Electronics LP2000_VAR User Manual

Page 12

Fig. 21 The amount of this cur-
vature, called arc height, is an
indication of the blast stream in-
tensity and the value, as meas-
ured on a standard Almen gage,
can be placed into a standard
SPC process control chart.
There are three strip thickness to
choose from, low intensity (N),
medium intensity (A), and high
intensity (C). Most abrasive blast
cleaning is performed at high in-
tensity with the (C) strip.
An arc height of .005" to .007"
was found to be ideal for this
blast cleaning application.

Fig 20

Fig 21

Fig. 20 Once the final conveyor speed
and shot flow rate (motor amps) have
been determined, the standard Almen
strip (SAE specification J-442) can be
used to check for proper operation.
The Almen strip, shown here, is
mounted with four hold-down screws
onto a standard Almen holder that has
been welded into place on the pipe.
This is the industry standard test for
the shot peening and blast cleaning
intensity.

The Almen test strip is blasted on one side only and then removed from the holder. Once re-
leased from the hold-down screws the strip will curve.