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Mountain High Equipment & Supply Company

Mountain High Overview

Overview | EDS O2D1 | EDS O2D2 | Constant Flow | Cannulas & Face Masks | Cylinders | Regulators | CO-PILO2T | Transfillers

Product Overview
Electronic Pulse
Delivery System
Electronic Pulse
Delivery System
Constant Flow Systems
with MH3 and MH4
Cannulas & Face Masks Cylinders
Regulators CO-PILO2T
oxygen system
Ground Support Equipment (GSE),
Transfillers, Adapters
and Accessories

Related Pages


October 1, 2015
New EDS O2D1-2G System

Mountain High Oxygen is pleased to announce the release of our next generation of EDS (Electronic Delivery System) Pulse Demand oxygen controllers, the O2D1-2G and O2D2-2G.

These changes are common to both the O2D1 and O2D2 family of EDS.

Our new Pulse Demand systems still incorporate all of the benefits of our legacy controllers but with many improvements.

We started with the control switch: The EDS unit now incorporates a MIL spec ruggedized easy-to- grip rotary control switch providing improved reliability, increased ease of function and visibility. This switch also has very positive position detents for excellent tactile feedback making it resistant to changes from causal rubbing or bumping.

While we were at it, we improved the manifold design to allow for better breathing response and effort tracking. This combined with a new circuit board, as well as a new micro-controller, gives improved power-conserving operations with even less RFI emissions, better respire-metric tracking and dispensing of oxygen in finer resolution resulting in smoother steps from altitude and breathing changes.

Other improvements include a dedicated bi-color system battery status light allowing much easier monitoring and definitive indication of battery condition without being confused as a station operation. The original O2Dx units encoded the low battery notification into the station lights. This status light also responds to each control switch change with a beep and green flash to confirm your actions. Also the audio alerts and warnings are louder, more crisp and dynamic to human hearing in an effort of being heard over modest cabin noise. The O2D2 has a 600 Ohm stereo external audio jack as well as a USB compatible (5VDC) external power port.

More intuitive F-Mode settings labeled as 1, 2, 3 & 4 for use with face masks or when more oxygen is required.

Abandoned Unit Auto Shut-Off
If you should forget to turn your EDS off after use, it will now go into auto shut-down (drawing very little power) after 3 hours of detecting no use in an attempt to save the batteries for another flight.

August 2011
Mountain High Builds 3000th Pulse Demand Oxygen Unit.  Details

Warranty Update
Starting in 2009, items made by Mountain High have a 3 year warranty.  Previously they had a "limited life" warrant.

September, 2006 -
New EDS O2D1 System Released
The new EDS O2D1 oxygen system replaces the EDS-D1 system as the standard system used for single-place pulse-demand oxygen applications.  The EDS O2D2 remains the standard system used in multiple-place applications.  The EDS O2D1 is based on the same technology used in the EDS-D1a but uses 2 AA batteries for much greater battery life.  The new EDS O2D1 is smaller in size than the EDS-D1.

What's Different?

  • The new EDS O2D1 uses 2 AA batteries for a much longer battery life of 100+ hours
  • The EDS D1a uses a single 9 V battery for a battery life of 40+ hours
  • The price of the new EDS O2D1 is $50 higher than the EDS-D1a sold for.

Is My EDS-D1 Obsolete?

  • The EDS-D1 is no longer in production, however, it will be supported for many years.  It is a proven system that is in use in aircraft around the world.  If you own an EDS-D1 system you do not need to upgrade to an EDS O2D1 - unless you want the longer battery life or slightly smaller size offered by the O2D1.  All part numbers and model numbers that formerly included the EDS-D1a now include the new EDS O2D1.

Is the O2D1 a Drop-In Replacement for an EDS-D1?

  • Yes, the oxygen input and output connectors are identical.
  • I'm not certain, but I believe the power input may be different so if you were powering it using external power, you may need to change the power input to the unit.

Mountain High Equipment & Supply Co. is the maker of state-of-the-art aviation oxygen equipment.

Founded by recreational pilot and engineer Patrick L. Mclaughlin, Mountain High has been supplying aviation oxygen equipment and supplies since 1985. The company is known particularly for it's EDS product, an electronic 'Pulse-Demand' adaptive oxygen delivery device.

