standard Circular mating interface is designed for compatibility with corresponding SubConn and SEACON underwater electrical connector configurations.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 research platforms.

Key Features and Benefits

1. High-Density 25-Pin Female Electrical Interface

The BH25F incorporates twenty-five female electrical contact positions within a single circular bulkhead connector.This high-density arrangement provides an efficient solution for subsea equipment requiring multiple electrical circuits through one enclosure penetration.The contacts can be allocated to appropriately designed applications involving:

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

Compared with several lower-pin-count bulkhead connectors, a single 25-pin female underwater connector may reduce the number of separate penetrations required in a pressure housing.This can simplify equipment integration, cable routing, and enclosure design.The actual contact functions should be selected according to the approved electrical schematic and wiring arrangement.

2. Nominal 5A per Contact Current Rating

The BH25F belongs to the HYSF Standard Circular 12/16/25 Pin connector family.The standard 25-pin configuration has a nominal current rating of 5A per contact.This differs from the Standard Circular 12-pin and 16-pin configurations, which have a catalog current rating of 10A per contact.The manufacturer’s series documentation also references selected higher-current configurations reaching 10A.However, the specific contact arrangement and permitted operating conditions must be verified before applying a higher current rating.The electrical loading capability of a complete assembly depends on:

• Individual contact specifications
• Internal wire cross-sectional area
• Number of simultaneously loaded contacts
• Operating temperature
• Conductor insulation
• Termination quality
• Heat dissipation
• Connected equipment requirements

For systems requiring continuous operation near the maximum contact current, the complete electrical assembly should be evaluated for thermal performance and voltage drop.

3. Rated Voltage of 550V AC/DC

The HYSF Standard Circular connector series has a rated voltage of 550V AC/DC.The BH25F can be used in appropriately designed subsea electrical systems operating within the approved voltage rating.When multiple electrical circuits share one connector, engineers should consider insulation requirements, voltage differences between contacts, grounding, and circuit separation.The allowable system voltage must not exceed the rating of the lowest-rated component in the complete electrical assembly.

4. SubConn and SEACON Compatible Standard Circular Design

The HYSF BH25F is designed for mating compatibility with corresponding SubConn and SEACON Standard Circular 25-pin underwater connector interfaces.This makes the BH25F suitable for consideration in new underwater equipment designs and compatible replacement applications.Typical projects include:

• Replacement underwater bulkhead connectors
• ROV electrical system upgrades
• Offshore instrument maintenance
• Marine scientific equipment
• OEM subsea electronics
• Customized underwater cable assemblies
• Compatible subsea connector replacement

The primary HYSF mating connector is IL25M, a 25-pin male inline underwater cable connector.Before mating the BH25F with another manufacturer’s connector, verify the exact series, contact configuration, mating dimensions, and locking arrangement.Compatibility should be confirmed using the applicable product drawings.

5. Designed for Deep-Sea Applications up to 6,000 Meters

The HYSF Standard Circular connector family is designed for demanding underwater environments involving high hydrostatic pressure.The series supports a design depth capability of up to 6,000 meters, corresponding to approximately 60 MPa.The BH25F can therefore be considered for suitable applications involving:

• Deep-sea exploration
• Oceanographic research
• Seabed monitoring
• Offshore underwater inspection
• Subsea robotic systems
• Deep-water scientific instruments
• Marine environmental monitoring

The bulkhead connector provides an electrical connection through a pressure housing wall while helping maintain enclosure sealing integrity.Actual operating depth depends on the complete installed assembly, including the connector housing, O-ring seal, equipment enclosure, internal wiring, external mating connector, and required environmental qualification.For critical subsea applications, the complete installation should be tested and verified for the intended working pressure.

6. Corrosion-Resistant 316L Stainless Steel Housing

The standard BH25F features a 316L stainless steel bulkhead housing.316L stainless steel is widely used in marine equipment because of its mechanical strength, corrosion resistance, and durability.Its principal benefits include:

• Good corrosion resistance in marine environments
• High mechanical strength
• Durable threaded mounting
• Dimensional stability
• Suitability for pressure housing installations
• Resistance to routine handling and mechanical wear

The metal housing provides structural support for the electrical contact assembly and bulkhead mounting arrangement.Alternative housing materials may be considered for customized applications.When stainless steel connectors are installed in aluminum pressure housings, potential galvanic corrosion should be evaluated.Suitable protective coatings, material selection, and isolation measures may be required.

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

The BH25F features a threaded mounting arrangement designed for installation through subsea equipment enclosures.The corresponding 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
• Mounting Surface Roughness: Ra 1.6
• Mounting Configuration: Threaded Bulkhead

The threaded design allows the BH25F to be secured to a compatible pressure housing or underwater equipment panel.The standard mounting arrangement includes the specified locking nut. POM is the standard nut material, while 316L stainless steel is available as an alternative.Before machining the enclosure, the installation hole dimensions, sealing geometry, panel thickness, and installation clearances should be verified against the approved BH25F mechanical drawing.The mounting thread alone does not define the complete installation requirements.

8. Watertight O-Ring Sealing System

The BH25F incorporates an O-ring sealing arrangement designed to help prevent seawater ingress through the mounting interface.The seal provides a protective barrier between the connector housing and the equipment enclosure wall.Effective sealing depends on:

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

The sealing components should be inspected before installation.For equipment operating under high hydrostatic pressure, the complete connector and enclosure assembly should be included in the pressure qualification process.

9. Standard 0.3-Meter Internal Wire Leads

The standard BH25F is normally supplied with approximately 0.3 meters of internal wire leads.These leads extend from the rear of the bulkhead connector into the underwater equipment housing.They provide electrical integration with components such as:

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

Customized internal wire lengths and termination configurations can be specified according to equipment requirements.The actual conductor identification and pin assignments must be confirmed using the approved production drawing.

10. Gold-Plated Female Electrical Contacts

The BH25F incorporates gold-plated female electrical contacts.Gold plating provides a conductive contact surface and helps reduce oxidation.Stable electrical contact performance is particularly important for subsea instrumentation and monitoring equipment requiring reliable electrical continuity.The female contact interface is designed to mate with the corresponding IL25M male connector.Before connection, the mating interface should be inspected for sand, sediment, salt deposits, contamination, and visible mechanical damage.Correct handling and routine maintenance help maintain connector reliability.

11. Wet-Mateable Underwater Connector Design

The BH25F belongs to HYSF SUBSEA’s wet-mateable Standard Circular connector family.Its mating interface is designed to support underwater connection and disconnection under the applicable procedures.Wet-mateable connector technology can be useful for:

• Modular underwater instrumentation
• Removable subsea sensors
• ROV maintenance operations
• Underwater cable replacement
• Marine scientific equipment servicing
• Subsea equipment reconfiguration

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

BH25F Technical Specifications

Parameter	Specification
Brand	HYSF SUBSEA
Model Number	BH25F
Product Series	Standard Circular
Connector Type	Female Bulkhead Underwater Connector
Number of Contacts	25
Contact Gender	Female
Contact Finish	Gold-Plated
Standard Housing Material	316L Stainless Steel
Alternative 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	IL25M
Protective Dummy Plug	DC25M
Compatibility	Corresponding SubConn and SEACON Standard Circular Interfaces
Warranty	12 Months

Engineering Note: The nominal current rating is 5A per contact. Any higher-current configuration requires verification of the exact contact arrangement, internal wiring, and complete electrical assembly.

25-Pin Wiring and Conductor Identification

The BH25F provides twenty-five electrical contact positions for multiple power, control, and signal circuits.Depending on the ordered configuration, its internal wire leads may use individual conductor colors, numbered identification sleeves, or customized markings.The HYSF Standard Circular 25-pin inline cable family includes wiring configurations with individual conductors and twisted-pair arrangements.However, the inline cable color sequence should not automatically be applied to BH25F bulkhead internal leads.The actual BH25F wiring arrangement depends on the approved production configuration.

