News on Pressure Testing Services

Small Parts Pressure Testing & Autofrettage for Diesel Engines

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AutofrettageHarwood Engineering has supplied pressurizing equipment for autofrettage service since its inception in 1948. Generally, the requirement has been for the autofrettage of large steel forgings. Recently, however, we have developed a system for the pressure testing and autofrettage of small parts, such as diesel nozzles and manifolds for diesel engines.

 

The system, as far as the pressure generation is concerned, is quite automated – once the pieces to be autofrettaged are connected to the output of the system, the operator presses “start” and the system will generate the necessary high pressure, hold it for a predetermined time, and release the pressure.

 

The unit shown in the photograph has a 5 horsepower hydraulic drive, and requires 3 phase power, “shop” air, and cooling water for its operation. The unit requires a floor space of 50” x 58” and stands 76” tall.  If desired, it can be supplied with casters with brakes (this adds about 6” to the height) for improved mobility in the plant. This particular unit (pictured here) uses a Harwood SA6 type intensifier to deliver 3.6 in3 per stroke at 150,000 psi. Other sizes are available.
For more information or for any questions, please contact us via the website contact form or call us.


A Contemporary Version of the Bridgeman-Birch 30 Kilobar Apparatus

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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 30 kb, in some cases extending the temperature range.

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Hydraulically Driven Pumps

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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, which result in less maintenance and longer life. Without rotational inertia, controllability is increased which in turn increase safety.

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Piston Gauges as a Precise-Measuring Instrument

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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 those resulting from elastic distortion.  A check list of errors inherent to piston gauges is presented.

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