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Scraper Sight Glass: A Observation Tool for Ensuring the Work Safety & Quality of Industrial Containers

Flange scraper sight glass on the white background
Scraper sight glass

Scraper sight glass is a kind of flat sight glass, also known as a scraping plate sight glass or brush sight glass. It is commonly used in petroleum, chemical, food and other industries. It is primarily used to observe and monitor the working reaction of the medium inside the containers to ensure production safety and product quality.

The unique scraper design allows it to be applied in media with high viscosity. It effectively cleans the surface of the sight glass from substances and deposits without stopping the machine or affecting the production progress. This not only ensures a clear observation field, but also improves the production efficiency. Additionally, the sight glass is made from corrosion-resistant materials, allowing it to adapt to various working environments with different mediums. We can also customize the size and shape of the container according to your requirements to meet specific process needs.


  • Compact structure. Elaborate design and small footprint.
  • Enhanced efficiency. You can use the handle to clean the dirt on the glass directly without interrupting the work.
  • Good sealing performance. High-quality sealing materials are adopted to ensure good sealing performance of the equipment under various working conditions.
  • Low temperature resistance. It can work normally even in low temperature and have good anti-freezing performance.
  • Safe and reliable. It undergoes strict quality control and testing to ensure the stability and reliability of the equipment.

Technical Data

  • Body material: carbon steel WCB, stainless steel 304, 316, 316L
  • Window material: tempered borosilicate glass, quartz glass
  • Seal material: NBR, PTFE, high temperature graphite
  • Operating pressure: 0–2.5 MPa
  • Operating temperature: 0–550 °C (Asbestos gasket or PTFE gasket is enough for ambient working temperature within 280 °C; graphite gasket is recommended when the ambient working temperature exceeds 500 °C. Note: The thicker the glass, the thickness of the gasket should be increased accordingly.)


A simple scraper sight glass drawing with marks
Table 1: Specifications of Scraper Sight Glass
80 95 × 10 126 10 16 110
100 115 × 12 146 10 16 130
130 15 0× 15 182 10 16 166


  • To ensure the safe transportation of the brush sight glass, the scraper assembly is debugged on the lens, and then disassembled and packaged separately for shipment. The user should assemble the scraper assembly first after welding the edge flange and then install the lens.
  • Cleaning treatment. Before use, you can lightly wipe the surface with a sufficient amount of alcohol cotton. Avoid using acid-containing liquids for cleaning, so as to not to corrode the outer surface of the glass and scraper.
  • Choose the right gasket. Asbestos gasket or PTFE gasket is enough for ambient working temperature within 280 °C; graphite gasket is recommended when the ambient working temperature exceeds 500 °C. Note: The thicker the glass, the thickness of the gasket should be increased accordingly.
  • Apply force evenly. During installation, avoid applying excessive force. It is recommended to tighten the screws evenly in a diagonal way.
  • Regular inspections. When the sight glass installation is finished, regular inspections must be carried out, especially in environments with acidic or alkaline liquids. It is important to regularly check the degree of corrosion on the glass surface to ensure safety.

Maintenance & Care

  • Sight glass is a reaction equipment used to observe the flow of media such as liquids, gases and steams. The window glass should be kept clean and dust-free.
  • The window glass of the sight glass is a fragile part, so it should be handled with care during installation.
  • The temperature and pressure resistance of the sight glass are limited. Temperature resistance: borosilicate glass ≤ 250 °C, quartz glass ≤ 800 °C. Pressure resistance: borosilicate glass ≤ 2.0 MPa, quartz glass ≤ 4.0 MPa, ordinary soda-lime glass < 0.6 MPa.
  • Allowable rapid temperature change < 60 °C, the glass will be ruptured due to excessive temperature difference.


  • Weakly corrosive materials in chemical and petrochemical production, such as water, ammonia, oils, hydrocarbons, etc.
  • Strongly corrosive materials in chemical production, such as caustic soda, concentrated and dilute sulfuric acid, carbonates, acetic acid, esters, etc.
  • Low-temperature materials in refrigeration, such as liquid methane, liquid ammonia, liquid oxygen, and various refrigerants.
  • Materials with hygiene requirements in light industry, food, and pharmaceutical production, such as beer, beverages, dairy products, granular pharmaceuticals, etc.
The application of scraper sight glass in the pharmaceutical industry
For pharmaceutical industry
The application of scraper sight glass in the reactor
For chemical production

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