Druck PTX300 Subsea Pressure Transmitter, 228 to 1035 bar

A compact subsea transmitter for hydraulic control systems

The Druck PTX300 is a 4 to 20 mA pressure transmitter developed for offshore oil and gas subsea use. It is built for subsea control module hydraulics: operating ranges run from 228 bar to 1035 bar sealed gauge, and the housing is rated for ambient (external) pressure up to 300 bar, equivalent to 3000 m of water.

The sensor uses micromachined piezo-resistive silicon technology that Druck says was originally designed for aerospace hydraulic systems and continuously developed for 30 years. The assembly is all electron-beam welded from Inconel 625 and stainless steel, which gives high containment pressure, hydraulic transient protection and integrity of the cable connection. The transmitter is maintenance free and reverse-polarity protected.

Accuracy is better than 0.1% FS, with long-term stability not exceeding 0.1% FS per annum under reference conditions.

Technical specifications

Ordering code

The ordering string is PTX300 followed by a pressure connector digit (1 spigot, 2 flat face) and the pressure range code: 228, 379, 569, 690, 759 or 1035 bar sealed gauge. For example, a flat-face connector with a 690 bar range is PTX300-2-690.

Each sensor is supplied with a Certificate of Conformance. A manufacturing record book (MRB) is available for this sensor family as a separate line item, 123M8389-1 MRB for PTX300. Druck notes the PTX300 can be adapted to individual user requirements, so ask about customised versions.

What to confirm before ordering

Confirm the working pressure of the hydraulic line, the required range code and connector style, the depth rating needed for the installation, the cable and termination method for the subsea control module, and whether an MRB is part of the purchase order. The datasheet is dated 2021 so ask for the latest revision.

Key features of the PTX300

• Silicon piezo-resistive sensing – a micromachined silicon element gives a stable, repeatable signal with the accuracy and drift figures listed in the specification table.
• All-welded construction – electron-beam welding of the Inconel 625 and stainless steel assembly removes elastomer seals from the primary pressure boundary and from the cable entry.
• Secondary pressure containment – the design is intended to contain the process fluid even if the primary diaphragm fails, protecting the electronics compartment and the control module.
• External pressure resistance – the housing is tested against ambient sea pressure, so calibration is not affected at the rated depth.
• Simple two-wire loop – a 4 to 20 mA output that integrates easily with subsea electronics modules.
• Small and light – useful where space inside a subsea control module or on a manifold is limited.

Where the PTX300 is used

The transmitter is designed for hydraulic pressure measurement inside subsea control modules and associated equipment. Typical measurement points include the high and low pressure hydraulic supplies to directional control valves, the pressure downstream of valves operating actuators, and accumulator banks. Monitoring these pressures lets the topside control system confirm valve operation, detect leaks and track the condition of the hydraulic system over the life of a field.

Choosing the range

The standard ranges cover the low pressure and high pressure hydraulic circuits commonly found on subsea production systems. Pick the range closest above the maximum working pressure of the circuit, while making sure that possible pressure transients stay within the overpressure rating. Selecting an unnecessarily high range reduces resolution at normal operating pressure.

Integration and handling guidance

• Check that the hydraulic fluid is compatible with the wetted materials, including any water-based control fluids specified for the system.
• Prepare the mounting face or spigot port to the manufacturer’s drawing and use the specified O-ring so the seal performs at full pressure.
• Handle the flying lead carefully; avoid sharp bends near the cable entry and protect the conductor ends during assembly.
• Calculate the loop resistance and supply voltage together to confirm the transmitter receives sufficient voltage at full scale.
• Keep the Certificate of Conformance and any manufacturing record book with the project documentation for traceability.

Relevance for Oman and GCC operators

Offshore developments in the Gulf region and the Arabian Sea, together with subsea integration and test workshops onshore, need traceable pressure instruments for control modules, test stands and spares holding. The PTX300 is also suited to factory acceptance testing and system integration tests where the same sensor type as the subsea equipment is required. For operators and contractors in Oman, holding spare transmitters of the most common ranges reduces downtime during module repairs and workovers. Because the process and ambient temperature range is narrow compared with land instruments, store spares in a controlled indoor environment rather than in an outdoor yard container.

What to include in your RFQ

State the complete ordering code (for example PTX300-2-690), the quantity of each range, and whether the MRB is required as a separate line item. Mention any project documentation requirements, such as material certificates or specific inspection and test plans, and the end-use equipment so the correct connector type can be confirmed. If you are replacing a sensor in an existing module, include the part number from the old unit.

Documents and quotation

The attached file is the four-page Druck PTX 300 series datasheet. Send the range, connector and documentation requirements to Seven Star LLC for a quotation. Other pressure sensors are grouped in Pressure Instrumentation, including the Druck UNIK 5000 platform.