Reflex Gauge Glass With Gasket Working Principle

1. Introduction

A reflex gauge glass with gasket is the primary sensing element of a reflex level gauge. It consists of a borosilicate prism glass element assembled with a sealing gasket. The device uses the principle of communicating vessels and optical reflection. Liquid and vapor create clear optical interfaces on the prism face. Liquid areas look dark, while vapor areas appear bright (silver-white). This design allows for clear level readings. The gasket sits between the glass and the metal groove. It stops leaks and resists corrosive materials and high pressures. Knowing how the reflex gauge glass works is key. Choosing the right glass and gasket ensures accurate measurements and a longer lifespan.

2. Technical data

3. Typical applications

Many industries use the reflex gauge glass with gasket. Its working principle gives clear and reliable visual level indications.

• Chemical Storage Tanks: Tanks with FKM (fluoroelastomer) gaskets resist hydrochloric acid and caustic solutions. At a Jiangsu plant, there were no leakages reported after three years of use.

• Boiler Steam Drums:

• Reflex glass manufacturers rate it for boiler service (up to 1.6 MPa of steam) and high temperatures.

• Asbestos or graphite gaskets are available when needed.

• Food fermenters: Use food-grade silicone gaskets for cleanliness. They provide clear and stable readings in brewery setups.

• Crude oil storage: NBR (nitrile) gaskets resist oil. Companies use them for bulk storage  projects in the Middle East.

• Pharmaceutical reactors use high-flatness glass (≤0.08 mm) with PTFE gaskets. This setup meets GMP cleanability standards.

4. Installation and operation best practices

• Check the glass length and width. Make sure they match the gauge housing groove according to DIN 7081. Gasket thickness tolerance must be ≤ ±0.2 mm. This prevents under-compression, which can cause leaks. It also stops over-compression, which might break the glass.

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  Seal Face Preparation:

  Apply a light silicone-based sealant to improve initial sealing where specified.

• Clean the glass and chamber sealing faces to remove oil, grease, and scratches.

• Aim for a surface roughness of Ra ≤ 1.6 μm.

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  Gasket seating and bolt torque:

  Use a torque wrench and apply 15–20 N·m of torque in a star pattern to avoid uneven stress and glass breakage.

• Insert the gasket into the groove.

• Place the glass gently.

• Then, tighten the bolts evenly.

• Avoid impact zones: Place the gauge away from direct inlet jets and agitator paths. This helps reduce abrasive wear on the prism face.

• Inspection Schedule:

• Inspect the gasket's condition every three months under normal service.

• For high-temperature installations, inspect monthly.

• Replace any deformed or aged gaskets immediately.

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5. Frequently asked questions

Q — How to choose glass length for a given vessel range? A — Select glass length to match the level gauge span. For a 1 m measurement range, glass lengths are usually 218 mm or 250 mm. The width is typically 30 mm or 34 mm, and the thickness is 17 mm.

Q — What problems does gasket aging cause?

A — Gasket embrittlement or shrinkage can cause seal failure and leakage. Losing gasket elasticity can cause uneven glass loading. This raises the risk of rupture. Replace gaskets every 6–12 months, depending on media aggressiveness.

Q — Which gasket for high-temperature/high-pressure service?

A — For temperatures between 250–350°C, use asbestos or graphite gaskets. If it's above 350°C, think about metal gaskets instead. For pressures > 4.0 MPa, specify reinforced glass assemblies.

Q — Why can readings appear blurred?

A — Common causes:

• Surface fouling on the glass (clean it with a neutral detergent).

• Gasket leakage is causing vapor condensation.

• Prism surface abrasion. If you wear the prism, replace the glass.

Q — How to select a reliable manufacturer?

A — Choose suppliers that meet DIN 7081 and HG standards. They should provide material certificates and seal performance test data. Factory testing records reduce the risk of nonconforming batches.

6. Conclusions and engineering recommendations

Conclusion: A well-made reflex gauge glass with a gasket uses a prism for clear liquid level reading. It operates between 0 and 4.0 MPa and 0 to 250°C. To get accurate measurements, use the right glass size and gasket material for the media. Also, follow standard installation practices.

Engineer recommendations

1. 
   

• Use FKM for acids.

• Use NBR for oils.

• Use silicone or PTFE for sanitary services.

• Use a dual-match selection.

• Match glass dimensions to the gauge model DIN 7081 tables.

• Match gasket material to the process media.

2. 
   

• Use torque control during installation.

• Document torque values with a torque wrench.

• This helps with traceability and future maintenance.

3. Source from full-inspection suppliers

• Need flatness reports for each production lot.

• Also, I need pressure test reports to reduce field failures.

For custom samples, check gasket material selection tables or ask local manufacturers. Consult a qualified supplier for application verification and to get your samples delivered.