Nova Eclipse TG950 - Users Manual
6
•
Single or two-point calibration.
•
High and low alarm limits. RS232 data transfer port permits up- and
down-loading of log data and software upgrades.
The NOVA TG950 incorporates the latest technology available in
microprocessor design. Through sophisticated on-chip programming, the
microprocessor computes, linearizes, and directs numerous operations at
high speeds. It also offers intuitive, simplified setup, calibration, and
operation via the TOUCH-COMMAND pushbuttons and intuitive Menus.
The high-powered transmitter (pulser), high-sensitivity receiver, and
informative digital display function together with the microprocessor to
produce exceptional performance from a compact, light-weight, precision
measurement instrument.
2. GETTING STARTED
2.1 Lay Out Shipment Contents
Separate and lay out the NOVA TG950, probe(s), cable(s), couplant, and
any accessories ordered. The NOVA comes with two AA-size alkaline
batteries installed in its battery chamber.
2.2 Connect Probe and Cable
All probes, with the exception of “Mini-Probes”, use a detachable cable for
connecting to the TG950. Connect the cable to the probe. Connect the
other end of the cable to the corresponding receptacle located on front of
the gage.
Various probes are available to optimize performance for the broad
spectrum of gaging applications that may be encountered. The General
Purpose Delay-Line Transducer (D11) can be used for most applications
encompassing a thickness range in steel from approximately 0.0050 to
0.700 inch (0.130 to 1.780 mm), and for surface temperatures up to about
250ºF (120ºC). The General Purpose Contact Transducer (C11) has a
range of approximately 0.062 inch to 20.000 inches (1.57 to 50.00 mm). It
is recommended to use the C11 Contact Transducer for the familiarization
procedures that follow.
For the extensive listing of probes for higher temperature and specialized
applications, see Section 9 of this manual.
Nova Eclipse TG950 - Users Manual
7
2.3 Reference Standards
To calibrate the NOVA TG950, it is necessary to have one or more known
thicknesses of the same material as that of the test object. Initial calibration
procedures require reference samples representative of the material to be
gaged.
Machined stepped-wedges having thicknesses across the range of interest
are convenient and commonly used reference standards. For the purposes
of familiarization with the NOVA TG950, it is recommended to use steel
stepped-wedges having several steps with thicknesses ranging from 0.020
to 0.500 inch (0.50 to 12.7 millimeters). Other stepped wedges
encompassing that general range of thicknesses can also be used. Such
standards are readily available or can be custom-produced. Contact NDT
Systems for further information.
For high-accuracy calibration and subsequent high-resolution
measurements, Users of high-resolution instruments, such as those in the
NOVA 900 Series, may be required to use thickness-certified precision
gage blocks and shims.
NOTE: Selection and use of reference standards is of primary
importance in order to calibrate and assure the accuracy of any
ultrasonic thickness gage. For more detailed discussion on the
selection and use of reference standards, see Section 6, Gaging Tips
and Techniques, and Section 7, Gaging Precautions.
2.4 Using Couplants
A couplant film is needed to transfer the high frequency ultrasonic energy
from the probe into the test material. Adequate probe coupling is essential
to qualify the integrity of a thickness reading. Typically, couplant is applied
to the test material surface, although it can be applied to the tip of the probe
(as during some high temperature applications).
The type of couplant used is very important for optimum performance.
Smooth material surfaces require a lower viscosity couplant, such as water,
glycerin, oil, or similar fluid. Rougher surfaces may require use of grease or
specially formulated gels. The couplant used must be compatible with the
test material. W hile it is usually removed following inspection, remnant
couplant residue can produce surface corrosion or discoloration of the test
