An orifice plate is to be used in conjunction with a differential pressure transmitter to measure the flow rate of water in a 0.15 m diameter pipe. The maximum flow rate is 50 m3 h-1, the density of water is 103 kg m-3 and the viscosity is 10-3 Pa s.
(a) Explain why an orifice plate meter is suitable for this application.
(b) Estimate the required orifice plate hole diameter if the transmitter has an input range of 0 to 1.25 x 104 Pa.
A turbine flowmeter consists of an assembly of four ferromagnetic blades rotating at an angular velocity ω rad s-1 given by:
ω= 4.5 x 104 Q
where Q m3 s-1 is the volume flow rate of the fluid. The total flux N linked by the coil of the magnetic transducer is given by:
N= 3.75 + 0.88 cos 4θ milliwebers
where θ is the angle between the blade assembly and the transducer. The range of the flow-meter is 0.15 x 10-3 to 3.15 x 10-3 m3 s-1.
Calculate the amplitude and frequency of the transducer output signal at minimum and maximum flows.