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Stable media circuits

Cooling water and pneumatic circuits in vacuum coating systems

The only good connection is a leakproof connection. If this basic condition is fulfilled, it is worth taking a closer look at the various possibilities for connecting hoses and pipes to create a closed circuit. Engineer Carsten Warnke has had only the best experiences with connections from Eisele.

As one example Warnke mentions a vacuum coating system that is equipped with different media circuits. One of them is the water cooling, which requires one large pipe into the system and another large pipe back out for the waste water. Inside, the cooling system branches out into many smaller lines, which ensure a reliable flow rate with hoses and plug-type connections from Eisele. Here, one can see the practical advantage of the Eisele plug-type connection concept. Where the connections of other manufacturers require the use of tools for coupling and uncoupling, the plug-type connection offers enormous advantages with respect to installation. Also during troubleshooting, when a connection has to be released quickly, it is extremely practical to be able to do this without tools. Since not all plug-type connectors are the same, however, a leakproof connection is the basic prerequisite for this type of connection. This is the case with high-quality connections from Eisele, and that is the only reason why they are an installation-friendly and cost-effective alternative to costly and over-sized screw-type pressure connections. Especially for cooling water, Eisele offers the LiquidLine, which consists of connections made of dezincification resistant brass and matching hoses. Cooling water, with a pH value of about 6, is slightly acidic. Dezincification resistant brass is the optimal material here, whereas stainless steel is used in more acidic environments. The matching hoses have a high volume flow rate, which is necessary for the task of cooling.

The cleaning that is necessary prior to coating opens up another area of application for water circuits: on a cleaning line, the workpieces are immersed in an aqueous solution for degreasing before coating. The grease applied to protect the surface during production and any impurities must be eliminated. For the water supply in this cleaning system, Warnke uses the LiquidLine and the ProWeld hoses from Eisele.

The third area of application for the Eisele connections in a vacuum coating system is sandblasting. There are always parts that are coated unintentionally. Sandblasting is the most common method of cleaning these parts. This process requires compressed air, resulting in an area of application for the pneumatic connections, for example from Eisele’s BasicLine products, which feature practical plug-type connections that are designed for the pressures involved.

For Warnke there are two important reasons for using the Eisele connections. First, the quality of the products themselves is convincing, because they have excellent leakage ratings and the material is optimally adapted to the intended purpose. Another definite advantage for the customer is the user-friendly mounting of these connections. Since they can be coupled and uncoupled quickly and without the use of tools, without affecting the leakproof qualities, they offer a unique cost-performance ratio in comparatively low pressure ranges.

In a vacuum coating system it is possible to equip the entire cooling water and compressed air circuits with plug-type connections from Eisele. The advantages with respect to installation increase with the number of connections needed. Warnke estimates that retrofitting with plug-type connections from Eisele in a vacuum coating system saves about 80% of the installation costs for the connections.

Everything fits

The LiquidLine products range from straight screw-in connections to angled, swivelling (single or T-joint) and bulkhead connections. This product line already includes standardised accessories for many applications, such as double nipple adapters, various reducing adapters, connections and coupling sleeves. The parts are equipped with standard Whitworth threads and enclosed O-rings. All possible standard types and sizes are listed in the new catalogue, with descriptions of the parts, including drawings and ordering numbers, as well as information on the possible customised special versions.


Other industrial areas requiring cooling are for example welding applications or power electronics. In welding it is especially important that all components used, including the cooling circuit, are protected against flying sparks and weld spatter. For the plug-type connections this also means that it has to be possible to uncouple them easily after extended operation; this is achieved by the dirt-resistant release sleeve. To safeguard the transition between hoses and pipes the LiquidLine has an adapter with a cutting ring that replaces conventional hose clamp connections as a reliable and installation-friendly alternative.

Also in the cooling of electronic parts, leakproof connections are crucial. The expertise of the engineers at Eisele produced a development in which the LiquidLine plug-type connections – despite prejudices to the contrary – are used directly in the switch cabinet or in the cleanroom, in order to implement reliable and cost-effective from one source throughout the entire cooling water circuit. For the LiquidLine, Eisele relied on connection technology used for example for leak detection in such demanding products as cardiac catheters. Therefore, the use of these high-quality connections in switch cabinets is also quite safe. They are designed for working pressures between -0.95 and 16 bar. Connections of the 2400 series with two seals are designed for pressures up to 100 bar. Applications with a high degree of movement, such as welding robots, require maximum holding power of the connection technology used. For such applications, the 2500 series of the LiquidLine offers plug-type connections with a full nominal diameter.


In cooling water circuits the hoses have to support heat dissipation. For this purpose Eisele offers flow-optimised hose types with a large inner diameter that are compatible with the LiquidLine. The hoses are designed for easy plug-in coupling and uncoupling by means of external release sleeves, which protect the connection against weld spatter: they can be uncoupled without the use of tools, even after extended periods of operation. For such applications, the ProWeld hose brand is flame resistant in accordance with UL 94 V2 to V0. For clear marking of the different circuits, colour coded sleeves are available that can easily be slipped on for optimal organisation of even large-scale systems.

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