DOCSLIB.ORG

Safetygram 7: Liquid Nitrogen

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Safetygram 7: Liquid Nitrogen Safetygram #7 Liquid Nitrogen General inner vessel. Vaporizers convert the liquid nitrogen to its gaseous state. A pressure control manifold Liquid nitrogen is inert, colorless, odorless, non- controls the pressure at which the gas is fed to corrosive, nonflammable, and extremely cold. the process. Processes that use nitrogen as a Nitrogen makes up the major portion of the atmo- liquid do not require the vaporizers and pressure sphere (78.03% by volume, 75.5% by weight). control manifold. Nitrogen is inert and will not support combustion; however, it is not life supporting. Physical and chemical properties are listed in Table 1. Nitrogen is inert except when heated to very high temperatures where it combines with some of the Manufacture more active metals, such as lithium and magne- sium, to form nitrides. It will also combine with Nitrogen is produced at air separation plants by oxygen to form oxides of nitrogen and, when com- liquefaction of atmospheric air and separation of bined with hydrogen in the presence of catalysts, the nitrogen by continuous cryogenic distillation. will form ammonia. The nitrogen is then recovered as a cryogenic liquid. Since nitrogen is noncorrosive, special materials of construction are not required to prevent corro- Uses sion. However, materials of construction must be Nitrogen is the largest volume inorganic chemical selected to withstand the low temperature of liquid sold in the world, supporting a multitude of com- nitrogen. Vessels and piping should be designed to mercial and technical applications. In its liquid American Society of Mechanical Engineers (ASME) state, nitrogen is used for food freezing, plastic specifications or the Department of Transportation and rubber deflashing and grinding, cooling, metal (DOT) codes for the pressures and temperatures treating, biological sample preservation, pulveriza- involved. tion, and other temperature-related applications. Although used more commonly in the gaseous state, nitrogen is commonly stored and transported Health Effects as a liquid, affording a more cost-effective way of Being odorless, colorless, tasteless, and nonirritat- providing product supply. ing, nitrogen has no warning properties. Humans When nitrogen is converted to liquid form it possess no senses that can detect the presence becomes a cryogenic liquid. Cryogenic liquids are of nitrogen. Although nitrogen is nontoxic and liquefied gases that have a normal boiling point inert, it can act as a simple asphyxiant by displac- below –238°F (–150°C). Liquid nitrogen has a ing the oxygen in air to levels below that required boiling point of –320.5°F (–195.8°C). The tem- to support life. Inhalation of nitrogen in excessive perature difference between the product and the amounts can cause dizziness, nausea, vomiting, surrounding environment, even in winter, is sub- loss of consciousness, and death. Death may stantial. Keeping this surrounding heat from the result from errors in judgment, confusion, or loss product requires special equipment to store and of consciousness that prevents self-rescue. At handle cryogenic liquids. low oxygen concentrations, unconsciousness and death may occur in seconds and without warning. A typical system consists of the following com- ponents: a cryogenic storage tank, one or more Personnel, including rescue workers, should vaporizers, a pressure and temperature control not enter areas where the oxygen concentra- system. The cryogenic tank is constructed like, in tion is below 19.5%, unless provided with a principle, a vacuum bottle. It is designed to keep self-contained breathing apparatus or air-line heat away from the liquid that is contained in the respirator. For more information on oxygen-deficient atmo- Table 1 spheres, consult Air Products’ Safetygram #17, “Dangers of Oxygen-Deficient Atmospheres.” Liquid Nitrogen Physical and Chemical Properties Extensive tissue damage or burns can result Chemical Formula N2 from exposure to liquid nitrogen or cold nitrogen Molecular Weight 28.01 vapors. Boiling Point @ 1 atm –320.5°F (–195.8°C) Containers Freezing Point @ 1 atm –346.0°F (–210.0°C) Liquid nitrogen is stored, shipped and handled in several types of containers, depending upon Critical Temperature –232.5°F (–146.9°C) the quantity required by the user. The types of Critical Pressure 492.3 psia (33.5 atm) containers in use are the dewar, cryogenic liquid cylinder, and cryogenic storage tank. Storage Density, Liquid @ BP, 1 atm 50.45 lb/scf quantities vary from a few liters to many thou- Density, Gas @ 68°F (20°C), 1 atm 0.0725 lb/scf sands of gallons. Since heat leak is always pres- ent, vaporization takes place continuously. Rates Specific Gravity, Gas (air=1) @ 68°F (20°C), 1 atm 0.967 of vaporization vary, depending on the design of Specific Gravity, Liquid (water=1) @ 68°F (20°C), 1 atm 0.808 the container and the volume of stored product. Specific Volume @ 68°F (20°C), 1 atm 13.80 scf/lb Containers are designed and manufactured according to the applicable codes and Latent Heat of Vaporization 2,399 Btu/lb mole specifications for the temperatures and pressures Expansion Ratio, Liquid to Gas, BP to 68°F (20°C 1 to 694 involved. Figure 1 protect the cylinders from pressure buildup. These Figure 2a containers operate at pressures up to 350 psig A Typical Dewar and have capacities between 80 and 450 liters of Typical Cryogenic Liquid Cylinder, side view liquid. Liquid Level Gauge Product may be withdrawn as a gas by passing Handling Ring liquid through an internal vaporizer or as a liquid Handling Post Annular Space under its own vapor pressure. For more details on Rupture Disk the construction and operation of cryogenic liquid Inner Vessel Vent Tube cylinders, consult Air Products’ Safetygram #27, Gas Use Liquid Tube Vaporizer Float Assembly “Cryogenic Liquid Containers.” (Optional) Outer Vessel Rubber Shock Cryogenic Storage Tanks Mounts A typical customer installation (see Figure 3) Foot Ring includes a tank, a vaporizer, and a pressure control manifold. Tanks may be spherical or cylindrical Dewars in shape. They are mounted in fixed locations as Figure 2b Figure 1 illustrates a typical, vacuum-jacketed stationary vessels or on railroad car or truck chas- dewar. A loose fitting dust cap over the outlet of sis for easy transportation. Sizes range from 500 Typical Cryogenic Liquid Cylinder, top view the neck tubes prevents atmospheric moisture to 420,000 gallons and all tanks are powder- and Vent Pressure Rupture Vent Relief Pressure Rupture from plugging the neck and allows gas produced vacuum-insulated in the annular space. Tanks are Valve Gauge Disk Valve Valve Gauge Disk from vaporized liquid to escape. This type of con- equipped with various circuits to control product tainer is a nonpressurized container. The unit of fill, pressure buildup, pressure relief, product measure for the capacity of a dewar is typically withdrawal, and tank vacuum. Tanks are designed the liter. Five to 200 liter dewars are available. to ASME specifications for the pressures and tem- Product may be removed from small dewars by peratures involved. pouring, while larger sizes will require a transfer Transfer Lines Pressure tube. Cryogenic liquid cylinders that are pressur- Liquid Pressure Building Building Economizer Liquid Gas ized vessels are sometimes incorrectly referred to A liquid transfer line is used to safely remove liquid Valve Regulator Valve Regulator Valve Disk as dewars. product from dewars or cryogenic liquid cylinders. A typical transfer line for dewars is connected to Liquid product is typically removed through Cryogenic Liquid Cylinders a bayonet that provides a means of using product insulated withdrawal lines to minimize the loss Figure 2 shows a typical cryogenic liquid cylinder. vapor pressure buildup or an external pressure of liquid product to gas. Insulated flexible or rigid Cryogenic liquid cylinders are insulated, vacuum- source to remove the liquid. For cryogenic liquid lines are used to withdraw product from storage jacketed pressure vessels. They come equipped cylinders, the transfer line is connected to the tanks. Connections on the lines and tanks vary by with safety relief valves and rupture discs to cylinder’s liquid withdrawal valve. manufacturer. Figure 3 Figure 4 Use only transfer lines and equipment designed for use with cryogenic liquids. Some elastomers and A Typical Customer Station with a Nonflammable Gas Shipping Label metals, such as carbon steel, may become brittle at Cryogenic Storage Tank extremely low temperatures and may easily frac- ture. These materials must be avoided in cryogenic service. On gas withdrawal systems use check valves or other protective apparatus to prevent reverse flow into the container.On liquid systems pressure relief devices must be used in lines where there is the potential to trap liquid between valves. It is recom- mended that all vents be piped to the exterior of the building. Liquid containers should not be left open to the atmosphere for extended periods. Keep all valves closed and outlet caps in place when not in use. If NOTE: Liquid cylinders designed to dispense If oxygen-deficient atmospheres are suspected or restriction results from freezing moisture or foreign gaseous nitrogen have valves equipped with can occur, use oxygen monitoring equipment to test material present in openings and vents contact the standard Compressed Gas Association (CGA) for oxygen-deficient atmospheres. Review the liquid vendor for instructions. Restrictions and blockages outlets. Suitable pressure regulating equipment nitrogen Material Safety Data Sheet (MSDS). may result in damgerous over-pressurization. Do not may be attached. Valves provided for the with- attempt to remove the restriction without proper in- drawal of liquid product are also equipped with Buildings structions. If possible move the cylinder to a remote standard CGA outlets, but are different than the location. connections used for gaseous withdrawal. This Because of the large expansion ratio of liquid to gas, is to prevent cross connections between pro- it is very important to provide adequate ventilation For additional information on the storage and cesses using liquid or gaseous product.
