孔板流量計(jì)技術(shù)資料(老大節(jié)選)

1、（4）孔板流量計(jì)煤礦瓦斯抽采流量測(cè)量中使用最廣泛的流量計(jì)是徑距取壓的標(biāo)準(zhǔn)孔板，其適用條件為：孔板圓孔直徑d≥12.5mm管道直徑50≤D≤769mm直徑比0.20≤β＝dD≤0.75雷諾數(shù)1260β2D≤Reo≤1081）結(jié)構(gòu)孔板流量計(jì)由孔板、取壓嘴和鋼管組成，如圖83所示?？装迨且粔K具有圓形開(kāi)孔并相對(duì)于開(kāi)孔軸線(xiàn)對(duì)稱(chēng)的圓形薄板，如圖84所示。不同管道內(nèi)徑的孔板，其結(jié)構(gòu)形式是幾何相似的。孔板開(kāi)孔上游側(cè)直角入口邊緣應(yīng)銳利，邊緣角應(yīng)不大于0.

2、0004d?？装彘_(kāi)孔圓筒形部分長(zhǎng)度e＝（0.005～0.02）D；孔板厚度E在e和0.05D之間，一般不小于2mm；出口處向下游側(cè)擴(kuò)散的錐面的圓錐角為30～45?？装寮庸?yīng)達(dá)到下列要求：①孔板上游側(cè)端面A面，如圖84所示，應(yīng)無(wú)可見(jiàn)損傷，在離中心1.5d，范圍內(nèi)輪廓的算術(shù)平均偏差Ra≤0.000d，它相當(dāng)于如下粗糙度：當(dāng)50㎜≤D≤125mm時(shí)，為；當(dāng)125mm≤D≤250㎜時(shí)，為；當(dāng)250mm≤D≤760mm時(shí)，為；②孔板下游側(cè)端面B面

3、如圖84所示應(yīng)與A面平行其粗糙度可較A面低一級(jí)。③在兩點(diǎn)或多點(diǎn)測(cè)得的e值之間最大偏差不得超過(guò)0.001De表面的粗糙度為。④各處測(cè)得的E值之間偏差不超過(guò)0.001D如圖84所示。⑤孔板出口錐面粗糙度為。⑥孔板開(kāi)孔圓筒形直徑d的加工誤差為0.0005d。ρ—工作狀態(tài)下孔板上游取壓孔處的瓦斯密度kgm3。流量系數(shù)α與孔板直徑比及雷諾數(shù)ReD有關(guān)，可查表84求得。ReD=354103MDε。式中：：M—工作狀態(tài)下的質(zhì)量流量kgh；ε—工作狀態(tài)

4、下瓦斯的動(dòng)力粘度，PaSo見(jiàn)表85。D和D2取壓孔板適用的最小雷諾數(shù)ReDmin見(jiàn)表86。表84D和D2取壓孔板的流量系數(shù)ReDβ10421043104510471041051061071080.230.240.260.280.300.320.400.420.440.460.480.500.520.540.560.580.600.620.640.660.680.700.720.740.760.780.800.5990.6000.6020

5、.6030.6050.6070.6170.6210.6240.6280.6330.6370.6430.6490.6550.6620.6710.6800.6900.7100.7140.7280.7450.7640.7860.8120.8430.5980.5980.5990.6010.6030.6040.6140.6170.6200.6240.6280.6330.6380.6430.6490.6560.6640.6720.6820.6930

6、.7050.7180.7340.7520.7720.7970.8250.5970.5970.5990.6000.6020.6030.6120.6150.6180.6220.6260.6300.6350.6410.6470.6530.6610.6690.6780.6890.7010.7140.7290.7460.7560.7900.8170.5960.5970.5980.5990.6000.6020.6110.6140.6170.6200

7、.6240.6280.6330.6380.6440.6510.6580.6660.6750.6850.6970.7090.7240.7410.7600.7830.8090.5960.5960.5970.5980.6000.6010.6100.6130.6160.6190.6230.6270.6320.6370.6430.6490.6560.6640.6730.6830.6940.7070.7210.7380.7570.7790.8050

8、.5950.5960.5970.5980.5990.6010.6070.6120.6150.6180.6220.6260.6310.6360.6410.6480.6550.6630.6710.6810.6920.7050.7190.7350.7540.7760.8010.5940.5940.5950.5960.5980.5990.6070.6090.6120.6150.6190.6230.6270.6320.6370.6430.6500

9、.6570.6660.6750.6860.6970.7110.7260.7440.7640.7880.5940.5940.5950.5960.5970.5980.6060.6080.6110.6140.6180.6210.6260.6300.6360.6420.6480.6560.6640.6730.6830.6950.7080.7230.7410.7610.7840.5930.5940.5950.5960.5970.5980.6050

10、.6080.6110.6140.6170.6210.6250.6300.6350.6410.6480.6550.6630.6720.6830.6940.7070.7720.7400.7590.783表85在0℃和1標(biāo)準(zhǔn)大氣壓時(shí)甲烷與空氣的混合氣體動(dòng)力粘度表甲烷濃度%012345678901020304050607080901.75301.68751.62101.55371.48511.41551.34481.27311.20021.12

11、601.74651.68091.61431.54671.47821.40851.33771.26581.19271.11831.74001.67431.60781.54011.47121.40141.33071.25891.18521.11111.73351.66771.60091.53311.46441.39451.32341.25111.17791.10361.72701.66101.59431.52641.45751.38741.

12、31641.24421.17071.09611.72051.65451.58751.51941.45051.38041.30901.23671.16331.08861.71371.64761.58081.51261.44341.37331.30201.22941.15581.08091.70941.64111.57401.50571.43651.36621.29471.22211.14851.07351.70061.63441.5672