1、Safetygram-18安全程序-18Carbon Dioxide二氧化碳General概述Carbon dioxide is nonflammable, colorless, and odorless in the gaseous and liquid states. The gas is approximately one and one-half times as heavy as air. Carbon dioxide is a minor but important constituent of the atmosphere, averaging about 0.03% or 30

2、0 ppm by volume. Since dry carbon dioxide is a relatively inert gas, special materials of construction are not required. In the event moisture is present in high concentrations, carbonic acid may be formed and materials resistant to this acid should be used. High flow rates or rapid depressurization

3、 of a system can cause temperatures approaching the sublimation point (-109.3°F-78.5°C) to be attained within the system. Carbon dioxide will convert directly from a liquid to a solid if the liquid is depressurized below76 psia (61 psig). The use of materials which become brittle at low te

4、mperatures should be avoided in applications where temperatures less than -20°F(-29°C) are expected. Vessels and piping used in carbon dioxide service should be designed to the American Society of Mechanical Engineers (ASME) or Department of Transportation(DOT) codes for the pressures and

5、temperatures involved. 在液態和氣態時二氧化碳是不可燃、無色、無嗅的。氣體比空氣重大約1.5倍。二氧化碳是空氣的含量較小但很重要的組成成分，體積比平均約為0.03%或300 ppm。由于干燥的二氧化碳是相對不活潑的氣體，不要求特殊的建材。在水蒸汽濃度很高的情況下，可以生成碳酸，這時應使用對該酸有抵抗力的材料。系統的高流速或迅速降壓可以在系統內獲得接近升華點(-109.3°F-78.5°C)的溫度。 如果液體壓力降到76 psia (61 psig)以下，直接從液態轉化到固態。在預期溫度低于-20°F(-29°C)的應用中應該避免使用

6、在低溫下變脆的材料。用于二氧化碳設施的容器和管道要根據相關的壓力和溫度按照美國機械工程師協會(ASME)或交通部(DOT)的規范來設計。Carbon dioxide can be stored as a bulk liquid in large storage vessels with capacities up to 50 tons and larger. The liquid in the tank is maintained between 245 psig and 305 psig. When the tank pressure reaches 305 psig, a mechanic

7、al air-cooled refrigeration unit is activated which cools the tank contents and thereby reduces the pressure to about 295 psig. When pressure drops to 245 psig, a portion of the liquid is passed through a pressure buildup coil which vaporizes the liquid in the coil, and the resultant vapor is sent t

8、o the tanks vapor space until a tank pressure of 255 psig is attained. In isolated instances where carbon dioxide usage is extremely low, heat leak into the tank is sufficient to maintain the contents above 245 psig and a pressure buildup coil is not needed. The bulk storage tank can either supply g

9、as from the vapor space or liquid from the bottom of the tank. If warmer carbon dioxide gas is desired, vapor is withdrawn from the vapor space in the storage tank and superheated. Bulk storage tanks are filled by liquid transport trailers. 二氧化碳可以作為液體大量儲存在容量大到50噸和更大的大型儲存容器內。容器內的液體壓力維持在245 psig和305 p

10、sig。當容器壓力達到305 psig時，啟動機械空氣冷卻制冷設備，使容器內容物降溫，從而壓力降到約295 psig。當壓力降到245 psig時，部分液體流過一個壓力積累蛇管，蛇管使其內部的液體蒸發，產生的蒸氣送到容器的蒸氣空間，直到容器壓力達到255 psig。在二氧化碳用量極低的隔熱場合，泄漏進容器的熱量足以使內容物的壓力維持在245 psig以上，因此不需要壓力積累蛇管。大容量儲存容器能夠或者從蒸氣空間供應氣體，或者從容器底部供應液體。如果需要溫度更高的二氧化碳氣體，可以從蒸氣空間提取出蒸氣，并使其過熱。由液體運輸拖車來灌裝大容量容器。Carbon dioxide is also pu

