Most SIGMA transducers can be fabricated to operate at higher temperatures than is generally available in the marketplace at large. For immersions and contacts the primary concern in withstanding higher temperatures, (other than fabricating materials such as epoxies, insulators, and solders), would be the lens on an immersion and the wearface on a contact. Selection of the proper materials, allows operation of these units up to 400 degrees F continuous. For contact transducers, a vespel delay line can raise operation to 450 F continuous and 800 degrees with a 15% duty cycle.
SIGMA transducers that utilize wedges, such as the integral wedge transducers and the wedges for the SIGMA wedgemounts, have significant temperature range depending on the material selected.

The following list provides the specifications for SIGMA High Temperature Transducers. Temperatures given are for continuous contact:

350 degrees F - Standard integral wedge transducers utilizing "Loten" wedges and high temperature epoxies. Available manual or mechanized 450 degrees F - Standard integral wedge transducers utilizing vespel wedges and high temperature manufacturing materials. Available manual or mechanized 1500 degrees F - utilizing steel wedges cut to the desired angle of propagation, and mounted with compressional or transverse LiNbO3

All SIGMA high temperature transducers can withstand proportionately higher temperatures, by observing a proportionately lower duty cycle on time to off time.

All the above materials are available for use with SIGMA wedges for wedgemount transducers, except steel.

When ordering, determine the unit to be fabricated to withstand the higher temperature, specify the unit by part number, add the temperature indicator, and specify "mechanized Unit" if desired.

To order please call SIGMA, or define the unit according to the "PART NUMBER GUIDELINE"

The following is an example of a typical part No.:

SDHA2-2(18x10)60L-F30-45F describes the following unit:

Sigma Dual For testing in

Carbon steel material

High temperature

For testing in Austinetic material

Operating frequency 2 MHz

2 elements 18mm long by 10mm wide

Refracted Exit Angle 60 degree Long.

Focal soundpath 30 mm

450 degreeF continuous capability

SIGMA's Stainless steel wedge high temp transducers have been tested to 565 degrees C for up to 600 hours. During this test the signal amplitude improved with time at temperature. The probes have also been placed in a 500 C-550 C furnace three different times for a total of 1100 hours When the probes are returned to room temperature the signal amplitude has changed very little from the original. Each SIGMA Transducer is certified using the Sonix ProbeTEST™. A permanent record is maintained at SIGMA to verify comparison with probes manufactured at a later time. A copy of the certification is supplied to the customer at
NO ADDITIONAL COST.

© 1998 - 2002 Sigma Transducers, Inc.