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Flat Gage Glass

FLAT GAGE GLASSflat glass

Molded borosilicate SUPRAX(R) 8488 glass disks to be used as a replacement for the glass in sight flow indicators, sight windows, bull’s eyes, and boiler flame view peep sights. The glass we offer is often the very same as was installed by the original equipment manufacturer.

 

In some cases upgrades for higher temperature and pressure are available.

Annealed (non-tempered) Borosilicate Circles are stocked in many diameters and thickness. The borosilicate material we use is Auer SUPRAX(R) 8488, similar to Schott Borofloat, or Tempax. Both have excellent optical properties for maximum visibility.  Annealed borosilicate offers exceptional mechanical strength and corrosion resistance. You can feel confident using annealed "boro" in many applications throughout your plant.

 

Tempered Borosilicate Circles are heat hardened to give that added measure of mechanical strength needed in applications where higher pressures and greater working temperatures are present. Tempered "Boro" with its greater surface hardness and bend resistance, offers a greater margin of safety in most applications.

MAXOS® Annular Edge Replacement Circles are a size for size replacement for Pyrex Brand Annular Edge sight glass. MAXOS® is clearly a better choice!

MAXOS® sight glass is available in the exact same diameters and thickness as Annular Edge Sight Glass. MAXOS® is molded from specially formulated borosilicate 8488 glass, which gives it a superior quality over cut and ground glass. MAXOS® has a 3/4" uniform thickness as compared to a 5/8" minimum thickness of the Pyrex Annular Edge. This gives MAXOS® an extra margin of safety for your application. The MAXOS® molding process produces a uniform product with excellent optical clarity, and greater thermal shock resistance at an economical price. Testing procedures subject the sight glass to 8 times its rated pressure for maximum user safety. The SUPRAX(R) 8488-borosilicate features chemical attack resistance to all acids except hydrofluoric and hot phosphoric. MAXOS® disks are suitable for temperatures up to 572°F at atmospheric pressure. Shields* may be used on MAXOS® disks as needed for service conditions.


MAXOS® Molded Circles, stocked in many sizes, are molded from specially formulated borosilicate 8488 glass, which gives it a superior quality over cut and ground plate glass. MAXOS® molding process produces a uniform product with excellent optical clarity, and greater thermal shock resistance at an economical price. Testing procedures subject the sight glass to 8 times its rated pressure for maximum user safety. SUPRAX(R) 8488-borosilicate features chemical attack resistance to all acids except hydrofluoric and hot phosphoric. MAXOS® disks are suitable for temperatures up to 572°F at atmospheric pressure. Shields* may be used on MAXOS® disks as needed for service conditions.


The tables on this page list availble MAXOS molded sight glass discs.  Although this list represents a great variety of diameters and thicknesses, your application may require a size not shown.  In these cases we offer from stock and custom order, sight glass discs made from clear borosilicate place glass.  They are avilable in diameters as large as 24" and up to 2.25" thickness. Tempering and hole drilling is also available.



Important Note: Regardless of the glass ratings shown never exceed the gage manufacturer’s pressure and temperature limitations.

For further information refer to the gage or sight window manufacturer’s installation, operation and maintenance instruction manual.

MAXOS® and SUPRAX(R) 8488 are registered trademarks of Auer Lighting, Bad Gandersheim, Germany

*Shields offer some resistance to chemical attack but hinder visibility. 

Used in flat glass level gages to protect the glass from being corroded by hot alkaline or acidic solutions.  Also used in steam water applications, Mica shields prevent etching and weakening of the glass.  Although often very thin, Mica shields add a level of safety by preventing erosion of the sight glass.

Gaskets for long-form flat gage glass

TGR Non-Asbestos Cushion - Gaskets
A general purpose gasket material, similar to Garlock 3000 for service in hot water, mild acids, alkalines, and inert gases.  Maximum temperatures to 600°F and pressures to 1200 PSI in non-steam service.

TGR Grafoil Gasket, GH-R and GH-P
Flexible graphite gasket material widely used for applications in refinery, petro-chemical and power plants in high temperature and high pressure applications.  GH-R laminated graphite has a flat .002 thick 316/316L stainless steel insert for added strength.  Temperature and pressure range in an oxidizing environment is reduced to 400°F to 750°F and as high as 1800°F in a non-oxidizing environment.  Maximum pressure is 2000 PSIG.  GH-R is suitable for 1500 PSIG and 596°F saturated steam service.  Maximum PxT factor value is 700,000.

The fine print...
Your TGR Gage glass distributor may offer gaskets sold in packages of six (6) twelve (12) or by the piece.  Regardless of pressures and temperatures mentioned on this site, always follow the gage manufacturers' published recommendations
Flat (Long Form) Gage Glass 

 
At TG Rankin Co replacement industrial sight glass for all applications are available.  Featuring Maxos(R) borosilicate the premier brand chosen by all major manufacturers of liquid level gages.

Long form borosilicate flat gage glass is available in plain (transparent) and reflex designs. To the right is a diagram to show the difference:


 To observe liquid level, plain (transparent) gages require back lighting through the liquid. Transparent gages may allow observation of fluid properties such as color, turbidity, foaming etc.
 
Reflex glass gages allow only a view of liquid level. From the portion of the glass where there is no liquid, light from the view angle is reflected producing a silver-color.  Below the liquid level light is absorbed through the glass giving a black appearance.  Reflex gages offer a fast  image depicting the presence of water in a boiler feed application.
 
 Please contact us if you need assistance to determine which type glass you need. For higher temperature applications; up to 800F, long form gage glass is also available in aluminosilicate in most popular sizes. 

Gage glass gaskets are required to seal flat gage glass.  They are available in various materials and thickness for all sizes and applications of flat gage glass.  TGR stocks all standard size gaskets in various thickness and materials dictated by your gage or application. 

Mica Shields are used to prevent corrosion of glass exposed to harsh chemicals and steam.  Mica shields are available in various thicknesses and clarity for all sizes of transparent flat gage glass. TGR also stocks Klinger and DIN-spec 30mm wide flat glass sizes. For additional information including price and packaging, please contact us.
 
Liquid Level Gages
If your liquid level gage is beyond simply replacing the glass and gasket, TGR offeres replacement valves and entire gages.  We specialize in replacement gages for McDonnell & Miller boiler controls.   Contact us if your tubular glass seems to be wearing out (leaking) prematurely.  You may need a flat glass gage upgrade. 

Important note: Always follow your liquid level gage manufacturer's temperature and pressure ratings.
 
MAXOS(R) is a trademark of Auer Lighting GmbH, Bad Gandersheim, Germany