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Which of the following "fundamentals" of biological safety are true? This is no accident. Make sure that ice buildup is not blocking the safety devices of the cylinder. Any exposed glass areas of dewars should be taped to prevent the generation of broken glass projectiles in the event the container implodes. Cryogenic liquids with a boiling point below that of liquid oxygen (i.e. This is especially important for helium, as it is cold enough to solidify air. Cryogens are liquefied gases such as nitrogen, argon, or helium that pose significant hazards due to their low temperatures. Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached. of the 26th Intersociety Energy Conversion Engineering Conference, Vol. }G32QK4%{pz]ST@:]TMt vPcB&Q{tdX0pf(t5| y{|%$p1HJ0y$x Hl$`$0Rj"J c:?2 F@Gc}#>; I`.' $IPX(!ygwowv6uZ|_^'/ ux;3~\3M_>?? The freezing of portions of the body to destroy unwanted or malfunctioning tissue is known as cryosurgery. Alert researchers in the area and inform DRS. Store all containers with cryogens, pressurized or non-pressurized, in well ventilated areas. The concentration of oxygen in the condensed air will increase and lead to oxygen enriched conditions. It is best to use service elevators with good ventilation (e.g., with screen walls or doors). Oxygen is not flammable, but it vigorously accelerates and supports combustion. Never use rubber or plastic tubing. Cryogenics is the study and use of materials at ultra low temperatures (less than -150C), and includes . The term cryogenic means producing or related to low temperatures. Liquid oxygen mixed with organics increases the explosion hazard significantly. Its the direct result of exceptional scholarship as well as thousands and thousands of donations from our loyal alumni and friends. cold temperatures associated with the use of cryogens. Do NOT rub the frozen skin. Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Introduction. Q: What kinds of gloves are needed for working with cryogenics and dry ice? Small, open dewars used as transfer vessels usually come with loosely fitting stoppers. Larger, low-pressure dewars may come with casters/wheels attached to the bottom. J. M. Nash, 1991, "Vortex Expansion Devices for High Temperature Cryogenics", Proc. Do not lower experiments into storage dewars unless provisions have been made to vent the dewar and prevent freezing in the narrow neck. 0. NEVER seal a vessel containing a cryogen, including dry ice. Some models have replaceable clear shields so that when the shield becomes scratched or dirty, it can be replaced without purchasing new headgear. d#oUidf[Rv /Ja)^6d~sX>4fc8aqT\jRr+rHG0{vn^Y^_ob:yTxZ/~A U_=wz,A? Beitrags-Autor: Beitrag verffentlicht: 22. Personal Protective Equipment for Cryogenic Liquids and Dry Ice Safety. (217) 333-2755 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. Use care in transporting fragile cryogenic containers. Cryogens are stored in confined containers such as pressurized dewars and cylinders. All cylinders should bear a cylinder status tag stating one of the three conditions: full, in-serviceor empty. However, where cryogenic liquids and dry ice are involved, metallic materials are not the only ones that cause this risk. Always be familiar with the hazards of the liquid in use. Certain rare blood groups are stored at low temperatures, such as 165C, at blood banks. Extra precautions must also be documented in your standard operating procedures (SOPs) for these chemicals. %%EOF Fill cryogenic liquids only into manufacturer-approved containers that can withstand the extremely low temperatures. This page was last edited on 28 February 2023, at 03:09. Never roll cryogenic liquid cylinders. Within 24 hours, 5-10 pounds of dry ice can sublimate. The remarkable breadth and depth of resources available to our students readies them as chemists and chemical engineers to address societys most urgent 21st-century issues. Liquid cryogens have an extremely low temperature. do australian shepherds have a good sense of smell; matan adelson net worth; words that rhyme with crime; fattmerchant customers; shoulder holster for ruger lcrx 3 inch barrel Non-pressurized containers for holding cryogenic liquids are referred to as dewars. A cryogenic liquid is defined as a liquid with a normal boiling point below -240F (-150C, 123K). [soeL&\Zi{hit^@4th_D jZ/I9&#OEc"V,dww8M-9e&g2^Cttj)$+0N,-\]Qp/. A 2-inch diameter LHe3 cooled work surface is sustained at a temperature of 300 mK. ]. Cylinder manufacturers include engraved markings on cylinders to allow proper identification of substances in the container. Cryogenic liquid storage at warm temperature for an extended time can cause flash vaporization and produce extremely high pressure. What are 'Dark Factories,' and Do They Really Exist? Do You Know How to Handle Dry Ice Safely. - the use of radioactive materials is highly regulated and requires additional training and approvals by your institution. Avoid mechanical or thermal shock. In addition to the hazards of frostbite or flesh sticking to cold materials, objects that are soft and pliable at room temperature, are easily broken because they become hard and brittle at extremely low temperatures and will easily fracture. 