Apparatus for measuring a gas mass flowing per unit of time through a pipe.

摘要

An apparatus for measuring a gas mass flowing through a pipe per unit of time comprises a constriction (5) into which a pin (6) is inserted which may be moved a greater or lesser distance into the constriction thereby varying the smallest section of the constriction. The constriction is intended for the passage of gas through it at sonic speed. If the area of the sonic section and the nature of gas are known, only the total pressure and temperature will have to be measured in order to enable the mass flow to be calculated. For an accurate measurement of the total pressure and upstream of the constriction the gas should have come to rest. Therefore upstream of the constriction a stilling chamber 7 of relatively large section is disposed and this stilling chamber contains the means (8, 9) for measuring the temperature and pressure. Further the constriction is bounded by a truncated De Laval jet pipe (4).