Gate valves with indicator scales usually refer to valves equipped with a device that can visually display the degree of valve opening (degree of opening).

The standard gate valve itself does not have a scale: when operating a regular gate valve (through handwheel, gearbox, electric actuator, etc.), the operator can only judge whether the valve is fully open, fully closed, or in a certain intermediate state based on feeling or experience, and cannot accurately know the specific position of the valve disc (gate) inside the valve body (i.e. opening percentage).
The function of indicator scale: The function of "with indicator scale" is to solve this problem. It converts the linear displacement of the gate valve stem (the key component that drives the up and down movement of the gate) into a visible, usually graduated indicator through some mechanical means. The operator can directly read the scale to understand the current opening of the valve (such as fully closed 0%, 50% opening, fully open 100%).

Implementation method:
Directly engraved on the stem nut/bracket: For some small-diameter gate valves with relatively short stroke (stem lifting distance) and structural allowance, sometimes a scale line is directly engraved on the bracket or valve cover that fixes the stem nut, and there will be a pointer or marking line on the upper end of the stem (or the lifting component connected to it). As the valve stem rises and falls, this pointer/marking line moves on the scale to indicate the opening. This method has the simplest structure, but its accuracy and visibility may be limited, and it may not be suitable for longer journeys.
Specialized opening indicator component: This is a more common and reliable method (especially for medium to large diameter and long stroke gate valves). It is an independent mechanical device that typically includes:
Transmission mechanism: connected to the valve stem (or valve stem nut), converting the linear motion of the valve stem into rotational motion (such as through rack and pinion gears, screw nuts, and connecting rods).
Dial/Indicator: A circular dial or rectangular scale with 0% -100% scale.
Pointer/Indicator: Driven by a transmission mechanism, it moves on the dial to accurately indicate the opening.
Indicator bracket/housing: Fix and protect the internal mechanism, and install it in the appropriate position on the valve body or valve cover.