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. If oxygen loss overcomes a person working with cryogenic liquids or dry ice, move the victim to a well-ventilated area. Otherwise, the dewar may need to be secured to a dolly or cart. Other cryogenic liquids requiring additional safety considerations. High temperature resistant thermal insulation for cryogenic tanksHigh temperature resistant thermal insulation for cryogenic tanks .. .. Thawed frostbitten skin will be very painful, red and swollen and can become infected. Prolonged contact may result in blood clots. Here is a list of other states that are pretty cold and their average temperatures according to the World Population Review 2020 state rankings: North Dakota - 40 degrees Fahrenheit. NEVER pour cryogenic liquids down the drain, as the pipes are not made to withstand the low temperature. Thermos bottles are smaller vacuum flasks fitted in a protective casing. Wearing a cryogenic apron is suggested to help prevent this from occurring. Violent reactions (e.g. When cryogenic liquids are spilled on the skin, a thin gaseous layer apparently forms next the skin. Liquid nitrogen can also cause argon to condense and form liquid argon. The required apparel and PPE for handling cryogens include: EH&S offers a recommended Liquid Nitrogen Training found on MyTraining under the course code UF_EHS966_OLT. %%EOF Use only fitted transfer tubes designed for use with the dewar container. Pgina principal. Dry ice, most cryogenic liquids and the gasses they produce can be placed into one of three groups: Cryogenics and dry ice have many uses and often play a role in industrial and medical applications. Since all cryogenic liquids and their cold boil-off vapors are extremely cold they can rapidly freeze human tissue and cause frostbite. It is important to remember that even nonmetallic materials are extremely dangerous to touch. Wear full length pants. Q: How cold is liquid nitrogen, and how cold is dry ice? Because the boiling points of liquid nitrogen and helium are lower than that of oxygen, oxygen can condense and liquefy on outer surfaces of non-insulated lines. Loose-fitting, insulatedcryogenic glovesshould also be worn. 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). Loose, non-asbestos insulating gloves that can be easily removed may be worn. Compressed gases may also be referred to as gas cylinders. Loose fitting thermal insulated or leather gloves (these are not the same as heat gloves!). Prolonged exposure of the skin or contact with cold surfaces can cause frostbite. June 30, 2022 . 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. 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. 2 Prior to ordering these gases, you are encouraged to contact EH&S at 206.543.7262 for an assessment and to ensure proper safeguards are met. If the cylinder is empty, depending upon original contents, the valve can be removed and the cylinder disposed of as scrap metal. Typical laboratory Dewar flasks are spherical, made of glass and protected in a metal outer container. which of the following statements made by the PI reflects an incomplete or mistaken misunderstanding of the hazards found in their lab? Any pipe or transfer line in which cryogenic liquid can become trapped must be equipped with a pressure relief valve. Leave the area immediately and get to a source of fresh air. A regular thermos bottle is NOT an adequate vessel. Do NOT use plastic or Teflon tubing as they will become brittle from the cold temperature. Cold traps are used in instrumentation and other systems to prevent the introduction of liquids, vapors, or contaminants into the system. Single finger traps, U-traps, or other shaped lines are submerged in cryogenic liquids or slushes to provide a very low temperature surface on which the molecules condense. Shoes should have an enclosed heel and entirely covered tops. The decrease in oxygen accompanied by gradual asphyxia is usually NOT noticeable by the victim. In many situations LN2 and LHe2 can condense the surrounding air. The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear. Oxygen-enriched atmospheres may lead to violent reactions, such as rapid combustion or explosions, with incompatible materials. Physical Effects of Cryogenic Liquids and Dry Ice. Enumerate and discuss the function of the three types of glia cells. University of Texas at Austin students, faculty, staff, and affiliate researchers who work in labs containing cryogen materials must complete OH 241 Cryogen Safety training. Both cryogenic liquids and dry ice can produce very large volumes of gas at room temperatures. Liquid hydrogen and liquid helium are both so cold that they can liquefy air on contact resulting in an oxygen-enriched atmosphere. However, the extremely cold liquid and vapor have a built in warning property as the cold boil off gases condense moisture in the