Tank Sight Glass type 225 | Noris

Tank Sight Glass Noris Type 225

The Noris Bauform 225 is a longitudinal rectangular sight glass designed for direct welding onto tanks, vessels, and silos. It is intended for local visual observation of liquid level or interface, not for continuous level measurement or remote indication.

Operating Conditions

• Design pressure: 3 / 6 / 25 bar
• Temperature: 100 °C or 280 °C (depending on version)
• Connection: welded mounting to tank shell
• Glass: borosilicate per DIN 7081 or soda-lime per DIN 8903
• Sealing: asbestos-free as standard; alternative materials on request
• Body/Cover materials: WN 1.4571 (stainless) or RSt 37-2 / H II (carbon steel)
• Bolting: A4-70 stainless or 8.8 galvanized

Viewing Dimensions

Visible area depends on pressure class. At 3 bar, viewing width is 50 mm; at 6 bar, 30 mm; at 25 bar, 20 mm. Typical viewing lengths range from 126 mm to 690 mm, subject to pressure and installation size.

Typical Applications

• Storage tanks and process vessels
• Silos requiring side inspection
• Monitoring liquid surface, foaming, or deposits
• Installations needing a larger viewing field than circular sight glasses

Selection Criteria

Type 225 is selected where an elongated viewing area with welded integration is required. Pressure rating directly affects glass geometry and available optical opening. After welding, sealing surface flatness must be verified and re-machined if necessary. Prior to operation, reinforcement strength of the opening must be checked per TÜV leaflet B9 / AD Merkblatt B9.

FAQ

Is an actuator required?
No. This is a static visual inspection device with no moving parts.

When is it preferred over Type 220?
When an elongated viewing slot is needed and 3, 6, or 25 bar versions are required.

What is checked during maintenance?
Glass, gaskets, bolts, sealing surface, and signs of leakage after thermal cycles.