Nova Eclipse TG950 - Users Manual
18
To access this option, press the MENU Touch Command to display the
Main Menu. W ith the Down ARROW , toggle down to
2 POINT CAL
, and
press ENTER. A Measurement screen will be displayed similar to the one
shown above:
From this display, calibration on both high and low thicknesses can be
established. To use this calibration procedure, couple the probe to the low
thickness location on the reference standard, and use the Right and Left
ARROW keys to scroll
Lo Thick
to the known low thickness value.
Reposition the probe to the high thickness location, toggle down, and set
Hi
Thick
to the known high thickness. It may be necessary to repeat this
procedure until the precise thicknesses are set. Following two-point
calibration, press MENU to return to the Measurement Display.
Velocity Calibration:
For the Velocity Measurement and Calibration
procedure, refer to
Section 5.3, Ultrasonic Velocity
.
As recommended with any precision measurement tool, calibration
accuracy should be checked periodically during use. More frequent checks
are recommended if there are changes in the temperature of the test object,
or in the ambient temperature.
4.5 THICKNESS M ODE Sub-M enu:
Return to the Main Menu, toggle down to
THICKNESS MODE
, and press
ENTER. In this Sub-Menu, there are three choices:
Normal
,
Diff.
, and
MinHold
.
Normal:
In this mode, when
Normal
is highlighted and ENTER is pressed,
the Measurement Display will open. Thickness readouts are presented and
held when the probe is removed from current measurement locations. If the
Scan Bar scale has been set, it will also be held and relate to the same
thicknesses.
Differential:
In the Differential Thickness Mode, the difference between the
measured thickness and a pre-set, or nominal, thickness is displayed. To
set the thickness from which the difference will be displayed, ENTER
THICKNESS MODE
from the Main Menu, and
Diff.
from the Sub-Menu. A
Measurement display opens. Immediately below the readout is a line
reading,
Nom. :
, followed by the value from a previous setting. The desired
Nominal thickness (
Nom.
) is set by using the Up and Down ARROW keys.
Nova Eclipse TG950 - Users Manual
19
Press ENTER. Any thickness measurement taken thereafter will be
displayed as a value (+) or (
-
) from the Nominal setting.
An alternative way to set the nominal thickness value is to couple the probe
to a reliable reference standard. After a stable reading is obtained, press
ENTER.
To exit the Differential mode, return to the Main Menu, select
THICKNESS
MODE
, return the highlight to
Normal
, and press ENTER.
MinHold:
Entering
MinHold
from the
THICKNESS MODE
Sub-Menu
provides for retention and display of the minimum thickness obtained during
a continuous scan across the surface of a test object.
Following a scan, to clear the displayed
MinHold
thickness, press the
ENTER key. This sets a blank value next to
Min. :
, and readies the gage
for a new Minimum Thickness Hold scan.
4.6 ALARMS Sub-M enu:
Setting alarms produces a visual indication if a
thickness measurement exceeds pre-set limits – below, above, or both
below and above. The Alarm indicator is a red LED located above and to
the left of the MENU Touch Command key
To set Alarm levels, press MENU, highlight
ALARMS
, and press ENTER. A
Sub-Menu opens with three items –
Mode:
,
Low:
,
and
High:
. W ith
Mode:
highlighted, toggling the Left or Right ARROW keys sequences through
Off
,
Hi
,
Lo
, and
Lo/Hi
. After choosing the desired Mode, the Alarm levels
are set by toggling to
Low:
and/or
High:
, and using the Right and Left
ARROW keys to scroll in the desired Alarm limits. After setting the Alarms,
press MENU to return to the Measurement Display.
Additionally, when the Low Alarm is activated, and
MinHold
is also active, if
MinHold
captures a value below that set for the low alarm, the alarm LED
will flash. This Alarm feature indicates that the minimum thickness was
below the low alarm setting somewhere in the area last scanned. The
Alarm serves to prompt the User to re-inspect the scanned area to locate
the low thickness that triggered the Alarm. The Alarm Mode is also
interactive with the Data Logger as described in
Section 5.2, Data
Logging
,
below.