air, creating a highly visible fog. Please provide a budget number with your request. Cryogens have boiling points below - 73 C (- 100 F) at 14.7 psia (an absolute pressure of 101kPa). Be sure to contact the manufacturer if you are unsure of a cylinder's contents. Using cryogensin high ionizing radiation fields can generate ozone or nitrogen oxides. Contact with dry ice, cryogenic liquids and their gases, and any cooled surfaces should be avoided. cold temperatures associated with the use of cryogens. - 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. Keep containers vertical at all times. Our two departments provide fundamental and applied studies of an outstanding caliber. [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. endstream endobj startxref endstream endobj startxref cold temperatures associated with the use of cryogens. hb```~V] ea`( d%f|g z p@ys - hbbd``b` @-A\-!$Vk;`Jy@"2%H30124)'3` 7 One pound of dry ice will produce 250 L of carbon dioxide gas. Therefore, always consult with the most appropriate reference when selecting materials for cryogenic applications. %PDF-1.5 % According to United States Department of Transportation (DOT) and Occupational Safety and Health Administration (OSHA) regulations, the labeling must list contents, concentrations, hazard classifications, safety precautions and the manufacturer or supplier. Do NOT rub the frozen skin. Cold Temperature As seen in the table above, the most obvious hazard with cryogenic liquids are the extreme cold temperatures associated with them. Always use a freight elevator to carry cryogenic containers and cylinders. 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. 0 Cryogen gloves are usually loose fitting and easy to remove quickly. 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. - carelessness and bad luck are the leading cause of laboratory fires. Typical use of cryogens at the NCNR create three lethal hazards: 1) The cold can cause cold burns even frostbite -and hypothermia. Heavy cryogenic liquid cylinders must be transported with an appropriate cart designed for the specific cylinder model. The extremely cold surface of the cooled material will cause the flesh to stick fast and tear when one attempts to withdraw from it. - reduced by good housekeeping and organization. If you are not able or willing to de-valve your cylinder, we can do it for you. Health Hazards of Cryogenic Liquids and Dry Ice. They have a loose-fitting cap or plug that prevents air and moisture from entering yet allows excess pressure to vent. When filling dewars or transferring cyrogenic liquids from one container to another, face shields must also be worn. Dry ice starts subliming at 109.3F. Seek medical attention. College faculty have been leaders at the frontiers of knowledge since 1872. Special Fire Department permits and engineering controls such as a gas storage cabinet may be required to use toxic or corrosive gases. which of the following statements apply to a Chemical Risk Assessment? 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. The best control measure is to minimize the accumulation of oxygen coming into contact with the cryogenand to keep containers free of hydrocarbon contamination. Do not transport cryogenic liquids in open dewars. b 0;8?O90XXN | \O9-Pa|XdpAjAgf?pjEK=oI9Sa2+6G@\)91omcTCFl,"qn@f_9M4w]-{aPldVQ6Bm,[{}p2U- 7\%U(9qKAA5q. Rapid changes in temperature can result in tank or vessel explosions. Gainesville, FL 32611 Pressurizedcontainers have vents, dispensing hoses, and pressure gauges. The fire code requires rooms or cabinets containing compressed gases to be conspicuously labeled COMPRESSED GAS. Thecaution sign generated though theMyChemsystem can be used to meet these requirements. Materials that are normally structurally sound such as carbon steel, zinc . The hazards associated with liquid nitrogen. W3J/ox/_J||\ ?Q:A(>3m [zW|B,)>azq!eMS,3fJ'i^ The most commonly used industrial gases that are transported, handled, and stored in the liquid state at cryogenic temperatures are argon, helium, hydrogen, nitrogen, and oxygen. Do not use Teflon tape, putty or other such materials on the threads unless specifically required (or applied) by the manufacturer or vendor. In addition to the hazard of extreme cold, the hazards associated with the chemical pose a risk: reactivity, corrosivity, toxicity, asphyxiation, and vigorous . endobj MORE ABOUT >. protect the eyes and skin from the hazards associated with cryogens. Read the pressure gauge of a cylinder to make sure it is at the required pressure. Prolonged contact may result in blood clots. - contamination refers to the unintended contact of radioactive materials on individuals, surfaces, and objects 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 Liquid nitrogen is the most frequently used cryogen on campus. - institutional oversight and approval is important in the use of non-ionizing radiation Cryogenic liquids exhibit large volume exchange ratios which can cause rapid pressure changes. Which of the following statements on non-ionizing radiation are true? When you contribute to the exceptional scholarship of our students and faculty, you help to improve the lives of people all over the world. The plane uses a fuel referred to as liquefied natural gas or LNG, and made its first flight in 1989. Prevent infection--use a mild soap to clean the affected area. I`k6MRjfD#J>v'8Q83EOsWy3>}[F#`;"cj~Hj/Nof'G&#g6D>}C6X1+P1QJ?