Four Subsea Pressure Transmitters, Four Specialist Solutions

Subsea pressure measurement presents challenges that few other environments can match. High external pressures, corrosive seawater, extreme depths and the need for long-term reliability all place demanding requirements on pressure instrumentation.

For offshore oil and gas, subsea control systems, ROVs and deep-sea testing equipment, pressure transmitters must continue to provide accurate and dependable measurements when access for maintenance is limited or impossible.

ESI Technology has developed a dedicated range of subsea pressure transmitters to meet these challenges. The PR3913, PR3915, PR3920 and PR3930 each use ESI’s Silicon-on-Sapphire (SOS) sensor technology, but each has been designed around a different measurement requirement.

From valve-mounted pressure monitoring and dual redundancy to differential pressure measurement and digital communication, the range provides a solution for a wide variety of subsea applications.

What makes subsea pressure measurement so demanding?

Pressure measurement underwater is not simply a case of putting a standard pressure transmitter inside a waterproof housing.

As depth increases, so does the external pressure acting on the instrument. At the same time, subsea equipment must withstand exposure to seawater, temperature variations, pressure transients and, in many applications, years of continuous operation.

For permanently installed equipment, reliability is particularly important. A failed transmitter may require an expensive and complex subsea intervention before it can be replaced.

This makes the design of the pressure sensor, housing, materials, electrical connections and sealing system critical to overall performance.

ESI’s subsea pressure transmitters combine Silicon-on-Sapphire sensor technology with robust mechanical construction and testing designed specifically for demanding underwater environments. Hyperbaric testing and Environmental Stress Screening (ESS) are also available on selected models to help verify performance before deployment.

PR3913: Subsea control valve pressure measurement

The PR3913 Subsea Control Valve Pressure Transmitter is designed specifically for valve-mounted applications within the subsea oil and gas industry.

Its compact design allows it to mount directly to an industry-standard control valve flange arrangement, making it well suited to permanent installation on subsea control systems.

The PR3913 uses ESI’s Silicon-on-Sapphire technology to provide stable and repeatable pressure measurement, with pressure ranges available up to 1,000 bar. Its fully welded construction and corrosion-resistant wetted materials are designed for long-term operation in demanding subsea environments.

The transmitter can withstand external pressures associated with depths of up to 3,000 metres, while its secondary pressure containment provides additional protection in the event of sensor overpressure.

Key features include:

• Pressure ranges up to 1,000 bar
• Submersion to 3,000 metres
• Silicon-on-Sapphire sensor technology
• Inconel 625 pressure connection
• Fully welded construction
• 4-20 mA output
• Hyperbaric testing available
• Environmental Stress Screening available
• ATEX/IECEx options available

The PR3913 is therefore particularly suited to subsea control valves, permanent subsea installations and offshore oil and gas applications where compact, reliable pressure measurement is essential.

PR3915: Dual redundancy for critical subsea applications

When pressure measurement is critical to the operation of a subsea system, redundancy can provide an additional layer of reliability.

The PR3915 Dual Redundant Subsea Pressure Transmitter takes the core design principles of the PR3913 and incorporates two completely independent pressure sensors and electronic circuits within a single transmitter housing.

This dual-redundant configuration can provide significant advantages where measurement availability is particularly important. It also allows designers to achieve redundancy without necessarily requiring two separate transmitter housings, helping to reduce the space and materials required within subsea valve assemblies.

Like the PR3913, the PR3915 is designed to mount directly to an industry-standard subsea control valve flange arrangement. It uses Silicon-on-Sapphire sensor technology and a fully welded body for long-term stability in extreme subsea environments.

The PR3915 offers:

• Two independent pressure sensors and electronic circuits
• Pressure ranges up to 1,000 bar
• Submersion to 3,000 metres
• High accuracy option
• Silicon-on-Sapphire sensor technology
• NACE-compliant wetted materials
• Hyperbaric testing to 3,300 metres
• Environmental Stress Screening

For applications where redundancy, reliability and compact installation are priorities, the PR3915 provides a highly specialised subsea pressure measurement solution.

PR3920: Differential pressure measurement at depth

Not every subsea application requires a standard gauge pressure measurement.

The PR3920 Differential Subsea Pressure Transmitter has been developed for applications where the difference between two pressures needs to be measured accurately, even when both pressures are relatively high.

It provides low-range wet-wet differential pressure measurement while handling high line pressures, making it particularly suitable for subsea hydraulic and chemical injection applications.