11、mped as a liquid into high-pressure cylinders which are filled by weight. The amount of carbon dioxide gas contained in a cylinder is determined by multiplying the weight of the liquid by the specific volume at 68°F (20°C) and 1 atmosphere pressure, (8.70 cu. ft./lb.). The vapor pressure o

12、f the liquid stored in the cylinder 68°F (20°C) is 816 pounds per square inch gauge (psig).Cylinders can be supplied with standard valves for gas withdrawal or with siphon tubes connected internally to the valves for liquid withdrawal. 還可以把二氧化碳泵入根據重量來灌裝的高壓鋼瓶。液體的重量乘以在68°F (20°C)和1

13、個大氣壓時的比容(8.70 cu. ft./lb.)，就是在鋼瓶內容納的二氧化碳氣體的數量。儲存在68°F (20°C)的鋼瓶內的液體的蒸氣壓是816磅每平方英寸（psig）。鋼瓶可以配有用于氣體提取的標準閥門或在內部連接到閥門的用于液體提取的虹吸管。Carbon dioxide is also stored and shipped as a liquid in cryogenic cylinders at reduced temperature and at a pressure of about 300 psig. 二氧化碳還可以作為液體在壓力減小到大約300 psig

14、的低溫鋼瓶內儲存和運輸，The molecular symbol for carbon dioxide is CO2.二氧化碳的分子式是CO2。Toxicity毒性Carbon dioxide does not support life and may produce immediately hazardous atmospheres. At concentrations in excess of 1.5%, carbon dioxide may produce hyperventilation, headaches, visual disturbances, tremor, loss of

15、consciousness, and death. Symptoms of exposure in the concentration ranges of 1.55% may be highly variable but typical symptoms of carbon dioxide intoxication are listed under Exposure Reactions. 二氧化碳不支持生命，可以立刻產生危險的空氣。在濃度超過1.5%時，二氧化碳可以造成換氣過度、頭痛、視力紊亂、顫抖、失去知覺和死亡。在1.5到5%的濃度中暴露的癥狀有很多種，但是二氧化碳中毒的典型癥狀列在“暴露

16、反應”中。If the concentration of carbon dioxide exceeds 10%, exposure may produce profound metabolic aberrations, disturbances of the central nervous system, and cardiac irritability; unconsciousness can occur without warning, preventing self-rescue. At much higher concentrations, carbon dioxide displac

17、es the oxygen in air below levels necessary to support life.如果二氧化碳的濃度超過10%，暴露可以造成復雜的代謝失常、中樞神經系統紊亂和心過敏；沒有警告就會造成意識不清，阻止了自救。在更高的濃度下，二氧化碳取代了空氣中的氧，氧濃度降到維持生命所必須的濃度以下。Exposure Limit暴露極限The TLV-TWA for CO2, as listed by American Conference of Governmental Industrial Hygienists and by the Occupational Safety

18、 and Health Administration, is 5000 parts per million, or 0.5%.The CAS # for CO2 is 124-38-9.正如美國政府工業衛生學者會議和職業安全和健康管理局所列出的，對于二氧化碳的TLV-TWA值是百萬分之5000或0.5%。對于二氧化碳，CAS #是124-38-9。Threshold Limit Value-Time Weighted Average (TLV-TWA) is the time-weighted average concentration for a normal 8-hour workday

19、and 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.閾值極限-時間權重平均值(TLV-TWA)是對于正常的8小時工作日和40小時工作周的時間權重平均值，在該值下，大多數工人日復一日的重復暴露在其中而不會受到有害影響。Manufacture生產Carbon dioxide is produced as a crude by-product of a number of manufacturing processes. C

20、arbon dioxide is a by-product of steam reforming of methane, propane or naphtha. The fermentation of sugar to alcohol and the production of lime and sodium phosphate also generate carbon dioxide. Additionally, carbon dioxide exists in natural wells. Once the product has been isolated, impurities are

