Physiological Research

True Altitude Simulation

What does it mean to simulate altitude?
Geographically, altitude is the height above sea level. But physiologically, altitude is the partial pressure of oxygen – the product of oxygen concentration and atmospheric pressure. Altitude simulation requires modifying oxygen levels according to barometric pressure.

Altitude is not an oxygen percentage. An oxygen level at low pressure yields a different altitude than it does at higher pressure. And atmospheric pressure is constantly changing. Regulating only oxygen levels without regard to atmospheric pressure cannot simulate altitude with accuracy or stability.

Calculating simulated altitude requires four steps:
  1. Measure barometric pressure – An essential step in calculating the partial pressure of oxygen. Barometric pressure is continually changing. Calculations without barometric readings cannot yield accurate altitude simulation.
  2. Accurately measure oxygen concentration – Because oxygen readings are so critical, ACT uses two state of the art sensors. These are made specifically for altitude simulation. These sensors validate their readings with a cross-referencing software protocol. There is no more accurate way to measure oxygen.
  3. Calculate the partial pressure of oxygen – Using actual barometric pressure and oxygen percentage.
  4. Convert the partial pressure of oxygen to a simulated altitude – This conversion requires empirically validated algorithms. ACT uses the West Equations, which are based on the most recent science.
1Physiological

Reliability

Reliable Uninterrupted Operation
ACT designs its systems for continuous, uninterrupted use. Here is how we do it:
  • Multiple air units – Each room is served with several air separation units. Not multiple rooms served by one. The advantage is obvious. When one air unit is offline for maintenance or repairs, your system continues operating normally. With systems having only one large air unit, the entire system must shut down for even routine maintenance. This can complicate plans, research protocols, training schedules, and occupancy calendars. ACT systems provide reliable service 24/7/365.
  • Plug and Play – Every component of ACT’s system is plug-and-play. The heaviest item is only 26 kg. They can be replaced in minutes, even by untrained personnel.
  • Immediate replacement – In the event of equipment failure, we immediately replace faulty equipment. There is no need to wait for diagnostics, spare parts, or repair time.
  • Minimal maintenance – ACT controllers, sensors, and vents are maintenance-free over their entire life. They never need replacing sooner than ten years. Air units require only filter replacements that take only minutes. Your system can operate even during maintenance.
  • No oil changes – Unlike large compressors, ACT air units never need oil.
  • Redundancy – ACT systems are engineered so that an air unit’s failure does not shut down service.
  • On-site replacement parts – ACT can provide a spare controller, sensor box, and two air units to hold on-site.

Uninterrupted operation is particularly important during scientific research. Interruptions can be costly or threaten studies’ validity.

Accuracy and Control

Scientific research requires accuracy. ACT’s technology and engineering lead the field in accuracy and control. ACT’s system is not approximate. It is exact. It is the only scientific instrument for normobaric altitude simulation. ACT’s has solved four major issues concerning accuracy measurement, conversion, and control:
  1. Problem: Sensor Drift – When sensors drift out of calibration, readings become inaccurate.
    Solution: ACT pioneered the use of Sensor Validation™ technology. Dual oxygen sensors compare readings to each other to avoid sensor drift. ACT is the only company employing this sensor technology.
  2. Problem: Sensor Calibration – Even the best sensors require calibration.
    Solution: ACT’s sensors self-calibrate. There is no need for support gases or time-consuming processes.
  3. Problem: Barometric Pressure Changes– Changing barometric pressure can create swings in altitude simulation.
    Solution: ACT incorporates barometric pressure in its altitude calculations. You will always have accurate altitude simulation.
  4. Problem: Altitude Algorithms – Outdated atmospheric tables and algorithms give inaccurate approximations of altitude.
    Solution: Recent work in the field has corrected these errors. ACT uses the most advanced algorithms for altitude simulation – the West Equations.

These errors are often compounded and can lead to readings that are not reliable. With ACT, you can be assured of the latest engineering advances and precision that meets the highest standards.

Stability

If a system creates wide swings in oxygen, it is neither valid nor accurate. ACT solved four significant problems in oxygen control. ACT’s system is a scientific instrument suited for scientific research. This is why ACT leads the field in altitude science and normobaric altitude simulation.
  1. Problem: Anoxic Air-  Nitrogen generators use anoxic air that overshoots oxygen targets. The effect is even greater at altitude simulations above 3,000 meters.
    Solution: ACT’s system of ratio control brings rooms to altitude quickly. Then it provides modulated oxygen mixes to create a “soft landing” on oxygen targets.
  2. Problem: On-Off Switching – Most systems deliver concentrated nitrogen and have only two modes: on or off. They either deliver nearly pure nitrogen or nothing at all with no modulation or fine control. This creates significant swings in oxygen concentration that destabilize altitude simulation.
    Solution: ACT’s ratio control system allows each of ACT’s air units to function independently and in different modes, giving exact oxygen control. This eliminates the instability created by simple off-on systems.
  3. Problem: Air Infiltration – Air infiltration is a fundamental concern in normobaric altitude simulation. Engineering for the best-case scenario means accurate altitude simulation only in the best case.
    Solution: Proper engineering. ACT engineers its systems to deal with higher than normal air exchange.
  4. Problem: Periods of High Air Exchange – Air exchange is not constant. Air exchange can change due to temperature gradients, moving air, changes in atmospheric pressure, entries, and exits. Most normobaric systems have difficulty adjusting for changes in air infiltration.
    Solution: During periods of high air exchange, ACT’s controller triggers the most rapid means possible to restore and stabilize oxygen levels: oxygen extraction. No other system offers a response this powerful to increased air infiltration.

ACT takes altitude control seriously. Most normobaric systems offer only a generic membrane or nitrogen generator. ACT provides a fully integrated system designed specifically for altitude simulation. Without ACT’s unique technology, inadequate oxygen control can easily invalidate your studies.

Safety

Safety is integral to ACT systems. We do not depend on hardware or software for safety. ACT systems employ benign failure modes in every design. Safety is assured even in the event of operator error or a mechanical, electrical, or software failure.
  • High-Pressure Risk: ACT does not employ high-pressure tanks or compressors in human-occupied systems. ACT air separation units use low-pressure compressors, and ACT systems do not store air in pressure vessels.
  • Electrical: All electrical components meet the highest international standards. Our system only requires ordinary household current.
  • Alarms: Alarms alert occupants and administrators of oxygen or CO2 going out of range.
  • Oxygen Safety: ACT systems deliver air that is always safe to breathe.
  • Sensors: Sensors constantly self-validate for accuracy and safety.
  • Air Quality: ACT systems meet OSHA standards for air quality
  • Fire Safety – ACT takes care of oxygen levels in the treated space and mechanical rooms. ACT meets NFPA standards for fire-safe oxygen.
  • Monitoring – ACT systems even monitors environmental conditions in mechanical rooms. Our system shuts off equipment when conditions warrant.
  • History – In millions of hours of use, ACT has never had a safety incident of any kind.