Abstract: A method of correcting measurement errors of an instrument for measuring the flow of a gas, the instrument having a selected measuring range and being constructed to produce a reading indicating the value of a gas flow in the selected measuring range, by the steps of: selecting a limited number of gas flow values which are spaced apart across the measuring range; determining the readings produced by the instrument when the instrument is measuring gas flows at the selected values; measuring the flow of the gas with the instrument to produce a reading indicating the value of the gas flow; and producing a corrected reading by calculating a function of the reading produced in the measuring step and the readings produced in the determining step.

Abstract: A method and apparatus for calibrating a flow sensor composed of two heat sensors each having an electrical impedance parameter which varies as a defined function of the temperature of the heat sensor and disposed in thermal communication with a fluid such that the relation between heat flow to or from one sensor and heat flow to or from the other sensor varies with the rate of fluid flow, a source supplying electric power at a selected level to the heat sensors, and an output device connected to produce an output signal representative of that heat flow relation, calibration being performed by: establishing a known flow rate for the fluid; electrically connecting one of the heat sensors to a circuit element which alters the magnitude of current flowing through the one heat sensor; and determining, in a first determining step, output signal value while the one heat sensor is electrically connected to the circuit element.

Abstract: A disconnectable flow connector is formed of (a) a frusto-conical taper pin having a longitudinal bore through which the end portion of a flow tube of a mass flow sensor is inserted and secured and (b) a connector base containing a matched frusto-conical taper bore. The taper pin can be press-fit into the taper bore to form a fluid flow passage having a leakage level less than about 10.sup.-9 scc/sec helium. with a series of spaced apart, transverse grooves separated by lands in sealing engagement with the matched taper bore.

Abstract: A hermetically sealed, precision fluid valve assembly including a ball valve element is disclosed. The assembly includes a valve element retainer comprising a thin, flexible member having a first portion operatively associated with the valve element and a second portion, extending from the first, secured to the body of the valve assembly. The valve element retainer guides the motion of the valve element and is designed to reduce friction and eliminate the generation and entrapment of contaminants, thereby minimizing hysteresis in the operation of the valve.