cold temperatures associated with the use of cryogens
Contact with the cryogenic liquids causes not only frostbite or cryogenic burns but can also damage materials like water pipes, flooring, sinks, and electrical cables. OSHA: Compressed Gases, 20 UW Environmental Health & Safety Department | 201 Hall Health Center, Box 354400, Seattle, WA | Tel: 206.543.7262 | Fax: 206.543.3351 | ehsdept@uw.edu, Fume Hoods: Use, Inspection and Maintenance, Building Emergency Procedures and Resources, Fire Code Hazardous Materials (HazMat) Compliance, Radiation Detection Instrument Calibration, Use of Radiation in Human Subjects Research, UW Research & Training Building Remediation, Asbestos and Other Regulated Building Materials, Hazardous Energy Control - Lockout/Tagout, GHS-DOTClassification Comparisons Relevant to Compressed Gases, Transporting Compressed Gases and CryogensFocus Sheet, WAC: Permissible Exposure Limits for Airborne Contaminants, Transporting Compressed Gases and Cryogens, GHS DOT Classification Comparisons Relevant to Compressed Gases, A Guide to the Globally Harmonized System of Classification and Labeling of Chemicals (OSHA), List of Chemicals Immediately Dangerous to Life and Health (IDLH). It is essential to choose the right PPE for each job. If the initial pressure of iodoethane is 894 torr at 245C,245 ^ { \circ } \mathrm { C } ,245C, what is the pressure of iodoethane after three half-lives? Appropriate PPE is still required when transporting cryogenic liquids around buildings. Always use the proper regulator for the gas in the cylinder. Wearing a cryogenic apron is suggested to help prevent this from occurring. Do You Know How to Handle Dry Ice Safely. Refer to the manufacturers instructions on correct valve positions and how to extract liquid. Contact with cryogenic liquids and their cold gases can produce effects on the skin similar to a thermal burn, as can contact with dry ice. f@TzgJ%@9m0^q&XWkk)E+vjZmj/tI{Yzb/[ ^4(=ZsG[J protect the eyes and skin from the hazards associated with cryogens. There are a number of general precautions and safe practices that must be observed because of the extremely low temperatures and high rates of conversion into gas of all the cryogenic liquids. mary poppins drug theory; monitor stuck on disconnect this display; does cranberry juice make your poop smell; . A cryogen or cryogenic liquid is defined by the National Institute for Standards and Technology (NIST) as any liquid with a boiling point below 93K (-180C or -240F) at 1 atmosphere of pressure. Prolonged contact may result in blood clots. Supply oxygen if the victim has difficulty breathing and summon emergency medical help. Classification Emergency Procedures Room Signage Labeling Cylinder status tags Gas delivery systems Regulators Procurement Cryogenic fluids have large liquid-to-gas expansion ratios: These ratios mean that any accidental release or overflow of these cryogenic liquids will quickly boil into gas and createan asphyxiation hazardby displacing the oxygen content of the surrounding area. Ear plugs can be worn to protect the ear in case a cryogenic vial explodes. 22 febrero, 2022 . The course covers the following topics: University of Florida Both cryogenic liquids and dry ice can produce very large volumes of gas at room temperatures. Environment, Health and Safety Information for the Berkeley Campus #77: Cryogenic Liquids Precautions and Safe Handling Procedures. In the case of liquid argon and liquid nitrogen, the gas generated from malfunctioning equipment or spills will be cold and denser than ambient air. Cryogens have boiling points below - 73 C (- 100 F) at 14.7 psia (an absolute pressure of 101kPa). Introduction. Unprotected skin can stick to materials that are cooled by cryogenic liquids and dry ice, similar to the way some children stick their tongues to flagpoles in the winter. When you are done with the cylinder, you contact the company listed on the cylinder and they will pick it up. Q: What kinds of gloves are needed for working with cryogenics and dry ice? Generally,chemical-splash gogglesandface shieldsshould always be worn during the transfer and handling process of cryogenic liquids to guard against splashes and spills. For example, one liter of liquid nitrogen vaporizes into 695 liters of nitrogen gas when at room temperature. Safety goggles provide the best protection for the eyes. Store all containers with cryogens, pressurized or non-pressurized, in well ventilated areas. Air Products: Safetygrams. Contact with dry ice, cryogenic liquids and their gases, and any cooled surfaces should be avoided. Cryotubes stored under liquid nitrogen can explode while thawing. Yan men ve dolam a/kapat. The basic PPE that should be worn Small