The Sun Hydraulics DAAA valve is a 2- position, 2-way cartridge valve. When the solenoid is energized the valve switches from blocking the flow to a fully open flow. The data sheet is at www.sunhydraulics.com. Some of the key valve specs are: Max flow = .25 gpm (1 L/m), Max pressure = 5000 psi (350 bar), Response time = 30 ms. The figure below shows a photo of the valve, the valve schematic and the experimental pressure vs. flow characteristics for the valve in its open position. These are cartridge valves, designed to screw into a manifold with the solenoid on top. The following approximate data points can be read off the graph, in units of (gpm,psi): (0,0), (0.3,50), (0.5,100), (1,410). Assume that the data set is for water.
Find:
a) Find an equation that relates the loss coefficient KL with the data given in the figure. Can you calculate KL?
b) Valves are often characterized by the ?valve coefficient? Cv, defined in terms of specific gravity (SG), pressure drop, and flow rate
C_v=Q\sqrt{\frac{SG}{\Delta p}}
What are the dimensions of Cv, and how does this compare with KL? (hint: I am asking for dimensions, not units)
c) Can you calculate Cv for this valve (open) with hydraulic oil at specific gravity of 0.864? (hint: use units of gpm and psi for your final numerical answer, as this is standard practice in the fluid power industry).