Abstract: Method and system for sampling and determining chemical substances such as blood gases, in a fluid matrix, such as blood, by bringing the chemical substances into equilibrium with a liquid in a fiber probe, passing the equilibrated liquid to a sensor adjacent the equilibrium region and on into a hollow fiber line enclosed in a calibration chamber. Calibration of the sensors is accomplished by reversing the flow of liquid from the hollow fiber line to the sensors. In the system chemical substances for sensor calibration are provided by an electric proportioner whose output is continuously controlled by the output of the sensors such that the substances proportioned into a fluid in the calibration chamber surrounding the hollow fiber line are substantially the same as the substances within the matrix. The concentration of substances is determined by the output of the sensors and the amount of substances fed from the proportioner to the fluid surrounding the hollow fiber line.

Abstract: A piston rod having a variable volume auxiliary chamber extends into a primary chamber in a casing. Normally open valve means are arranged between the primary and auxiliary chambers which are filled with a compressible medium and which are in communication when the shock absorber is at rest. The variable volume auxiliary chamber accommodates changes in volume of the compressible medium resulting from changes in temperature of the medium. When impact forces are imposed on the piston rod, initial movement of the piston rod closes the valve means and subsequent movement of the piston rod into the primary chamber reduces the volume of the compressible medium therein thereby effecting energy absorption.