Load more

Recommended publications
  • Liquid Argon
    Safetygram 8 Liquid argon Liquid argon is tasteless, colorless, odorless, noncorrosive, nonflammable, and extremely cold. Belonging to the family of rare gases, argon is the most plentiful, making up approximately 1% of the earth’s atmosphere. It is monatomic and extremely inert, forming no known chemical compounds. Since argon is inert, special materials of construction are not required. However, materials of construction must be selected to withstand the low temperature of liquid argon. Vessels and piping should be designed to American Society of Mechanical Engineers (ASME) specifications or the Department of Transportation (DOT) codes for the pressures and temperatures involved. Although used more commonly in the gaseous state, argon is commonly stored and transported as a liquid, affording a more cost-effective way of providing product supply. Liquid argon is a cryogenic liquid. Cryogenic liquids are liquefied gases that have a normal boiling point below –130°F (–90°C). Liquid argon has a boiling point of –303°F (–186°C). The temperature difference between the product and the surrounding environment, even in winter, is substantial. Keeping this surrounding heat from the product requires special equipment to store and handle cryogenic liquids. A typical system consists of the following components: a cryogenic storage tank, one or more vaporizers, a pressure control system, and all of the piping required for fill, vaporization. The cryogenic tank is constructed, in principle, like a vacuum bottle. It is designed to keep heat away from the liquid that is contained in the inner vessel. Vaporizers convert the liquid argon to its gaseous state. A pressure control manifold controls the pressure at which the gas is fed to the process.
    [Show full text]
  • Compressed Liquid Gases (Cryogens) Laboratory Safe Work Practices
    Compressed Liquid Gases (Cryogens) Laboratory Safe Work Practices Source: Section 3.9 of Guidelines for Safe Work Practices in Human and Animal Medical Diagnostic Laboratories: Recommendations of a CDC-convened, Biosafety Blue Ribbon Panel; excerpted by Vanderbilt OCRS, 10.2020. Compressed Liquid Gases (Cryogens) Cryogenic liquids are liquefied gases that have a normal boiling point below -238°F (-150°C). Liquid nitrogen is used in the microbiology laboratory to freeze and preserve cells and virus stocks. The electron microscopy laboratory, frozen section suites, and grossing stations for surgical pathology frequently use liquid nitrogen; some laboratories also use liquid helium. The principal hazards associated with handling cryogenic fluids include cold contact burns and freezing, asphyxiation, explosion and material embrittlement. Cold contact burns and freezing • Liquid nitrogen is dangerously cold (-320°F [-196°C]), and • Wear loose-fitting thermal gloves with elbow-length cuffs skin contact with either the liquid or gas phase can when filling dewars. Ensure that gloves are loose enough to immediately cause frostbite. At -450°F (-268°C), liquid be thrown off quickly if they contact the liquid. helium is dangerous and cold enough to solidify atmospheric • Never place gloved hands into liquid nitrogen or into the air. liquid nitrogen stream when filling dewars. Gloves are not • Always wear eye protection (face shield over safety goggles). rated for this type of exposure. Insulated gloves are The eyes are extremely sensitive to freezing, and liquid designed to provide short-term protection during handling of nitrogen or liquid nitrogen vapors can cause eye damage. hoses or dispensers and during incidental contact with the • Do not allow any unprotected skin to contact uninsulated liquid.
