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If the level glass on your reflex or transparent level gauge glass has become clouded or damaged, that means it’s time to replace it with a new one.

The installation process is tedious, but as long as you follow each step of the process carefully, you should have no trouble. Instead, your reflex or transparent level glass will be back up and working properly in no time. 

Below, we’ll go in-depth on the difference between reflex glass and transparent glass, the supplies you’ll need to complete your installation, and how to install your new glass plate in a series of easy-to-follow steps.



What Is The Difference Between Reflex Glass And Transparent Glass?

While a reflex glass and transparent glass level gauge may look the same, they are vastly different in terms of function.

A reflex level gauge contains a single prismatic glass plate and is divided into two separate zones, one for liquid and one for vapor.

When a ray of light hits the prism, it is bent at a 45-degree angle. The vapor will reflect this angle back out as light, whereas the liquid will refract the light and become dark in appearance. This makes for a stark contrast which the observer will note and then make an accurate measurement of the liquid.

A transparent level gauge contains two glass plates, but these are completely see-through. Liquid rises between the two plates, allowing the observer to determine the level in the larger vessel which the gauge is attached to.

While reflex is better for viewing clear, colorless liquid, transparent is more effective for observing colored liquids or checking a substance for dirtiness.

Both of these types of level gauge glass are constructed in a similar way, however, which means we can use the same installation process for reflex glass and transparent glass.


What Do I Need To Install Reflex And Transparent Level Gauge Glass?

To start the process of installing a reflex or transparent level gauge glass, gather up these important supplies:


  • Protective gloves
  • Safety goggles
  • Wrench
  • Torque wrench
  • Tempered level glass (reflex or transparent)
  • New Gaskets / Cushions for the glass

How To Install Reflex And Transparent Level Gauge Glass 

Here is a step-by-step method for installing reflex glass or transparent glass.

Step 1: Isolate The Gauge From Pressure And Drain It

First, you’ll need to isolate the gauge from the pressure of the vessel to which it is attached. Then, you should drain the gauge to ensure there is no internal pressure. This way, you will not be sprayed with liquid or vapor during the gauge disassembly and removal process.

Step 2: Loosen Bolts On Cover Plate

Next, you should loosen the bolts on the cover flange of the gauge with a wrench. Alternatively, your gauge may have its tightening bolts located at the back, and a simple cover plate on the front. Regardless of where they are situated, you need to loosen and remove them.

Step 3: Remove Gauge Component Parts

In this step, you should remove the gauge’s component parts, including: the nuts and bolts, the cover flange (or cover plate), the gaskets, the level glass (or level glasses, if this is a transparent level gauge glass), and the centerpiece.

Step 4: Clean And Inspect Gauge Component Parts

You’re already planning to replace the level glass, so you may as well inspect the other parts of the gauge to make sure they’re in good working condition. Parts like the cover plate and the centerpiece may just need a bit of cleaning

Step 5: Attach New Gaskets To Reflex Or Transparent Glass Plates

Always replace the gaskets when you’re installing new level glass. These gaskets wear down and loosen over time, compromising the seal inside the gauge and increasing the likelihood that a leak will spring.

Step 6: Reassemble Gauge

After you’ve cleaned all the parts that can be salvaged and obtained new gaskets and level glass, it’s time to reassemble your level gauge.

Slide all the pieces into place in the reverse order that you took them off: centerpiece, gasket, level glass, gasket, and finally cover flange or cover plate. If you’re working on a transparent level gauge glass, then there will be more pieces, including a second level glass and at least two more gaskets.

Secure the final piece – the cover plate or flange – into place with the nuts and bolts. Use your torque wrench for this step and tighten the bolts in a crosswise motion so that the torque is applied equally to each bolt. The manufacturer of the gauge will recommend the correct torque. 

And that’s it! You’re done!



Replacing the level glass in a reflex or transparent level gauge may seem complicated, what with the many parts and the variations in style. But in the end, the internal construction is relatively simple and similar across both gauges. 

The key to success is to remember the order that you disassembled the parts in, and also carefully apply the proper amount of torque when tightening the gauge.

Regardless of whether you need to replace a reflex glass or a transparent glass, Zight provides tempered borosilicate glass plates you require. They’re manufactured in adherence with DIN 7081, the international industry standard for sight glass quality, strength, and pressure resistance. Check out our full lineup here.