Transparent Borosilicate Level Tube

Made from borosilicate glass, it is used in numerous applications where both chemical resistance and low thermal expansion coefficient are required. The outer diameters of the level tube are available in various sizes ranging from ½” to 1 ½”, and the lengths vary up to 144″.

Transparent Borosilicate Level Tubes

Made from borosilicate glass, it is used in numerous applications where both chemical resistance and low thermal expansion coefficient are required. The outer diameters of the level tube are available in various sizes ranging from ½” to 1 ½”, and the lengths vary up to 144″.

The level tube is available in different wall thicknesses according to the pressure requirements of the equipment and is supplied with ends cut using a diamond disc and squared to ensure proper sealing and avoid sharp edges.

Transparent Borosilicate Glass – Features

The level tube is available in both red-line and transparent versions. The red-line version provides a special optical effect where the red line between the two white sides magnifies the central line, thus increasing the liquid observation distance.

Glass TypeBorosilicate 3.3
Manufacturing Parameters
Manufacturing Diameters1/2”, 5/8”, 3/4”, 7/8”, 1”, 1-1/4”, 1-1/2”
Manufacturing ThicknessesStandard wall, high pressure, and extra reinforced
Minimum Manufacturing Length10 mm
Maximum Manufacturing Length3700 mm
Operating Parameters
Maximum Continuous Working Temperature500 °C
Maximum Short-Term Temperature560 °C
Thermal Shock Resistance230 K
Maximum Operating Pressure*** (DIN7080)
Chemical Properties
Hydrolytic ResistanceHGB 1 (ISO 719)
Acid ResistanceClass S1 (ISO 1776)
Alkali ResistanceClass A2 (ISO 695)
Chemical Composition
SiO2Min 80% Content
B2O3Min 13% Content
Na2O + K2OMin 96% Content

Borosilicate Tubes – Recommendations

What to Do

  • Inspect the level indicator glass daily, keep maintenance records, and perform routine replacements.
  • Install protective covers where necessary to safeguard personnel.
  • Ensure that the level indicator glass, gland, nuts, gaskets, etc., are the correct size and type before installation.
  • Examine the level indicator glass for damage and check that the seals are free from hard deposits or tears.
  • Remove all deposits from sealing areas, gland nuts, glands (where used), and use a new gasket before installing the level indicator glass.
  • Protect the exterior of the level indicator glass from sudden temperature changes, such as drafts, water spray, etc.
  • Ensure that the system is protected by a safety shutoff system (such as a safety ball or check valve).

Transparent Borosilicate Level Tubes – What Not to Do

  • DO NOT allow contact between the glass and metal.
  • DO NOT subject the level indicator glass to bending or twisting stresses.
  • DO NOT allow the level indicator glass to come into contact with the bottom of the gland.
  • DO NOT hit, impact, or scratch the glass.
  • DO NOT reuse any tubular glass, gaskets, or seals.
  • DO NOT use glass that is scratched, chipped, or damaged in any way. Used glass may contain damage and pose safety risks.
  • DO NOT exceed the recommended working pressures specified by the glass or level indicator glass manufacturer, nor the maximum recommended length of the tubular glass.
  • DO NOT tighten the gland nut and gasket beyond the manufacturer’s recommendations for the level indicator glass.
  • DO NOT operate the level indicator glasses unless the valve sets are equipped with drainage, ventilation, and a safety ball.
  • DO NOT attempt to clean the glass while the unit is operating. Cleaning should be done without removing the level indicator glass.
  • DO NOT attempt to inspect the glass, adjust the support rods, gasket nuts, or glands, or inspect or tighten other fittings without isolating the level indicator glass from the pressure vessel and opening the drainage ventilation.
  • DO NOT perform welding, impacts, or sandblasting in the level indicator glass area without protecting the glass.

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