Case study · Extreme environment simulation systems

High-pressure fluid injection in microgravity: a 330 bar system for onboard research

For an aerospace research consortium, IRIAN Mecatronics designed and built a reagent injection system for a microgravity experiment. The equipment provides a stable, programmable supply and metering of three fluids at 330 bar (4785 psi) in an environment where gravity cannot be used to separate liquid and gas phases.

Client: Aerospace research consortium
Field: Aerospace & onboard research
Technique: High-pressure fluid injection in microgravity

01 — The research question

How can you inject a liquid at a controlled flow rate when gravity is not available?

Laboratory pumping systems rely on a simple principle: gravity. It keeps liquids at the bottom of reservoirs, allowing pumps to draw a homogeneous liquid phase. When this force disappears—in space or in onboard environments with movement and vibrations—liquids float, gas bubbles can be drawn in, and the equipment's operation becomes unpredictable.

Our client needed to conduct a supercritical water oxidation (SCWO) experiment in microgravity, which required injecting three reagents with precise stoichiometry. Standard hardware was unusable: without gravity to ensure a free surface, the pump supply was unreliable. The constant risk of injecting gas instead of liquid would have invalidated the entire experiment.

The challenge: to guarantee a stable liquid supply and injection without the force (gravity) that naturally ensures phase separation and flow direction.

02 — Our approach

A design driven by autonomy and reliability in zero gravity

To meet the project's requirements, our engineering team made three key design choices to make the system orientation-agnostic and ensure injection accuracy at 330 bar (4785 psi).

Storing fluids without relying on gravity

In microgravity, a liquid does not stay at the bottom of a tank. To avoid drawing in gas, we ruled out standard reservoirs and instead stored the fluids in variable-volume containers. An external pressure applied to a flexible membrane ensures positive displacement of the liquid, guaranteeing a stable supply to the pumps regardless of orientation.
Ensuring stable, programmable injection at 330 bar

The reaction demanded very fine stoichiometric control. We selected a positive displacement injection technology (syringe pumps) where the flow rate is directly proportional to a mechanical speed. This principle makes the flow rate independent of pressure variations and ensures a continuous, pulse-free injection from the microliter-per-minute range up to 330 bar.
Regulating reactor back-pressure autonomously

To maintain the outlet pressure at 330 bar without relying on an external gas source—a major constraint in onboard environments—the regulator is piloted by hydraulic pressure. This setpoint pressure is generated by the system itself, making it completely autonomous and simplifying its integration and operation.

03 — Beyond this project

Does your project require reliable fluid metering in challenging conditions?

Continuous flow chemistry

The challenge is to guarantee a stable, pulse-free flow rate to control stoichiometry in microreactors. The principle of high-precision injection with positive displacement pumps and fine pressure regulation would remain identical.

Geosciences

This involves injecting fluids (brines, CO₂) at a controlled flow rate into rock cores under HPHT conditions. The precise volumetric injection architecture and back-pressure regulation are directly transferable to porous media flow studies.

Onboard systems (naval, submarine)

The challenge is to ensure a metering system operates reliably despite constant motion (roll, pitch). The principle of positive displacement storage, which makes the system insensitive to its orientation, is the most robust solution.

04 — Specifications

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

Show specifications · 330 bar (4785 psi) · 3 · 1 µL/min to 100 µL/min

Technical specifications — High-pressure fluid injection in microgravity: a 330 bar system for onboard research
Operating pressure	330 bar (4785 psi)
Number of injection lines	3
Injection flow rate range	1 µL/min to 100 µL/min
Volume per syringe pump	3.5 mL
Storage volume per fluid	200 mL

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 injection system be used with highly corrosive fluids like concentrated acids?

Yes, the operating principle remains the same. For fluids like chloride-rich media or acids, the wetted parts (pump body, seals, tubing) would be made from suitable materials such as Hastelloy C-276, titanium, or PEEK, with FFKM seals. Our engineering team selects materials based on each project's specifications.

Can this system be adapted for much higher flow rates, in the liter-per-minute range?

Not directly. The architecture shown here is optimized for high precision at very low flow rates. For flow rates in the L/min range, a different pump technology (e.g., piston or diaphragm) would be more appropriate. However, the principle of using bladder-style reservoirs to ensure a gravity-independent supply would still be perfectly applicable.

Can the equipment be made compact and lightweight for integration into a satellite or probe?

Yes, compactness and mass are key parameters for space applications. The design can be optimized accordingly by selecting miniaturized components and high-performance materials (aluminum alloys, titanium). The autonomous control system, which requires no external consumables, is already a major advantage for this type of integration.

How is the safety of the 330 bar injection system ensured?

Safety is integrated at several levels. The positive displacement injection system is inherently safe because it is pressure-controlled: if an overpressure is detected, the injection stops immediately. Furthermore, like all our pressure equipment, it is designed in accordance with the European Pressure Equipment Directive (PED 2014/68/EU) and undergoes comprehensive factory acceptance testing (FAT) before delivery.

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