Mountain High has also been at the forefront of providing pilots of all types of aircraft with affordable and easy-to-use oxygen transfillers and adapters.

Please Buy From Me
I have tried to make the web site a useful resource.  I have included many of the technical documents from the MH web site.  Also, I found it difficult to figure out exactly what parts are included in the system kits when browsing the MH web site, so I have worked hard to make it very clear what parts are included with each system.  I included photos of all the parts found in each system.  I also created system duration tables for every complete system to help you find a complete system with the desired duration.


What is an aviation oxygen system?
An aviation oxygen system is designed for and with components, such as the main reducing regulator (SAE AS1197, AS1248, ARP1109), developed for airborne aviation purposes.  Unlike a medical-type oxygen system, an aviation system is generally much lighter, compact and calibrated to deliver oxygen per established FAA, FAR protocols based on extensive research in human flight physiology (SAE AIR822, AIR825B, AIR1389, ARP4259).  Because of lower cost, ease of filling, servicing and certification testing, many portable aviation oxygen systems have been designed around a set of so-called standardized light-weight aluminum cylinders originally intended for the ambulatory medical market (AIR AS1065, AS1066, AS8010). An aviation oxygen system should meet minimum standards (SAE AS861, AS1046) for airborne applications.  This includes the ability to be safely contained so that the system will not become a hazard during times of turbulence.  The aviation oxygen system must be capable of being stored somewhat out of the crew's way and become available and operational at a moment's notice without much thought and distraction (SAE AIR1390). The human interface devices (cannulas & face masks) are very similar to medical types but generally modified or designed differently to facilitate items such as head-gear, microphones and other oxygen delivery devices and yield a more comfortable fit (SAE AS1224, AS8025).

A portable aviation oxygen system, in the basic sense, consists of four main components.

  1. Supply of oxygen (cylinder) with on/off valve and gauge
  2. Main reducing oxygen regulator (sometimes built-on the cylinder), The main reducing regulator takes the (wild) oxygen pressure from the cylinder and regulates it down to some manageable pressure for the delivery device.  May types of regulators are found in aviation oxygen systems.  Some include pressure gauges for monitoring the high pressure on the oxygen cylinder side.
  3. Oxygen delivery (flow control) device, automatic or manually controlled.  The job of the oxygen delivery device (Pulse-Demand EDS or constant flow MH3 or MH4) is to provide oxygen at a pressure and flow needed for humans at varios altitudes.  Often, the flow control is built into the main reducing regulator.  Newer systems have separated this for easier use and control. 
  4. Application (human interface) device, Cannulas can be used for flight operations below 18,000 ft.  Face masks can be used for flight operations at and above 18,000 ft. (FAA, FAR 23.1447)

Physiological Facts in Aviation
With many of today's home built aircraft capable of transporting man to high altitudes in near record time and where the average age of the pilot base is well over 45 years old, a practical knowledge of physiological human principals and atmospheric physics are not only desirable, but necessary in order to sustain safe operating parameters.  Therefore, the pilot should have a firm understanding of the relationships between oxygen, altitude and the body.

Man can live for weeks without food and for days without water, but only a few minutes without oxygen.  Because man can not store oxygen in his body, as he can food and water, he lives a breath-to-breath existence.  He continues to live and function only as long as he can continually replenish the oxygen consumed by his metabolic process.

Oxygen becomes more difficult for your body to obtain with altitude because the air becomes less dense, and the total (absolute) air pressure decreases compromising your primary (lungs) and secondary (bloodstream) respiratory system the ability to transport and exchange oxygen throughout the body, even though the percentage of oxygen (21%) remains constant with respect to the atmosphere.

As altitude is increased and the pressure of oxygen is reduced, the amount of oxygen transferred into the lungs is reduced which results in a decrease in the amount of oxygen available in the blood.  It is when oxygen saturation in the blood begins to decrease that the chances of becoming hypoxic increase. 

