Sight Glass Designs and Applications in Industrial Sectors|
Article - July 17, 2017 By LarsonElectronics.com
Sight Glass Designs and Applications in Industrial Sectors
Monitoring operations in real-time comes with several benefits for industrial processing facilities. By having the ability to check on critical parts of operations, such as pipes, storage tanks, nuclear reactors, and mixing containers, it would be possible to catch issues before they escalate or spread to other sections of the site.
From cameras to sensors, there are a handful of different ways to streamline monitoring. One of the most straightforward ways to monitor liquids and potentially harmful substances in a safe manner includes the use of sight glasses.
Read on to learn more about the viewing apparatus and its importance in industrial processing.
What is a Sight Glass?
By definition a sight glass is a heavy-duty viewing panel that typically takes on the form of a cylindrical or circular window, which can be very short, long, wide or narrow – depending on its intended application. When found in pipelines, the sight glass is part of the component, allowing liquids to pass through. Due to direct, continuous exposure with potentially hazardous elements, chemicals and pressure, the units are made out of resilient material, such as 316 stainless steel, bronze, iron and thick borosilicate glass, quartz disc or sapphire for clarity. For less intense applications, fused soda lime glass may be used. These components support temperature thresholds between 300°F and 500°F.
When used as indicators, sight glasses may include gauges or lines for accurate measuring. Furthermore, a colored or striped background may be used to improve visibility, making it easier to view fluid levels and markers. They can also be applied to verify flow rates, direction of flow and quality. It is possible to have multiple viewing windows or a fully transparent design for a complete, 360-degree view.
At a very basic level, sight glasses can be found in mainstream products, such as lawn mowers and boats. Fuel containers have a faded sight gauge that can be used to quickly determine the amount of gas inside the unit. Commercial espresso machines come with sight glasses for viewing and adjusting pressure levels during operation. Compared to industrial sight glasses, such components are not as sturdy, as low-cost materials are used, such as plastic, to drive adoption.
Designs and Types of Sight Glasses
As mentioned earlier, sight glasses take on different shapes and sizes, ranging from 0.25 inches to 16 inches (long or wide). During construction, the glass component is fused to the frame (usually metal) for extra durability, forming a single unified piece. Because glass is stronger when it is compressed (compared when it is to tensioned), the viewing panel can take persistent exposure and rough handling at the work site.
The way the units are structured heavily depends on their use and the environment. Below are some common types of sight glasses:
• Flat Sight Glass DIN 8050: This variant is supported by a DIN union, which secures the position of the glass viewing piece.
• Boiler Sight Glass: This contraption takes on the shape of a clear tube. As the name suggests, the component is utilized in commercial or industrial boilers for monitoring water levels.
• Clamp Flat Sight Glass: This type of sight glass features a clamp that is secured by a screw, mostly found in food and chemical processing.
• Double Window Sight Glass: Used for monitoring steam traps, this carbon steel unit has dual viewing options and female screwed or flanged connecting parts. Double window sight glasses also allow light to pass through for detailed screening. Inspectors could shine UV, infrared or colored lights to monitor different types of interaction with the liquid.
• Gauge Sight Glass: Applied to observe fluid levels in pipes or tanks. May contain ridges or markers.
• Columnar Sight Glass: Like a standard gauge sight glass but longer; used for monitoring oil volume and levels.
• Bull’s Eye Sight Glass: This variant is mounted horizontally to avoid the formation of traps in pipes.
Importance, Benefits and Applications
Industrial sight glasses are very effective tools for reducing errors (human and machine related) that arise from faulty sensors and careless oversight. For verification, inspectors could first check a digital reading of the pipe or container, then verify the reading manually by checking the sight glass. This process could be used to check on pressure, quality and direction of flow.
Another benefit of using a sight glass for monitoring is reduced exposure to the air or external environments. For example, using a dipstick to check oil levels exposes the inside of the vessel to foreign compounds. Should an inspector sneeze or accidentally spill water inside, it could contaminate the contents of the pipe. Using the same example, sight glasses add another layer of safety for inspectors. Such individuals are less prone to accidental contact when checking on hazardous liquids.
Sight Glass and Lighting
Some sight glasses incorporate a compact light in their design to improve viewing accuracy. The lamps could be halogen, LEDs or fluorescent. High CRI levels and proper color temperature settings must be used to ensure colors are properly discerned. This type of sight glass is useful for monitoring non-transparent or colored liquids. The luminary can be installed outside of the sight glass, with the light aimed into the pipe. It could also be installed inside the sight glass, with the light shining outwards or indirectly illuminating the background of the pipe. It is important to highlight that when sight glasses with lights are used in hazardous locations, the lighting component must be explosion proof.