Patent ID: 8219329
Filing Date: 2012-07-10
Classification: G01F,G05D

Abstract:
1. A thermal type mass flow meter including a thermal type mass flow sensor portion which is additionally provided to a main body block having a fluid flow path in an inner portion and has a flow rate measuring conduit connected to the fluid flow path in a parallel manner and having a pair of thermal type sensors, further including: means for storing a first measurement value of a flow rate of the fluid flow path and the flow rate measuring conduit at a time of depressurizing the fluid flow path and the flow rate measuring conduit to at least an atmospheric pressure or less and a second measurement value of a flow rate at a time of charging an actual fluid into the fluid flow path and the flow rate measuring conduit; correction value computing means for calculating a correction value based on the stored first measurement value at the time of depressurizing the fluid flow path and the flow rate measuring conduit to at least an atmospheric pressure or less, a difference between the stored first measurement value and the stored second measurement value at the time of charging the actual fluid into the fluid flow path and the flow rate measuring conduit, a kind of the actual fluid, a pressure at a time of charging the actual fluid, and a flow ratio of the fluid flowing in the fluid flow path and the flow rate measuring conduit; memory means for storing the correction value calculated by the correction value computing means; and output correcting means for correcting an actual measured output value at a time of flowing the actual fluid in the fluid flow path and the flow rate measuring conduit by the correction value read from the memory means.