The standard sensing range is approximately 0-50 bar differential pressure, while line pressure capability extends to 690 bar. The transmitter also incorporates secondary containment rated to 1,200 bar.

Designed for permanent subsea installation, the PR3920 can operate at depths of up to 3,000 metres. Its titanium alloy wetted parts provide strong corrosion resistance, while the sealed housing is designed to withstand the demanding external pressures encountered at depth.

Key features include:

• Differential pressure measurement
• Standard range of 0-50 bar DP
• Line pressure up to 690 bar
• Secondary containment to 1,200 bar
• Submersion to 3,000 metres
• Titanium alloy wetted parts
• NACE corrosion resistance
• 4-20 mA output
• High accuracy option
• ATEX/IECEx option available
• Hyperbaric testing available

The PR3920 is particularly well suited to subsea well control valves, chemical injection systems and hydraulic pressure measurement, where accurate differential pressure readings are required in a high-pressure environment.

PR3930: Digital subsea pressure measurement

As subsea systems become increasingly connected, pressure measurement is no longer just about generating an analogue signal.

The PR3930 Subsea Pressure Transmitter adds digital communication capability through RS-485 or Modbus RTU, making it a strong choice for applications where multiple sensors need to communicate with a central monitoring or control system.

Designed for ROVs, deep-sea test equipment and permanent subsea installations, the PR3930 can withstand immersion to depths of up to 6,000 metres and offers pressure ranges up to 1,500 bar.

Its fully welded construction and titanium wetted parts provide durability and media compatibility, while the digital interface allows individual sensors to be addressed and connected together on the same communication link.

Depending on configuration, the PR3930 can provide:

• RS-485 and 0-5 V analogue output
• Or Modbus RTU and 0-5 V analogue output
• Pressure ranges up to 1,500 bar
• Submersion to 6,000 metres
• Digital accuracy of 0.15%
• Selectable baud rate
• RS-485 communication distances up to 1,200 metres
• Resistance to noise interference
• Silicon-on-Sapphire sensor technology
• Hyperbaric testing available
• Environmental Stress Screening available

This makes the PR3930 particularly attractive for ROV systems, deep-sea testing and applications requiring digital subsea instrumentation.

Four transmitters, four different subsea challenges

Although the four products share ESI’s expertise in subsea pressure measurement and Silicon-on-Sapphire technology, their individual designs address very different requirements.

This makes selecting the right subsea pressure transmitter less about finding a single “best” product and more about matching the instrument to the application.

For valve-mounted pressure measurement, the PR3913 provides a proven and compact solution. Where redundancy is required, the PR3915 adds two independent measurement channels within one housing. For differential pressure applications, the PR3920 is designed to measure low differential pressures despite high line pressures. And where digital communication is a priority, the PR3930 brings RS-485 or Modbus RTU connectivity to deep subsea environments.

Built for reliable subsea pressure measurement

Across the range, ESI’s Silicon-on-Sapphire technology provides a foundation for stable, accurate pressure measurement. The technology offers high sensitivity and stability while also providing strong resistance to overpressure, pressure transients and demanding environmental conditions.

The mechanical designs are equally important. Fully welded housings, corrosion-resistant materials, specialist pressure connections and robust electrical interfaces all contribute to the long-term reliability required for subsea deployment.

ESI can also provide hyperbaric testing, Environmental Stress Screening and comprehensive documentation packages on applicable products. This gives engineers additional confidence when integrating pressure transmitters into critical subsea systems.

Subsea pressure measurement from ESI Technology

Subsea instrumentation has to perform where maintenance is difficult, environmental conditions are severe and measurement reliability matters.

ESI’s PR3913, PR3915, PR3920 and PR3930 pressure transmitters have been developed with these challenges in mind, providing dedicated solutions for valve monitoring, redundant measurement, differential pressure applications and digital subsea systems.

With Silicon-on-Sapphire sensor technology, robust construction and specialist testing options, ESI’s subsea pressure transmitter range provides dependable pressure measurement for demanding underwater applications.

Need a pressure measurement solution for a specific subsea application?

ESI Technology can work with engineers and system designers to identify the most suitable pressure transmitter for the required pressure range, depth, media, output and installation environment.

Contact ESI Technology to discuss your subsea pressure measurement requirements; [email protected], +44(0)1978 262255 or find your local sales partner here