Product Overview
Red line tubular gauge glass is also commonly searched as red line gauge glass, red line sight tube, redline tubular gauge glass, red line level gauge glass, and borosilicate gauge tube. The red line tube uses distinct red and white lines along the tube to create a refracted magnification effect and stronger contrast against the fluid or background.
Typical Applications
Red line tubular gauge glass is used in tanks, reservoirs, low-pressure boilers, and other direct-reading liquid-level applications where the operator needs a clear visual level line. Published product information also notes use in industrial fluid management and level monitoring where good chemical resistance and low thermal expansion are required.
Material and Performance
The product is manufactured in 3.3 borosilicate glass, which is used for applications requiring chemical resistance and low thermal expansion. Published technical data for red line and transparent tubular gauge glass lists a maximum working temperature of 500°C, a maximum short-term temperature of 560°C, a thermal shock resistance of 230 K, hydrolytic resistance HGB 1, acid resistance Class S1, and alkaline resistance Class A2.
Key Advantages
Red line tubular gauge glass is chosen for higher reading clarity, especially when the liquid is difficult to see against the background. The optical contrast from the red and white lines helps operators identify level changes more quickly, while borosilicate construction supports chemical resistance and dimensional stability.
Technical Parameters
| Item | Specification |
|---|---|
| Material | 3.3 borosilicate glass |
| Product type | Red line tubular gauge glass / red line sight tube / red line level gauge glass |
| Observation type | Red line tube for high contrast |
| Main function | Direct liquid-level indication |
| Optical feature | Red and white line contrast with refracted magnification |
| Maximum working temperature | 500°C |
| Maximum short-term temperature | 560°C |
| Thermal shock resistance | 230 K |
| Hydrolytic resistance | HGB 1 (ISO 719) |
| Acid resistance | Class S1 (ISO 1776) |
| Alkaline resistance | Class A2 (ISO 695) |
| Special dimensions | Available on request |
| Surface / finish options | Standard wall, high pressure, heavy wall |
The values above are taken from published red line tubular gauge glass technical information.
Common Sizes
| Parameter | Published Range / Common Size |
|---|---|
| Outside diameter | Min. 3/16″ to max. 1-1/2″ |
| Wall thickness | Min. 3/64″ to max. 1/2″ |
| Length | Min. 1″ to max. 145″ |
| Common OD sizes | 1/2″, 5/8″, 3/4″, 7/8″, 1″, 1-1/4″, 1-1/2″ |
| Standard example | 5/8″ OD × 7/64″ wall |
| Other options | Other diameters and lengths available |
Published catalog data gives the common OD and length envelope, with 5/8″ OD shown as a standard red line tube example and special dimensions available on request.
Example Pressure Ratings for 5/8″ Red Line Tube
| Length | Low Temperature, up to 90°C | Steam Service, 100°C–200°C |
|---|---|---|
| 12″ | 325 PSI | 275 PSI |
| 24″ | 250 PSI | 180 PSI |
| 36″ | 200 PSI | 150 PSI |
| 48″ | 170 PSI | 100 PSI |
| 60″ | 130 PSI | Not recommended |
| 72″ | 100 PSI | Not recommended |
These published pressure values apply to a 5/8″ OD, 7/64″ wall red line tube and vary by diameter, wall thickness, length, and service temperature.
