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The Problem – Measuring Hydraulic Transients What happens when the flow of a liquid is suddenly stopped? A hydraulic transient pressure occurs when the kinetic energy of the moving column of liquid is discharged into the surrounding piping. Transients can be very destructive; there are cases where storm drainage systems, overloaded by a sudden downpour, have been severely damaged. Process piping can also be damaged by hydraulic transients resulting from a suddenly closed valve. The creation and measurement of hydraulic transients in the laboratory is an important field of study. Transients can last just a few milliseconds or continue for several minutes, depending on the size of the hydraulic system under test. Accurate measurement of the pressure increase during a transient event is of critical importance.
The Solution Transducers used in hydraulic transient studies must have a fast response to changes in pressure. Validyne variable reluctance sensors have only a single moving part, the sensing diaphragm. The diaphragm is free to move quickly as the pressure changes; there are no linkages or other mechanical connections to slow the sensor down. Additionally, variable reluctance sensors have extremely small displacement volumes. The DP15 for example, needs just 6 x 10-4 cu inches of fluid to go from 0 to full scale reading. The combination of small displacement volume and only a single moving part makes the variable reluctance sensor ideal for measuring rapidly changing pressures. The DP15, for example, can accurately respond to a pressure wave changing at the rate of 300 times per second.
Validyne Products The Validyne DP15 transducer combined with the CD15 demodulator is the combination most typically used in transient testing up to 3000 psi. For higher pressures, models DP360 and DP363 have ranges available to 10,000 psi.
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| Phone: 818.886.2057 || Email: Sales@validyne.com |
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