Top 10 temperature measurement questions you must read!
Want to learn more about temperature measurement? First you may want to have a read about the difference between the vendors’ solutions and the customer’s pain! Agree, disagree? Please comment below with your opinion!
1. Temperature loop transmitter – I have a temperature loop system where I am receiving all information from the field directly into the PLC without a transmitter, It means that PLC is reading the RTD and thermocouple directly. Is there any advantage to apply a transmitter in the field? Expert’s answer: If you decide to go digital, then you’ll definitely benefit. With a digital protocol, you can read diagnostics as well as process values from your measurement points. Read more
2. Wireless temperature measurement logging- Hello, we have an application where requires a temperature measurement and logging, on up to 24 separate products for 12 hours. We always have cables issues and I would like to know if our application can be measured by a wireless solution, could you clarify? Expert’s answer: You sure can. In fact, wireless devices will not only help the cable issue, they’ll improve your update time and give you more sensor options. When you need to move the tanks, you can leave the sensors installed or remove them easily. Read more
3. Surface sensor installation- Hi. I need information for a surface RTD installation on pipes. Can you help? Expert’s answer: Sure! For starters, most solutions on the market will require good insulation. The vendors say that great insulation makes for great accuracy. As for installation, it depends on the device. It can vary from super simple, like a clamp-on sensor, to kind of complicated, like an inline sensor. Read more
4. Aggressive environment- Hey, we have a machine that needs a temperature feedback control. Unfortunately, the machine rotates at 800 rpm, which has made finding options difficult. I decided to try a thermocouple. Do you have any other ideas? Expert’s answer: Hey, there. I sure do. In your case, you need to focus less on what type of sensor to use and more on how to use it. Oho, this sounds like another job for wireless! Face it, you have a situation where a standard (wired) solution will need a lot of grunt work from your side to get ‘er done. You really wanna mess with that? I doubt it. Read more
5. Transmitter calibration range- Are there rules for calibration ranges? I have a transmitter with an operating range of 0-149 degrees Celsius. I asked for a calibration range up to 200, but my manager didn’t agree. When I asked why, he said it’s always been that way. Could you tell me if I need to follow this rule?Expert’s answer: When you buy a new device, it provides information about its measurement range. If you don’t request a certain calibration range, then the company will calibrate in a standard range. Read more
6. Temperature measurement between two parts- In reality, I could likely settle for thermocouples one/inch or so, but that would be a lot of inches at 36×36″. Does anyone know any devices, sensor matrix, and or material that may work here? Expert’s answer: Believe it or not, you can have a setup close to your ideal, with online thermographic cameras. These cameras will literally show you the temperatures in your machine. As a bonus, most of them have software to monitor the hot spots. On the other hand, they tend to cost more than other devices. Read more
7. Thermocouple basic- I want to test a thermocouple loop by injecting a millivoltage from the field where the thermocouple terminates in its compensating cable back to a substation and a thermocouple/mA converter card with cold junction compensation. Let’s say the field is 30 degrees Celsius and the substation is 10 degrees Celsius. Expert’s answer: Piece of cake! This goes all the way back to the basics. Come, children. Let’s have our lesson for the day. Read more
8. Multi-input termperature converter- I need an industrial-rated (preferably Class 1 Zone 2) handheld that accepts TC type J, K, T, or two- or three-wire RTD inputs with either a corresponding mv output or 4-20 mA output. Any leads would be appreciated! Expert’s answer: Tall order! So you want a converter that you can carry out to the field to verify your sensors. The market offers many thermocouples and resistance temperature detectors (RTD). You’ll need a signal converter to read your process values and convert to 4-20 mA. Read more
9. Type J temperature variation- We noticed that the DCS is reading 20 degrees Celsius lower than the real process temperature.The cable between the second and third junction boxes is about 80 feet, with 65 feet outdoors in conduit and 15 feet indoors. Why do we have a temperature difference? Expert’s answer: Many factors can cause this error in your system. I’ll list steps to isolate the problem and give you a recommendation for a fix. Good to hear you’ve already verified each junction box and found that the problem begins at the third box. Read more
10. Rosemount 3144p temperature transmitter- I have a Rosemount 3144P with a range of 0 to 150 degrees Fahrenheit. I was using a test device to simulate RTD input to the transmitter, where on 0 degrees Fahrenheit I have 4 mA and on 150 I have 20. Do I need to calibrate or adjust the transmitter to read the same temperature as the probe? Is the RTD bad? Expert’s answer: So you tested the Rosemount 3144P temperature transmitter using the calibrated probe and the transmitter reads the values accurately, right? Now test the field sensor. You’ll need to pull the sensor from the process and verify the temperature curve using the bath in your workshop. If the sensor reads out of spec, replace it. But if not, adjust the trim in the transmitter. To do that, you need to install the sensor and transmitter together. Read more
Want more information? If so, here are temperature transmitters that might interest you: