he DAKOTA SEAL targets predictive maintenance applications and condition based monitoring. This will be incorporated into the next generation of smart machines. Smart machines are those that are capable of diagnosing problems and either correcting them or notifying the operator before failure. The DAKOTA SEAL is a sensing system that will detect the condition of the seal. This system can be multiplexed with other diagnostic equipment on motors and controllers.

y putting a circuit on the seal at the point of maximum allowable wear and then monitoring the circuit with a simple resistance test, we can continuously or periodically know the condition of the seal. As long as the circuit is intact and has not failed or grounded out, the seal is still within operational guidelines. Once the circuit is destroyed, maintenance should be scheduled before complete seal failure occurs. Initially a wire was placed on or embedded in the seal for the circuit and this method may have some application. Other circuits can be made from Polymer Thick Film, Conductive Epoxy, Conductive Silicon, and Flexible Film Circuits.

he sensor circuit that is put on the seal can be as thin as .002 in. This alows parrallel circuits on some applications. With more then one circuit, information can be obtained on wear rate. Thickness of the circuit and the size of the seal are factors in the performance of the circuit. The bigger the seal is, the longer the circuit must be to circumscribe it. The longer and thinner the circuit, the more ohms of resistance. This is especially important in intrinsic safety design. The DAKOTA SEAL is an excellent way to monitor equipment on the hazardous side of an intrinsic barrier.

ome application contain a seal that is made of material that the sensor circuit will not bond to. These materials can be plasma etched, laser etched, or chemical etched to change the molecules on the surface of the seal. This allows the sensor circuit to adhere to the seal.

t might be helpful to treat the DAKOTA SEAL as three processes.
1.) Deciding on the ideal circuit: This would include positioning of the circuit and pattern. For example a _-_-_-_-_ may work for static seals or a helical pattern for O-rings. 2.) Finding the optimum shape for the seal: This will very from seal to seal. It could be beneficial both for ease of monitoring and manufacturing to have a seal specifically designed to be a DAKOTA SEAL. 3.) Monitoring the seal: Monitoring the sensor circuit after it has been placed on the seal depends on the application and on the frequency of monitoring required.

Patents are pending for static seals and mechanical seal.

If you have an application for this technology please contact me.

Ralph Heinzen
Design Engineer
MID DAKOTA CORP.
Garrison Industrial Park
P. O. Box 728
Garrison, ND 58540
(701) 337-5619
E-Mail: dakseal@restel.net