How to Select the Right Sight Glass?

A. Villafranca
Aug 4
2 min read

Source: Blog 5 Things to Consider When Picking a Sight Glass (2016), LJ Star.

Choosing the right sight glass to monitor the production line for pharmaceutical and food industry processes, is essential to ensure the safety, performance and durability of the production line.

Sight glasses are essential accessories or components that play a crucial role by providing real-time visibility in tanks, vessels, and process lines, making them indispensable for efficient operation. However, selecting the wrong option can lead to safety risks, operational inefficiencies, and unnecessary maintenance costs.

To select the appropriate sight glass and ensure maximum efficiency and safety, the following points should be considered:

Process Requirements:

It is important to take time to thoroughly evaluate the specific requirements of the process, considering factors such as the type of fluid, environmental conditions, and possible fluctuations like temperature and pressure. This is crucial to select a sight glass capable of withstanding the system’s maximum limits and to ensure optimal performance, resisting wear and operational conditions over time.

Type of Glass:

The type of glass plays a key role in the performance of a sight glass:

Soda glass is suitable for low-temperature applications with no drastic temperature changes.
A borosilicate glass tube can withstand temperatures of up to 260°C.
For highly aggressive chemical environments, METAGLAS by LJ STAR offers exceptional corrosion resistance, while maintaining clarity and durability under extreme conditions.
For extreme temperatures, quartz and sapphire glass are excellent alternatives.

Integrating Remote Monitoring and Cameras:

Para mejorar el monitoreo y optimizar la eficiencia operativa, se puede considerar integrar cámaras con su mirilla, permitiendo visibilidad en tiempo real y reduciendo el riesgo de errores humanos, además de proporcionar imágenes detalladas sin que los trabajadores ingresen a áreas peligrosas.

Safety Standards:

Es necesario asegurarse de que la mirilla cumpla con los estándares de seguridad, certificados de calidad y requisitos normativos necesarios para el tipo de ambiente en el que se utilizará.

Additionally, the following mistakes should be avoided when selecting a sight glass:

Failing to consider process changes and upgrades: Industrial processes evolve, so sight glasses should not be selected based only on initial process conditions.
Picking based on price: Cheap sight glasses may not meet required safety and quality standards, leading to frequent failures and higher maintenance costs. Quality is non-negotiable and comes at a price—investing in reliable equipment that reduces long-term maintenance expenses is the best decision.
Ignoring safety regulations: Non-compliance can result in serious hazards, injuries, and legal consequences.
Overlooking installation details and gasket compatibility: Since connection type affects pressure limits, the appropriate connection (flanged, weld-on, clamp, or bolted) must be selected according to installation specifications. Additionally, the gasket material must be chemically compatible with the process fluid to prevent leaks and ensure proper operation.