Success has many parents but failure is an orphan
To keep your temperature project negatives to a minimum, it helps to have some warning signs when such obstacles may be approaching.
Here are some key pieces of advice in the areas of temperature sensors, installation, maintenance and specification in the hope that this information can help you avoid some of the most common pitfalls that confront temperature sensor users in real-world application environments.
- Dally not with other folk's spouses or money: Talk to a specialist about cost. Many projects flounder at purchase date when the cost is much higher than estimates made earlier in the game.
- Silence is the hardest argument to refute Tell All & Sleep Peacefully: Include all information on the application, and let a specialist make the application and compatibility decisions. A layman in a specific technical field will often make assumptions, which could throw flags up for a specialist.
- Knowledge is more than equivalent to force: Make sure you really know what you need and want. For instance, a temperature sensor might be specified for 100 C MAX Temp +/- .25 C, but what if the minimum is -40 C ? What accuracy is realistic for your process? An RTD may give you the accuracy but might not stand up to the environment.
- Don't treat the symptom, instead find the cause. If a temperature sensor is to interface with a control system, don’t let the control dictate the input that forces the use of a less-efficient temperature sensor. For example, I’ve often had the computer folks ask for an analog input on a batching system, which would completely skew accuracy.
- Buyer beware: Beware of selecting equipment by browsing Web sites. Much of the information you encounter is marketing material written by the manufacturer and is intended to convince you to select their sensor or that probe. To ensure proper temperature sensor specification, you must perform a thorough and complete evaluation of all of the viable solutions for your application. There are no shortcuts to proper temperature sensor specification.
- Check you’re Parameters: Make certain the person installing the temperature sensor understands the installation parameters and have him check with the vendor regarding specific piping, power, and classification requirements.
- Don’t Push the Envelope: Many times problems arise because the specifier has not done the necessary homework and/or the piping plans have changed due to “as built” requirements.
- Be Nice: Consider your maintenance folks when you select and position the temperature sensor. For example, it’s a good idea to pay the extra money for the option of wall-mounted remote electronics when the equipment is, say, 20 feet in the air. Go with a N.U.N. so the sensors can be easily removed for testing with having to unwire the unit.
- Mind Your Manuals: Make sure the installer doesn’t throw away the installation and operating literature after the initial installation is complete. You can be sure you’ll need this information again, especially if you don’t have it. All of the sensors we supply come with a drawing as the minimum.
- Be Proactive & Benefit: Be sure to read the maintenance section of the manual, and list the requirements on Preventive Maintenance Schedules. In our experience, approximately 25 percent of catastrophic failures are maintenance-related. Check your sensors on a regular bases to see if they have drifted. If they are ungrounded you can test for insulation failure
- Have Your Resources Ready: Most medium and small plants do not have an instrument technician on staff, even though the equipment continues to become more and more sophisticated. As such, it is important to maintain good relations with a qualified technician who can respond quickly and effectively when the inevitable crisis occurs.
- Plan Ahead or Face the Consequences: Keep a long-term working life log with expected replacement dates, looking out as much as 10 years. This helps ensure accurate budgeting and reduces the number of those pesky surprises that always seem to occur at the worst possible time.
