When engineers and procurement managers need to replace a liquid level indicator glass, they often encounter a specific size code, such as “Size 6” or “Size 9”. However, many do not realize that a strict global engineering standard dictates these codes. Specifically, DIN 7081 governs these dimensions, serving as the international benchmark for standardizing elongated level gauge glasses.
In this technical guide, we will break down the DIN 7081 standard. Furthermore, we will explain why global industries universally adopt it, and we will provide the definitive size chart for the most common 34 mm x 17 mm gauge glasses.
What is the DIN 7081 Standard?
DIN 7081 is a German standardization code that specifies the design, dimensions, material, and testing requirements for both transparent level gauge glasses and reflex gauge glasses. Because this standard ensures high safety under extreme pressure and temperature, the global engineering community recognizes it as the ultimate benchmark.
Moreover, for the sake of global component interchangeability, other national standards—such as the British Standard (BS 3463), Japanese Standard (JIS B 8211), and US Military Specification (MIL-G-16356 D)—have implicitly adopted the DIN 7081 “Size X” naming system. Therefore, whether you use a top-tier European instrument from WIKA, or you replace a MAXOS® (Schott/Auer) or Klinger glass, you will see the exact same DIN 7081 size codes.
The DIN 7081 Size Chart (34mm x 17mm Series)
The most widely used industrial gauge glass format features a standard width of 34 mm and a thickness of 17 mm. Consequently, the length of the glass remains the only variable. To identify this length, the industry uses a simple “Size” number ranging from 1 to 11.
Below, you will find the definitive DIN 7081 level gauge glass dimensions chart. (Note: These dimensions apply to both reflex and transparent types, provided that manufacturers make them from thermally toughened borosilicate glass).
| Size Code | Length (L) | Width (W) | Thickness (T) |
|---|---|---|---|
| Size 1 | 115 mm | 34 mm | 17 mm |
| Size 2 | 140 mm | 34 mm | 17 mm |
| Size 3 | 165 mm | 34 mm | 17 mm |
| Size 4 | 190 mm | 34 mm | 17 mm |
| Size 5 | 220 mm | 34 mm | 17 mm |
| Size 6 | 250 mm | 34 mm | 17 mm |
| Size 7 | 280 mm | 34 mm | 17 mm |
| Size 8 | 320 mm | 34 mm | 17 mm |
| Size 9 | 340 mm | 34 mm | 17 mm |
| Size 10 | 370 mm | 34 mm | 17 mm |
| Size 11 | 400 mm | 34 mm | 17 mm |
Material Requirements for DIN 7081
In addition to precise physical dimensions, DIN 7081 dictates strict material properties. The standard requires manufacturers to use high-purity, thermally toughened borosilicate glass. As a result, the glass easily withstands severe thermal shocks and handles continuous operating temperatures up to 280°C. Additionally, if an operator adds a mica shield to protect the glass in transparent applications, the temperature limit increases to 300°C.
Conclusion: Replacing Your Gauge Glass
If your current level gauge leaks or corrosion damages the glass, you can easily identify the correct replacement. First, measure the length of your existing glass. Then, match that measurement against the DIN 7081 size chart above. For example, if your glass measures 250 mm in length, you simply need to order a Size 6 gauge glass.
Looking for Premium DIN 7081 Gauge Glasses?
Lumiglas manufactures high-pressure borosilicate gauge glasses strictly according to DIN 7081. Our products are 100% interchangeable with major brands like WIKA, Maxos, and Klinger.
