Appendix A to Subpart S - Decompression Tables  


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  • 1. Explanation. The decompression tables are computed for working chamber pressures from 0 to 14 pounds, and from 14 to 50 pounds per square inch gauge inclusive by 2-pound increments and for exposure times for each pressure extending from one-half to over 8 hours inclusive. Decompressions will be conducted by two or more stages with a maximum of four stages, the latter for a working chamber pressure of 40 pounds per square inch gauge or over.

    Stage 1 consists of a reduction in ambient pressure ranging from 10 to a maximum of 16 pounds per square inch, but in no instance will the pressure be reduced below 4 pounds at the end of stage 1. This reduction in pressure in stage 1 will always take place at a rate not greater than 5 pounds per minute.

    Further reduction in pressure will take place during stage 2 and subsequent stages as required at a slower rate, but in no event at a rate greater than 1 pound per minute.

    Decompression Table No. 1 indicates in the body of the table the total decompression time in minutes for various combinations of working chamber pressure and exposure time.

    Decompression Table No. 2 indicates for the same various combinations of working chamber pressure and exposure time the following:

    a. The number of stages required;

    b. The reduction in pressure and the terminal pressure for each required stage;

    c. The time in minutes through which the reduction in pressure is accomplished for each required stage;

    d. The pressure reduction rate in minutes per pound for each required stage;

