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1、孔板流量计的测定与计算在孔板流量计的前后端测出压差后可按以下两种方法进行计算;（一）、可按公式计算出瓦斯流量。计算公式：式中:Q =Kb(A h)i/2。6 丁混P TQ = Q X纯混(1)Q 抽放的瓦斯混合量，m3/min；混Q 抽放的瓦斯纯量，m3/min；纯K实际孔板流量特性系数，计算见（2）式;b瓦斯浓度校正系数，计算见（3）式；6 气压校正系数，计算见（4）式；6 T温度校正系数，计算见（5）式； h在孔板前后端所测之压差，mmH2O；X混合气体中瓦斯浓度，。式中:K=189.76a0mD2(2)a0-标准孔板流量系数；m= (d/D) 2m-截面比；D-管道直径，米；d1-孔板直
2、径，米；b=1/ (1-0.00446X) 1/2(3)6 = (P/760) 1/2(4)式中:p丄PT孔板上风端测得的绝对压力，mmHg；PT=测定当地压力（mmHg） +该点管内正压（正）或负压（负）（mmH2O） /13.6760标准大气压，mmHg；6 t=293 / (273 +t) 1/2(5)式中:t瓦斯管内测点温度，C；293 标准绝对温度，C；四寸管路d=49.50mmD=98.28mm贝I：m=0.2536 查(表一)得 a0=O.6327K=0.3001 六寸管路d=74.68mmD=151.20mm贝U： m=0.2439 查(表一)得 a=0.6294K=0.671
3、8(二)、在计算过程中为加快计算速度，可把公式中的各项数值表格化，査表 得出b、6、6。p T瓦斯浓度校正系数b值表二；瓦斯 浓度 (%)012345678901.0001.0021.0041.0071.0091.0111.0141.00161.0191.021101.0241.0261.0281.0311.0321.0351.0381.0401.0431.045201.0481.0501.0531.0561.0581.0601.0631.0661.0681.071301.0741.0771.0801.0821.0851.0881.0911.0951.0971.100401.1031.1061
4、.1091.1131.1161.1191.1221.1251.1281.131501.1341.1371.1411.1441.1481.1511.1541.1581.1621.164601.1681.1721.1761.1791.1821.1861.1901.1941.1981.202701.2061.2101.2141.2201.2221.2251.2291.2341.2381.243801.2471.2511.2561.2601.2631.2691.2741.2781.2831.287901001.2921.3441.2971.3021.3081.3131.3181.3241.3281.3
5、341.339气压校正系数6值表三;压力(mmHg)6p压力(mmHg)6p压力(mmHg)-p6 p压力(mmHg)6p压力(mmHg)6p1500.4442900.6174300.7525700.8667100.9671550.4522950.6234350.7565750.8707150.9701600.4583000.6294400.7615800.8747200.9731650.4663050.6334450.7655850.8787250.9771700.4723100.6394500.7695900.8817300.9801750.4803150.6434550.7745950.
6、8867350.9841800.4883200.6494600.7786000.8897400.9871850.4933250.6544650.7826050.8927450.9901900.5003300.6594700.7866100.8967500.9931950.5063350.6634750.7916150.9007550.9972000.5133400.6694800.7946200.9037601.0002050.5193450.6744850.7996250.9077651.0032100.5253500.6784900.8036300.9107701.0062150.5323
7、550.6834950.8076350.9147751.0092200.5383600.6895000.8116400.9187801.0132250.5443650.6935050.8156450.9227851.0162300.5503700.6985100.8196500.9257901.0192350.5563750.7025150.8236550.9287951.0232400.5623800.7075200.8276600.9328001.0262450.5683850.7125250.8316650.9358051.0292500.5743900.7165300.8356700.
8、9398101.0312550.5793950.7205350.8396750.9428151.0342600.5854000.7255400.8436800.9468201.0372650.5904050.7295450.8476850.9498251.0402700.5964100.7345500.8506900.9538301.0432750.6014150.7395550.8546950.9568351.0472800.6074200.7435600,8587000.9608401.0502850.6124250.7485650.8627050.9638451.053温度校正系数5值表
9、四;温 度 C0123456789400. 9680. 9660. 9640. 9630. 9610. 9600. 9580. 9570. 9550. 954300. 9830. 9820. 9800. 9790. 9770. 9750. 9740. 9720. 9710. 969201. 0000. 9980. 9970. 9950. 9930. 9920. 9900. 9880. 9870. 985101. 0171. 0161. 0141. 0121. 0101. 0081. 0071. 0051. 0031. 00101. 0351. 0341. 0331. 0321. 0291. 0
10、271. 0251. 0231. 0211. 019-01. 0351. 0371. 0391. 0411. 0431. 0451. 0471. 0491. 0521. 054-101. 0561. 0581. 0591. 0611. 0631. 0661. 0681. 0701. 0721. 074-201. 0761. 0781. 0801. 0831. 0851. 0861. 0891. 0911. 0941. 095-301. 0981. 0991. 1031. 1051. 1081. 1091. 1151. 1151. 1171. 119-401. 1221. 1231. 1261.
11、 1291. 1311. 1331. 1391. 1391. 1411. 143例题：某钻场瓦斯支管路D=25.4mm,孔板直径d1=12.7mm,在井下实测，测 得压差为30mmH2O，瓦斯浓度30%，测得大气压力1.01x105pa，管内负压 0.07Mpa，瓦斯管内温度为20C，求瓦斯流量？解：由公式 Q 混=K*b*(A h)1/2* 6 p*6 T求 K 值m=(d/D)1/2=(12.7/25.4) b=0.25查表一得：a0=0.6417K=0.0190b值查表二得：b=1.074求 6 值 PT=1.01*105/(9.8*13.6)-0.07*106/(9.8*13.6)=2
12、32.6mmHg求6卩查表三得：6 =0.556pp求6 T查表四得：6 t=0.983则 Q =0.019*1.074*301/2*0.556*0.983混=0.061m3/minQ = Q *X=0.061*30%=0.0183m3/min纯混(举例)YD-2型孔板流量计的应用与计算孔板流量计用以测定瓦斯管路中的瓦斯流量(如下图)。Pi q 台流右向尸、抽放瓦斯管路中孔板流量计的安装与使用：(1) 、在抽放瓦斯管路中安装孔板时，孔板的孔口必须与 管道同心，其端面与管路轴线垂直，偏心度12%；(2) 、安装孔板的管道内壁，在孔板前后距离2D的范围 内，不应有凸凹不平，焊缝和垫片等。(3) 、孔板流量计的上游(前端)，管道直线长度20D， 下游(后端)长度10D;
