Miselli SM Series Oil Level Sight Glass

Description

Operating Principle

The Miselli SM Series Oil Level Sight Glass is designed to allow quick and accurate visual monitoring of fluid levels inside tanks, gearboxes, and hydraulic components. Its operating principle is based on the transparency of the sight window combined with a contrast screen positioned inside the metal body. This internal screen, made of aluminum and painted white, features a central logo or, alternatively, a red dot. This clear color contrast creates an optimal background that highlights the fluid line, allowing operators to read the hydraulic level immediately and reducing the risk of errors during routine maintenance inspections.

Construction Features

Mechanically, these level sight glasses feature a hexagonal-head design and a threaded connection for easy and stable installation. The range includes two main construction configurations:

• SM Series (Plastic Window): The main body is made of 2011 aluminum alloy. The transparent element is a polyamide resin sight window. Hydraulic sealing between the sight glass and the component wall is ensured by a flat sealing gasket made of Fasit 202 inorganic fiber. Depending on requirements, an aluminum gasket can be supplied on request.
• SM/HP Series (High Performance): Specifically designed to withstand higher mechanical stress, this version uses 115 aluminum alloy for the external body. Unlike the standard series, it features a natural glass window and an internal FKM VITON elastomer O-ring for sealing. This configuration also uses a flat inorganic fiber gasket, with the same aluminum option available on request.

Applications and Industries

Applications vary according to the operating pressure and temperature limits of the two variants. The SM series with resin window is recommended for standard circuits with a maximum recommended working pressure of 5 bar and a temperature range from -10°C to +100°C. The SM/HP series, on the other hand, is the engineered solution for more demanding applications. It can operate with a maximum recommended pressure of 20 bar and withstand thermal peaks up to +130°C (266°F). This high thermal and mechanical resistance makes SM/HP indicators ideal for installation on industrial compressors. For both lines, the maximum tightening torque (Nm) specified must be strictly observed during installation to prevent structural damage.

Fluid Specifications

Chemical compatibility between the component and the system fluid is a key requirement. The polyamide resin window of the standard SM series has documented resistance to synthetic and mineral oils, diesel, brake fluid, and certain types of gasoline. However, there is a strict operating limitation: contact with alcohol, alcohol-based cleaning liquids, and coolant fluids must be avoided. For hydraulic systems using more aggressive fluids, or where temperature conditions exceed polymer material limits, the HP version with glass window and FKM VITON seals is the optimal choice.

Technical Summary Table

Summary table of the main characteristics of the Miselli SM Series Oil Level Sight Glass.