VPI

calibration marking device for calibrating media blasting system metering valves, namely, a device in the nature of a scale that provides a visual indicator of how opened or how closed a valve is for use in monitoring the amount of abrasive media flowing through a valve and for accurately positioning the valve stem to control an integral component of manually adjustable fluid control valves for forcibly propelling a stream of abrasive material under pressure toward a surface to be cleaned or treated