Coolants

Aerodyn slip rings typically require recirculating cooling fluid to lubricate the contacts and remove frictional heat. The coolant also flushes wear debris out of the slip ring. Some low speed applications have been done with sealed coolant cavities, but these are custom applications. Return coolant is also sometimes used to control cavity temperatures and bearing housing temperatures.

 There are several coolants available, depending on rotational velocity. Aerodyn recommends synthetic heat transfer fluids for low speed operations (below 15,000 rpm) and solvent-based coolants for higher speed applications. Current coolants include Syltherm XLT, Syltherm 800, AK-225, and Vertrel XL. The recommended coolant depends on several factors of the application. Coolant recommendations are determined on a case-by-case basis.

Generally, Syltherm XLT and Syltherm 800 are used for lower speed operations. These fluids offer higher temperature operations because they have an elevated boiling point. They are also a single fluid and not a mixture of fluid with oil. However, Syltherm XLT has a low flash point, and both are flammable. Both fluids can be heated to 140° F to reduce their viscosity and increase their speed capability.

AK-225 and Vertrel XL are solvent-based coolants and are used for all-speed applications. These coolants have relatively low boiling points and require a two- to five-percent mixture of turbine oil for lubricity.  

Generally, air is not an acceptable solution for coolant on a gold brush on gold ring configuration due to the heat build up in friction. Air is used as a cooling fluid mostly with applications that utilize silver graphite contacts.

 If coolant flow is interrupted to an operating slip ring, it would only take a few seconds to destroy the contacts in a slip ring due to excessive heat build up. Therefore, Aerodyn Engineering builds many redundant systems into their cooling carts; these include battery backups, high reliability gear pumps, relays, filters, etc.

For technical data sheets and material safety data sheets (MSDS), please refer to the technical index located under OUR SUPPORT.