    [Show full text]
  • Cryogenics – the Basics Or Pre-Basics Lesson 1 D
    Cryogenics – The Basics or Pre-Basics Lesson 1 D. Kashy Version 3 Lesson 1 - Objectives • Look at common liquids and gases to get a feeling for their properties • Look at Nitrogen and Helium • Discuss Pressure and Temperature Scales • Learn more about different phases of these fluids • Become familiar with some cryogenic fluids properties Liquids – Water (a good reference) H2O density is 1 g/cc 10cm Total weight 1000g or 1kg (2.2lbs) Cube of water – volume 1000cc = 1 liter Liquids – Motor Oil 10cm 15W30 density is 0.9 g/cc Total weight 900g or 0.9 kg (2lbs) Cube of motor oil – volume 1000cc = 1 liter Density can and usually does change with temperature 15W30 Oil Properties Density Curve Density scale Viscosity scale Viscosity Curve Water density vs temperature What happens here? What happens here? Note: This plot is for SATURATED Water – Discussed soon Water and Ice Water Phase Diagram Temperature and Pressure scales • Fahrenheit: 32F water freezes 212 water boils (at atmospheric pressure) • Celsius: 0C water freezes and 100C water boils (again at atmospheric pressure) • Kelvin: 273.15 water freezes and 373.15 water boils (0K is absolute zero – All motion would stop even electrons around a nucleus) • psi (pounds per square in) one can reference absolute pressure or “gage” pressure (psia or psig) • 14.7psia is one Atmosphere • 0 Atmosphere is absolute vacuum, and 0psia and -14.7psig • Standard Temperature and Pressure (STP) is 20C (68F) and 1 atm Temperature Scales Gases– Air Air density is 1.2kg/m3 => NO Kidding! 100cm =1m Total weight
    [Show full text]
  • Cryogenic Liquid Nitrogen Vehicles (ZEV's)
    International Journal of Scientific and Research Publications, Volume 6, Issue 9, September 2016 562 ISSN 2250-3153 Cryogenic Liquid Nitrogen Vehicles (ZEV’S) K J Yogesh Department Of Mechanical Engineering, Jain Engineering College, Belagavi Abstract- As a result of widely increasing air pollution available zero emission vehicle (ZEV) meeting it's standards are throughout the world & vehicle emissions having a major the electrically recharged ones, however these vehicles are also contribution towards the same, it makes its very essential to not a great success in the society due to its own limitations like engineer or design an alternative to the present traditional initial cost, slow recharge, speeds etc. Lead acid & Ni-Cd gasoline vehicles. Liquid nitrogen fueled vehicles can act as an batteries are the past of major technologies in the electric excellent alternative for the same. Liquefied N2 at cryogenic vehicles. They exhibit specific energy in the range of 30-40 W- temperatures can replace conventional fuels in cryogenic heat hr/kg. Lead- acid batteries take hours to recharge & the major engines used as a propellant. The ambient temperature of the drawback of the batteries in all the cases is their replacement surrounding vaporizes the liquid form of N2 under pressure & periodically. This directly/indirectly increases the operating cost leads to the formation of compressed N2 gas. This gas actuates a when studied carefully & thereby not 100% acceptable. pneumatic motor. A combination of multiple reheat open Recent studies make it clear that the vehicles using liquid Rankine cycle & closed Brayton cycle are involved in the nitrogen as their means provide an excellent alternative before process to make use of liquid N2 as a non-polluting fuel.
