Before diving into the advanced testing technologies that power Micropore’s innovation, it is important to understand the core product that drives our mission: ExtendAir® CO₂ absorbent cartridges. Unlike traditional granular absorbents, ExtendAir® offers a pre-formed, molded dust-free solution engineered for reliability and performance. With extremely low work of breathing, uniform CO₂ scrubbing, and elimination of user error from manual packing, ExtendAir® ensures safer and more consistent rebreather operation in both recreational and mission-critical environments.

Its water tolerance and lack of dust reduce the risk of caustic cocktail formation, and its structure is resilient to shock, vibration, and channeling—all common failure points in loose-fill systems. Even in the event of a flooded loop, ExtendAir® allows for recovery and safe mission abort, where granular absorbents often fail.  

Superior safety, consistency, and simplicity—qualities we test, validate, and continuously improve in Micropore’s state-of-the-art dive testing facility.

In the world of underwater life support, reliability is not optional; it is everything. That is why Micropore, a leader in advanced rebreather technology and CO₂ absorbent systems, has built a state-of-the-art dive testing facility designed to simulate real-world underwater conditions without the use of human subjects. At the heart of this innovation is the Micropore Breathing Machine (MBM)—a meticulously engineered system based on many of the same unmanned testing methodologies pioneered by the U.S. Navy’s Experimental Diving Unit (NEDU).

Micropore’s hyperbaric dive simulator uses precise control of pressure, temperature, and breathing loop parameters to assess the performance and safety of underwater breathing apparatuses (UBAs). Within the MBM, a 120-gallon (450L) chamber can be pressurized up to 12 bar, replicating dive depths up to 300 feet of seawater. This allows engineers to evaluate how life support systems behave under stress, gathering critical data on breathing resistance, inspired CO₂, and absorbent duration—all without ever sending a human diver underwater.

The MBM is designed for versatility. A manikin is mounted beneath the chamber lid, equipped with ports for inspired and expired air, differential pressure measurement, temperature measurement, and the ability to connect front or back-mounted UBAs. The lid with the manikin, and UBA, is then lowered into the water-filled hyperbaric chamber and sealed. Depending on the dive profile, the manikin can be positioned vertically or horizontally.

To simulate real-life respiratory patterns, Micropore developed a piston-driven system with adjustable speed and volume, allowing precise control over respiratory minute volumes (RMVs). For canister duration testing, a continuous CO₂ injection method is used, simulating diver workload conditions and measuring time until the moment when inhaled CO₂ reaches 0.5% Surface Equivalent Value (SEV).

Three CO₂ injection profiles are employed:

• Resting diver: 0.9 L/min at 22.5 L/min RMV

• Moderate work (NEDU standard): 1.35 L/min at 40 L/min RMV

• Moderate work (EU standard): 1.6 L/min at 40 L/min RMV

The choice of injection rate impacts test outcomes—particularly canister duration—and allows alignment with both U.S. and European standards.

Understanding lung pressure is critical to testing accuracy. Since most test manikins do not allow internal access to a true lung centroid, Micropore references an anatomical landmark familiar to physiologists: the suprasternal notch, located just above the sternum. In vertical testing configurations, a pressure transducer is placed 14 - 17 cm below the UBA’s breathing block to approximate the pressure at this notch—matching the pressure gradients a diver would naturally experience.

Breathing loop calibration is conducted using the NEDU Standard Orifice, developed by Cowgill, Landstra, and Mobley. This precisely machined, fixed-resistance orifice is used to validate the breathing simulator’s accuracy at various RMVs. By measuring pressure-volume (P-V) loops at 1 ATA, Micropore ensures the simulator's resistive effort remains within tight tolerance bands—anything outside these limits may indicate issues like water in hoses, faulty calibration, or excess loop volume.

To simulate true respiratory conditions, gas volumes are evaluated at BTPS (Body Temperature and Pressure, Saturated) conditions. This reflects how air is warmed and humidified by human upper airways—critical for ensuring simulations align with real-life physiology. Exhaled gas is heated and moisturized to simulate this warm, moist gas exiting the diver's mouth and is channeled directly into the mouthpiece before making its way into the rebreather—phenomena carefully managed in Micropore’s testing.

