Standard Test Pieces
MPI Test Pieces
Johnson & Allen supply a range of test pieces for validation of MPI systems.
|TP1 - Test Piece 1||
Current Flow 0 to 1,000A
|TP2 - Test Piece 2||Current Flow 1,000 to 3,000A
|TP3 - Test Piece 3||Current Flow 3,000 to 10,000A
|TP4 - Test Piece 4||Mag. Flow - Contains 5 Holes
|TP5 - Test Piece 5||Mag. Flow & Coil - Contains 1 Hole
Method of use for TP1, TP2 & TP3
For the first use of your test piece, follow the procedure outlined below when the unit has just been calibrated and there is fresh ink in the tank:
- Ensure that the test piece is thoroughly degreased and free from corrosion and oxidation.
- Clamp the test piece between the contacts on the head and tailstock of your bench unit.
- Apply magnetic ink while the current is flowing.
- Establish the current required to make the hole nearest the outer surface of the ring visible on the outer surface.
- Further increase the current to establish indications from the other two holes on the outer surface of the ring.
- Note the current required to establish each hole indication.
- If the MPI process is functioning correctly each hole should be visible at each subsequent use of the test piece.
- Repeat the test for each current wave form which your magnetising unit is equipped with.
- Please note that the deeper hole is unlikely to show positively using an alternating current wave form.