    Important Note: The Pressure Reduction in Each Stage is Accomplished at a Uniform Rate. Do Not Interpolate Between Values Shown on the Tables. Use the Next Higher Value of Working Chamber Pressure or Exposure Time Should the Actual Working Chamber Pressure or the Actual Exposure Time, Respectively, Fall Between Those for Which Calculated Values Are Shown in the Body of the Tables. ExamplesMinutesExample No. 1: 4 hours working period at 20 pounds gauge.Decompression Table No. 1: 20 pounds for 4 hours, total decompression time43Decompression Table No. 2:Stage 1: Reduce pressure from 20 pounds to 4 pounds at the uniform rate of 5 pounds per minute.Elapsed time stage 1: 16/53Stage 2 (final stage): Reduce pressure at a uniform rate from 4 pounds to 0-pound gage over a period of 40 minutes.Rate—0.10 pound per minute or 10 minutes per pound.Stage 2 (final) elapsed time40Total time43Example No. 2: 5-hour working period at 24 pounds gage.Decompression Table No. 1: 24 pounds for 5 hours, total decompression time117Decompression Table No. 2:Stage 1: Reduce pressure from 24 pounds to 8 pounds at the uniform rate of 5 pounds per minute.Elapsed time stage 1: 16/53Stage 2: Reduce pressure at a uniform rate from 8 pounds to 4 pounds over a period of 4 minutes. Rate, 1 pound per minute elapsed time, stage 24Transfer men to special decompression chamber maintaining the 4-pound pressure during the transfer operation.Stage 3 (final stage): In the special decompression chamber, reduce the pressure at a uniform rate from 4 pounds to 0-pound gage over a period of 110 minutes. Rate, 0.037 pound per minute or 27.5 minutes per pound. Stage 3 (final) elapsed time110Total time117 Decompression Table No. 1—Total Decompression TimeWork pressure p.s.i.g.Working period hours1/2111/22345678Over 89 to 1233333333333146666666616163316777777173348486218777811174863637387207781515436373831031132299162438689310311312813324111223275292117122127137151261314293469104126141142142163281523314198127143153153165183301728386210514316516817818820432193543851261631781932032132263421395898151178195218223233248362444631131701982232332432532733828497312817820322323825326327840314984143183213233248258278288423756102144189215245260263268293444364118154199234254264269269293464474139171214244269274289299318485189144189229269299309319319505894164209249279309329 Decompression Table No. 2[Do not interpolate, use next higher value for conditions not computed]Working chamber pressure p.s.i.g.Working period hoursDecompression dataStage No.Pressure reduc. p.s.i.g.FromToTime in stage minutesPressure reduc. rate Min/poundTotal time decompress minutes141/2114420.20624041.0061114420.20624041.00611/2114420.20624041.0062114420.20624041.0063114420.20624041.0064114020.20624041.0065114420.20624041.0066114420.2024041.0067114420.20240143.50168114420.20240143.5016Over 8114420.20240307.5032161/2116430.2024041.0071116430.20724041.00711/2116430.2024041.0072116430.2024041.0073116430.2024041.0074114430.2024041.0075114430.20724043.50176114430.20240307.50337114430.202404511.25488114430.202404511.2548Over 8114430.202406015.0063181/2118430.2024041.0071118430.2024041.00711/2118430.2024041.0072118430.2024051.2583118430.2024082.00114118430.20240143.50175118430.202404511.25486118430.202406015.00637118430.202406015.00638118430.202407017.5073Over 8118430.202408421.0087201/2120430.2024041.0071120430.2024041.00711/2120430.2024051.2582120430.20240123.00153120430.20240123.00154120430.202404010.00435120430.202406015.00636120430.202407017.50737120430.202408020.00838120430.2024010025.00103Over 8120430.2024011027.50113221/2122630.2026061.0091122630.2026061.00911/2122630.20260132.20162122630.20260213.50243122630.20260355.85384122630.202606510.83685122630.202609015.00936122630.2024010016.671037122630.2026011018.351138122630.2026012520.80128Over 8122630.2026013021.70133241/2124830.2028441.0034041.00111124830.2028441.0034051.251211/2124830.2028441.00340164.00232124830.2028441.00340205.00273124830.2028441.003404511.25524124830.2028441.003408521.25925124830.2028441.0034011027.501176124830.2028441.0034011528.801227124830.2028441.0034012030.001278124830.2028441.0034013032.50137Over 8124830.2028482.0034014035.00151261/21261030.20210461.0034041.001311261030.20210461.0034051.251411/21261030.20210461.00340205.002921261030.20210461.00340256.253431261030.20210461.003406015.006941261030.20210461.003409523.7510451261030.20210481.3334011528.8012661261030.20210481.3334013032.5014171261032.20210491.5034013032.5014281261030.20210491.5034013032.50142Over 81261030.202104305.003403032.50163281/21281230.20212481.0034041.001511281230.20212481.00340123.002311/21281230.20212481.00340205.003121281230.20212481.00340307.504131281230.202124101.253408521.209841281230.202124141.7534011027.5012751281230.202124202.5034012030.0014361281230.202124202.5034013032.5015371281230.202124202.5034012032.5015381281230.202124324.0034013032.50165Over 