According to the Webster dictionary, hypoxia is defined as "a deficiency of oxygen reaching the tissues of the body".  Some of the most common indications (symptoms) of hypoxia are:

  1. An increased breathing rate
  2. Lightheadedness or dizzy sensation
  3. Tingling or a warm sensation
  4. Cold chills and/or cold extremities
  5. Sweating and increased heart rate
  6. Reduced color vision and visual field
  7. Sleepiness, insomnia and/or nervousness
  8. Blue coloring of skin, fingernails and lips
  9. Behavior change, giddiness, belligerence, cockiness, anxiousness or euphoria

Hypoxia does not hit you all at once.  It comes on slowly, at a speed that is mainly a function of your altitude and somewhat of your condition.  The higher you go, the faster hypoxia will take effect. Experiencing any of the effects indicating the onset of hypoxia is just as, if not more, insidious as the condition itself. Simply put, once you have convinced yourself you are experiencing hypoxia, it's simply too late.  You are now mentally and physically operating at a fraction of your capacity and losing more at a fast rate.  Supplemental oxygen will prevent this dangerous phenomena.

Many pilots who have experienced hypoxia claim they never know at what altitude and what effect they will experience hypoxia when it strikes.  In fact, some pilots go on to say that they can practice a breathing technique to reduce or control it.  Unfortunately, in this case this practice simply yields little or nothing at all.  You need to use supplemental oxygen.

Many high altitude chamber experiments have shown that a person affected by hypoxia may not recognize but a fraction of it's know indications.  In fact, some experienced pilots don't even report experiencing any effects at all while they are obviously incapacitated.  This is where the insidious nature of hypoxia is so dangerous.  Without oxygen you are not going to reverse it anywhere as quick as you bought it on.  But with oxygen you can speed up the reversal.  The trick is to not get hypoxia in the first place.  Many pilots black-out or faint in flight each year from hypoxia.  Some now fly with oxygen.  Most don't.  Many of the so-called pilot error deaths and serious accidents, where to mechanical failure was found for cause, are in fact thought to have been caused by hypoxia.

While it is true that some pilots can tell that hypoxia has taken effect and pilot themselves to safety, premature landing without oxygen is neither reliable nor safe.  At one altitude you may experience one effect and yet another at another time at the same or less altitude experience yet another incapacitating effect, thus not recognizing you have hypoxia.  In addition, what works for one pilot may not work for another.  It is much less a problem and far safer to keep ahead of and out of the hypoxia area than to catch up and get out of it.  The best way to accomplish this is by using supplemental oxygen.

Mountain High offers a wide selection of systems and components for both carry-on and built-in oxygen needs.

Q & A

What is Air?
The air surrounding us is a mixture of gases consisting of 78% nitrogen and 21% oxygen.  The remaining 1% is made up of argon, carbon dioxide, and traces of rare gases.

What is Oxygen?
Under normal conditions, pure oxygen is a colorless, tasteless, odorless, non-combustible gas.  It is the most important single element in our universe.

Why is Oxygen So Important?
Although it will not burn alone, oxygen supports combustion; in fact, without oxygen there can be no fire.  Oxygen, therefore, is not only necessary for the burning of combustible materials, but it is also absolutely essential to support the process of "vital combustion" which maintains human life.  Although a person can live for weeks without food or for days without water, he or she dies in minutes if deprived of oxygen.  The human body is essentially a converter which consumes fuel and produces heat and energy.  It is like a furnace which utilizes the oxygen in the air to burn coal, thus producing heat and power.  The human body must have oxygen to convert fuel (the carbohydrates, fats, and proteins in our diet) into heat, energy and life.  The conversion of body fuels into life is similar to the process of combustion; fuel and oxygen are consumed, while heat and energy are generated.  This process is known as "metabolism".

Where And How Do We Normally Obtain Our Oxygen?
At each breath we fill our lungs with air containing 21% oxygen.  Millions of tiny air sacs (know as "alveola" in our lungs inflate like tiny balloons.  In the minutely thin walls enclosing each sac are microscopic capillaries, through which blood is constantly transporting oxygen from the lungs to every cell in the body.  Because the body has no way to store oxygen, it leads to a breath-to-breath existence.

