What is a slip ring union?
A slip ring union is a unit that combines a rotary union with an electrical slip ring.
The rotary union portion of the assembly allows for the movement of a fluid media (oil, coolant, water, air, etc.) from a stationary object to a rotating object, or vice versa. This transfer is made possible by securing the input valve to the stationary media source and attaching the rotating machine to the outlet valve which rotates concurrently with the machine while in operation.
The slip ring portion is designed to carry a current from a stationary wire into a rotating device (or again, vice versa). Slip rings consist of a stationary contact brush which rubs on a rotating metal ring. As the metal ring turns, the electrical current is conducted through the stationary brush to the metal ring. Slip rings usually operate with multiple rings, providing an even flow of current to multiple portions of a device.
A combination unit such as this allows for easy transfer of a multitude of media through a small physical space, and can help reduce or eliminate the costs associated with a complete redesign of a system.
This type of all-encompassing media transfer system is becoming more common in various industries, and as the first company to offer a single source assembly for this product Rotary Systems sets the standard for the functionality of this complex device.
What do you need to know to specify a slip ring union for an application?
In order to properly specify a slip ring union combination we will need to know details pertaining to the individual slip ring and rotary union components, as well as details pertaining to the overall application.
The basic details needed for the rotary union portion of the assembly will be as follows:
- Total number of passages required
- Media passing through the union
- Max pressure of media
This information is needed to ensure that the recommended rotary union will adequately handle the fluid transfer requirements for the given application.
The basic details needed for the slip ring portion of the assembly are:
- Total number of pathways (circuits) required
- Type of signal (power, data, thermocouple, etc.) being passed through the slip ring
- Max current and voltage needs for each circuit
This information will help determine the best type of internal contacts to be used in the slip ring, and will help determine the correct ring cross-section (for current), and spacing between adjacent rings and brushes (for voltage).
In addition to the rotary union and slip ring specific data, there are a few details about the overall assembly that must be taken into account:
- Any requirements and/or restrictions pertaining to the physical size of the completed assembly (inside diameter, outside diameter, length)
- Maximum rotational speed of the application
- Duty cycle (time rotating vs. time stationary, ramp-up time to achieve max speed, hours per day the assembly will be rotating)
This information will ensure that the final assembly will fit in the given space of an application, and that it will handle the mechanical requirements that the system calls for.
