EMCO Liquid Level Gauge – Series ET10. EMCO offers a wide variety of liquid level gauges to fit your need. Our level gauges can be equipped with transparent or reflex glass. Using the reflex glass, the day light is refracted in the prism when liquid is present and the liquid level is presented as a dark or black column. The liquid level indication can be improved for difficult to see liquids by applying an Illuminator. EMCO liquid glass level gauges are designed for direct observation of liquid levels in vessels, drums and other tanks where direct dependable observation is required for pressure ratings up to PN 40, 300 lbs.