While the Micropore Breathing Machine (MBM) was originally developed with diving applications in mind, its capabilities extend far beyond traditional rebreather testing. One of the most powerful aspects of the MBM is its ability to support confined space life-support system development and validation.

The MBM’s precision control over environmental variables—such as pressure, gas composition, and thermal conditions—makes it an ideal platform for testing fan-powered air recirculation systems used in closed environments like diving habitats, bells, submersibles, and submarines. These systems, critical for extended missions and saturation diving operations, must maintain breathable air while managing CO₂ buildup, and airflow efficiency—all areas the MBM can rigorously evaluate.

By simulating operational profiles and environmental stressors, Micropore engineers can assess system response to failure conditions, breakthrough timelines, and overall air quality maintenance under controlled, repeatable scenarios. This testing capability supports both military and commercial applications, ensuring confined space life support systems are not only functional but optimized for real-world use.

With this expanded testing scope, the MBM is more than a dive simulator—it is a multi-domain life support testing platform, bridging underwater and enclosed-atmosphere technologies to improve safety wherever breathable air must be managed under pressure.

Behind every high-tech system is a visionary, and behind every breakthrough test is a master at the controls.

ExtendAir® Absorbent Technology was invented by Micropore Founder Doug McKenna, who has been a pioneering force in CO2 absorbent and life support technologies for more than 25 years. His vision was to create the safest and highest performance CO2 absorbent for military and technical divers alike. The pursuit of these objectives naturally led to the requirement of a precision dive simulation platform. With special thanks to Dr. Clark and others at the Navy Experimental Diving Unit and driven by the desire to make a difference to the industry, the Micropore Breathing Machine (MBM) was born.

But building the machine is only part of the story. Keeping it on the cutting-edge requires someone with experience, instinct, and a deep understanding of what is at stake beneath the surface.

At the core of Micropore’s advanced dive testing capabilities is not just technology—but also talent and real-world user experience. Wayne Riddell, a veteran military diver and accomplished technical diver, is the driving force behind the operation and continuous innovation of the Micropore Breathing Machine (MBM). Far more than an operator, Wayne is one of the architects of its evolution.

With certifications on multiple closed-circuit rebreathers and years of operational dive experience in both military and civilian sectors, Wayne brings an unmatched combination of field knowledge and technical prowess. He is not just running tests; he is pushing boundaries. Constantly upgrading and refining the MBM’s capabilities, Riddell ensures the platform stays ahead of global testing standards and real-world demands.

Known for his precision, adaptability, and deep understanding of rebreather physiology, Wayne conducts every experimental dive simulation with the same attention to detail as if his own life depended on the gear. He collaborates directly with multiple closed-circuit rebreather (CCR) OEMs, offering critical performance data and design recommendations that have directly led to improved safety margins and longer dive durations.

Whether recommending changes to canister flow dynamics, analyzing post-test P-V curves, or engineering the next leap in system capability, Wayne Riddell is not just testing equipment, he is reshaping the future of rebreather performance.

At Micropore, quality assurance is not a final step—it is built into every stage of production. Each lot of ExtendAir® CO₂ absorbent undergoes rigorous testing on its respective rebreather platform before it leaves the facility. This ensures that not only are performance goals met, but that actual cartridge durations exceed expectations.

Micropore’s dive testing facility – the MBM - represents a convergence of deep physiological understanding and innovative engineering. By eliminating guesswork and human risk from testing, the company not only validates its technologies with precision but pushes the entire industry toward safer, more effective diving solutions. Whether calibrating a breathing loop, certifying ExtendAir® absorbent, or simulating a 300-foot dive, Micropore is proving that the future of underwater safety lies in the details you can’t always see—but can absolutely measure.

About Micropore, Inc.

Micropore uses proprietary technologies to form CO2 absorbent powders into solid molded matrix materials for revolutionary CO2 absorbent systems used in rebreathing and other life support applications. The company's patented technologies are the first major advances in CO2 absorbent technology in over 100 years, providing superior performance advantages over traditional granular absorbents. Micropore’s CO2 absorbent cartridges and canisters are marketed under the ExtendAir® and SpiraLith® brand names and are used for life support in anesthesia, dive, submarine, manned spacecraft, fire-fighting and mining applications. All of Micropore’s products are manufactured in the U.S.A. at Micropore’s facilities in Elkton, Maryland and Newark, Delaware. See microporeusa.com.