VE4002S1T1B2
样本计算以下计算是在60°F（16°C）和500 psig（34.47 barg）条件下测量分子量为19.5的CMF300M天然气的大建议气体质量流率的示例：（ݏܽ݃）ṁ =0.3*24（݇݃/݉3）*430（݉/ݏ*（1 4π*.0447݉2*2（ݏܽ݃）ṁ =34988千克/小时；CMF300M管道内径44.7 mm零稳定性当流量接近流量计精度开始偏离的流量范围低端时，使用CMF300M管道内径44.7 mm零稳定性根据规定的精度等级，如turndown部分所述。当在流量计精度开始偏离规定精度额定值的流量下运行时，精度由以下公式决定：精度=（零稳定性/流量）x 100%。重复性同样受到低流量条件的影响。下表和图表显示了各种流量条件下的测量特性示例。在需要大幅度调节（大于30:1）的流速下，零稳定值可能开始控制性能，具体取决于使用的流量条件和流量计。60.1 30:1 10:1 2:1 B A C 0.1 0 0 10 20 30 40 50 60 70 80 90 100 0.5 0.4 0.3 0.2 4.0 0 0 20.0 16.0 12.0 8.0 A.精度，%（蓝线）B.流量，%标称C.压降；psig，barg（红线）准确度和流量压降样本

Sample calculation The following calculation is an example of the maximum recommended gas mass flow rate for a CMF300M measuring natural gas with a molecular weight of 19.5 at 60 °F (16 °C) and 500 psig (34.47 barg): (ݏܽ݃)ṁ  =  0.3 * 24 (݇݃/݉3 ) * 430 (݉/ݏ * (1 4 π  * .0447݉2   *  2 (ݏܽ݃)ṁ  =  34,988 kg/hr; maximum recommended rate for CMF300M with natural gas at given conditions %M 0.3 (used for calculating maximum recommended rate) Gas density 24 kg/m3 VOS(NG) 430 m/s (Velocity of Sound of natural gas at given conditions) CMF300M tube ID 44.7 mm Zero stability Zero stability is used when the flow rate approaches the low end of the flow range where the meter accuracy begins to deviate from the stated accuracy rating, as depicted in the turndown section. When operating at flow rates where meter accuracy begins to deviate from the stated accuracy rating, accuracy is governed by the formula: Accuracy = (zero stability / flow rate) x 100%. Repeatability is similarly affected by low flow conditions. Turndown The graph and table below represent an example of the measurement characteristics under various flow conditions. At flow rates requiring large turndowns (greater than 30:1), the zero stability values may begin to govern capability dependent upon flow conditions and meter in use. 60.1 30:1 10:1 2:1 B A C 0.1 0 0 10 20 30 40 50 60 70 80 90 100 0.5 0.4 0.3 0.2 4.0 0 20.0 16.0 12.0 8.0 A. Accuracy, % (blue line) B. Flow rate, % of nominal C. Pressure drop; psig, barg (red line) Sample of accuracy and pressure drop across flow rate