UNITHERM ™ 3141
THERMAL CONDUCTIVITY MEASURING SYSTEM

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UNITHERM ™ Model 3141 Thermal Conductivity Measuring System uses a time-proven hot-wire method to determine the thermal conductivity of moderate to low conductivity non-carbonaceous materials, such as fibrous panel insulators, fire bricks, etc. The size and shape of the sample is historically that of a standard fire brick with an equal companion piece used for thermal symmetry. A powder testing container is also available.

The hot-wire method is an absolute one in that it does not require a known material for reference. The specimen, shaped as a rectangular slab, is placed in the center of a uniformly heated furnace. A central line-source heater is placed in the axis of the sample.

A line source, in this case a very fine platinum alloy wire, is embedded in one face of the bottom sample block and covered with another block of the same size and identical material. The rate at which this wire heats up after power is applied to it depends on the ability of the surrounding material to conduct the heat away. The temperature of the wire is determined from its resistance and known temperature coefficient. An additional thermocouple is used for verification. The Unitherm ™ Model 3141 is produced with several refinements, such as independent temperature verification (reducing the resistance thermometry to a differential measurement), and fully automated temperature cycling with multiple test sequences at selected temperatures, among others. The physical execution of the device has taken into consideration the ease of operation, economy with precious metal wire, and a high rate of testing. To allow improved time economy, the device is available with multiple furnaces, so one furnace may be heating while another is cooling or several samples may be tested in parallel. Sample preparation and loading, usually a very time consuming and tedious task, has been greatly simplified. OPERATION is fully automated, including the highly complex data analysis process that has made this method very difficult to use in the past. All control routines and calculations are performed by a personal computer, utilizing Windows™ software that requires absolutely no programming knowledge on the part of the operator. The results are provided in a variety of tables and charts selected by user.

Ambient to 1400/1500°C Fully-automated Hot-wire method Ideal for refractories and insulators ASTM C1113 & ISO 8894

The Unitherm ™ line of instruments features fully computerized systems and is designed to measure the various thermophysical properties of solids. All instruments in this family of devices employ a standard serial interface to the control computer, and multiple unit operation is standard.

An extensive tutorial is supplied with each instrument to allow self-teaching of the operation. On-line help screens are available in every phase of the program, greatly minimizing the need for referring back to the manual in case questions arise while setting up or running a test.

Temperature Programming and Control

The system offers a user-programmable mix of ramps, dwells, soaks, printing rates, delayed start, repeat-cycle capability, program capacity of 16 thermal cycles (64 program segments), and the ability to store and recall frequently used programs. The temperature program is fully displayed and is editable during a run. All vital test parameters are continuously displayed and updated. Digital temperature control with optimized adaptive routines is used to achieve accurate sample, rather than furnace, temperatures. Internal logic is included for thermal equilibration detection (where applicable) and for optimized cycles.

Data Recording

Measured data is monitored on the screen and is continuously stored on disk for further analysis. All test and program parameters along with system correction and standards data (if applicable) are also stored in each test data file for easy comparison of samples at a later date.

Data Reduction, Analysis and Reporting

Data reduction is done continuously and as a post-test analysis. The results are continuously displayed, and when analyzed, may be subjected to a variety of statistical processes and plotting options.

Safety and Diagnostic Features

An extensive array of safety provisions ensures that the operational malfunctions of each key part will not cause catastrophic failure of the system or destruction of the specimen. Open thermocouple and loss of water flow monitoring, four levels of furnace and sample over-temperature interlocks, and dead computer detection are among the functions that are continuously performed. Some automatically shut down the equipment while others summon the operator via audio-visual indicators. Built-in diagnostic routines allow the operator to exercise and interrogate a failed system to determine the cause. All circuitry is homogeneously integrated on several proprietary circuit boards, which can be easily removed and replaced in a matter of minutes for quick repair when necessary.

To request a quote, please fill out our Request for Particulars form.
Specifications are subject to change without notice.