21、 filtered out, moisture is removed in driers, and the purified carbon dioxide is compressed for liquefaction.二氧化碳是作為許多工業生產過程的天然副產品生產的。二氧化碳是甲烷、丙烷或石腦油的蒸氣重整的一個副產品。糖發酵成酒精和石灰和磷酸鈉的生產也產生二氧化碳。另外，二氧化碳存在于天然井里。產品分離出來以后，過濾掉雜質，在干燥劑里去除水蒸汽，凈化了的二氧化碳被壓縮液化。Uses用途Liquid carbon dioxide is used widely in the food indust

22、ry for freezing meats, poultry, vegetables, and fruits. Solid carbon dioxide (dry ice) is used to cool meats prior to grinding and also to refrigerate meat and poultry during transit. Soft drinks, wines, and beers are produced using gaseous carbon dioxide for carbonation. Carbon dioxide is used in w

23、ater treatment to neutralize alkaline water. Liquid carbon dioxide is also used to increase recovery from oil and gas wells. Other industrial uses include the production of chemicals, plastics, rubber, metals, and electronic components.液態二氧化碳在食品工業中得到了廣泛的應用，用于冷凍肉類、家禽、蔬菜和水果。固態二氧化碳（干冰）用于在粉碎之前給肉類降溫，還用于在

24、運輸過程中冷藏肉類和家禽。使用氣態二氧化碳利用碳酸化作用生產軟飲料、葡萄酒和啤酒。在水處理中，二氧化碳用于中和堿水。液態二氧化碳還用于油井和氣井以增加開采。其它的工業用途包括生產化學品、塑料、橡膠、金屬和電子元器件。Containers容器Bulk carbon dioxide is typically stored as a liquid in storage tanks with capacities of 6, 14, 26, and 50 tons. Tanks are insulated by polyurethane foam with a vapor barrier which

25、provides weather protection. The tanks are fabricated from carbon steel according to ASME Standards. Carbon dioxide is maintained below 305 psig by a refrigeration unit and above 245 psig with a pressure buildup coil so that carbon dioxide can be stored for an in definite period without venting. Sma

26、ller liquid quantities are stored and shipped in cryogenic liquid cylinders with a capacity of 384 pounds (3352 standard cubic feet). Cryogenic liquid cylinders are vacuum-jacketed and can hold product for long periods without venting. Cryogenic liquid cylinders can either supply liquid or gas and l

27、iquid. A typical cryogenic liquid cylinder is illustrated in Figure 1.大量的二氧化碳典型地作為液體儲存在容量為6、14、26、和50噸的儲存罐里。用聚亞安酯泡沫把儲存罐和防止惡劣天氣的蒸氣屏障隔離開。按照ASME的標準用碳素鋼制造儲存罐。通過一個制冷裝置把二氧化碳維持在305 psig以下，同時通過一個壓力積累蛇管把二氧化碳維持在245 psig以上，這樣不用通風二氧化碳就可以儲存一定的時間。較小量的液體在容量為384磅（3352標準立方英尺）的低溫液體鋼瓶中儲存和運輸。低溫液體鋼瓶帶有真空夾層，可以不用通風而長期儲存產品。

28、低溫液體鋼瓶可以或者供應液體，或者供應氣體和液體。一個典型的低溫液體鋼瓶如圖1所示。Properties 性質Molecular Weight分子量 . 44.01Boiling Point沸點 l atm (sublimes升華) . -109.3°F (-78.5°C)Freezing Point凝固點 76 psia . -69.9°F (-56.6°C)Critical Temperature臨界溫度 . 87.9°F (31.0°C)Critical Pressure臨界壓力 . 1070 psia (72.9 atm)De

29、nsity密度, Liquid液體 -35°F (-37°C), 11 atm . 68.74 lb./cu. ft.Density密度, Gas氣體 68°F (20°C), 1 atm . 0.115 lb./cu. ft.Density密度, Solid固體 -110°F (-79°C), 1 atm . 97.4 lb./cu. ft.Specific Gravity比重, Gas氣體(Air空氣 = 1) 68°F (20°C), 1 atm . 1.53Specific Gravity比重, Liqui

