Test Media System

Classification of Test liquids

Test liquids for magnetic particle testing are generally classified as the following:

Wet test liquids
Wet test liquids have to consist of fine distributed non fluorescent or fluorescent magnetic particles, composed in a sufficient carrier. When agitated they have to get in a uniform suspension.

As a carrier oil or water can be used.

Wet test liquids may be manufactured as concentrates, pastes or powders, or can be provided as ready to use products.

Dry test materials
Test materials for dry testing have to consist of fine distributed non fluorescent and/or fluorescent magnetic particles.

Furthermore magnetic test liquids can be classified according to the way the contrast is generated:

A distinction is drawn between following types:

I. Fluorescent (Indications visible under UV - Light)

II. Non fluorescent (Indications visible under Day light conditions)

III. Daylight and fluorescent.

Fluorescent testing fluids will preferably be used for stationary series testing. If testing takes place outside and/or at permanently differing locations, daylight visible magnetic powder offers advantages. Hereby the different sensitivity of the testing media must be considered.

Suspensions or dry powder
Due to the high requirements concerning indication sensitivity, today usually suspensions are used. The rough graining of the magnetizable particle of dry testing process (approx. 20 µm - 300µm) restricts the application field, in addition to the difficult handling. The detection sensitivity with suspensions is considerably higher, due to the grain size up to 1µm. In addition additives e.g. for corrosion protection can be already part of the product and do not have to be added by users.

Delivery form
Suspensions are usually offered as concentrate, ready-to-use suspensions or as Aerosols. Concentrates are containing already all wetting and corrosion protection agents next to the ferromagnetic particles and has to be diluted according to the instructions.

Dry test materials are mainly sold in bags of 500g or 1kg.