#ltxxOgN*hg07Np\gf? Hh r@*l:&vA^3? Closed toed shoes are required when handling cryogenic liquids. Keep regulators clean and free of surface oil and grease, especially oxidizing gases. Study of the production and behaviour of materials at very low temperatures, "Low temperature physics" redirects here. Therefore, it is important to evaluate the pressure relief valve, venting valve, rupture disk and integrity of the container at least every month or before using it. Wearing a cryogenic apron is suggested to help prevent this from occurring. Without adequate oxygen, one can lose consciousness in a few seconds and die of asphyxiation in a few minutes. Never use rags to handle cold surfaces. Before transporting cryogenic liquid cylinders, the user must ensure that all process valves (gas supply, liquid supply, pressure builder, and vent) are closed. When it falls below 18 percent, we do not have enough oxygen to function normally. Expansion: cryogens, such as liquid nitrogen, can expand up to 700x when changing from liquid to gas. 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 . NASA's workhorse Space Shuttle used cryogenic hydrogen/oxygen propellant as its primary means of getting into orbit. When there is not enough air, asphyxiation and death can occur. Dewar flasks are named after their inventor, James Dewar, the man who first liquefied hydrogen. One volume of liquid nitrogen, for example, will vaporize to approximately 700 volumes of nitrogen gas when warmed to room temperature at one atmosphere. As always, end users should have and be thoroughly familiar with the SDS for their specific product. 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). There are two kinds of pressure regulator designs, which appear similar: single-stage and two-stage. A: Nitrogen itself is not a danger. This thin layer protects the skin from freezing, provided the contact with the cryogen is brief and in small quantities. Do not remove manufacturer applied labels. Keep all sources of ignition away from cryogenic liquids. Pulling can cause injury if they tip and fall on you. This definition includes liquid nitrogen (LN2), liquid argon (LAr), liquid helium (LHe), liquid hydrogen (LH2), and liquid oxygen (LO2 . Note that a cold room does NOT slow down the evaporation rate. Tissues that have been frozen will be painless while still frozen and might look waxy yellow. The danger is that liquid nitrogen vaporizes so quickly that it displaces oxygen. Oxygen deficiency monitors should be used in these areas. 8 B;jk%`;@M`$>7}J@v[` @=T} @RkD4iRde~R~Ru8) IaIB{gFcJ"DKH >D[[(B17pR!t"@>>NdB^WQNUxgVJh-ocu/1s ~07Y If skin or the eyes are exposed to cryogens or the cold vapor, use warm water (up to 108 F/42 C, NOT above 112 F/44 C) to restore normal body temperature. Maintain the affected area of the victim at normal body temperature until medical help arrives. The NIH requires oversight of most recombinant DNA activities. Materials such as carbon steel, plastics and rubber should not be used in direct contact with cryogenic liquids or dry ice because they can fracture or shatter extremely easily. @Y8L Prolonged breathing of extremely cold air may damage the lungs. Division of Research Safety A: Gloves should be insulated and made to withstand the low temperatures of cryogenic liquids and dry ice. Even well-ventilated lab spaces that have pits or other low-lying areas could have the oxygen displaced by this cold, dense gas. Use tongs with insulated handles to withdraw objects immersed in cryogenic liquids. The most commonly used industrial gases that are transported, handled, and stored in the liquid state at cryogenic temperatures are argon, helium, hydrogen, nitrogen, and oxygen. 521525. To protect any exposed skin, long-sleeve shirts and trousers without cuffs are suggested. Cryogenic liquids are liquefied gases created by cooling a liquid to a low temperature under high pressure, which creates special health and safety hazards. 27 Min Read . Be sure to contact the manufacturer if you are unsure of cylinder contents. These cold, heavy gases do not disperse well, tend to accumulate near the floor and displace air. Liquid oxygen (LOX) is even more widely used but as an oxidizer, not a fuel. 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. By freezing the automobile or truck tire in liquid nitrogen, the rubber is made brittle and can be crushed into small particles. Pressure Build-Up/Explosions Dressings need not be applied if the skin is intact. Any visible damage or malfunctioning of the cylinder. 