30、d液體 -35°F (-37°C), 11 atm . 1.10Specific Volume比容 68°F (20°C), 1 atm . 8.70 cu. ft./lb.Latent Heat of Sublimation潛在升華熱 . 10900 Btu/lb. moleSolubility in Water在水中的溶解度 68°F (20°C), 1 atm . 87.8% by volumeExposure ReactionsConcentration濃度 Effect影響1% . Slight increase in br

31、eathing rate.呼吸頻率稍微增加2% . Breathing rate increases to 50% above normal level. Prolonged exposure can cause headache, tiredness. 呼吸頻率增加到正常水平以上50% 。持續暴露會導致頭痛、疲勞。3% . Breathing increases to twice normal rate and becomes labored. Weak narcotic effect. Impaired hearing, headache, increase in blood p

32、ressure and pulse rate.呼吸增加到正常水平的兩倍和變得吃力。弱麻醉作用削弱了聽力，頭痛，血壓和脈搏增加。45% . Breathing increases to approximately four times normal rate; symptoms of intoxication become evident and slight choking may be felt呼吸增加到正常水平的大約四倍；中毒癥狀變得明顯，可以感到輕微的窒息。510% . Characteristic sharp odor noticeable. Very labored breathin

33、g, headache, visual impairment, and ringing in the ears. Judgment may be impaired, followed within minutes by loss of consciousness.特征性的強烈氣味顯而易見。呼吸非常吃力，頭痛，視力減弱和耳鳴。判斷力下降，幾分鐘內失去知覺。50100%. Unconsciousness occurs more rapidly above 10% level. Prolonged exposure to high concentrations may eventually resu

34、lt in death from asphyxiation.意識不清在10%水平上發生得更加迅速。持續暴露于高濃度會最終導致由于窒息而死亡。Carbon dioxide is shipped and stored as a liquefied compressed gas in hollow steel and aluminum cylinders. The cylinders have a concave base which allows the cylinders to stand upright and are tapered to a small opening on the top

35、. The tapered or open end is threaded to receive a cylinder valve or other suitable outlet connection. Safety relief devices are part of the cylinder valve or the outlet connections. A threaded neck ring is secured to the tapered end of the cylinder to allow a protective cylinder cap to be installed

36、. Cylinders are manufactured according to Department of Transportation(DOT) specifications. Cylinders in carbon dioxide service are hydrostatically tested upon manufacture, and every five years thereafter at 5/3 times the service pressure.二氧化碳作為液化壓縮氣體在空心鋼瓶和鋁瓶中運輸和儲存。瓶子底座是凹陷的，這樣鋼瓶可以垂直站立。鋼瓶頂部是錐形的，最上端有個

37、小開口。錐形或開口端車有螺紋，可以安裝閥門或排氣口接頭。車有螺紋的頸環固定在鋼瓶的錐形端，可以安裝保護性瓶帽。按照交通部的規范制造鋼瓶。用于二氧化碳的鋼瓶在制造時經過了流體靜力學測試，之后每五年進行一次在5/3倍工作壓力下的測試。Gas Cylinder Valves氣體鋼瓶閥門The Compressed Gas Association and the American National Standards Institute have adopted a thread size of 0.825 inch14 external right-hand threads per inchdesi

38、gnated as valve connection No. 320 for cylinders. This fitting incorporates a flat nipple and fiber washer for making the gas-tight seal. See Figure 2. For additional information on cylinder valves, request Air Products Safetygram-23: Cylinder Valves.壓縮氣體協會和美國國家標準化學會已經采用了0.825英寸的螺距每英寸14個右手外螺紋指定它作為閥門

39、的第320號接頭用于鋼瓶。這種裝置結合一個平面螺紋接頭和纖維墊圈，用于制造氣密密封。見圖2。要得到關于鋼瓶閥門另外的資料，請參考Air Products的安全程序-23：鋼瓶閥門。Safety Devices安全裝置Bulk liquid storage tanks are protected against excessive pressures, which may result from heat leak, by reseatable relief devices. Cryogenic liquid cylinders are equipped with reseat able rel

