Conversion of Gate Valve into a Flow Measuring Device

A gate valve is traditionally used for controlling discharge in pipes. It is operated by rotating a wheel provided on top of a stem which is connected to a circular disc (i.e. gate) on the other side. Every single rotation of the wheel produces specific linear movement of the disc, which in turn tends to change the area of flow. It is expected that for the same disc position discharge should be the same, but analysis showed that the discharge varied considerably. Further analysis revealed that it occurs on account of the fluctuating separation zones formed on either side of the disc. To address this issue, it is proposed to use a flexible membrane pipe inside the gate valve. This membrane will not allow the separation zones to form, as its shape will automatically adapt depending upon the disc position and intensity of discharge. It is similar to that of a venturimeter with dynamically changing convergent and divergent cones. With this novel adaption, an experimental set-up with 65 mm acrylic pipe was used. The results have shown good improvement in the relationship between disc position and discharge. Further, it has been calibrated with respect to rotation angle of the wheel. The experimental study has shown that the modified gate valve can also be used as a flow measuring device. This communication describes the conversion of a gate valve from flow control device to flow measuring device.