Residual Magnetism Test on Electrical Solenoid Valves
A residual magnetism test on electrically operated solenoid valves can be critical. We recommend a residual magnetism test should be conducted before installation in all manufacturing operations. The minimum sensitivity must be 3 gauss or lower. The Mag-Probe meets this requirement. Please note the following critical industries that would benefit by this test:
Nuclear and Conventional Power Plants, Aircraft, Ships, Trains, and Oil and Gas Production.
Here is a phone conversation between Bob Bartol (Inventor of the Mag-Probe) and Mark Lindsey a customer that was using a glue machine in a manufacturing process. The conversation covered a residual magnetism problem Mark was experiencing with a newly installed electrically operated solenoid valve.
Mark Lindsey (Supervisor)
Using a Mag probe, I detected a small magnetic field around a solenoid valve’s core with the power off.
Bob Bartol (Mag-Probe Inventor)
Are you sure the power was completely off?
Mark Lindsey (Supervisor)
Yes, the wires were disconnected from the power source and the test was made on a bench. I then made a residual magnetism test on a new solenoid valve core after applying power several times, no residual magnetism was detected when I conducted the test using the Mag-Probe. So I replaced the old solenoid valve with the new one that I did the Residual Magnetism Test on and the problem was solved.
IMPORTANT NOTE: the core in the solenoid valve remained partially magnetized when the power was switched off. This caused intermittent operation. It became obvious that the material used in the core remained partially magnetized. This is a manufacturing defect and could result in catastrophic problems in aircraft. Fortunately, in this case, it was in a manufacturing plant. All solenoid valves used on aircraft should be tested for residual magnetism prior to installation. It only takes a few seconds, but these seconds can be critical in the aircraft industry. Turn around time in the commercial aircraft business is critical. Expediting troubleshooting time is paramount. The cost to the airlines can be substantial when they have to offload passengers and replace the aircraft in order to remain on schedule. Especially when the cost of substituting an aircraft can be as high as $5 million dollars.
While not a requirement, I would recommend conducting a Residual Magnetism Test in all critical applications.
Keep in mind, solenoid valves are manufactured in factories around the world. The question is, How Precise are Manufacturer’s Quality Control Inspections for Residual Magnetism on Newly Assembled Solenoid Valves?
Or Call Bob Bartol (208) 866-7895