40、ief devices and are additionally protected with burst discs. Gas cylinders are protected from rupture due to fire by a frangible disc sometimes backed by a fusible metal with a melting temperature of about 212°F(100°C).使用可以復位的減壓裝置來保護大容量液體儲存罐，以防止可能由熱泄漏產生的過大的壓力。低溫液體鋼瓶配備有可以復位的減壓裝置，另外還用破裂盤來保護鋼

41、瓶。用破裂盤，有時后候后面還有一個熔化溫度為212°F(100°C)易熔金屬，來保護氣體鋼瓶，防止由于起火而破裂。Identification: Gas Cylinders鑒別：氣體鋼瓶Each cylinder is identified between the neck ring and shoulder by: 在頸環和肩部之間鑒別每個鋼瓶的是通過：1. The DOT specifications (3A, 3AA,etc.) controlling the manufacture of the container, followed by the service

42、pressure rating in pounds per square inch.控制容器制造的DOT規格(3A, 3AA等)，隨后是以磅每平方英寸為單位的工作額定壓力。2. Serial number of the container.容器的序列號。3. Manufacturers symbol and the owners symbol.制造商的標志和所有者的標志。4. Month and year of the container manufacture.容器制造的月和年。5. Month and year of subsequent 5-year retest of the cont

43、ainer.容器隨后五年一次重新測試的月和年。6. Original inspectors identification stamp.最初檢查者的鑒別印記。The neck ring usually is identified by the owners symbol or name.通常通過所有者的標志或名字來鑒別頸環。Identification: Cryogenic Liquid Cylinders鑒別：低溫液體鋼瓶Each cryogenic liquid cylinder is identified with the following information stamped per

44、manently on the shoulder or top head of the jacket, on a permanently attached plate, or on the head protective ring.通過下列信息來鑒別每一個低溫液體鋼瓶，這些信息永久性地印在外殼的肩部或頂部上，印在一個永久性的附屬板上，或者在頂部保護環上。1. DOT-4L followed by the service pressure rating in pounds per square inch. DOT-4L，隨后是以磅每平方英寸為單位的額定工作壓力。2. Serial number

45、and identifying symbol; location of the number to be just below or immediately following the DOT mark; location of the symbol to be just below or immediately following the number.序列號和鑒別標志；數字的位置剛好在DOT標記的下面或緊隨其后；標志的位置剛好在數字的下面或緊隨其后。3. Month and year of the container manufacture.容器制造的月和年。Shipment of Car

46、bon Dioxide: Bulk二氧化碳的運輸：大量Carbon dioxide is transported to bulk supply systems by insulated liquid tankers which must conform to DOT Regulations as set forth in the Code of Federal Regulations, Title 49. DOT 103/4" x 103/4" nonflammable gas placards are required on the trailer.通過隔熱液體罐車來把

47、運輸到大量供應系統。液體罐車必須符合DOT規格，正如Code of Federal Regulations, Title 49里闡明的。在拖車上要求有DOT的103/4英尺x 103/4英尺的不可燃氣體張貼。Shipment of Carbon Dioxide: Cylinders二氧化碳的運輸：鋼瓶The shipment of carbon dioxide gas cylinders by surface transportation must conform to DOT Regulations, Title49, which describes labeling and identif

48、ication required. A DOT 4" x 4" nonflammable gas label or tag is required for common carrier shipments. Figure 3 illustrates the label (black printing on green) that is required.通過水陸交通的二氧化碳氣體鋼瓶的運輸必須符合DOT規范的49條，它說明了所要求的標簽和鑒別。對于公用運輸業者運輸，要求貼有一個DOT的4英尺x4英尺的不可燃氣體標志或標簽。圖3說明了所要求的標簽。Cryogenic liqu

49、id carbon dioxide cylinders are shipped under DOT Exemption Number 7638. A copy of this exemption must be carried aboard each vessel, aircraft or motor vehicle used to transport the cylinders. Each cryogenic cylinder must be plainly marked on both sides near the middle, in letters at least two inche