    [Show full text]
  • Capacity Enhancement of Indigenous Expansion Engine Based Helium Liquefier
    IOP Conference Series: Materials Science and Engineering PAPER • OPEN ACCESS Capacity enhancement of indigenous expansion engine based helium liquefier To cite this article: R S Doohan et al 2017 IOP Conf. Ser.: Mater. Sci. Eng. 171 012011 View the article online for updates and enhancements. This content was downloaded from IP address 170.106.202.8 on 27/09/2021 at 00:16 ICECICMC IOP Publishing IOP Conf. Series: Materials Science and Engineering 171 (2017) 012011 doi:10.1088/1757-899X/171/1/012011 International Conference on Recent Trends in Physics 2016 (ICRTP2016) IOP Publishing Journal of Physics: Conference Series 755 (2016) 011001 doi:10.1088/1742-6596/755/1/011001 Capacity enhancement of indigenous expansion engine based helium liquefier R S Doohan1, P K Kush1, G Maheshwari2 1Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh India. 2Institute of Engineering and Technology, DAVV, Indore, Madhya Pradesh, India. E-mail: doohan@rrcat.gov.in Abstract. Development of technology and understanding for large capacity helium refrigeration and liquefaction at helium temperature is indispensable for coming-up projects. A new version of helium liquefier designed and built to provide approximately 35 liters of liquid helium per hour. The refrigeration capacity of this reciprocating type expansion engine machine has been increased from its predecessor version with continuous improvement and deficiency debugging. The helium liquefier has been built using components by local industries including cryogenic Aluminum plate fin heat exchangers. Two compressors with nearly identical capacity have been deployed for the operation of system. Together they consume about 110 kW of electric power. The system employs liquid Nitrogen precooling to enhance liquid Helium yield.
    [Show full text]
  • 3.10. Cryogenic Liquids – Procedures for Safe Handling and Storage Cryogenic Liquids Are Liquefied Gases Having Boiling Points of Less Than -73.3O C (-100O F)
    3.10. Cryogenic Liquids – Procedures for Safe Handling and Storage Cryogenic liquids are liquefied gases having boiling points of less than -73.3o C (-100o F). The primary hazards of cryogenic liquids include both physical hazards such as fire, explosion, and pressure buildup and health hazards such as severe frostbite and asphyxiation. Potential fire or explosion hazards exist because cryogenic liquids are capable, under the right conditions, of condensing oxygen from the atmosphere. This oxygen-rich environment in combination with flammable/combustible materials and an ignition source are particularly hazardous. Pressure is also a hazard because of the large volume expansion ratio from liquid to gas that a cryogen exhibits as it warms and the liquid evaporates. This expansion ratio also makes cryogenic liquids more prone to splash and therefore skin and eye contact is more likely to occur. Contact with living tissue can cause frostbite or thermal burns, and prolonged contact can cause blood clots that have very serious consequences. All laboratory personnel must follow prudent safety practices when handling and storing cryogenic liquids. 3.10.1. Properties of Common Cryogenic Liquids Liquid to Gas Gas Boiling Point oF (oC) Volume Expansion Ratio Helium -452 (-268.9) 1-757 Hydrogen -423 (-252.7) 1-851 Nitrogen -321 (-195.8) 1-696 Fluorine -307 (-187.0) 1-888 Argon -303 (-185.7) 1-847 Oxygen -297 (-183.0) 1-860 Methane -256 (-161.4) 1-578 Note: Absolute zero = - 459.67 oF (- 273.15 oC) 3.10.2. Handling Appropriate personal protective equipment must be worn when handling cryogenic liquids.
    [Show full text]
  • Cryogenic Liquid Safety
    Cryogenic Liquid Safety Hazards and Safe Handling of Cryogenic Liquids Cryogenic liquids have boiling points less than -73ºC (-100ºF). Liquid nitrogen, liquid oxygen and carbon dioxide are the most common cryogenic materials used in the laboratory. Hazards may include fire, explosion, embrittlement, pressure buildup, frostbite and asphyxiation. Many of the safety precautions observed for compressed gases also apply to cryogenic liquids. There are also additional hazards due to the unique properties of cryogenic liquids: • Extremely Low Temperatures: The cold boil-off vapor of cryogenic liquids rapidly freezes human tissue. Most metals become stronger upon exposure to cold temperatures, but materials, such as; carbon steel, plastics and rubber become brittle or fracture under stress at these temperatures. Proper material selection is important. Cold burns and frostbite caused by cryogenic liquids can result in extensive tissue damage. • Vaporization: All cryogenic liquids produce large volumes of gas when they vaporize. Liquid nitrogen will expand 696 times as it vaporizes. The expansion ratio of argon is 847:1, hydrogen is 851:1 and oxygen is 862:1. If these liquids vaporize in a sealed container, they can produce enormous pressures that could rupture the vessel. For this reason, pressurized cryogenic containers are usually protected with multiple pressure relief devices. • Vaporization of cryogenic liquids (except oxygen) in an enclosed area can cause asphyxiation! • Vaporization of liquid O2 can produce an oxygen-rich atmosphere, supporting and accelerating combustion of other materials. Vaporization of liquid hydrogen can form an extremely flammable mixture with air. Most cryogenic liquids are odorless, colorless, and tasteless when vaporized. When cryogenic liquids are exposed to the atmosphere, cold boil-off gases condense the moisture in the air, creating a highly visible fog.