81281230.202124506.2534013032.50183301/21301430.202144101.0034041.001711301430.202144101.00340153.752811/21301430.202144101.00340256.253821301430.202144141.403404511.256231301430.202144171.703408521.2010541301430.202144303.0034011027.5014351301430.202144353.5034013032.5016561301430.202144353.5034013032.5016871301430.202144454.5034013032.5017881301430.202144555.5034013032.50188Over 81301430.202144717.1034013032.50204321/21321630.202164121.0034041.001911321630.202164121.00340205.003511/21321630.202164151.25340256.254321321630.202164221.833406015.008531321630.202164282.333409523.7512641321630.202164403.3334012030.0016351321630.202164453.7534013032.5017861321630.202164605.0034013032.5019371321630.202164705.8334013032.5020381321630.202164806.6734013032.50213Over 81321630.202164937.7534013032.50226341/21341830.202184141.0034041.002111341830.202184141.00340225.503911/21341830.202184251.80340307.505821341830.202184352.503406015.009831341830.202184433.1034010526.2515141341830.202184553.9334012030.0017851341830.202184624.4334013032.5019561341830.202184856.0734013032.5021871341830.202184906.4334013032.5022381341830.2021841007.1534013032.50233Over 81341830.2021841158.2334013032.50248361/21362030.202204161.0034051.252411362030.202204161.00340256.254411/21362030.202204301.88340307.506321362030.202204402.503407017.5011331362030.202204523.2534011528.7517041362030.202204654.0634013032.5019851362030.202204905.6334013032.5022361362030.2022041006.2534013032.5023371362030.2022041106.8834013032.5024381362030.2022041207.5034013032.50253Over 81362030.2022041408.7534013032.50273381/21382230.202226161.0036091.502811382230.202226161.00360305.004911/21382230.202226201.25360508.347321382230.202226301.883609515.8312831382230.202226352.1936014023.3517841382230.202226503.1236015025.0020351382230.202226553.4436016527.5022361382230.202226704.3836016527.5023871382230.202226855.3236016527.5025381382230.202226955.9336016527.50263Over 81382230.2022261106.8836016527.50278401/21402430.202248161.0038441.0044082.003111402430.202248161.0038451.25440256.254911/21402430.202248161.00384205.004404511.258422402430.201248251.56384205.004409523.7514331402430.202248301.88384307.5044012030.0018341402430.202248452.81384358.7544013032.5021351402430.202248472.943845313.2544013032.5023361402430.202248553.443846015.0044013032.5024871402430.202248654.063846015.0044013032.5025881402430.202248754.703846015.0044013032.50268Over 81402430.202248955.933846015.0044013032.50288421/21422630.2022610161.00310461.00440123.003711422630.2022610161.003104122.00440256.255611/21422630.2022610161.003104233.834406015.0010221422630.2022610161.003104305.004409523.7514431422630.2022610161.003104508.3444012030.0018941422630.2022610171.0631046510.8344013032.5021551422630.2022610271.6931048514.1844013032.5024561422630.2022610271.69310410016.6744013032.5026071422630.2022610301.88310410016.6744013032.5026381422630.2022610352.19310410016.6744013032.50268Over 81422630.2022610603.75310410016.6744013032.50293441/21442830.2022812161.00312481.00440164.004311442830.2022812161.003124202.50440256.256411/21442830.2022812161.003124273.384407218.0011821442830.2022812161.003124405.004409523.7515431442830.2022812161.003124607.5044012030.0019941442830.2022812161.0031248510.6244013032.5023451442830.2022812161.00312410513.1344013032.5025461442830.2022812161.00312411514.3844013032.5026471442830.2022812161.00312412015.0044013032.5026981442830.2022812161.00312412015.0044013032.50269Over 81442830.2022812402.50312412015.0044013032.50293461/21463030.2023014161.003144101.00440153.754411463030.2023014161.003144252.50440307.507411/21463030.2023014161.003144353.504408521.2013921463030.2023014161.003144474.7044010526.2517131463030.2023014161.003144656.5044013032.5021441463030.2023014161.003144959.5044013032.5024451463030.2023014161.00314412012.0044013032.5026961463030.2023014161.00314412512.5044013032.5027471463030.2023414161.00310414014.0044013032.5028981463030.2023014161.00314415015.0044013032.50299Over 81463030.2023014251.56314416016.0044013032.50318481/21483230.2023216161.003164121.00440205.005111483230.2023216161.003164352.92440358.758911/21483230.2023216161.003164453.754408020.0014421483230.2023216161.003164605.0044011027.5018931483230.2023216161.003164907.5044012030.0022941483230.2023216161.00316412010.0044013032.5026951483230.2023216161.00316414011.6744013032.5020961483230.2023216161.00316416013.3344013032.5030971483230.2023216161.00316417014.1744013032.5081483230.2023216161.00316417014.1744013032.50501/21503430.2023418161.003184141.00440256.255811503430.2023418161.003184402.86440358.759411/21503430.2023418161.003184553.934409022.5016421503430.2023418161.003184705.0044012030.0020931503430.2023418161.0031841007.1544013032.5024941503430.2023418161.0031841308.5844013032.5027951503430.2023418161.00318416011.42 Decompression Table No. 2—Continued[Do not interpolate, use next higher value for conditions not computed]Working chamber pressure p.s.i.g.Working period hoursDecompression dataStage No.Pressure reduc. p.s.i.g.FromToTime in stage minutesPressure reduc. rate Min/poundTotal time decompress minutes44013032.5030961503430.2023418161.00318418012.8544013032.50329