Miselli Oil Level Sight Glass – SLNS / SLNT Series
The Miselli SLNS / SLNT Series Oil Level Sight Glass is a threaded hex-head indicator designed for precise visual monitoring in gearboxes, tanks, and oil chambers. Made of transparent polyamide resin, it provides excellent resistance to mineral oils, synthetic oils, and diesel. It features a maximum operating temperature of 100°C and a flat sealing gasket. The SLNT version includes a white contrast screen to improve visibility in low-light environments.
The threaded hex-head indicators of this series are designed for visual monitoring of hydraulic fluid levels inside gearboxes, tanks, and oil chambers. Fluid level reading is consistently facilitated by a central red dot, hot-stamped directly onto the transparent viewing window. For industrial applications in low-light environments, the SLNT configuration includes a white plastic contrast screen positioned behind the thread. This feature significantly enhances oil level visibility, ensuring accurate readings even in poorly lit environments and on complex machinery.
The Miselli SLNS / SLNT Series Oil Level Sight Glass components are entirely manufactured using high-strength transparent polyamide resin. The standard hydraulic sealing system is ensured by a flat gasket made of asbestos-free fiber. Upon specific request, the indicator can be equipped with an NBR 70 Shore synthetic rubber gasket, adaptable to various system requirements. For critical installations on thin walls up to 5 mm thickness, the manufacturer recommends using a special hexagonal brass fixing ring from the GF series, supplied separately upon request.
During installation, it is essential to strictly follow the maximum tightening torque values (Nm) specified in the technical data to preserve the structural integrity of the plastic threads and prevent damage. The dimensional range covers a wide variety of thread types to suit multiple mechanical interfaces, including BSP (G) threads from G 1/4 up to G 2, and metric threads from M14x1.5 up to M40x1.5. Hex key sizes (across flats) vary proportionally from 17 mm for smaller sizes up to 64 mm for the 2-inch versions. Maximum tightening torque values vary depending on nominal diameter, ranging from 5 Nm for smaller threads up to 22 Nm for intermediate sizes such as G 1 1/2.
The standard polyamide resin used in SLNS and SLNT models ensures full compatibility with synthetic oils, mineral oils, diesel, and certain gasoline types. However, contact with alcohol, alcohol-based cleaning agents, and coolant fluids must be strictly avoided, as these may damage or cloud the material. To overcome these chemical limitations, the manufacturer has developed the special SLNS/T-CX model. This advanced variant is made from a specially formulated polyamide resin designed to withstand alcohol-based fluids.
These visual indicators are widely used across the hydraulic and power transmission sectors. The excellent thermal performance of the plastic material allows safe continuous operation at a maximum recommended temperature of 100°C. Standard use is intended for atmospheric pressure conditions. If application in pressurized tanks is required, it is mandatory to consult the technical department for proper evaluation.
Summary of the main characteristics of the Miselli SLNS / SLNT Series Oil Level Sight Glass.
| Feature | Value |
|---|---|
| Product type | Threaded hex-head level indicator |
| Standard body material | Transparent polyamide resin |
| CX version material | Special polyamide resin (alcohol-resistant) |
| Fluid compatibility | Synthetic oils, mineral oils, diesel, some gasoline types |
| Non-compatible fluids (standard model) | Alcohol, alcohol-based cleaners, coolant fluids |
| Standard gasket | Flat asbestos-free fiber gasket |
| Optional gasket | NBR 70 Shore synthetic rubber |
| Maximum operating temperature | 100°C continuous |
| SLNT series feature | White plastic contrast screen behind thread |
| Recommended accessories | Brass fixing ring GF series (for wall thickness < 5 mm) |
| BSP thread range | From G 1/4 to G 2 |
| Metric thread range | From M14x1.5 to M40x1.5 |