– 6 –
The DOWN arrow key has two functions. When the
TI-25M-MMX is in the CAL mode, this key is used to decrease
numeric values on the display. An auto-repeat function is built in,
so that when the key is held down, numeric values will decrement
at an increasing rate. When the TI-25M-MMX is not in calibration
mode, the DOWN arrow key switches the display backlight
between three available settings. OFF will be displayed when the
backlight is switched off. AUTO will be displayed when the back
light is set to automatic mode, and ON will be displayed when the
backlight is set to stay on. In the AUTO setting, the backlight will
illuminate while the TI-25M-MMX is making a measurement and
turn off after several seconds to conserve battery life.
The ALRM key has two functions. By holding down the ALRM
key when powering up the TI-25M-MMX, the audible beeper will
be turned on or off accordingly. After the unit has been turned on,
pressing the ALRM key will toggle the alarm mode to the on/off
positions and allow the user to enter a nominal thickness value.
Refer to page 18 for details on how to use the alarm feature.
The DUAL-MULTI key is used to toggle pulse-echo ( flaw & pit
detection), and echo-echo ( eliminate paint & coating thickness ).
This enables the user to very conveniently switch between modes
depending on application requirements. Refer to page 17 for a
complete explanation of this feature.
The SEND key is used to send the currently displayed
thickness measurement to an external storage device via the
TI-25M-MMX’s RS232 port. Refer to page 18 for an explanation
of how to use this feature
3.5 LCD Display
The numeric portion of the display consists four
complete digits preceded by a leading “1”, and
is used to display numeric values, as well as
occasional simple words, to indicate the status of
various settings. When the TI-25M-MMX is displaying thickness measure-
ments, the display will hold the last value measured, until a new measure-
ment is made. Additionally, when the battery voltage is low, the entire dis-
play will begin to flash. When this occurs, the batteries should be replaced.
These eight vertical bars form the Stability
Indicator. When the TI-25M-MMX is idle, only
the left-most bar and the underline will be on.
While the gauge is taking a measurement, six or
seven of the bars should be on. If fewer than five bars are on, the
TI-25M-MMX is having difficulty achieving a stable measurement, and
the thickness value displayed will most likely be erroneous.
1.8.8.8.8
+
IN MM/
µ
s
ALRM
SEND
DUAL
MULTI
1.8.8.8.8
+
IN MM/
µ
s
– 23–
11.2 Acoustic Velocity Table
Aluminum
0.2500
6350
Bismuth
0.8600
2184
Brass
0.1730
4394
Cadmium
0.1090
2769
Cast Iron
0.18000
4572
Constantan
0.2060
5232
Copper
0.1840
4674
Epoxy resin
0.1000
2540
German silver
0.1870
4750
Glass, crown
0.2230
5664
Glass, flint
0.1680
4267
Gold
0.1280
3251
Ice
0.1570
3988
Iron
0.2320
5898
Lead
0.8500
2159
Magnesium
0.2280
5791
Nickel
0.2220
5639
Nylon
0.1020
2591
Paraffin
0.0870
2210
Platinum
0.1560
3962
Plexiglass
0.1060
2692
Polystyrene
0.0920
2337
Porcelain
0.2300
5842
PVC
0.0940
2388
Quartz glass
0.2220
5639
Rubber, vulcanized
0.0910
2311
Silver
0.1420
3607
Steel, common
0.2330
5920
Steel, stainless
0.2230
5664
Stellite
0.2750
6985
Tin
0.1310
3327
Titanium
0.2400
6096
Tungsten
0.2100
5334
Zinc
0.1660
4216
Material
Velocity
Velocity
Type
Inches/µs
Meters/s
Notes: 1. These values are to be used only when a suitable sample of known thick-
ness is not available for calibrating, as slight variations in material
composition, finishing (hardening, polishing, etc.) or shape can affect the
acoustic velocity.
...
Notes:
2. “
✔
”denotes the factory default setting for acoustic velocity.
✔
