Ermeto fittings

The cutting-ring principle of Ermeto fittings was invented and developed by Ermeto back in the 1930s. This type of fitting quickly gained popularity mainly due to its very simple installation. Using only two spanners, an Ermeto fitting can be installed in a short time.

Today, Ermeto fittings are among the most widely used high-pressure fitting systems for metric pipes and lines. They are dimensioned for installation on metric pipes. The dimensions of threads, through bores and spanner flats are metric. The historical basis for these dimensions are the German standards DIN 3861, DIN 2353 and DIN 3859. Today, these standards are represented by international standards such as ISO 8434. Ermeto fittings are characterised in particular by very high resistance to high pressure with small external dimensions. They are a very compact connection technology component.

Three series of Ermeto fittings:

Ermeto fittings are available in three series. This provides space-saving and cost-effective solutions for a wide range of applications. The LL series is suitable for low-pressure applications up to 200 bar. Fittings in the L series are designed for medium-pressure applications up to 500 bar. For high pressures up to 800 bar, Ermeto fittings in the S series are used. Fitting components for higher nominal pressures are characterised by stronger, higher-grade materials, which are further hardened by special heat treatment. This special heat treatment significantly expands the application range of Ermeto fittings: where the S series previously had to be used for higher pressures due to design constraints, the L series can now be used for the medium-pressure range up to 500 bar. This offers major economic advantages, among other benefits.

Ermeto fittings with multifunctional Progressive Stop Rings:

Instead of the cutting ring developed by Ermeto, modern applications of the Ermeto cutting-ring principle use new, multifunctional PSRs. PSR stands for Progressive Stop Ring, which provides a completely leak-tight connection of components in fluid systems as well as of pipework. During installation, this state-of-the-art cutting ring penetrates the pipe with the front cutting edge of the fitting element. The second cutting edge is only engaged later. Once the functionally intended cut of the two cutting edges into the pipe section has been reached, any further advance of the fitting element can be ruled out. This is ensured by the stop contour of the Ermeto fitting and by a specially developed over-tightening protection.

At the beginning of the collar of the Progressive Stop Ring there is a special knurling that enables inspection of the installation status. The forces that occur are transmitted as favourably as possible in terms of strength over the entire cone length of the fitting element. In addition to the features mentioned above, at the end of the collar of multifunctional Progressive Stop Rings there is a specially designed internal contour that ensures increased safety. Any vibrations that occur are damped as soon as they enter the ring of the Ermeto fitting element. Thanks to the over-tightening protection and the stop contour, the fitting element cannot be tightened beyond the so-called installation fixed point. After installation, the space in front of the first cutting edge of the Ermeto fitting element must be completely filled with the visible collar flare. A slight spring-back of the ring is desirable. This spring effect compensates for settling behaviour in the thread of the two union nuts as well as unwanted bending vibrations.