计量孔板由铸铁法兰，密封垫，孔板（铸铁或不锈钢）组成。
They are built with cast iron flanges, gaskets and orifice plates (either mild steel or stainless).
天然气计量现在仍以差压式流量计中的孔板流量计为主。
The metering of natural gas still presently depends on orifice flowmeter, one of differential pressure flowmeters.
仪器重量轻，操作简便，便于携带，是深孔加工行业质量检测部门不可多得的实用计量仪器。
This instrument is greatly welcomed by quality test department of deep-hole process industry because of its light weight, simple operation and convenient carrying.
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