孔板文档资料

煤层瓦斯压力参数测定-PAGE6-孔板流量计抽放管路中的瓦斯流量测定与计算瓦斯量是一种气体，用来测定气体流量的仪表形式和种类较多，但在矿井抽放瓦斯管路中大都使用孔板流量计，其结构如图19。图19孔板流量计10.1参数测定(1)测定孔板上风端的绝对压力(Pl),可用真空表(负压表)或U型汞柱计直接测定，并按下式计算：Pl＝Pa－P(10―1)式中：Pl＝――孔板上风端的绝对压力，(mmHg)Pa――大气压力，(mmHg)P――表压力或水银柱高差，(mmHg)。(2)测定管内气体温度(ｔº)，可近视取测量地点温度。(3)测定孔板前后端压差(Δh)，用U型水柱计测量。(4)测定管内瓦斯浓度(x)，气样可用高负压抽气筒采集，见图20。采用时，抽气筒的进气口和平衡压力口分别通过胶管与孔板前后的气咀相连通，起着平衡负压和保证抽气筒前方压力大于后方压力的作用，因而避免了经活塞漏入空气。在打气时，瓦斯经气门芯排到高浓度瓦斯检定器中。图 20FW-1型高负压瓦斯采样器10.2流量计算Q＝Kb(10－2)式中：Q流――用标准孔板观测时混合瓦斯流量，m3/min；K――孔板实际流量系数，K＝189.76aomD2(10－3)ao――标准孔板流量系数；m――截面比；m＝D――管道直径，m；Δh――在孔板前后端所测之压差，mmH2O。δT――温度校正系数；δP――压力校正系数；δT＝(10－4)δP＝(10－5)实际孔板流量特征系数K值表表10－4管径D(mm)ma0K0.050.100.150.200.250.300.350.400.450.500.550.600.650.7015a00.61550.61920.62570.63350.64260.65320.66540.68150.69920.71920.74060.76730.79610.8223K0.00130.00260.00400.00540.00690.00700.00990.01180.01340.01540.01740.01970.02210.024620a00.61510.61880.62520.63300.64230.65280.66470.68080.69840.71840.73980.76640.79530.8218K0.00230.00470.00710.00960.01220.01250.01770.02070.02390.02730.03090.03490.03930.043725a00.61370.61840.62470.63250.64170.65240.66400.68010.69760.71760.73900.76550.79450.8215K0.00370.00730.01110.01500.01900.02320.02750.03220.03710.04250.04810.05440.06120.068138a00.61370.61730.62340.63130.64020.65120.66240.67830.69540.71540.73710.76330.78230.8208K0.00840.01690.02560.02360.03290.04250.05250.06340.07480.08700.10010.11450.13010.146450a00.61280.61620.62210.62930.63870.64920.66070.67640.69340.71340.73500.76100.79000.8200K0.01450.02920.03330.04870.06330.07990.09720.11590.13550.15670.17930.20410.23110.259875a00.61090.61400.61960.62610.63570.64600.65740.67270.68920.70920.73100.75650.78580.8185K0.03060.06550.09920.13370.16960.20620.24560.28720.33100.37850.42920.48450.54520.6116100a00.60900.61170.61700.6238063270.64280.65410.66900.68500.70500.72700.75200.78150.8170K0.05780.11610.17550.23660.30010.35470.42310.49650.57360.65760.74610.84360.95131.0726125a00.60780.61050.61600.62230.63100.64110.65240.66750.68350.70320.72520.75000.77940.8145K0.09010.18100.27400.36900.46770.57030.67700.79170.91201.04251.18261.33431.50211.6905150a00.60670.60930.61500.62090.62940.63940.65060.66600.68200.70150.72350.74800.77730.8120K0.12930.26020.39390.53020.67180.81900.97221.13741.31031.49761.69901.91622.15722.4268175a00.60550.60810.61340.61950.62770.63770.64880.66450.68050.69980.72180.74600.77510.8095K0.17600.35340.53470.72000.91201.11181.31971.54471.78002.03342.30712.60122.92793.2756200a00.60430.60690.61190.61800.62600.63600.64700.66300.67900.69800.72000.74400.77300.8070K0.22940.46070.69790.93821.18791.44831.71892.01302.31932.64913.00583.38843.81384.2651225a00.60350.60590.61090.61720.62550.63550.64650.66220.67820.69720.71900.74300.77190.8057K0.28990.58120.88041.18581.50231.83152.17382.54462.93183.34893.79904.28264.81885.3892250a00.60270.60500.61000.61650.62500.63500.64600.66150.67750.69650.71800.74200.77050.8045K0.35750.71751.08521.46231.85312.25932.68163.13823.61594.13034.68385.28015.93986.6434275a00.60180.60400.60900.61570.62450.63450.64550.66080.67680.69580.71700.74100.76930.8033K0.43180.86391.31091.77102.24062.73163.24223.79324.37064.99265.66636.38037.17608.0264300a00.60100.60300.60800.61500.62400.6340