quantities of liquid nitrogen or liquid argon may be transported in and around buildings provided they are contained within an appropriate low pressure dewar (fitted with a lid) and carried by their handles. Alert researchers in the area and inform DRS. 521525. Health Hazards of Cryogenic Liquids and Dry Ice. These compounds may causea potential explosion hazard when the cryogen condenses oxygen from the atmosphere. one of the leading cause of laboratory fires is ______. Have pot holders or appropriate gloves on hand. The basic model used in assessing the toxicity of a chemical includes its route(s) of entry into the body and, emergency response experts recommend that you should be prepared to take of yourself (and those that depend on you) in you home for approximately ____ hours after a major disaster, Assignment 11 - Eyes & Face Safety and Protec, Nutr 304 childhood pt 4 - middle childhood an, Patho Chapter 26 Stress and Associated Proble. People with frostbitten feet should not walk on them. It is important that this is an open system to minimize the risk of an explosion upon warming. Some dewar flasks have an outer vessel of liquid nitrogen for insulation. Liquid hydrogen and liquid helium are both so cold that they can liquefy air on contact resulting in an oxygen-enriched atmosphere. Safety glasses must be worn at all times while handling cryogenic liquids, because the liquid is almost always boiling and can splash into the eyes. A: Nitrogen condenses to a liquid at 320F. [4][5] The U.S. National Institute of Standards and Technology considers the field of cryogenics as that involving temperatures below -153 Celsius (120K; -243.4 Fahrenheit) [6], Discovery of superconducting materials with critical temperatures significantly above the boiling point of nitrogen has provided new interest in reliable, low cost methods of producing high temperature cryogenic refrigeration. Exactly how cold a substance has to be to be considered "cryogenic" is a matter of some debate by the scientific community. What is the rate constant for this firstorder decomposition at 325C?325 ^ { \circ } \mathrm { C }?325C? which statements apply to physical hazards in the laboratory? Consult each materials SDS for specific guidance. Cryogen gloves are usually loose fitting and easy to remove quickly. The verdict: Cold weather does not cause colds. The methods disclosed are suitable for removing the solvents with a broad range of volatility, having normal (STP) boiling points from 30 up to at least 202 C. (vapor pressures at least of 0.1 to 500 torr; higher boiling point . x][~7M67 0NI;8HFFPL_u~VU7/5#`dI]U_TM]74jK7W?_}UOM! Cryogenic liquids can boil or splash when added to a warm container or when inserting warm objects in the liquid. Do not attempt to identify the compressed gas in the cylinder on your own. Use tongs to add or remove materials from cryogenic liquids. Contact the Environmental Programs office at 206.616.5835 for guidance on removing the valve on your particular cylinder. The word cryogenics stems from Greek (cryos) "cold" + (genis) "generating". Call 911. Always inspect the cryogen gloves integrity before each use for rips, tears, or holes where cryogen could get inside. Release of these cryogens into the work area can damage equipment and property (e.g., frozen water pipes, damaged flooring, damaged electrical cables and their insulation). Carbon steel, metals, plastics, porcelain, and many other materials increase their brittleness in contact with cryogen and become susceptible to failure or malfunction. nitrogen and helium each have boiling points lower than oxygen's boiling point) have the ability to condense oxygen out of the air if exposed to the atmosphere. Hand protection is primarily required to guard against the hazard of touching cold surfaces. If you are not able or willing to de-valve your cylinder, we can do it for you. To find out why, a group of scientists . Use a hand truck for transport. College faculty have been leaders at the frontiers of knowledge since 1872. cold temperatures associated with the use of cryogens. