Method and device for measuring magnetic particles in a fluid

• US 4,686,469 A
• Filed: 08/12/1985
• Issued: 08/11/1987
• Est. Priority Date: 08/12/1985
• Status: Expired due to Fees

• Current Assignee: Nc., Berkeley, Ca. Tribometrics
• Original Assignee: Tribometrics Incorporated
• Inventors: Lewis, Robert T.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US06/764,552
• Time in Patent Office: 729 Days
• Field of Search: 324/204, 324/71.1, 324/71.4, 340/631, 73/64
• US Class Current: 324/204
• CPC Class Codes: G01N 15/0656 using electric, e.g. electrostatic methods or magnetic methods by investigating individual particles G01N15/1031, G01N15/12

Abstract

A method and device for measuring the amount of magnetic particles in a fluid such as ferrous wear particles in the lubricant of a machine. The particles are entraped by contacting a volume of the fluid with a means to entrap the particles and magnetized by subjecting the entraped particles to a magnetic field. The amount of magnetic particles entraped is measured by measuring the magnetization of the entraped and magnetized particles.

Claims

1. A device for measuring the amount of magnetic particles in a flowing fluid comprising:

a filter with holes sized to pass the fluid but entrap the particles;

a magnet with a magnetic field of sufficient strength to magnetize said particles positioned to have said filter in said magnetic field;

a long cylindrical tube located within said filter and having an opening to the outside of said filter, with the axis of said tube perpendicular to the magnetic field of said magnet; and

a magnetic field measuring means positioned within said cylindrical tube through said opening.

2. The device of claim 1 wherein the major dimension of said holes is between about 0.5 and 200 micrometers.

3. The device of claim 1 wherein the strength of said magnetic field is at least 0.1T.

4. A method for measuring the amount of magnetic particles in a flowing fluid comprising:

flowing said fluid through a filter with holes sized to pass the fluid but entrap the particles;

subjecting said filter to the field of a magnet of sufficient strengh to magnetize said particles; and

measuring the magnetic field from said magnetized particles with a magnetic field measuring means inserted from the outside of said filter through an opening in a long cylindrical tube located within said filter with the long axis of said tube perpendicular to the magnetic field of said magnet.