Manual balancing valve

A method for controlling flow rate across a manual balancing valve, the method comprising:

• providing a butterfly valve comprising a valve body having an axially extending fluid passage defining an upstream end and a downstream end and comprising a valve body having a valve seat and a valve disc configured in the valve body, the valve disc being pivotally mounted to the valve seat with the help of a valve shaft and adapted to rotate with the shaft so as to attain an angular orientation, relative to the valve seat, between a position substantially perpendicular to the valve seat and another position substantially parallel to the valve seat for controlling flow of fluid through the valve body, and a gear box coupled to the valve disc, the gear box being adapted to set a value for the angular orientation of valve disc relative to the valve seat, and lock the set value to prevent alteration thereof;
• configuring a first equalizing ring and a second equalizing ring at the upstream end and the downstream end, respectively, for providing static pressure value at each of the ends, each of the first and the second equalizing rings comprising an annular body defined between an inner peripheral edge portion and an outer peripheral edge portion, an annular chamber configured adjacent to the inner peripheral edge portion, a plurality of holes configured on the inner peripheral edge portion, the holes being in fluid communication with the annular chamber and extending into the annular chamber, and a pressure tap configured in fluid communication with the annular chamber and extending radially outward of the annular body;
• setting the angular orientation of the valve disc to a desired value;
• determining differential pressure between the upstream end and the downstream end by measuring static pressure using the first equalizing ring and the second equalizing ring;
• computing fluid flow rate across the valve based on the differential pressure and the angular orientation of the valve disc so as to control the fluid flow rate through the manual balancing valve;
• and
• manually adjusting the angular orientation of the valve disc by rotating the valve shaft until the computed fluid flow rate reaches a desired value.

An equalizing ring adapted to enable measurement of static pressure at a pre-determined position, the equalizing ring comprising:

• an annular body defined between an inner peripheral edge portion and an outer peripheral edge portion;
• an annular chamber configured adjacent to the inner peripheral edge portion;
• a plurality of holes configured on the inner peripheral edge portion, the holes being in fluid communication with the annular chamber and extending into the annular chamber;
• and
• a pressure tap configured to be in fluid communication with the annular chamber and extending radially outward of the annular body for enabling determination of static pressure at the pre-determined position.