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  • Tubular Sight Glass

  • 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.

    Keystone Steam Supplies provides tubular gauge glass in both red-line and clear patterns with heavy wall and high-pressure varieties. Heavy wall is available with O.D.'s of 3/4" and 5/8" and high pressure is available with O.D.'s of 1/2", 3/4" and 5/8". In all cases, the glass can be cut to length to match your specifications.

    NOTE: Once glass has been cut it can no longer be returned. Stock lengths (36" and 48") may be returned if in good condition.

    We also sell tubular sight glass cutters.

    You can see the pictures below for an accurate depiction of what each type of sight glass looks like.

  • When Should You Use Each Type of Tubular Sight Glass?

  • High Pressure:

    • Used where pressure and glass lengths fall outside of the design parameters for High Pressure Glass but within the parameters for Heavy Wall Glass. Use when you want a more durable product that will need less maintenance and replacing.

    Heavy Wall:

    • Use when you have a higher steam pressure and you need a product able to withstand more pressure.
    • Use when you want a more durable product that will need less maintenance and replacing.

    Clear Sight Glass:

    • Use when you have a better close-up view of the sight glass.
    • Use when you don't need to easily see the water level inside your tank or boiler.

    Red-Line Sight Glass:

    • Use when you want an easy way to gauge the current water level inside your tank or boiler.
    • Applications: Tanks, reservoirs, low pressure boilers.
    • Benefits: The red line shaded with white lines make it easier to read the liquid level.

    Finally, do you want the best protection for both your tubular sight glass and and your boiler room personnel? Check out our exclusive Gauge Glass Guardian; polycarbonate tubing. Designed to prevent your tubular sight glass from accidentally shattering and to protect anyone nearby from scalding steam and hot water, should a malfunction occur with either the tubular glass or gauge valves. 

    For Detailed information and specs on High Pressure & Heavy Wall, Clear & Red Line Tubular sight glass, please click the button below. You can also right-click and choose "Save As" to save the PDF to your computer.

    Product Specs

  • Keystone Steam Supplies is here to help you with your tubular sight glass needs.