50、s high on a contrasting background, “DOT-E7638.” The DOT 4" x 4" green nonflammable gas label or tag is also required for common carrier shipments. Shipments by air must conform with Title 49 Code of Federal Regulations(FAA Regulations). The official publication of the Department of Transp

51、ortation concerning transport of hazardous materials by any mode is 49 CFR.低溫液體二氧化碳鋼瓶運輸的DOT免稅號是7638。用于運輸鋼瓶的每個船舶、飛機或汽車上必須攜帶一個免稅的拷貝。必須在每個低溫液體鋼瓶的兩邊靠近中間的位置上用至少兩英寸高的字母在對比強烈的背景上標明：“DOT-E7638”。對于公用運輸業者運輸，也要求貼有一個DOT的4英尺x4英尺的不可燃氣體標志或標簽。空運必須遵守Title 49 Code of Federal Regulations(FAA Regulations)。49 CFR是交通部的關于

52、以任何方式運輸危險物質的官方出版物。Safety Considerations對安全的考慮Carbon dioxide is stored and transported as a liquefied compressed gas. The following hazards are associated with liquefied compressed carbon dioxide.二氧化碳是以液態壓縮氣體的方式儲存和運輸的。同液化壓縮二氧化碳相聯系的是下列危險。1. High pressure involved in storage and service equipment.同儲存和使

53、用設備相關的高壓。2. Carbon dioxide is 1.5 times heavier than air and will not readily disperse in the atmosphere. Asphyxiation may be a hazard in confined areas. 二氧化碳比空氣重1.5倍，在空氣中不易擴散。窒息是在狹窄區域的危險。3. Carbon dioxide in high concentrations is toxic to humans. See the toxicity section for effects on humans.高濃度二

54、氧化碳對人體有毒。關于對人體的影響，見毒性部分。4. Vaporizing carbon dioxide can produce very cold temperatures. Spillage of liquid carbon dioxide on the skin can cause freeze burn or frostbite. Carbon dioxide, solid below 61 psig, is very cold and sublimes so quickly that prolonged contact with the skin causes freeze burn

55、 or frostbite.正在蒸發的二氧化碳會造成極低的溫度。液體二氧化碳濺到皮膚上會導致凍傷。壓力在61 psig以下的二氧化碳固體溫度極低，升華得非常快，持續接觸皮膚會導致凍傷。Buildings建筑物1. Provide adequate ventilation. 提供充分的通風。2. The atmosphere in areas in which carbon dioxide gas may be vented and collect should be tested with a portable or continuous monitoring carbon dioxide g

56、as analyzer to ensure ventilation is adequate.應該用移動或連續的二氧化碳監測分析儀來測試可能排出或積累二氧化碳氣體的區域，以保證通風是充分的。Handling and Storage操作和儲存1. Never drop cylinders or permit them to strike each other violently. 禁止使鋼瓶摔倒或使它們彼此劇烈碰撞。2. Cylinders should be assigned a definite area for storage. The area should be dry, cool, a

57、nd well ventilated, and preferably fire-resistant. Keep cylinders protected from excessive temperatures by storing them away from radiators or other sources of heat. 應安排有確定的鋼瓶存放區域。該區域應該使干燥、涼爽、通風良好，最好是防火的。遠離散熱器或其它熱源，使鋼瓶接觸不到過高的溫度。3. Cylinders may be stored in the open, but in such cases should be prot

58、ected against extremes of weather and from damp ground to prevent rusting. 鋼瓶可以存放在室外，但應防止受到惡劣天氣的影響，同時不能接觸潮濕的地面，以防生銹。4. The valve protection cap should be left in place until the cylinder has been secured against a wall, a bench, or placed in a cylinder stand, and is ready to be used. 在鋼瓶靠著墻壁、工作臺固定或放置在鋼瓶座準備使用之前，閥門保護帽要一直留