Sight Glass, Polycarbonate and Accessories

Find everything from tubular sight glass, to gauge glass guardian, and all the associated products and accessories.

Tubular sight glass (also called ‘tubular gauge glass’) is found on the outside of a boiler or tank and it provides a simple and efficient way to view the liquid level within the structure. It fits between an upper and lower gauge glass valve which in turn is mounted on the structure.

Gauge Glass Guardian, sold exclusively through Keystone Steam Supplies, is your safeguard against personal injury, which could be caused by the accidental breakage of tubular Gauge Glass and the leakage of steam or hot water that occurs as a result.

Reflex sight glass (‘B’ Series) is a molded glass section that is available in various lengths and which has a smooth exterior (room) side and a grooved interior (liquid) side.

Flat sight glass (‘A’ Series) is a molded glass section that is available in various lengths. This glass is completely flat on all sides. 

Polycarbonate tubing is a cost effective alternative to standard borosilicate sight glass in some non-boiler applications, coming in a range of diameters and wall thicknesses.

Sight glass cutters (also called “gauge glass cutters”) are used to trim pieces of tubular sight glass. Although Keystone does supply trimmed lengths of glass, if you frequently need various sizes of sight glass, purchasing your own cutter can be a good option. 

Liquid level gauge valve sets come in a variety of sizes, materials, and features. The most common sets are either 1/2″ threaded connections with 5/8″ O.D. Glass, or 3/4″ threaded connections with 3/4″ O.D. Glass.

Most gauge glass valve sets require either 2 or 4 guard rods which help protect against side impact and also help keep the valves aligned over the glass distance. Guard rods are made of either copper or stainless steel and can be cut to length for your specific needs.

Washers come in a variety of dimensions and materials depending on the valves they’re going into and other application factors.

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