搜索
内容时长气体危害原理气体检测设备钻井现场气体检测Biosystem气检仪Threebasickindsofhazards:三种基本危险•Oxygen(deficiencyandenrichment)氧气（缺乏或过量）•Flammablegasesandvapors易燃气体和蒸汽•Toxiccontaminants有毒污染物AtmosphericMonitoring大气检测AtmosphericMonitoring大气检测Compositionoffreshair新鲜空气的组成成分•78%nitrogen78%氮气•20.9%oxygen20.9%氧气•1.1%allothergases1.1%的其他气体•Watervapor水蒸气•CO2二氧化碳•Argon氩气•Othertracegases其他气体Airisoxygendeficientwheneverconcentrationislessthan19.5%O2当空气中氧气浓度低于19.5%时就为氧气缺乏OxygenDeficiency氧气不足SymptomsofOxygenDeficiency氧气缺乏的特征20.9%新鲜空气中氧气含量19.5%-12%判断力降低，脉搏和呼吸加快，疲劳，协调能力降低12%-10%呼吸紊乱,循环降低,疲劳恶化和失去重要功能，在几秒钟到几分钟内出现其他症状10%-6%恶心,呕吐,行动无力,失去直觉,直至死亡6%-0%抽搐,呼吸急促,呼吸停止,心跳停止,在数分钟内出现失去直觉，死亡症状•Displacement惰性气体置换•Microbialaction生物/细菌行为•Oxidation氧化•Combustion燃烧•Absorption吸收CausesofOxygenDeficiency造成氧气不足的原因“Fuelcell”principle燃料电池原理•SensorgenerateselectricalcurrentproportionaltotheO2concentration传感器产生同氧气浓度成比例的电流•Sensorusedupovertime(usuallylastonetotwoyears)传感器长期使用将会失效（通常持续1到2年）OxygenSensorDetectionPrinciple氧气检测传感器原理AtmosphericMonitoring大气检测氧气链反应燃烧物燃烧源ExplosionTetrahedron爆炸机理•Dramaticallypromotesandacceleratescombustion明显加强和加速燃烧•NeveruseO2toventilateaconfinedspace!禁止使用将氧气直接通过通风进入密闭空间•Proportionallyincreasestherateofmanychemicalreactions相应地增加化学品反应的速率•Cancauseordinarycombustiblematerialstobecomeflammableorexplosive可将普通可燃物变成易燃或可爆炸物OxygenEnrichment氧气过量•29CFR1910.146specifies23.5%isoxygenenriched氧气含量超过23.5%为氧气过量•Othercodesaremorestringent其他法规更严格•Mostconservativeapproachistouse22%astakeactionpoint大部分保守观点是含量超过22%OxygenEnrichment氧气过量•Minimumconcentrationofacombustiblegasorvaporinairwhichwilligniteifasourceofignitionispresent可燃气体或蒸气在空气中引起燃烧的最低浓度LowerExplosiveLimit(L.E.L.)爆炸下限气体浓度LELUEL燃烧范围0100%LEL气体浓度燃烧范围CombustibleGas/vaporInstrumentsReadin“PercentLEL”可燃气体/蒸气仪器的读数以百分比指示“LEL”Acombustiblehazardexistswheneverreadingsexceed10%LEL当爆炸下限超过10%时就会存在燃烧危险CombustibleHazard燃烧危害•等同于100%LEL的气体浓度:–甲烷5.0%/vol.–丙烷2.2%/vol.–戊烷1.8%/vol.–硫化氢4.3%/vol.–一氧化碳12.5%/vol.•完全燃烧环境的气体浓度(100%LEL)…和…爆炸下限传感器反应的比率不是线性的,无论如何,顺序通常是一样的LELConcentrationsforDifferentGases不同气体的LEL浓度CombustiblesensorsmaybepoisonedOrsufferdegradedperformancewithProlongedexposureto:可燃传感器有可能中毒或发生性能退化由于长期暴露于：•Silicones硅树脂•Tetraethyl-lead四已基-铅•Halogenatedhydrocarbons卤化碳氢化和物•Highconcentrationsofsulfides高浓度硫化物•Highconcentrationsofflammablegas高浓度易燃气体Poisoning中毒•AsanLELsensorbecomepoisonedthesensorssurfaceandthesensorsporeswillbecoatedwithoxidizedsilicone当LEL探头的表面和通道涂上氧化硅时将造成探头中毒•Asiliconepoisonedsensorwillfirstlooseitsabilitytodetectmethane,whilenotexhibitinganynoticeableinhibitiontodetectothercombustiblegases硅中毒的探头将首先失去检测甲烷的能力，•AspoisoningprogressesthetheLELsensorwilleventuallyloseisabilitytodetectanycombustiblegases当LEL探头中毒时将最终失去检测任何可燃气体的能力Poisoning中毒AtmosphericMonitoring大气检测•最普遍的:–Carbonmonoxide(CO)一氧化碳–Hydrogensulfide(H2S)硫化氢•Combinationsensorsareavailable可以提供复合型探头BiosystemsToxicGasSensors有毒气体探头•不常见:–Sulfurdioxide(SO2)二氧化硫–Chlorine(Cl2)/chlorinedioxide(ClO2)氯气/二氧化氯–Ammonia(NH3)氨气–Phosphine(PH3)磷化氢–Nitrogendioxide(NO2)二氧化氮–Hydrogencyanide(HCN)氰化氢–Nitricoxide(NO)氧化氮BiosystemsToxicGasSensors有毒气体探头•MicrobialactiononmaterialinCS密闭空间内微生物活动•ProductsorchemicalsstoredinCS储藏在密闭空间内的化学产品•WorkbeingperformedinCS密闭空间中间进行的工作•AreasadjacenttoCS紧挨密闭空间的区域SourcesofToxicContaminants有毒污染物来源Permissibleexposurelimitsgivenin“parts-per-million”(PPM)concentrations以“百万分之多少”来定义允许的暴露极限的浓度1%=10,000ppmUnitOfMeasureforToxicContaminants有毒污染物的度量单位•Timeweightedaverage(TWA)-allmeasurementsaveragedoverexactlyeighthours8小时平均暴露浓度•Ceiling峰值ceilingisthemaximumconcentrationtowhichanunprotectedworkermaybeexposedforanyperiodoftime峰值指为保护员工可能暴露的最大浓度•Shorttermexposurelimit(STEL)-averageconcentrationforthemostrecent15minuteperiod短时间暴露极限15分钟的平均暴露极限ThePELforaparticulargasmayhaveonlyone,ormayhaveallthreetermsPEL针对颗粒型气体可以是一种，也可是三种方式3WaystoDetermineExposureLimits3种判定暴露极限的方法暴露时间浓度平均暴露浓度4hours100PPM50PPM8hours100PPM100PPM12hours100PPM150PPMTWACalculation平均暴露浓度计算•Usethelowestnumericvalueofanyapplicableceiling,STELorTWAPELasthedefaultceilingalarmlevel使用最低适用的Ceiling,STELorTWAPEL数值来作为默认报警值举例:PEL类型PEL默认报警值TWA:35PPM35PPMSTEL:100PPM100PPMCeiling:200PPM35PPMSimplest(AndSafest)ApproachtoPEL最简单（安全）PEL方法AtmosphericMonitoring大气检测COistheleadingcauseofaccidentalPoisoninginAmerica!一氧化碳造成的事故在美国排在前列•COcausesmoreaccidentalpoisoningsthananyotherchemicalsubstance一氧化碳比其他化学物质引起中毒事故要多•AccordingtothejournaloftheAmericanmedicalassociation(JAMA)atleast:根据美国医疗机构的统计，至少–1,500personskilledperyear1500人每年死于一氧化碳中毒–10,000moreforcedtoseekmedicalattention10000人需要医疗CarbonMonoxide一氧化碳•Producedasabyproductofincompletecombustion不完全燃烧产物•Associatedwithinternalcombustionengineexhaust由可燃发动机排放–Vehicles交通车辆–Pumps泵–Compressors压缩机CarbonMonoxide一氧化碳•Bondstohemoglobininredbloodcells附着在血液中的红血球上•Contaminatedcellscan’ttransportO2污染细胞而不能输送氧气•Chronicexposureatevenlowlevelsharmful低浓度状况下降造成慢性暴露CarbonMonoxide一氧化碳•Colorless无色•Odorless无味•Aboutthesameweightasair同空气重量差不多•Flammable(LELis12.5%)易燃（爆炸下限为12.5%）•Toxic!有毒CharacteristicsofCarbonMonoxide一氧化碳特征•OSHA(1989)PEL:TWA=35PPMceiling=200PPM•Osha(1996)pel:TWA=50ppm•Niosh/acgihtlv(1996):TWA=25ppmExposuretoCarb