USS Enterprise (CVN 65)
The Shuttle Newsletter Edition
“We are Legend”
June 18, 2012 Issue
Deep Freeze: Cryogenics Lab
Story by Mass Communication Specialist 3rd Class (SW/AW) Jesse L. Gonzalez USS ENTERPRISE, At Sea -- Sailors assigned to the Cryogenics shop aboard aircraft carrier USS Enterprise (CVN 65) are critical to a variety of mission-essential operations, from making liquid nitrogen for medical use to manufacturing breathable oxygen for pilots. According to Machinist Mate 1st Class Matthew Lewis, Engineering department’s Auxiliary division’s Cryogenics leading petty officer, Cryogenics is responsible for three main spaces on the ship - The forward O2N2 plant, located in the forward-most part of hangar bay, the administration office, located in the AIMD tunnel, and the aft producing plant. “In the (O2N2) plant, we have one oxygen/nitrogen producing plant, a refrigeration unit and four high pressure air compressors,” said Lewis. “There are two liquid storage tanks per plant that hold 750 gallons of liquid nitrogen and the other, which is a split tank, holds 250 gallons of nitrogen and 750 gallons of oxygen.” The Cryogenics shop supports the air wing, medical, dental, engineering, AIMD, and several other departments. Sailors assigned to cryogenics produce liquid oxygen and liquid nitrogen for uses throughout the ship, said Lewis. Some uses of the oxygen and nitrogen produced are liquid Oxygen Carts (LOX Carts) for air wing LOX. These carts are filled with 50 gallons of liquid oxygen that is put into LOX converters which goes into some of the planes for later use by the pilots. “As they fly, the liquid oxygen is converted to a breathable gas for the pilots,” said Lewis. “Also, the pilots have what we refer to as a seat pan, which is actually just the seat they’re on, that houses a small gaseous oxygen cylinder they use for breathing in case of having to eject.” According to Lewis, Sailors assigned to the Cryogenics shop fill oxygen bottles for the engineers on Enterprise. This allows the pipe shop Hull Technicians to perform various welding jobs throughout the ship. “If anyone has seen HTs walking about the ship with a green and yellow gas cylinder on their back, then you know they are off to a welding job with some of the oxygen we produced in the cryogenics shop on their back,” said Lewis. “We also fill oxygen cylinders for medical and dental for their breathing masks.” The Cryogenics shop is also responsible for the use of nitrogen aboard Enterprise. “The Cryogenics shop distributes 90 percent of the nitrogen produced as a gas, rather than as a liquid,” said Machinist Mate 3rd Class Julio Porta. Liquid nitrogen is given out to medical to use in their wart clinics, where it is used to freeze warts for removal. AIMD
Machinist’s Mate Fireman Andrew Kim, from Dallas, a cryogenics lab Sailor, fills liquid nitrogen for dewar. (Photo by MC3 Heath Zeigler)
uses nitrogen for their gauge calibration shop. Nitrogen is a moisture-free, inert gas, so it won’t cause any bad reactions or get anything wet inside. “Liquid nitrogen will also shrink parts for different types of installation,” said Porta. “We also supply gaseous nitrogen to the tire and wheel shop because all of the aircraft on board use nitrogen in their tires,” said Porta. According to Porta, the most prevalent danger in the Cryogenic shop is cryogenic burns. When one considers that working with and handling liquids that are anywhere from -297 to -312 degrees, there is a very obvious health risk involved. Any time there is a transfer of any liquids, multiple forms of personal protective equipment are required. “We use insulated cryogenic gloves which reach all the way to the elbow, full cryogenics aprons, slip-on boots and face shields,” said Porta. “We also wear white cotton coveralls with no zippers or metal on them or any spark producing material that could possibly cause liquid oxygen to explode.” Porta added that all the tools handled when working with cryogenic liquids are also made of a non-sparking material to further avoid any ignition. While oxygen itself is not technically flammable, it aides in combustion and presents a great danger when handled improperly. “It’s funny how we’re such a small shop, but we have such a big impact on the mission of the ship,” said Lewis. “For example, if our plants were down, and we couldn’t provide oxygen or nitrogen to the squadrons and divisions it would definitely hinder flight operations. No welding, no plane tires, no calibrated gauges, no breathing for some pilots, I’m pretty proud of the work we do here.”