FUNDAMENTALS OF UV MEASUREMENT
 

Types of Measurement

Online Monitoring

  • Online monitoring is more often used in places where a radiometer will not fit in the spatial requirement. The overall cost to monitor a multi-lamp system with individual online monitors is more than using one portable radiometer. But if using a radiometer is NOT an option, this system is desirable, effective, and reliable.

  • Use online monitoring when continuous monitoring is desired, not just spot-checking.

  • Online monitors read relative intensity only (percentage of original output when the bulb is new). The measurements are relative to that particular machine because the sensor records output in a particular location at a certain distance from and at a certain angle to the reflector and UV bulb -- measurements between different machines or different factories is not the aim of online monitoring. It is used to determine the ongoing efficiency of any given machine over a lengthy period of time.

  • No factory calibration is necessary for any online monitor.

  • You can choose one of four UV wavelengths to monitor.

  • All online monitors provide 0-10 volt output proportional to UV. You can feed the 1-10V signal back to a PLC. Multibrite can also output in milliamps.

  • The sensors need to be kept cool.

Radiometers
  • This is a good choice when a radiometer will fit into the application because readings of both dosage and peak UV intensity can be obtained.

  • Radiometers are calibrated and allow machine-to-machine comparison. Readings can also be compared between R&D and production or to other plants.

  • All radiometers are NIST traceable.

  • Information can be shared with lamp manufacturers, lamp suppliers, adhesive and ink manufacturers, etc.

  • One unit can be shared between multiple machines because it is portable.

  • A radiometer is exposed to temperature on the way through the UV application, not continuously.

  • The radiometer actually measures the amount of UV reaching the surface where the curing is to take place.

  • With multiple machines, a portable radiometer is less expensive than mounting a sensor on each individual lamp.

  • Recalibration is necessary to provide ongoing NIST traceability.

EIT, Inc., 108 Carpenter Drive, Sterling, VA 20164
Phone: 703-478-0700 · Fax:703-478-0815

Questions, problems, comments? Contact webmaster@eitinc.com
All contents © 1998 EIT Inc. except where noted. All rights reserved.

Last updated