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. All Rights Reserved. Fill cryogenic liquids only into manufacturer-approved containers that can withstand the extremely low temperatures. % Even a brief contact with a cryogenic liquid is capable of causing tissue damage similar to that of thermal burns. Typical use of cryogens at the NCNR create three lethal hazards: 1) The cold can cause cold burns even frostbite -and hypothermia. The most recent development in cryogenics is the use of magnets as regenerators as well as refrigerators. These devices work on the principle known as the magnetocaloric effect. If oxygen loss overcomes a person working with cryogenic liquids or dry ice, move the victim to a well-ventilated area. The concentration of oxygen can reach as high as 80% and amplify flammability and explosion hazards. %%EOF Never tip, slide, or roll them on their side. Solid carbon dioxide, referred to as dry ice, also has handling hazards due to its extreme cold temperature (-78 C). On this Wikipedia the language links are at the top of the page across from the article title. <> Other cryogenic liquids present specific hazards in addition to the above concerns. hb```f``rf`? Do not transport containers holding cryogens inside elevators at the same time as people. A regular thermos bottle is NOT an adequate vessel. Download the free OSH Answers app. A: Gloves should be insulated and made to withstand the low temperatures of cryogenic liquids and dry ice. Substances that burn in air will burn more vigorously in oxygen. Cryogenic Engineering: Fifty Years of Progress. In any situation, do not store or transport cryogen containing containers in the closed cabin or trunk of a vehicle. Select working materials carefully. yazan kategorisi how to look up beckett graded cards ak Yaymlanma tarihi 9 Haziran 2022 kategorisi how to look up beckett graded cards ak Yaymlanma tarihi 9 Haziran 2022 Normally, when an item is quenched, the final temperature is ambient. Accelerating combustion effect of liquid oxygen. With your help we are embarking on many exciting projects here at the College. This is no accident. hb```~V] ea`( d%f|g z p@ys - http://www.advancedlab.org/mediawiki/images/b/b4/77cryogenic.pdf (accessed Dec 2013). eF ^^K&e(LM cold temperatures associated with the use of cryogensteamsters local 710 ups contract 2021. If medical attention is needed following a skin or eye exposure to a cryogenic liquid, immediately call 9-911 and then call 2-9090 (the College Emergency Action Directors line). Pressure relief valves are spring loaded devices set at a specific pressure that relieve excessive pressure, reclose and reseal to prevent further release of product. All personnel using cyrogenic liquids must also be familiar with first aid procedures for treating frostbite: Return to Section 7 Guidelines & Safe Operating Procedures, Learn how to get free prescription safety glasses, 121 Gilman HallUniversity of CaliforniaBerkeley, CA 94720-1460(510) 664-5264, Graduate Office419 Latimer HallUniversity of CaliforniaBerkeley, CA 94720-1460(510) 642-5882, Graduate Office201 Gilman HallUniversity of CaliforniaBerkeley, CA 94720-1462(510) 642-2291, Admin, Finance, Technology Building Access College Relations Contact Us Diversity, Equity, & Inclusion Facilities Operations & Research Safety Information for Staff Information Technology Jobs Shipping & Receiving Staff Directory Website Update Request, Berkeley Website Berkeley News Campus Administration Campus Events Campus Map The Campaign for Berkeley Visiting Berkeley, Copyright 2023 UC Regents; all rights reserved, Advancing society through education and research, Guiding Outstanding Learners to Discover (GOLD), H&S Section 7: Safe Handling of Cryogenic Liquids. All cryogenic liquids have a significant potential for creating an oxygen deficient environment. Able to expand into very large volumes of gas from small amounts of refrigerated liquefied gas liquid. LOX is also widely used with RP-1 kerosene, a non-cryogenic hydrocarbon, such as in the rockets built for the Soviet space program by Sergei Korolev. Contact with cryogenic vapor or a non-insulated vessel containing cryogen is sufficient to sustain such injuries. This page was last edited on 28 February 2023, at 03:09. Low pressure cylinders are equipped with a liquid valve for extracting liquid and a vent valve. Never roll cryogenic liquid cylinders. Extra precautions must also be documented in your standard operating procedures (SOPs) for these chemicals. This ice can cause components or systems to malfunction (e.g., can plug vent lines and impede valve operation) or can damage piping systems. Compressed gases may also be referred to as gas cylinders. Do not lower experiments into storage dewars unless provisions have been made to vent the dewar and prevent freezing in the narrow neck. As a result, it is critical to contain these liquids in insulated dewars with pressure relief valves (see "Safe Handling Procedures" below). Cryogenic temperatures are most easily achieved and maintained with the aid of liquefied gases, or cryogens, the most commonly used being nitrogen and helium. At 660. Gainesville, FL 32611 They are either: Examples include: helium, nitrogen, oxygen, and argon. Different cryogens become liquids under different conditions of temperature and pressure, but all have two common properties: they are extremely