How Much Oxygen Does The Human Body Need?
The rate of metabolism, which determines the need for and consumption of oxygen, depends on the degree of physical activity or mental stress of the individual.  A person walking at a brisk pace will consume about four times as much oxygen as he or she would when sitting quietly.  Under severe exertion or stress, he or she would be consuming eight time as much oxygen as when resting.

What Happens If The Body Does Not Receive Enough Oxygen?
When the body is deprived of an adequate oxygen supply, even for a short period, various organs and processes in the body begin to suffer impairment from oxygen deficiency.  This condition is known as "hypoxia".  Hypoxia affects every cell in the body, but especially the brain and the body's nervous system.  This makes hypoxia extremely insidious, difficult to recognize, and a serious hazard especially for flight personnel.

What Are The Effects of Hypoxia?
Hypoxia causes impairment of vision (especially at night), lassitude, drowsiness, fatigue, headache, euphoria (a false sense of exhilaration), and temporary psychological disturbance.  These effects do not necessarily occur in the same sequence nor to the same extent in all individuals, but are typical in average persons who are affected by hypoxia.

When And Why Must We Use Extra Oxygen?
Supplementary oxygen must be used to enrich the air we breathe to compensate for either a deficiency on the part of the individual or a deficiency in the atmosphere in which we are breathing.  A person may have a respiratory or circulatory impairment which reduces the ability of the body to utilize the 21% oxygen in the air.  For such a person supplementary oxygen must be administered by an oxygen tent or by an oxygen mask to enrich the inhaled air.  The total volume of oxygen in each inhalation is then so much greater than normal that it compensates for the individual's own physical inability to utilize normal atmospheric oxygen.  When we ascend in altitude a different condition is encountered: a condition in which the individual may be perfectly normal, but in which there is an oxygen deficiency in the atmosphere and supplementary oxygen must therefore be used.

Does the Percentage of Oxygen In The Air Change With Altitude?
No, the ratio of oxygen to nitrogen in the composition of the air does not change.  The 21% of oxygen in the air remains relatively constant at altitudes up to one 100,000 feet.

Why Must We Use Extra Oxygen When We Ascend In Altitude?
The blanket of air which surrounds our planet is several hundred miles thick, compressible, and has weight.  The air closest to the earth is supporting the weight of the air above it and, therefore is more dense; its molecules are packed closer together.  As we ascend in altitude the air is less dense.  For example, at 10,000 feet, the atmospheric pressure is only 2/3 of that at ground level.  Consequently, the air is less dense, and each lungful of air contains only 2/3 as many molecules of oxygen as it did at ground level.  At 18,000 feet the atmospheric pressure is only 1/2 of that at ground level.  Although the percentage of oxygen is still the same as at ground level, the number of molecules of oxygen in each lungful is reduced by 1/2.

As we ascend, there is a progressive reduction in the amount of oxygen taken into the lungs with each breath, and a corresponding decrease in the amount of oxygen available for the bloodstream to pick up and transport to every cell in the body.  To compensate for this progressive oxygen deficiency, we must add pure oxygen to the air we breathe in order to maintain enough oxygen molecules to supply the metabolic needs of the body.

At What Altitudes Should Oxygen Be Used?
In general, it can be assumed that the normal, healthy individual in unlikely to need supplementary oxygen at altitudes below 8,000 feet.  One exception is night flying.  Because the retina of the eye is affected by even extremely mild hypoxia, deterioration of night vision becomes significant above 5,000 feet.  Between 8,000 and 12,000 feet, hypoxia may cause the first signs of fatigue, drowsiness, sluggishness, headache, and slower reaction time.  At 15,000 feet, the hypoxic effect becomes increasingly apparent in terms of impaired efficiency, increased drowsiness, errors in judgment, and difficulty with simple tasks requiring mental alertness or muscular coordination.  These symptoms become more intensified with progressively higher ascent or with prolonged exposure.  At 20,000 feet, a pilot may scarcely be able to see (much less read) the instruments.  His or her hearing, perception, judgment, comprehension, and general mental and physical faculties are practically useless.  The pilot may be on the verge of complete collapse.  Therefore, the availability and use of supplemental oxygen is recommended on nigh flights where altitudes above 5,000 feet are contemplated and for altitudes above 8,000 feet on daytime flights.

