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Technical Articles
January 19, 2016


Sight Glasses Provide Leak Monitoring in Dual Containment Piping System

Beneficial for Liquid & Gas Pipelines

Cedar Grove, New Jersey & Odessa, Texas — To satisfy a need for visual monitoring of leakage in dual containment systems, a petroleum plant has installed a series of Plast-O-Matic’s “sight glasses” in its diesel fuel piping. The devices, which are simpler and less expensive than other monitoring methods, provide instant visual confirmation of a leak in the primary pipeline.

The Sight Glasses are installed on 1/2″ connections at key points in the bottom of the outer containment pipe. In the event of a leak, the fuel will collect at the lowest point–the sight glass–and raise a day-glo float in the chamber. As the brightly colored float rises above a blackened portion of the sight glass, it creates instantly recognizable visual confirmation of the problem.

Constructed of corrosion-resistant Pyrex® on the inside wall and high-impact acrylic on the outside, the Plast-O-Matic sight glass meets the need for for dual containment throughout the system. O-rings allow the indicators to seal at low pressure as well as high pressure, an attractive feature for dual containment systems. A full 360° viewing area in the sight glass permits inspection from anywhere near the piping.

Please click here for an illustrated technical diagram of this application in .pdf format.

Useful in Many Applications

Plast-O-Matic’s sight glasses are designed to give instantaneous visual confirmation of pipeline flow. In another application, the sight glass is installed directly in a soil remediation system, where streamers within the chamber flutter when flow is present — please click here to view an illustrated technical diagram of the soil extraction application in .pdf format. It is also frequently used to visually confirm the presence of a process additive; in these cases the sight glass is installed downstream of an injection system. The sight glass is surprisingly rugged, and is available in pipe sizes from 1/2″ to 8″ NPT. Standard O-ring seals are of Viton or Buna-N.

The sight glasses, from Plast-O-Matic’s True-Blue line, are manufactured with PVC, Corzan® CPVC, Polypropylene, Kynar® PVDF or PTFE ends. Please click here for complete details.