cold and small amounts of the liquid can expand into very large volumes of gas. Pressurized cryogenic liquids are stored in cylinders equipped with pressure safety devices such as pressure relief valves and a rupture disc. This machine has been a workhorse for Pressure Build-Up/Explosions cold temperatures associated with the use of cryogens. which of the following statements apply to a Chemical Risk Assessment? The decrease in oxygen accompanied by gradual asphyxia is usually NOT noticeable by the victim. Use only fitted transfer tubes designed for use with the dewar container. Cryogens should never be brought onto a bus or shuttle. Q: Why can't I wear a cartridge-style air-purifying respirator to protect from liquid-nitrogen vapors? Close-toed shoes (without mesh tops) are required when handling cryogens. Address: 1200 E Martin Luther King Jr Blvd, Suite 1.200, Austin, Texas 78712Phone: 512-471-3511Find an EHS Email Contact, Website problems? Store all cryogenic liquids away from combustible material and do not leave containers uncovered for long periods of times. low temperatures [below -153C (-243F)] . 202 0 obj <> endobj assume you are working with an acutely toxic chemical; select all administrative controls relevant for your project. d#oUidf[Rv /Ja)^6d~sX>4fc8aqT\jRr+rHG0{vn^Y^_ob:yTxZ/~A U_=wz,A? (352) 392-3261, Bites, Scratches, Cuts & Abrasions from Animals, Bloodborne Pathogen & Needlestick Exposures, Inhalation Anesthetic Gases and Compressed Cylinders, Shipping and Transport of Biological Materials, Shipping and Transport of Human Specimens, Equipment Purchase Approval/Decontamination, Controlled Substances & Pharmaceutical Products, Computers, Electronic & Scientific Equipment, Equipment Breakdown (Boiler and Machinery), AED Decommissioning and Recycling Information, Applicable Building Codes for the State of Florida and the University of Florida, Temporary Structures on Campus Including Tents, Fire Safety for Open Flame Devices Policy. They are equipped with a loose-fitting cap or lid to prevent air from entering while allowing evolved gas to escape. Cryogenic liquids flow very freely and can penetrate woven or other porous clothing. The attached table indicates several physical properties of liquid nitrogen, helium and oxygen. cold temperatures associated with the use of cryogens. You must still wear safety glasses underneath the face shield. If working in an area where an oxygen-deficient atmosphere could be produced due to the off-gassing of cryogenic liquids or dry ice, an air-supplying respirator must be used, such as anairline respiratorwith an egress bottle or a self-contained breathing apparatus (SCBA). Also, when cryogenic liquids and dry ice form a gas, the gas is very cold and some are heavier than air. Loose, non-asbestos insulating gloves that can be easily removed may be worn. Even well-ventilated lab spaces that have pits or other low-lying areas could have the oxygen displaced by this cold, dense gas. 0;8?O90XXN | \O9-Pa|XdpAjAgf?pjEK=oI9Sa2+6G@\)91omcTCFl,"qn@f_9M4w]-{aPldVQ6Bm,[{}p2U- 7\%U(9qKAA5q. Cryogens are liquefied gases such as nitrogen, argon, or helium that pose significant hazards due to their low temperatures. There are various cryogenic detectors which are used to detect particles. Cryogens. A liquid having a vapor pressure exceeding 40 psi at 100 F (38 C); as determined by ASTM D-323-72. The touching of uninsulated containers or other materials that have been cooled by cryogenic liquids can cause serious skin injuries. Dry ice starts subliming at 109.3F. endstream endobj startxref High pressure cylinders are equipped with a vent valve, liquid valve, gas valve, and pressure building valve. Asphyxiation: can immediately displace oxygen, especially in poorly ventilated areas. Examples include: The primary function of a face shield is to protect the head and face from any splashes that may occur, especially during operations that are carried out at eye level (e.g. stream Safely transporting liquid nitrogen within a building. 2 Obtain medical attention as quickly as possible. Non-pressurizedcontainers are typically open-topped vessels or Dewars with loose fitting covers to minimize evaporation or off gassing and range from one to 50 liters in size. Read the pressure gauge of a cylinder to make sure it is at the required pressure. which of the following statements made by the PI reflects an incomplete or mistaken misunderstanding of the hazards found in their lab? June 30, 2022 . - reduced by good housekeeping and organization. [citation needed] This evolved in the late 1990s into the treatment of other parts. endobj Warm the affected area of the body rapidly by immersion in water not to exceed 105 F, with body heat, or by exposure