Liquid Oxygen, or LOX, is a highly efficient method of oxygen storage and delivery. This method enables a large quantity of oxygen to be stored in a small converter, saving both space and weight on an aircraft. Our lightweight converters are easy to handle, which can decrease injuries caused by lifting heavy cylinders. Additionally, the larger quantities of oxygen allow EMS operators to maintain mission tempo by eliminating the need to refill oxygen between flights, reducing downtime between missions. As a result, operators fly longer and accept more missions using LOX.


Safe, lightweight, and compact, the Essex LOX converter will accommodate all of your needs. Our product supplies oxygen to the patient by safely converting liquid oxygen to gaseous oxygen through a pneumatic pressure venting system. Our low-pressure (75-120 PSIG operating pressure) oxygen delivery system is available with 5, 7, and 10-liter converters. In addition, the quality-controlled high vacuum created between the inner and outer containers reduces the liquid's evaporation rate, extending the time between converter refills. Backed by military-grade standards and testing, Essex LOX converters will sustain your aircraft life support!


Essex designed a complete, self-contained oxygen sustainment system. LOX portables are low-pressure, portable liquid oxygen storage and gaseous delivery systems. These systems are easily transportable and mountable in an aircraft, helicopter, or ground vehicle. Our portables have built-in flow control valves that deliver oxygen to a patient fast. They require no external power, and the maximum flow rate ranges from 15-30 liters/min at 50 PSIG. Get your portable LOX converter and ensure military-grade standards now!


For decades, our Wall Outlets with integrated flow control have provided safe delivery of supplemental oxygen in both rotor and fixed-wing air ambulances worldwide. Now, Essex introduces a new and improved line of Wall Outlets. A wider range of fitting options is now available for both the controlled and max flow outlet ports. Also, by repositioning the flow values outside the knob and increasing the font size, the flow rates are easier to read. In addition, we increased outlet thread diameter to provide a more rugged design, reducing the chance of fittings breaking. Select your custom Essex Wall Outlets and take your space back!


Essex entered the cryogenics market in 1963 and today has become a leader in liquid oxygen equipment, having delivered over 100,000 new LOX systems for military/commercial applications.In 2010, Essex assembled a complete Battlefield Oxygen Sustainment System (BOSS) as part of the USAF Guardian Angels Integrated Oxygen System.  The BOSS provides a medevac team with equipment that works together to deliver oxygen to the patient both on the ground and during transport as well as devices to generate LOX and refill equipment in the field.

The technology developed for military LOX systems has led Essex to similar advancements in the commercial medevac marketplace.   Essex LOX converters for air medical transport are available in 5 liter, 7 liter and 10 liter sizes.  Essex also offers the Ready to Install (RTI) system that allows installation of the equipment on the aircraft without the expense of a costly retrofit.

In addition to supplying new equipment, Essex offers customers complete maintenance, repair and overhaul services on LOX equipment.

Contact us for the complete list of manufacturing capabilities, testing capabilities, certification/qualifications and to discuss your project requirements.


LOX systems function well in high altitude test and deliver sufficient oxygen to power ventilators or to support extracorporeal membrane oxygenation (ECMO) treatment. Used by the U.S. military for more than 50 years, LOX equipment is reliable and rugged enough for battlefield environments. LOX converters, as low-pressure systems, are less volatile than high pressure cylinders, and therefore safer in the event of an accident. LOX Converters are easier to handle, which can decrease injuries caused by lifting heavy cylinders.

Liquid Oxygen at -297ºF (-183ºC) 

Gaseous Oxygen at 70ºF (21ºC)

1 liter

860 liters

5 liters

4,300 liters

10 liters

8,600 liters

15 liters

12,900 liters

25 liters

21,500 liters

50 liters

43,000 liters

75 liters

64,500 liters

Size & Weight – The compact size of LOX systems, as compared to equivalent volume high-pressure cylinders, allows for reduced space requirements in air ambulances where storage space is at a premium. High pressure systems require thick-walled aluminum or steel vessels to contain the gases. In contrast, low pressure LOX systems are constructed out of lightweight stainless steel. This makes it easier to lift and move LOX converters, reducing possible workplace injuries.

Duration – Since an increased amount of oxygen can be stored in liquid form than as a gas, additional hospital transfers can be made before the LOX system needs to be refilled. LOX systems may fly 10 missions versus 2 or 3 with high pressure cylinders, depending on the needs of the patients. Also with LOX systems, virtually all of the LOX can be used. As long as there is pressure in the LOX system, oxygen gas will be supplied. High-pressure cylinders need to be removed from service once they reach a minimum pressure.

Fill Time - The required time to fill a low-pressure LOX system is less than a high pressure, gaseous system. Once the system has been introduced to enough liquid oxygen to bring the temperature in the dewar down below the boiling point of LOX (-297°F), the fill time is a matter of minutes. Unlike filling a high pressure gas cylinder, there is no need for energy draining compressors or micro-boost pumps.

Safety – LOX systems are low-pressure (under 300 psi) as compared to high-pressure cylinders (in excess of 2000 psi). In the event of an accident, if a LOX converter is pierced, the oxygen inside the dewar will simply change phases back into its gaseous state. A high pressure system has enough stored energy that if punctured, could explode.

Reliability – The natural state of oxygen is in its gaseous form. When stored as a liquid, the physics of the oxygen molecules attempting to change phase back into a gas creates enough pressure to power the LOX systems. This means that there are no moving parts and less required maintenance.

Availability – Most hospitals in the United States store their oxygen in liquid form. Major gas companies such as Air Liquide, Air Products and Praxair manufacture LOX throughout the United States. Local gas suppliers also store their oxygen in liquid form and then convert it to gas for filling high pressure cylinders. These suppliers deliver LOX as well as high pressure cylinders.