Case study · Fluid dynamics & phase behavior

Titanium HPHT variable-volume cell for stirred fluid studies (50 mL, 500 bar)

IRIAN Mecatronics designed and built a 50 mL HPHT cell for a public research center in materials chemistry. This custom equipment is used to study the phase behavior of fluids at 500 bar (7,250 psi) and 150°C (302°F), with full visual observation and stirring in a chemically inert (CO2) environment.

Client: Public research center in materials chemistry
Field: Materials Chemistry
Technique: Phase behavior, high-pressure visualization

01 — The research question

How can you characterize a high-pressure fluid in a minimal reactive volume, with both stirring and direct observation?

Studying the phase behavior of fluids (liquids, gases, CO2) under extreme conditions often requires combining several functions in a single piece of equipment: maintaining stable pressure and temperature, ensuring sample homogeneity, observing phenomena in real time, and guaranteeing complete chemical inertness. The challenge increases when the available sample volume is very small, which concentrates mechanical and thermal stresses in a confined space.

In this project, a laboratory needed to conduct these studies on 50 mL volumes at 500 bar (7,250 psi) and 150°C (302°F), with full CO2 compatibility. Standard HPHT reactors and cells or PVT cells do not combine all these requirements: a titanium body, a very small volume, internal stirring, a full-volume viewing window, and easy routine maintenance. Off-the-shelf solutions are either too specialized (e.g., a PVT cell without stirring, a stirred reactor without full visibility) or use unsuitable materials like stainless steel.

Integrating a magnetic drive, a full-view window, and multiple connections into a 50 mL titanium body rated for 500 bar, without compromising the reliability of critical seals or the ease of maintenance.

02 — Our approach

A design focused on reliability and maintainability

The cell's design is based on three technical choices that directly address the failure points of standard equipment under these intensive operating conditions.

Securing pressurization and volume control

To ensure stable pressure over long periods and secure the test in case of a power outage, we used a non-reversible mechanical power transmission. Unlike a direct drive, this system locks in position when motor torque is absent. The pressure is maintained passively, safeguarding the test without relying on an active safety brake.
Simplifying maintenance by decoupling functions

Disassembling a sapphire window for cleaning is a risky operation for the HP seal. We designed a double-flange assembly: the first, external flange, secures and seals the sapphire and is never touched during routine operations. The second provides access to the cell for cleaning. This eliminates the risk of damaging the critical seal.
Ensuring a leak-proof seal with a contactless drive

Introducing a stirrer into a 500 bar vessel creates a potential leak point. To prevent this, torque is transmitted via a magnetic coupling through a titanium diaphragm. This design eliminates any mechanical shaft pass-through and any dynamic rotating seal, ensuring an absolute seal and maximum reliability, even with corrosive fluids like CO2.

03 — Beyond this project

Does your project have similar requirements?

Pharmaceuticals / active ingredient synthesis

Common requirement: Reactions in supercritical media (CO2) in small reactors, requiring observation, stirring, and chemical inertness. What would remain the same: The principle of the HP variable-volume cell, the seal-less magnetic drive, high-pressure visualization, and CO2 compatibility.

Geosciences / reservoir fluid studies

Common requirement: Analyzing the phase behavior (PVT) of hydrocarbons or CO2 sequestration fluids under downhole conditions. What would remain the same: The HPHT cell, precise volume/pressure control, visualization, and stirring. A related piece of equipment is our Modular HPHT reactor for corrosive geochemistry.

Energy / hydrogen storage

Common requirement: Measuring hydrogen absorption/desorption by materials as a function of pressure and temperature. What would remain the same: The variable-volume cell principle for precise gas quantity control, temperature regulation, and intrinsic safety.

04 — Specifications

The values for this project. Every system is custom-built, so they adapt to your requirements.

Show specifications · 500 bar (7,250 psi) · 50 mL · 3°C to 150°C (37°F to 302°F)

Technical specifications — Titanium HPHT variable-volume cell for stirred fluid studies (50 mL, 500 bar)
Maximum operating pressure	500 bar (7,250 psi)
Maximum volume	50 mL
Operating temperature range	3°C to 150°C (37°F to 302°F)
Wetted materials	Titanium Ti-6Al-4V ELI (Grade 23), FFKM, PEEK, PTFE
Stirring speed range	50 to 1,000 rpm
Flow rate range (volume change)	1 µL/min to 20 mL/min
Fluid connections	4 x 1/16" Valco-type ports

IRIAN Mecatronics designs and builds custom high-pressure, high-temperature equipment for research laboratories, technical centres and industry.

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05 — FAQ

Frequently asked questions

Can this titanium cell operate at higher pressures and temperatures, for example, 1,000 bar and 300°C?

Yes, the design principle can be adapted to more severe conditions. Reaching 1,000 bar (14,500 psi) and 300°C (572°F) would require a complete redesign of the cell body and flanges, as well as selecting appropriate materials and seals (e.g., nickel alloys and metal seals). The key principles, such as the magnetic drive and intrinsically safe pressurization, would remain valid.

How would you adapt this reactor to work with highly corrosive fluids like H2S?

The main adaptation would be to change the material of construction. Titanium would be replaced by a nickel alloy such as Hastelloy C-276 or Inconel, known for their excellent resistance to acid corrosion (H2S). The design would remain very similar, as the sealing principles (magnetic drive, double-flange window) are material-independent and particularly well-suited for hazardous fluids.

Is it possible to build a similar cell with a larger volume, for example, 1 liter?

Yes, our reactors and cells are always custom-designed. Increasing the volume to 1 liter is entirely feasible. It would involve resizing all pressure-bearing parts and the magnetic stirrer to ensure effective homogenization. However, implementing the full-visibility feature would become more complex and costly for a large, high-pressure volume.

Can a version of this equipment be ATEX-certified for use in explosive atmospheres?

Yes, all our equipment can be designed for ATEX compliance. This involves integrating certified components (motors, sensors, instrumentation) and following specific design rules to prevent hot spots or ignition sources. The entire system, including the control cabinet, would then be designed and certified for the specified working environment, as seen in our autoclave bench for flammable gases.

Does your current equipment limit your test conditions for pressure, temperature, or chemical compatibility?

Describe your constraints, even if they seem non-standard. Our engineering team will analyze your project's feasibility and get back to you with a technical proposal.

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