R.B. Annis — Magnetic Field Indicator (Magnetometer) 20-0-20

Includes Certification

Overview

The R.B. Annis Magnetic Field Indicator (Magnetometer) 20-0-20 is a trusted, pocket-sized instrument used to measure the strength and direction of residual magnetic fields in ferromagnetic components. A staple in Magnetic Particle Inspection (MPI) workflows, this rugged and reliable tool gives inspectors an immediate, quantitative reading of residual magnetism — helping to confirm that a part has been properly demagnetized before it moves to the next stage of production or service.

With a measurement range of ±20 Gauss, this model is ideally suited for standard inspection environments where low to moderate levels of residual magnetism need to be detected and verified quickly and accurately.

How It Works

The magnetometer operates on a simple yet highly effective principle. The dual-color scale allows for two modes of use:

• Black Scale (Primary Use): Reads directly in Gauss of a uniform magnetic field oriented parallel with the centerline of the instrument scale — giving a direct, quantitative measurement of residual field strength.
• Red Scale (Field Direction): Used to determine both the magnitude and direction of an unknown magnetic field by orienting the instrument for maximum reading. At maximum deflection, the direction of the measured field runs parallel with the instrument pointer, and the magnitude is read directly in Gauss.

This dual-scale design makes the instrument not only a measurement tool, but a practical diagnostic aid for understanding the behavior of magnetic fields in and around a component.

Why Demagnetization Verification Matters

Residual magnetism left in a component after magnetic particle testing can cause a range of serious problems in subsequent operations. These include:

• Causing metal chips and cuttings to cling to machined surfaces during post-inspection machining
• Creating "arc blow" during welding, which can cause filler metal to be repelled from the weld zone
• Attracting abrasive particles to bearing or faying surfaces, accelerating wear
• Interfering with sensitive electronic or measuring equipment in proximity to the part

The R.B. Annis 20-0-20 Magnetometer provides a fast, reliable way to confirm that demagnetization has been carried out successfully — protecting both the component and downstream processes.

Key Features

• Scale Range: 20-0-20 Gauss (±20 Gauss)
• Dual-color scale — black scale for direct field strength readings, red scale for field direction and magnitude
• Pocket-sized and portable — ready for immediate use in the field, shop floor, or laboratory
• Ruggedly built to withstand years of demanding shop use
• Calibrated prior to shipment — comes with a dated calibration sticker
• Includes NIST Traceable Certification — serialized instrument with full certification documentation for quality and compliance requirements
• Calibration traceable to N.B.S. and N.I.S.T standards

Compliance & Standards

This instrument meets the requirements of the following industry standards:

• ASTM E709 — Standard Guide for Magnetic Particle Testing
• ASTM E1417 — Standard Practice for Liquid Penetrant Testing
• ASTM E1444 — Standard Practice for Magnetic Particle Testing
• ASME BPVC (Boiler and Pressure Vessel Code)

Ideal Applications

• Verification of demagnetization after Magnetic Particle Inspection (MPI)
• Tool room, stock room, and production line quality control
• Engineering and laboratory use
• Inspection of components destined for welding, precision machining, or bearing assembly
• Any application where residual magnetism in a ferromagnetic part is a concern

About R.B. Annis

For more than 60 years, R.B. Annis engineers and innovative designs have earned an international reputation for producing NDT instruments of consistent quality and performance. The Model 25 Pocket Magnetometer series — of which this 20-0-20 instrument is part — is one of the most recognized and trusted tools in the magnetic particle inspection industry worldwide.

SKU: MFI2520C