    [Show full text]
  • Liquid Helium
    Safetygram 22 Liquid helium Liquid helium is inert, colorless, odorless, noncorrosive, extremely cold, and nonflammable. Helium will not react with other elements or compounds under ordinary conditions. Since helium is noncorrosive, special materials of construction are not required. However, materials must be suitable for use at the extremely low temperatures of liquid helium. Vessels and piping must be selected and designed to withstand the pressure and temperatures involved and comply with applicable codes for transport and use. Manufacture Most of commercial helium is recovered from natural gas through a cryogenic separation process. Normally, helium is present in less than 1% by volume in natural gas. Helium is recovered, refined, and liquefied. Liquid helium is typically shipped from production sources to storage and transfill facilities. Tankers, ranging in size from 5,000 to 11,000 gallons, contain an annular space insulated with vacuum, nitrogen shielding, and multilayer insulation. This de- sign reduces heat leak and vaporization of liquid helium during transportation. Uses The extremely low temperature of liquid helium is utilized to maintain the superconducting properties of magnets in applications such as MRI, NMR spectroscopy, and particle physics research. The main application for gas- eous helium is for inert shielding gas in metal arc and laser welding. Helium provides a protective atmosphere in the production of reactive metals, such as titanium and zirconium. Gaseous helium is used as a coolant during the draw- ing of optical fibers, as a carrier gas for chromatography, and as a leak detection gas in a variety of industries. Being both lighter than air and nonflammable, helium is used to inflate balloons and airships.
    [Show full text]
  • Liquid Nitrogen Safety & Handling
    Liquid Nitrogen Safety & Handling 1.0 Liquid Nitrogen & Cryogenic Liquids a. Liquid nitrogen, LN2, is colorless, odorless and tasteless. It is non-flammable, physiologically inert and non-toxic. It is an extremely cold liquid with a boiling point of - 196ºC = -320ºF. b. Cryogenic liquids are liquefied gases that are kept in their liquid state at extremely low temperatures. Cryogenic liquids have boiling points below -150°C (-238°F) (Carbon dioxide and nitrous oxide, which have slightly higher boiling points are sometimes included in this category). All cryogenic liquids are gases at normal temperatures and pressures. All Cryogenic liquids produce large amounts of gas when they vaporize. c. There a many applications of LN2 in a biomedical research facility, one of the most common being cryopreservation, the storage of cells at temperatures below -130 ºC, which is essential in order to preserve biological material unaltered. 2.0 Safety Hazards Associated with Handling LN2 a. The extremely low temperature of the liquid can cause severe frostbite or eye damage upon contact. Symptoms of frostbite include change in skin color to white or grayish yellow and the pain after contact with LN2 may quickly subside. Items in contact with liquid nitrogen become extremely cold. Touching these items may result in torn flesh. Many substances become brittle upon contact with liquid nitrogen and may shatter when cold (such as common glass and large solid plastics), sending pieces of the material flying. b. Upon vaporization it expands by a factor of 700; one liter of liquid nitrogen becomes 24.6 cubic feet of nitrogen gas.