Recommended Wiring Verification

Before connecting the BH25F to internal equipment:

1. Confirm the connector contact numbering using the correct mating-face orientation.
2. Identify every internal conductor.
3. Review the approved pin-to-wire wiring diagram.
4. Verify electrical continuity for each contact.
5. Confirm all power, ground, control, and signal assignments.
6. Document customized wiring arrangements for maintenance purposes.

The actual conductor color mapping must be verified using the wiring documentation supplied with the completed connector.

Compatible Connectors and Accessories

IL25M – 25-Pin Male Inline Underwater Connector

The IL25M is the primary male inline connector designed to mate with the BH25F female bulkhead.It features twenty-five male electrical contacts and an integrated underwater cable.The standard IL25M is normally supplied with approximately one meter of cable.Normal electrical connection:BH25F Female Bulkhead + IL25M Male Inline ConnectorThis combination creates a detachable electrical connection between internal underwater equipment electronics and the external subsea cable assembly.

DC25M – 25-Pin Male Dummy Plug

The DC25M is the corresponding male protective dummy plug for the BH25F female bulkhead.When the operational IL25M cable connector is disconnected, the DC25M can be installed to help protect the exposed female mating interface.Protective configuration:BH25F Female Bulkhead + DC25M Male Dummy PlugThe DC25M is a non-electrical protective accessory and does not transmit power, data, or signals.Its environmental and pressure suitability should be verified for the complete capped connector assembly.

BH25M – 25-Pin Male Bulkhead Connector

The BH25M is the corresponding opposite-gender bulkhead connector in the Standard Circular 25-pin family.Its primary mating cable connector is IL25F, while its protective dummy plug is DC25F.

BH25F vs. BH25M

Feature	BH25F	BH25M
Connector Type	Female Bulkhead	Male Bulkhead
Number of Contacts	25	25
Contact Gender	Female	Male
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 Internal Leads	0.3 m	0.3 m
Mounting Thread	3/4-16 UNF-2A	3/4-16 UNF-2A
Primary Mating Connector	IL25M	IL25F
Protective Dummy Plug	DC25M	DC25F

Both models provide high-density bulkhead connections for appropriately designed subsea electrical systems.The correct gender configuration must be selected according to the external cable connector.

Typical Applications of BH25F Underwater Connectors

1. Remotely Operated Vehicles (ROVs)

ROVs require reliable electrical interfaces between sealed pressure housings and external equipment.The BH25F can provide a high-density electrical connection for suitable sensor, instrumentation, control, and monitoring circuits.Its twenty-five-contact arrangement may help reduce the number of separate housing penetrations.

2. Autonomous Underwater Vehicles (AUVs)

AUVs frequently incorporate modular electronic equipment and external scientific instruments.The BH25F provides a fixed electrical interface for appropriate AUV sensor and monitoring systems.Its detachable mating configuration supports external cable replacement and equipment maintenance.

3. Sonar and Hydrophone Systems

Underwater acoustic instruments may require numerous electrical channels for measurement, sensor excitation, monitoring, and control.The BH25F provides twenty-five contact positions for suitable acoustic instrumentation.For sensitive analog signals, appropriate shielding, grounding, conductor pairing, and electromagnetic interference control should be considered.

4. Oceanographic Research Instruments

Marine scientific instruments often require multiple electrical circuits through sealed housings.The BH25F can be incorporated into suitable:

• Oceanographic data acquisition systems
• Marine environmental monitoring platforms
• Scientific sensor arrays
• Underwater acoustic instruments
• Seabed observation equipment
• Deep-water measurement systems

5. Underwater Cameras and Imaging Systems

Subsea imaging equipment may require multiple circuits for power, control, and auxiliary sensors.The BH25F can provide a fixed electrical interface through a properly designed underwater camera or electronics housing.Compatibility with high-speed data protocols must be evaluated using the complete cable and electrical system specifications.

6. Offshore Monitoring Equipment

Offshore monitoring systems may operate under prolonged seawater exposure, mechanical loading, and high hydrostatic pressure.The BH25F provides a durable bulkhead connection for appropriately designed subsea instrumentation and monitoring systems.

