Revised 01/19/12 1 ME 4232: Fluid Power Control Lab University of Minnesota Prof. Perry Y. Li Lab. 3: Pressure-flow relationship across a needle valve Objective To study and characterize a needle valve. A needle valve is an adjustable orifice used to vary the flow in different branches of the circuit. The pressure-flow relationship, i.e. the pressure across the valve and the flow through it can fully characterize a needle valve at a given setting. The circuit shown below can be used to obtain the pressure vs. flow relationship of the needle valve A by manipulating the needle valve B. Pre-lab exercise – Due as a hardcopy at the beginning of lab 1. Study the schematic above and describe in a couple of paragraphs how the settings of the two needle valves influences: a) the division of flow between valve A and valve B and b) the system pressure, P s . 2. What pressure-flow relationship do you expect for a needle valve? What assumptions are you making? Procedure
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