Here at ifm, we want you to be as confident in your temperature instruments as we are in ours. Each TCC sensor is "tested beyond standards" to ensure we manufacture the most stable, reliable and accurate temperature products on the market today. Throughout the development of this product, our engineers identified the primary causes of drift and failure and they have tested our products and those of three other major manufacturers in our X-treme test lab. See the results for yourself.
CIP processes are among the most harsh to which instruments are exposed. The constant cycling between hot and cold temperatures can quickly cause fatigue of the electronic components and therefore, lead to drift and failure. Every CIP cycle is a potential source of drift.
We simulate CIP in our thermal shock chamber. Instruments are fully submerged in a bath at -15 °C for 10 minutes and then transferred immediately (< 10 seconds) to another bath at 140 °C. We test for drift after every 50 cycles at a measured temperature of 123 °C.
The chart shows the results for each manufacturer. The last measurement shown for Manufacturers B and C is point where each unit failed. Note that there is no data shown for Manufacturer A, since their products failed after two thermal cycles. The TCC measurement drifted < 0.2 °C and it did not fail even after 1000 cycles, at which point, we stopped the test.
ifm tests resistance to fatigue failure due to mechanical bending forces caused by high velocity flow and water hammer. The test simulates the forces experienced in pipes and measures the fatigue strength of the laser weld between the process connector and the tube of the probe. Most manufacturers recognize this weld as a weak spot. The image below is an example of a weld cross section and the weld bead overlap in the bottom is typical of laser welding processes.
Since we cannot guarantee the orientation of the assembly when installed, we test by applying a cyclic flow force over the entire weld pulling in all directions. The simulation below illustrates the stresses on the weld as we expose the weakest point—the weld bead overlap -- to the cyclic force. The red color indicates the highest stress being applied on the weld joint.
To test weld strength in the X-treme test, we capture the probe / connection assembly and rotate it as we apply 50 lbf to the assembly until the joint breaks. We believe this extreme test fairly subjects the assembly to the worst case situation. We tested 3 samples from each manufacturer with a 50 mm probe length.