How Can You Tell When You Need Oxygen?
Without some measuring device such as a portable pulse oximeter, you can't.  Therefore, oxygen should be used before it is needed.  The most dangerous aspect of hypoxia is the insidious, "sneaky" nature of its onset.  Because the effects of hypoxia are primarily on the brain and nervous system, there is a gradual loss of mental faculties, impairment of judgment, coordination, and skill; but these changes are so slow that they are completely unnoticed by the individual who is being affected.  Actually, a person suffering from mild or moderate hypoxia is apt to feel a sense of exhilaration or security, and may be quite proud of his or her proficiency and performance although he or she may be on the verge of complete incompetence.

Because hypoxia acts upon the brain and nervous system, its effects are very much like those of alcohol or other drugs which produce a false sense of well-being.  There is a complete loss of ability for self-criticism of self-analysis.  Some people believe that an individual can detect his or her need for oxygen by noting an increase in breathing rate, an accelerated heartbeat, and a slight bluish discoloration (cyanosis) of the fingernails.  However, by the time these symptoms develop, the individual is more likely to be mentally incapable of recognizing these signs.  The person may even decide that he or she has always wanted blue fingernails.  Even while "spiraling" out of control, the individual may be convinced (if conscious at all) that he or she is doing this deliberately and enjoying it immensely.

Oxygen Cylinder Dimensions and Duration Table
Mountain High Documents Page - Manuals, specifications, articles, etc.

Breathless - Oct 1st, 2003 - The German magazine, "aerokurier" ran an article in their March, 1997 edition comparing the Mountain High EDS with other O2 systems. The article follows.

Hypoxia - Apr 20th, 2001 - You placed a great deal of emphasis on the quality and integrity of your equipment and flying skills. Now it's time to put emphasis on the integrity of the most important, yet weakest, link in your system, . . yourself.

The Pilot's Atmosphere - Dec 31st, 1969 - Many of today's home built aircraft capable of transporting man to high altitudes in near record time, with the average age of the pilot base at well over 50 years old, a practical knowledge of physiological human principals and atmospheric physics.

A Breath of Fresh Air - by Billy Hill - 1992


  • Breathing Station - Includes flow control system (EDS or constant flow), cannula and face mask but does not include a regulator or oxygen cylinder.
  • Breathing System: A complete oxygen system.  It includes an oxygen cylinder, regulator, tubing, connectors, flow control device (constant flow or pulse-demand), nasal cannula and mask.
  • Cannula: Two small tubes which feed oxygen directly into the nose.
  • Constant Flow System: The oxygen flows at a continuous rate which is adjusted manually to a pressure and flow needed by humans at various altitudes.
  • Cylinder: The container for the oxygen.  It generally includes an on/off valve.
  • Delivery System: A complete oxygen system with everything except the oxygen cylinder.  It includes a regulator, tubing, flow control device (constant flow or pulse-demand), nasal cannula and mask
  • EDS: Electronic (Pulse Demand) Delivery System - A small pulse of oxygen is delivered at the beginning of every inhalation.  This method is much more efficient than constant flow oxygen systems.  EDS systems require as little as 1/8 the amount of oxygen and 1/4 the weight and volume of conventional systems.
  • Oxymizer Oxygen-Conserving Nasal Cannula: Includes an oxygen-conserving reservoir.  For use with constant flow systems only - not for use with the EDS system.
  • Regulator: The reducing regulator takes the oxygen pressure from the cylinder and regulates it down to a manageable pressure for the delivery device.  Many types of regulators are found in aviation oxygen systems.  Some include a pressure gauge.

Cylinder Valve Port Types
There are 2 types of cylinder valve port types commonly used in aircraft.  It is important to know which one is on your cylinder when ordering a regulator for it.  The regulator attaches to this port.

  • CGA-540 - US standard, Approximate outer diameter of threads: 0.875" (22.2 mm)
  • DIN-477 - European standard, Approximate outer diameter of threads: 1" (25.4 mm)

Regulations in the USA

Cumulus Soaring, Inc.
Paul E. Remde

8661 Connelly Place
Savage, Minnesota 55378

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