    [Show full text]
  • Liquid Oxygen
    Safetygram 6 Liquid oxygen Oxygen is the second largest component of the atmosphere, comprising 20.8% by volume. Liquid oxygen is pale blue and extremely cold. Although nonflammable, oxygen is a strong oxidizer. Oxygen is necessary to support life. Oxygen will react with nearly all organic materials and metals, usually forming an oxide. Materials that burn in air will burn more vigorously in oxygen. Equipment used in oxygen service must meet stringent cleaning requirements, and systems must be constructed of materials that have high ignition temperatures and that are nonreactive with oxygen under the service conditions. Vessels should be manufactured to American Society of Mechanical Engineers (ASME) codes and designed to withstand the process temperatures and pressures. Liquid oxygen is a cryogenic liquid. Cryogenic liquids are liquefied gases that have a normal boiling point below –130°F (–90°C). Liquid oxygen has a boiling point of –297°F (–183°C). Because the temperature difference between the product and the surrounding environment is substantial—even in the winter—keeping liquid oxygen insulated from the surrounding heat is essential. The product also requires special equipment for handling and storage. Oxygen is often stored as a liquid, although it is used primarily as a gas. Liquid storage is less bulky and less costly than the equivalent capacity of high-pressure gaseous storage. A typical storage system consists of a cryogenic storage tank, one or more vaporizers and a pressure control system. The cryogenic tank is constructed, in principle, like a vacuum bottle. There is an inner vessel surrounded by an outer vessel. Between the vessels is an annular space that contains an insulating medium from which all the air has been removed.
    [Show full text]
  • Protocol for Use and Maintenance of Oxygen Monitoring Devices 2021
    National Institutes of Health Protocol for Use and Maintenance of Oxygen Monitoring Devices 2021 Authored by the Division of Occupational Health and Safety (DOHS) Oxygen Monitoring Program Manager. CONTENTS INTRODUCTION………………………………………………………………... 2 I. PURPOSE………………………………………………………………… 2 II. SCOPE……………………………………………………………………. 2 III. APPLICABLE REGULATORY, POLICY, AND INDUSTRY STANDARDS………………………………………... 3 IV. RESPONSIBILITIES …………………………………………….………. 4 V. TECHNICAL INFORMATION………………………………………….. 6 VI. REFERENCES…………………………………………………….……… 9 APPENDIX A – MANDATORY SIGNAGE………………………………….… 11 APPENDIX B – RECOMMENDED SIGNAGE………………………………… 13 ACRONYMS BAS Building Automation System DOHS Division of Occupational Health and Safety DRM Design Requirements Manual IC Institute/Center MRI Magnetic Resonance Imaging NMR Nuclear Magnetic Resonance OSHA Occupational Safety and Health Administration PI Principal Investigator TEM Transmission Electron Microscope TAB Technical Assistance Branch Disclaimer of Endorsement: Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government, and shall not be used for advertising or product endorsement purposes. 1 INTRODUCTION Compressed gases and cryogenic liquids (e.g. nitrogen, helium, carbon dioxide, oxygen and argon)
    [Show full text]
  • Liquid Nitrogen Safety
    Michigan Technological University, Department of Physics Liquid Nitrogen Safety Adapted from Department of Chemical Engineering Safety Manual and: http://engineering.dartmouth.edu/microengineering/ln2.html Properties of Liquid Nitrogen (LN2) 1. It is extremely cold: 77.3K = -196C = -320F at atmospheric pressure. This can cause severe frost bite 2. On vaporization it expands by a factor of 700; one liter of liquid nitrogen becomes 24.6 cubic feet of nitrogen gas. This can cause explosion of a sealed container, or it can displace oxygen in the room and cause suffocation without warning. 3. It can become oxygen enriched and cause ordinarily noncombustible materials to burn rapidly. Personal Protection When Handling LN2 1. When handling LN2 you should maximize the protection offered by clothing. Wear full sleeves, long pants and non-porous closed-toe shoes. 2. Splashing is common, so safety goggles or a face shield should be worn at all times when working with LN2. 3. Wear protective gloves when touching any object cooled by liquid nitrogen. However, the gloves should be loose fitting, so they could be thrown off if liquid were to pour inside them. 4. Care must be taken to prevent uninsulated containers from contacting unprotected skin since they may become bonded to the skin and will serious injury. 5. Contact of the skin with LN2 can cause severe cryogenic burns (tissue damage is similar to frostbite or thermal burns). Although small amounts of LN2 quickly evaporate when on the skin surface, if the liquid becomes trapped under jewelry, watches, or inside gloves or folds of clothing, it can result in serious and painful burns.
    [Show full text]