7. Marine Research and Testing Equipment

Underwater equipment manufacturers and research organizations often require customized electrical interfaces for experimental instruments.The BH25F provides a Standard Circular high-density bulkhead connection suitable for appropriate prototype, scientific, and testing applications.

BH25F Installation Guidelines

Step 1: Verify the Mechanical Drawing

Confirm the 3/4-16 UNF-2A mounting thread, 25 mm nominal thread length, mounting opening, and sealing dimensions.Always use the approved BH25F installation drawing before machining the pressure housing.

Step 2: Inspect the Connector

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

Step 3: Prepare the Equipment Housing

Machine the mounting opening according to the approved technical drawing.Ensure the sealing surface is free from burrs, scratches, dirt, and contamination.

Step 4: Inspect and Install the O-Ring

Verify the specified O-ring dimensions and material.Inspect the seal for damage before installation and follow the approved sealing procedure.

Step 5: Mount the BH25F

Position the bulkhead connector through the prepared enclosure opening.Secure it using the appropriate mounting nut and approved tightening procedure.

Step 6: Connect the Internal Wiring

Route the internal wire leads to the appropriate equipment electronics.Verify the pin assignments and conductor identification before making electrical connections.

Step 7: Mate the IL25M Connector

Inspect both mating interfaces for contamination and mechanical damage.Align the IL25M male inline connector with the BH25F female bulkhead and complete the connection using the approved mating procedure.

Step 8: Verify Electrical and Sealing Performance

Perform the required electrical checks and verify the completed enclosure sealing arrangement.For pressure-critical equipment, confirm that the complete installation meets the intended operating conditions.

Quality Control and Testing

HYSF SUBSEA manufactures underwater electrical connectors and customized subsea interconnection assemblies.Depending on the product configuration and project specifications, 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 depend on the approved configuration and intended operating environment.

Frequently Asked Questions

Q1: What is the BH25F underwater connector?

The BH25F is a 25-pin female bulkhead underwater electrical connector belonging to the HYSF Standard Circular Series.It provides multiple electrical connections through sealed subsea equipment housings.

Q2: Which connector mates with BH25F?

The primary mating connector is the IL25M 25-Pin Male Inline Underwater Connector.

Q3: Is BH25F compatible with SubConn?

The BH25F is designed for mating compatibility with corresponding SubConn Standard Circular 25-pin interfaces.Exact compatibility should be verified using the relevant technical drawings.

Q4: What is the rated current?

The nominal rated current 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 qualification of the complete installation.

Q7: What is the mounting thread size?

The standard BH25F 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 BH25F housing is manufactured from 316L stainless steel.

Q10: What is the standard internal wire length?

The BH25F 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 may be specified according to project requirements.

Q12: Is BH25F wet-mateable?

Yes. The BH25F belongs to the HYSF 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 BH25F?

The corresponding protective accessory is the DC25M 25-Pin Male Dummy Plug.

Q14: What is the difference between BH25F and BH25M?

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

Q15: Can BH25F be installed in an aluminum housing?

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

Q16: Can BH25F support Ethernet communication?

The BH25F provides twenty-five electrical contacts, but contact count alone does not guarantee Ethernet compatibility.The complete cable design must satisfy the relevant impedance, conductor pairing, shielding, and signal performance requirements.

Why Choose HYSF SUBSEA BH25F?

The HYSF SUBSEA BH25F 25-Pin Female Bulkhead Underwater Connector provides a durable high-density electrical interface for marine and subsea equipment.Its main advantages include:

• Twenty-five gold-plated female electrical contacts
• SubConn-compatible Standard Circular mating interface
• Wet-mateable underwater connector design
• Nominal 5A per contact rating
• Selected higher-current configurations subject to verification
• 550V AC/DC rated voltage
• Design depth capability up to 6,000 meters
• Corrosion-resistant 316L stainless steel housing
• Precision 3/4-16 UNF-2A mounting thread
• Standard 0.3-meter internal wire leads
• O-ring bulkhead sealing
• Compatible IL25M male inline connector
• Corresponding DC25M 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 BH25F 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 BH25F suitable for demanding subsea electrical integration applications.