An alternating current (AC) bulk eraser (degausser) is used for complete erasure of data and other signals on magnetic media. Degaussing is a process where magnetic media is exposed to a powerful, alternating magnetic field. Degaussing removes any previously written data, leaving the media in a magnetically randomized (blank) state.

The degausser must subject the media to an alternating magnetic field of sufficient intensity to saturate the media and then by slowly withdrawing or reducing the field, the magnetic media is left in a magnetically neutral state.

To erase recorded data, it is necessary for the strength of the degaussing field to be greater in value than the coercivity of the magnetic media. Simply stated, coercivity is the magnetic field strength, rated in oersteds (Oe), required to change the magnetic orientation of the magnetic material. Check with knowledgeable dealers or degausser manufacturers to identify degausser models that meet your requirements.

Data is typically not lost until its level has been decreased 65% to 75% (or more) below its original saturation recording signal level, dependent upon the drive system.

 

For more information on cleaning data in a data warehouse, erasing hard drives, degaussing equipment, and degaussing services, see also: hd-1 professional hard drive eraser hd-1 video tape eraser sv91m diskette eraser erase ntfs hard drive free visual basic mshflexgrid erases row data recordset td1b tape degausser hard drive clean up reviews v92 video tape degausser v92 hard drive degausser digi tapemaster pf252 video tape degausser v-880 tape degausser erasing floppy disk degauss cleaning up a hard drive mds-4 video tape degausser software to erase hard disk mds-4 tape eraser v-94 gsa schedule sv91m degausser how to partition and erase a harddrive v-880 degausser erase hard drive with floppy disc wipe it: the hard drive eraser v92 hard drive degausser digi tapemaster v-860 video tape eraser v92 hard drive eraser hard drive degauser visual basic recordset mshflexgrid erases row data tv degauss wand program clear worksheet data delete dlt cleaning tv degauss wand erase media from 8mm tape mds-4 audio tape degausser hard drive file cleaning software hd-1 professional hard drive degausser permanantly delete data per-1100 drive eraser program clear worksheet data delete c64 disk erase windows xp delete unnecessary files second hard drive

A complete erasure level, for most users, is considered to be 60 dB below the original signal level – this of course depends on user requirements. A 60 dB signal decrease equates to reducing the signal to one tenth of one percent of its original value.

Magnetic media products that have factory prerecorded magnetic servo patterns should not be degaussed. Degaussing would erase the factory written magnetic servo signals and leave the media unusable. For all other magnetic media (without magnetic servo signals), after proper degaussing, the quality of subsequent data recording should be unchanged or even improved.

It is very important to understand and follow the degausser’s operating instructions. This is especially important for manual units where the operator controls the media’s movement through the degaussing field. For higher coercivity media, four passes are often recommended – two passes, with a 90 degree rotation for the second pass, and then repeat the process with the media turned upside-down. Of course, these and other important operating considerations will vary with the type, power and construction of the individual degausser models.

For more information on cleaning data in a data warehouse, degaussers, erasing hard drives, cleaning hard drives, degaussing, and erasing harddrives, see also: