One. Foreword

Device of standard of discharge of gas of standard watch law is to use device of more aeriform discharge standard, especially the manufacturing company of a few flowmeter builds this standard plant more. As speed of Chinese city industrialization accelerate, supply of the requirement of urban environmental protection and urban natural gas, vapour increases increasingly, uses aeriform flowmeter caliber is bigger and bigger. It is difficult that the calibrating of large requirements flowmeter reachs what the standard expresses to trace to the source to exist at present show.

But the kind that if use shunt-wound use level,expresses, use on curve of standard flowmeter calibrating one only finite paragraph, accuracy of standard flowmeter demarcate can rise. Also can make be achieved by the discharge limits of check flowmeter likewise demand. Use watch of shunt-wound type standard to be in as device of aeriform desired result already had wide application domestic and internationally, if home uses device of extensive standard of discharge of nozzle law gas,use shunt-wound means namely; The turbine flowmeter that the natural gas fact with the biggest North America that 90 time Canada builds 20 centuries sheds desired result unit is 6 DN400 and 2 DN200 comes as standard watch all sorts of caliber flowmeter under desired result DN750.

Shandong churchyard has flowmeter of tens of domestic eddy street to produce a business, use eddy street flow transducer to build list of shunt-wound type standard in recent years

Field of plant of calibrating of law gas discharge also accumulated a few experience, shunt-wound kind is having its advantage on flowmeter of desired result large requirements.

2. Fundamental

The accuracy of flow transducer of aeriform eddy street is commonly on the level of 1.5 class of 0.5 class ～ , cannot use as sensor of 0.5 grade level, should use on curve of calibrating of standard flow transducer one only finite paragraph when. Accuracy of standard flowmeter demarcate can get rising. Calibrating of same in order to also can be raised by the accuracy of check flowmeter. In this one finite the error of the will be less than appearance coefficient relative to the error full span that measures K of coefficient of the appearance inside limits.
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