The Flow-Measuring Apparatus is designed to accustom students to typical methods of measuring the discharge of an essentially incompressible fluid, whilst at the same time giving applications of the Steady-Flow Energy Equation (Bernoulli's Equation). The discharge is determined using a venturi meter, an orifice plate meter and a rotameter. Head losses associated with each meter are determined and compared as well as those arising in a rapid enlargement and a 90-degree elbow. The unit is designed for use with the TecQuipment HI Hydraulic Bench, which provides the necessary liquid service and gravimetric evaluation of flow rate. 1.1 Description of Apparatus Figure 1. Flow measuring apparatus.
The TecQuipment HI0 Flow-Measuring Apparatus is shown Figure 1. Water from the HI Hydraulic Bench enters the equipment through a Perspex venturi meter, which consists of a gradually-converging section, followed by a throat, and a long gradually-diverging section. After a change in cross- section through a rapidly diverging section, the flow continues along a settling length and through an orifice plate meter. This is manufactured in accordance with BSI042, from a plate with a hole of reduced diameter through which the fluid flows.
Following a further settling length and a right-angled bend, the flow enters the rotameter. This consists of a transparent tube in which a float takes up an equilibrium position. The position of this float is a measure of the flow rate.
After the rotameter the water returns via a control valve to the Hydraulic Bench and the weigh tank. The equipment has nine pressure tappings as detailed in Figure 2 each of which is connected to its own manometer for immediate read out.
Figure2. Explanatory diagram of a flow measuring apparatus.
1.2 Installation and Preparation a) To fit the rotameter float, remove the control valve support nut, top 'U' clamp assembly