to warm air. 243 0 obj <>stream Do NOT rub the frozen skin. To recycle empty, vented, and de-valved cylinders as scrap metal, remove or deface all labels, write empty on it, and contact UW Recycling to arrange a pickup. Cryogenic liquids and dry ice are shipped and used in thermally insulated containers specifically designed to withstand rapid temperature changes and extreme differences in temperature and vent gases to prevent pressure build-ups within the container. Small, open dewars used as transfer vessels usually come with loosely fitting stoppers. - secondary hazards are often associated with equipment that produces non-ionizing radiation, cold temperature associated with the use of cryogens may condense _______ and create potentially dangerous and difficult secondary hazard, as little as __ electrical current can cause cardiac arrest. What Are All Those Gadgets On A Multitool? It is best to use service elevators with good ventilation (e.g., with screen walls or doors). When transferring cryogenic liquid into experimental equipment, the recommended procedure is to purge air out of the transfer line and the equipment by using dry gas of the cryogenic liquid. Dry ice is a super-cooled solid (carbon dioxide) that sublimes directly into gaseous carbon dioxide at 109.3 F. Sublimationis the transition of a substance directly from the solid to the gas state, without passing through the liquid state. The only reason for this is that most heat treaters do not have cooling equipment. Cryogenic barcode labels are used to mark Dewar flasks containing these liquids, and will not frost over down to 195 degrees Celsius.[14]. The term "high temperature cryogenic" describes temperatures ranging from above the boiling point of liquid nitrogen, 195.79C (77.36K; 320.42F), up to 50C (223K; 58F). Face shields, as per ANSI Z87.1, are highly recommended. 260 0 obj <>/Filter/FlateDecode/ID[<217C0CAD2343F1EE7ABEB108C0AD2DFF>]/Index[242 35]/Info 241 0 R/Length 84/Prev 619554/Root 243 0 R/Size 277/Type/XRef/W[1 2 1]>>stream NEVER seal a vessel containing a cryogen, including dry ice. ]mk/\O Always use a freight elevator to carry cryogenic containers and cylinders. MORE ABOUT >. Personal protective equipment (PPE) is critical to cryogenic liquid and dry ice safety. Loose fitting thermal insulated or leather gloves (these are not the same as heat gloves!). When filling dewars or transferring cyrogenic liquids from one container to another, face shields must also be worn. Liquid helium, liquid hydrogen and liquid oxygen present additional hazards that liquid nitrogen and liquid argon do not. Open liquid cryogen containers can condense oxygen from the air into the liquid and reach levels as high as 80% O2, potentially increasing the flammability of combustible materials. Wear full length pants. cryocoolers and associated vacuum chambers capable to test at temperatures as low as 14 K. Consistent utilization of cryocoolers began at the Cryo Test Lab in the 2011 timeframe with the purchase of an AL230 Gifford-McMahon unit from Cryomech (CSA CSM). Place a blast shield in front of the apparatus and allow the system to slowly warm to room temperature. Do not transport cryogenic liquids in open dewars. A lab coat is required to minimize skin contact. Put the container into the elevator and place a sign on it the cylinder facing the door Do not enter elevator, asphyxiation hazard (Elevator Sign). The cryogenic process continues this action from ambient temperature down to 320F (140R; 78K; 196C). These liquids have boiling points below -238F (-150C) and are gases at normal temperatures and pressures. . Therefore, always consult with the most appropriate reference when selecting materials for cryogenic applications. Always be familiar with the hazards of the liquid in use. For cryogenic temperature measurement down to 30 K, Pt100 sensors, a resistance temperature detector (RTD), are used. @Y8L Be familiar with the functioning of the cylinder before using it. The College of Chemistry is consistently ranked as one of the best places on earth to learn, teach, and create new tools in the chemical sciences. 