Posts By: Harwood Engineering

A Contemporary Version of Bridgman-Birch 30 kb Apparatus This paper briefly describes the basic Harwood apparatus, particularly its deviations from the original Bridgman model and the elaboration thereof by Birch for uses with gases at high temperature.  Nearly all the physical measurements made by Bridgman at 12 kb can be made with this equipment at […]

Hydraulically Driven Pumps Excessive torque, side thrust, and friction make crank-driven pumps cumbersome and expensive at high pressures. But in hydraulically driven pumps, these effects are eliminated or minimized and higher pressures can be attained. Also, longer strokes are characteristic; therefore, rates of stress buildup are reduced in such areas as check valves and packings, […]

Piston Gauges as a Precise Pressure Measuring Instrument The errors which must be considered for accurate measurements of pressure with piston gauges are discussed. Harwood’s unique design of piston gauge which permits the operator to control the clearance between the piston and cylinder at any operating pressure is described. Instrument errors are thus substantially reduced, particularly […]

A Redetermination of the Freezing Pressure of Mercury A number of improvements in apparatus and technique have been made since the production of the prototype model of the controlled-clearance piston gage used by Johnson and Newhall in their 1953 determination of the freezing pressure of mercury at 0oC.