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Temperature Q&A with JR Madden: Flexible RTD Sensors Needed for Cold and Hot Fluid Lines

Temperature Q&A with JR Madden: Flexible RTD Sensors Needed for Cold and Hot Fluid Lines

Q: I have a project for six RTD measurements that makes using standard fixed length sensors difficult because there is little clearance near the top of the thermowell for sensor insertion.  It looks like your “WORM Sensor” would be an ideal fit for the application because of its flexible design.  These RTD sensors need to be 100 or 1000 ohm platinum elements with Class A or 1/3 DIN accuracy ratings. They will be used to monitor chilled and hot water lines with min and max temperature limits of 30 F and 180 F.  Maximum insertion length in these ¼ inch ID thermowells is about 10 inches.  I noticed that your standard WORM length is 24 or 36 inches.  Are custom length WORM sensors available?  If so, what cost is associated with ordering multiple sensors at custom lengths?  Lastly, we usually request test data with all of our sensors and check them in our air bath or heat block calibration units.  Can you offer a test report or test data points with these WORM sensors? 

WORM FLexible SensorA: We stock the WORM Sensor in standard lengths of 24 and 36 inches for quickest delivery.   At any time, you can order shorter lengths at any quantity at no additional cost.   However, one of the many unique advantages of the WORM sensor is that it is field-trimmable. All that you need to do to shorten the insertion length of any WORM sensor is trim the length of the spring and lead wires. This makes it the perfect sensor for stores or stockroom.  If you need a WORM sensor longer than 24 or 36 inches, contact us and we can build custom length WORMs to match your application requirements. 

The 24 and 36 inch WORM sensors are sold separately or you can save money if you purchase our prepackaged WORMs in a three pack or 10 pack.  The 10 pack of sensors, called the “Can of WORMS”, offers the greatest cost savings for your application of six elements.  The WORM sensor was designed to handle two temperature ranges: Standard and High Temperature, designated respectively by “WS” and “WH” in the model number.  The temperature limits in your application can easily be handled by the WS standard WORM element.   

With regard to sensor accuracy, we only build our RTD sensors to meet the newest IEC 60751 standards. This standard addresses the requirements needed to meet tolerance levels required for different classes of RTDs that include Class AA, A, B and C.  Moore Industries only supplies Class AA and A sensors when increased accuracy or calibration requests are mode on sensors and assemblies.  Additionally we thermally age our sensors for 1,000 hours. When the RTD element is temperature aged, it ensures that the platinum substrate material inside the sealed element will provide a more stable and long term repeatable output. This helps reduce the frequency of transmitter and input card calibration due to sensor drifting.

Calibration SuiteMoore Industries offers certified calibration services for sensors and sensor-transmitter assemblies.  For your application we can offer you a –VTD calibration option.  With this option we will use our NIST traceable oil calibration bath to take and record five temperature/resistance points within your requested temperature range, and offer a test data report.  This test report will list the sensor serial number, date of calibration and all of the NIST traceable calibration equipment we used to perform the test.

Most often our customers request that we calibrate and certify the full temperature assembly, using our –VTB option.  This offers the best accuracy since we are matching your sensor to the transmitter and calibrating them as an overall measurement assembly or system.  We only certify these assemblies utilizing Class A (.06%) or Class AA (.04%) sensors since they drift less and offer the most long term repeatable measurements.

WORM Flexible Sensor packageFor customers who are required to validate accuracy performance on a regular cycle, our -VTB calibration option reduces the need to calibrate so often.  In many cases customers do not have the equipment with the required accuracy levels to perform onsite calibrations.  Moreover, the cost of calibration performed by us is only a fraction of the cost that it would cost them.

Get the details on Moore Industries WORM Flexible Sensors. Download the Get Rid of Rigid technical paper for insights to using flexible sensors, and the WORM data sheet.


Published: August 3, 2016