Duran tubular gage glass of standard length and case quantities has, to certifly quality and authenticity, the following identification is imprinted on each glass: Type of Glass, Co-efficient of expansion, Style of glass. TGR stocks container loads of 1/2", 5/8" 3/4" and 1" OD of various Duran brands of borosilicate gage (gauge) glass. 
Duran Redline Gage Glass has a red line between two white lines, which, when filled or partially filled with a colorless liquid magnifies the red line.
The bold red line makes it possible to read the liquid level from greater distances. Redline tubular gage glass is widely used in tanks, reservoirs, and low-pressure boiler applications.
Duran Heavy Wall Gage Glass has the highest pressure rating of any tubular gage glass manufactured. It is available in Heavy Wall Clear and in Heavy Wall Redline. Heavy Wall Gage Glass is commonly used in liquid level gage and sight flow indicator applications that exceed the temperature and pressure of High Pressure Gage Glass. Heavy Wall Gage Glass has a maximum length of 48 inches.
Duran High Pressure Gage Glass is the most widely used clear tubular gage glass. It is specially formulated and manufactured for service that requires greater pressure temperature and corrosion resistance than Standard Gage Glass.
Other types of tubular gage glass are available and are often in stock at T.G. Rankin Company. We stock glass tubing with outer diameters up to 1-1/2". For sight glass replacement diameters through 6" are avaible. Although most of the glass offered is (formerly Corning Pyrex) borosilicate, for non-steam low corrision applications, TGR can also provide virtually any glass and acylic level gage or sight glass tubing. Production quantites, custom cutting, end finshing and packaging are available.
Packaging: For reliable shipping and storage, we offer standard factory lengths of Duran gage glass 12-pieces per case / cartons orcustom cut lengths in TGR 6-packs, bulk and custom packaging to your specifications. The TGR six-pack has long been used by distributors for efficient shelf-storage and reshipment. Contact us with your export packaging and documentaion needs.
Tubular Gage Valves and Level Gage Accessories
In addition to gage glass glass tubing TGR also stocks and can provide replacement level gage valves, level gage accessories, washer-seals, glass protectors, guard rods and appplication assistance.
Important Note: Never exceed the liquid level gage manufacturer or the glass manufacturer’s pressure or temperature ratings.