以前 ,测量天然气流量用的ＣＷＤ— 4 30型双波纹管差压计上、下流导压管路如图 1所示 ,已沿用了许多年。1996年底 ,我们将流量计导压管路作了局部改进 ,如图 2所示 ,增设了上下流放空阀和放空管 ,有利于粉尘或积液的收集与排放 ,避免了吹扫导压管时仪表室充满天然气 ,防止流量 Previously, CWD-4 30 dual bellows differential pressure gauges for measuring natural gas flow rates have been used for many years as shown in Figure 1 for the downstream pilot lines. At the end of 1996, we made a partial improvement on the pressure gauge pipeline of the flowmeter. As shown in Figure 2, an up-down flow vent valve and a vent pipe were added to facilitate the collection and discharge of dust or effusion, avoiding the purge pressure Tube chamber filled with natural gas to prevent traffic