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. Because there is no protective layer of gas formed, frostbite will occur almost instantaneously when touching surfaces that have been cooled by cryogenic liquids. If affected, flush eyes with warm water for 15 minutes. Use a loose fitting stopper or lid. Do not attempt to carry additional items while holding the dewar, such as books, beverages, samples or tools. Never used heat resistant gloves to handle cryogen. Always perform these operations slowly to minimize boiling and splashing. 1994-2020, W.W. Grainger, Inc. All Rights Reserved. [7], Cryogenicists use the Kelvin or Rankine temperature scale, both of which measure from absolute zero, rather than more usual scales such as Celsius which measures from the freezing point of water at sea level[8][9] or Fahrenheit which measures from the freezing point of a particular brine solution at sea level.[10][11]. The central mission of the College of Chemistry is to advance society through education and research, and we have made it our responsibility to fulfill this mission, year in and year out, for more than 140 years. - Risk Assessment and written procedures play an important role in the use of non-ionizing radiation Examples of liquefied gases include: ammonia, chlorine, methane, natural gas and liquefied petroleum gas or liquid petroleum gas (lpg) which are propane and butane. It is recommended to create a Standard Operating Procedure (SOP) to include a description of the work being performed and have this available for all lab workers. Gifford-McMahon cryocoolers, pulse tube cryocoolers and Stirling cryocoolers are in wide use with selection based on required base temperature and cooling capacity. Praxair, Inc. was selected for a University contract to provide compressed and liquid (cryogenic) gases after an open competitive solicitation process, and in consultation with several University departments. Allow excess cryogens to evaporate naturally in a well-ventilated place. Contact the manufacturer or vendor and have the cylinder checked in the case of: Attach only transfer lines with the correct fitting. Environment, Health and Safety Information for the Berkeley Campus #77: Cryogenic Liquids Precautions and Safe Handling Procedures. /``=~^U*6TrW*9T =Q`X2P;"nD%hEx/}_sxEH=`hQG{E uyh W{QN EBbWzB30bW~ X|m4T%gMPc+@wtw\] oQT. The attached table indicates several physical properties of liquid nitrogen, helium and oxygen. Never attempt to change or remove any fittings of the cylinder, and do NOT use adaptors. Store all cryogenic liquids away from combustible material and do not leave containers uncovered for long periods of times. Maine - 41 degrees Fahrenheit. Do not rub or massage the affected parts of the body. Use solid wood or plastic. Send the elevator to the desired floor and have somebody there to pick it up. <> 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. 11/18/20 Include procedural information regarding the use of equipment. Have pot holders or appropriate gloves on hand. The only reason for this is that most heat treaters do not have cooling equipment. Single-stage regulators are used when precise control of delivery pressure is not required. The freezing of foods and biotechnology products, like vaccines, requires nitrogen in blast freezing or immersion freezing systems. Low pressure cylinders are equipped with a liquid valve for extracting liquid and a vent valve. "When the . Accelerating combustion effect of liquid oxygen. 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. Contact with cryogenic vapor or a non-insulated vessel containing cryogen is sufficient to sustain such injuries. 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. Classification Emergency Procedures Room Signage Labeling Cylinder status tags Gas delivery systems Regulators Procurement The gloves must be loose so they can be thrown off quickly if cryogenic liquid spills into them. when topping up reservoirs on electron microscopes). Consult each materials SDS for specific guidance. The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. There is nothing metallurgically significant about ambient temperature. They can operate at up to 350 psig. 3) The boiloff can build up pressure in a sealed container, leading to an explosion. This class of gases that are referred to as dissolved gases are those that are dissolved in another substance. Piping and tubing containing gases must be carefully designed. frequent hand washing, use of lab coat, chemical disinfection for all potentially infectious agents including recombinant DNA. cold temperatures associated with the use of cryogens. If skin or the eyes are exposed to cryogens or the cold vapor, use warm water (up to 108 F/42 C, NOT above 112 F/44 C) to restore normal body temperature. Use an appropriate transfer line with phase separator to avoid splashing when filling into an open container. The use of an insulated pot holder is the preferred method of handling cold surfaces. 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. 102 Environmental Health and Safety Building101 South Gregory Street, MC-225 Two-stage regulators give precise control. When you are done with the cylinder, you contact the company listed on the cylinder and they will pick it up.