
Product
Borosilicate Gauge Glass Tube
Borosilicate gauge glass tubes provide clear, direct liquid-level observation in tanks, reservoirs, boilers and industrial process equipment.
Technical Specifications
| Product Type | Gauge glass tube |
|---|---|
| Material | Borosilicate Glass 3.3 |
| Wall thickness | Standard and heavy thickness |
| End Finish | Cut, Ground or Fire-Polished |
- Clear, direct and power-free observation of liquid levels.
- Standard and custom sizes are available.
- Compatible gaskets and accessories are available upon request.
Gauge Glass Tubes
Product Description
Borosilicate Gauge Glass Tube, also known as tubular gauge glass or level gauge glass tube, is designed for direct observation of liquid levels in tanks, reservoirs, boilers and process equipment. When installed between upper and lower gauge valves, the liquid inside the tube rises or falls with the liquid level in the connected vessel, providing a clear local indication without electricity or electronic instruments.
The tube is manufactured from transparent borosilicate glass with a low coefficient of thermal expansion. Compared with ordinary soda-lime glass, borosilicate glass offers better resistance to temperature changes, water, acids, salt solutions and many industrial fluids. Its clear and homogeneous structure helps operators observe the liquid level, color and condition easily.
Standard-wall tubes are suitable for general liquid-level observation, while heavy-wall tubes can be supplied for applications requiring greater mechanical strength. The ends may be cut, ground or fire-polished according to the sealing method and gauge assembly.
The actual allowable pressure and temperature must be determined according to the tube diameter, wall thickness, length, end finish, mounting arrangement, gasket material and process medium. Complete application details should therefore be confirmed before selection.

Key Features and Advantages
Excellent Optical Clarity
Clear, colorless glass provides direct observation of the liquid level and medium condition.
Low Thermal Expansion
A thermal expansion coefficient of approximately 3.3 × 10⁻⁶ K⁻¹ reduces stress caused by temperature changes.
Good Chemical Resistance
Resistant to water, acids, salt solutions, organic solvents and many industrial fluids.
Reliable Thermal Performance
Borosilicate Glass 3.3 has a softening point of approximately 820°C and an annealing point of approximately 560–565°C.
Multiple Wall Options
Standard-wall and heavy-wall versions are available for different installation requirements.
Custom Manufacturing
Outside diameter, wall thickness, length and end finish can be produced according to drawings or samples.
Easy Level Observation
Provides continuous, local and power-free liquid-level indication.
Technical Specifications
| Parameter | Specification |
| Glass Material | Borosilicate Glass 3.3 |
| Working temperature | 260 ℃ (depend on pressure, tube dimensions, installation design, thermal shock and process medium) |
| Working Pressure | 90 to 600 psi (6.2–41.4 bar). depending on the tube size, length, wall thickness and end finish. |
| Mean Linear Thermal Expansion | 3.3 × 10⁻⁶ K⁻¹ at 20–300°C |
| Density | Approx. 2.23 g/cm³ at 25°C |
| Softening Point | Approx. 820–821°C |
| Annealing Point | Approx. 560–565°C |
| Transformation Temperature | Approx. 525°C |
| Thermal Conductivity | Approx. 1.2 W/(m·K) at 100°C |
Sizes
Borosilicate gauge glass tubes are available in a wide range of standard and customized dimensions.
Common outside diameters include:
1/2″, 5/8″, 3/4″, 7/8″, 1″, 1-1/4″ and 1-1/2″ Approximately 12.7, 15.9, 19.1, 22.2, 25.4, 31.8 and 38.1 mm
Standard-wall and heavy-wall options are available. Tubes can be cut to the required length, with cut, ground or fire-polished ends.
GET IN TOUCH
KUNYO Industrial Components Co.,Ltd.
Send us your product specifications, dimensions or drawings. Our team will review your requirements and respond within 24 hours.
PHONE
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No. 555 Longxing Road, High-tech Zone, Hengshui City, Hebei Province, China 053000
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