225 0 obj <>/Filter/FlateDecode/ID[<9152C53260D4D64BB2C1530E525A7948><57F71CF2E9C85847A8F6B64F6F07010D>]/Index[202 42]/Info 201 0 R/Length 112/Prev 144945/Root 203 0 R/Size 244/Type/XRef/W[1 3 1]>>stream These liquids have boiling points below -238 F (-150 C) and are gases at normal room temperatures and pressures. Materials that are usually considered non-combustible, such as aluminum, carbon steel, cast iron, stainless steel and zinc may burn in the presence of liquid oxygen. Since all cryogenic liquids and their cold boil-off vapors are extremely cold they can rapidly freeze human tissue and cause frostbite. Always push containers on wheels. The links below are to the Fire Code definitions for compressed gases Web page and GHS and DOT definitions with pictograms to help identify how chemicals are classified. frequent hand washing, use of lab coat, chemical disinfection for all potentially infectious agents including recombinant DNA. 3 0 obj Apply CPR if the victim's breathing has stopped. Cylinders stored and used on campus must be clearly labeled. They are not designed to be submerged in a cryogenic liquid. Oxygen is not flammable, but it vigorously accelerates and supports combustion. This is thought to be caused by liquid nitrogen entering the tubes through minute cracks and then expanding rapidly as the tube warms up. These cold, heavy gases do not disperse well, tend to accumulate near the floor and displace air. Do NOT use plastic or Teflon tubing as they will become brittle from the cold temperature. Single-stage regulators are used when precise control of delivery pressure is not required. NASA's workhorse Space Shuttle used cryogenic hydrogen/oxygen propellant as its primary means of getting into orbit. Never use rubber or plastic tubing. By international agreement, a commercially purchased lab chemical today must include: for agents capable of causing a treatable or preventable disease in humans, for agents causing serious human or potentially lethal human disease, for which some treatment exists, specially designed for highly contagious agents for which no treatment or vaccination exists, and require extensive training. Gifford-McMahon cryocoolers, pulse tube cryocoolers and Stirling cryocoolers are in wide use with selection based on required base temperature and cooling capacity. J. M. Nash, 1991, "Vortex Expansion Devices for High Temperature Cryogenics", Proc. If the cylinder is not empty, but only contains common atmospheric gases such as nitrogen, it may be safely vented and emptied, de-valved and disposed of as scrap metal. Hydrogen is particularly hazardous. hbbd``b` @-A\-!$Vk;`Jy@"2%H30124)'3` 7 High temperature resistant thermal insulation for cryogenic tanksHigh temperature resistant thermal insulation for cryogenic tanks .. .. Cryogenic transfer pumps are the pumps used on LNG piers to transfer liquefied natural gas from LNG carriers to LNG storage tanks, as are cryogenic valves. Evaporation also leads to a rapid increase of pressure and possible vessel rupture if cryogens are stored in a container that is not adequately vented. Which of the following "fundamentals" of biological safety are true? There are also specific precautions that must be followed where a particular liquid may react with contaminants or may present other hazards associated with that particular product such as asphyxiation or flammability. The high rate of evaporation of cryogens displaces oxygen in the surrounding air and can reduce oxygen levels to the point where rapid suffocation can occur without warning. Thawed frostbitten skin will be very painful, red and swollen and can become infected. 0. Cylinders for helium may have additional valves for transportation. The following table summarizes the physical properties of common cryogens: aAlthough oxygen does not burn, it will support combustion. They operate at up to 22 psig. There are three groups of health hazards associated with cryogenic liquids and dry ice extreme cold, asphyxiation and toxicity. Certain soft or elastic materials become hard and brittle at very low temperatures, which makes cryogenic milling (cryomilling) an option for some materials that cannot easily be milled at higher temperatures. Pulling can cause injury if they tip and fall on you. The NIH requires oversight of most recombinant DNA activities. Cryogenic Liquid and Dry Ice-Specific Equipment. Cryogenic cooling of devices and material is usually achieved via the use of liquid nitrogen, liquid helium, or a mechanical cryocooler (which uses high-pressure helium lines). Keep all sources of ignition away from cryogenic liquids. Violent reactions (e.g. One volume of a cryogenic liquid will expand to about 700 equivalents of gas when evaporated. Do not remove manufacturer applied labels. Cartridge-style air-purifying respirators are only made to remove contaminants, so they are inappropriate for an environment that is oxygen deficient. There are two kinds of pressure regulator designs, which appear similar: single-stage and two-stage. - lasers are classified by their potential for harm Gases are classified in different ways according to definitions by different regulations including Department of Transportation (DOT) and Fire Code regulations as well as by classification systems such as the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).
