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Reflex vs. Transparent Level Gages: Which One Fits Your Application

  • Feb 1, 2024
  • 3 min read

Updated: Aug 12

Choosing between a reflex and transparent gage is one of the most fundamental decisions in specifying level indication - and the right choice depends entirely on what your application actually needs to show you.


Reflex Level Gages: Clean Total Level Indication

Jerguson® Reflex Level Gages are ideal for clean total level indication applications for refining, petrochemical, and general use applications. The reflex prisms are molded and polished to provide a crisp black-silver bi-color indication of the fluid level.


How the Reflex Principle Works

As light passes into the reflex glass, if fluid is present, the light continues through the glass and reflects off the back of the level gage, producing a black color for fluid level - regardless of the actual color properties of the process fluid itself. If fluid is not present, the light reflects off the glass back toward the user, producing a shiny silver or mirror-like appearance to indicate vapor space.


This is the key advantage of reflex design: because the black/silver contrast comes from light refraction rather than viewing through the fluid, a reflex gage gives clear, high-contrast indication even with fluids that would otherwise be hard to read - dark, opaque, or otherwise visually ambiguous process media all show the same crisp black-silver distinction.


Transparent Level Gages: Interface, Dirty Service, and Shielded Applications

Jerguson® Transparent Level Gages are selected for interface level indication, dirty service, or any application that requires the use of a shield to protect the glass from corrosion. A transparent gage is also known as a "thru-vision" gage, since it's constructed with two pieces of flat polished glass assembled on opposite sides of the level gage chamber.


Why Transparent Gages Show What Reflex Gages Can't

Since the user can see straight through a transparent gage, it's also easy to view the fluid's actual properties - color, clarity, or condition - something not possible with a reflex gage, where the black/silver indication doesn't reveal anything about the fluid itself beyond its presence or absence.


Illumination Is Always Recommended

The use of an illuminator is always recommended on a transparent gage. Because transparent design relies on directly viewing through the fluid rather than reflected light, readability depends much more heavily on adequate lighting - particularly with darker fluids or in dimly lit process areas, which is why backlighting is treated as a standard recommendation rather than an optional accessory.


Choosing Between Them: A Quick Reference

Need

Best Fit

Clean, high-contrast total level reading

Reflex

Reading level regardless of fluid color

Reflex

Viewing actual fluid color or clarity

Transparent

Interface level between two liquids

Transparent

Dirty service

Transparent

Application requiring a protective shield

Transparent

Why This Decision Matters Beyond Just Visibility

Choosing the wrong gage type for your application doesn't just create a minor inconvenience - it can mean installing a gage that structurally can't show you what you actually need to see. A reflex gage installed where interface level monitoring is required won't distinguish between two liquid layers the way a transparent gage would. A transparent gage installed for simple total-level monitoring in a dark process area, without the recommended illumination, may be harder to read reliably than a reflex gage would have been in the same location.


Applications

Reflex Gages are commonly specified for:

  • Refining and petrochemical process vessels

  • General industrial applications requiring fast, high-contrast level reading

  • Boiler applications where black/silver steam-water distinction is standard

Transparent Gages are commonly specified for:

  • Interface level applications between two liquid layers

  • Dirty or fouling-prone service

  • Corrosive applications requiring a protective shield

  • Applications where operators need to observe fluid color or condition directly


Learn More

For guidance on selecting reflex or transparent level gages for your specific application, contact our Jerguson team.

Email: sales@clark-reliance.com Phone: +1 (440) 572-1500


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