PIDs As HazMat Response Tools

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Technical Note TN-163 rev 5 ab.05-07 inside the probe, including a green dust filter and a white “C” filter. Both of these should be removed. The instrument should show little or no response from these tests. If the MiniRAE 2000 shows more than 5 ppm isobutylene units or the ppbRAE shows more than 500 ppb increase in reading, then something is wrong. The design of the instruments makes it quick and easy to remove and clean the probe, lamp, and sensor to address this problem. Focus on the following areas: 1. Replace filters 2. Clean the probe, PID lamp, and sensor 3. Inspect the sensor for damage or corrosio n. 4. Clean the sensor housing. 5. Clean the sensor using an ultrasonic bath. MiniRAE 2000, ppbRAE Plus, and UltraRAE When testing the UltraRAE monitor, make sure that the tube of interest is installed before proceeding with the test. If you plan to test for Benzene, install the Benzene tube and use the same moisture test discussed for the MiniRAE 2000. If the readings increase more than 2 ppm Benzene units, then there is a problem with dirt in the monitor. Replace Filter The MiniRAE 2000, ppbRAE, ppbRAE plus, and UltraRAE all use two filters, an external filter and a sintered metal filter. The external filter (PN 002- 3022-005 for a pack of 5, 002-3022-010 for a pack of 10, and PN 002-3022-100 for a pack of 100) is attached to the end of the probe and is white. If it appears to have any discoloration, then it is time to replace the filter. If the instrument goes into pump alarm with the filter attached and is able to run without any problems when not attached, it is time to replace the filter. When the instrument is responding to moisture, it is time to replace the filter. The metal sintered filter (PN 490-0047-005 for a pack of 5) should be replaced when it is dirty and when the instrument responds to moisture. The MiniRAE 2000 and ppbRAE instruments have other filters Clean the Probe Unscrew the lamp housing cap; inspect the sintered metal filter at the bottom of the probe. If it appears to be dirty, it needs to be replaced. A dirty internal filter indicates that the probe has dirt inside and requires cleaning. Cleaning the probe depends on the kind of exposure or dirt that has contaminated the probe. If it is a chemical that might affect the reading of the PID, use methanol to clean the probe. If it is just dirt or dust that has been sucked into the instrument, blow clean, dry air through the probe to clear the internal tubing. Clean the PID Lamp Access to both the lamp and the sensor of a MiniRAE 2000 and ppbRAE plus requires no tools. To remove the PID sensor, grasp the top lip of the sensor and pull straight out, to avoid bending the electrical pins on the sensor. If the sensor does not pull out immediately, a gentle rocking motion should help loosen the sensor. Also try rotating your grip as you pull the sensor. Once the PID sensor is removed, set it aside to clean or to inspect for damage or corrosion. The PID lamp has a white O-ring that keeps it from sitting too low in the lamp housing. Before reaching for the lamp, get out the lamp cleaning kit (PN 081-0002- 000), which includes methanol, finger cots, cotton swabs, and lens tissue. Use finger cots on the fingers that will handle the lamp. CAUTION: Never touch the window surface with anything that might scratch, including your fingers, or any liquid that might leave a film. Carefully remove the lamp by grabbing onto the white O-ring, and set the instrument aside. Dip a cotton swab into the methanol and wipe the window surface of the lamp. The sides of the lamp can be cleaned if it is obviously dirty, but the flat-surface window of the lamp is the only part of the PID lamp that requires cleaning. Once the lamp is cleaned, use a piece of the lens tissue to dry and polish the lamp before dropping it back into the instrument. If there is visible dirt, clean the lamp housing prior to placing the lamp back into the instrument. Do not force the lamp all the way down to the bottom of the lamp housing. Allow the PID sensor to push the lamp the rest of the way into place. 2 RAE Systems Inc. 3775 N. First St., San Jose, CA 95134-1708 USA Phone: +1.888.723.8823 Email: raesales@raesystems.com Web Site: www.raesystems.com
Technical Note TN-163 rev 5 ab.05-07 To access the UltraRAE lamp for cleaning, you will need to first remove any RAE-SEP tube from the probe. Then unscrew the four screws holding the bar code reader cap to the instrument base. Lift the Bar Code Reader cap straight off of the instrument base until the PCB (printed circuit board) clears. Set it aside and make sure that the screws do not fall out and disappear. Take the silver sensor adapter off of the PID senso r. Underneath is a rubber tube connector and a silver sintered filter. Remove the rubber tube connector with filter. If it appears to be dirty, it needs to be replaced. A dirty internal filter indicates that the probe has dirt inside and requires cleaning. Cleaning the probe depends on the kind of exposure or dirt that has contaminated the probe. If it is a chemical that might affect the reading of the PID, use methanol to clean the probe. If it is just dirt or dust that has been sucked into the instrument, blow clean, dry air through the probe to clear the internal tubing. bent or the Teflon mask is warped, the sensor needs replacement. Note: A warped Teflon mask can be a sign that the sensor has been exposed to too much heat. Straight Electrodes with mask removed for clarity Good Sensor (partly disassembled) Warped Teflon Mask Damaged Sensor Bent Electrode If the sensing electrode is exposed to UV light from the lamp, it gives an undesired positive response to the light. If the fingers look aligned but are not in the same plane (some fingers are bent towards or away from the lamp), then the sensor should be replaced. The fingers should be close to, but not touching, the Teflon mask. In some cases it is possible to carefully bend the electrodes back into the correct position if the damage is very minor. Clean the Sensor Housing If the PID sensor is not damaged, thoroughly wipe clean the sensor housing area using a cotton swab dipped in lamp-cleaning methanol. Let the sensor housing area dry completely. Reassemble the PID, and perform a humidity response test. If it shows no response, calibrate the instrument and return it to service. Follow the directions for the MiniRAE 2000 and ppbRAE plus for PID sensor and lamp removal. The UltraRAE PID sensor and lamp are the same as those in the MiniRAE 2000. Sensor Housing Inspect the Sensor for Damage or Corrosion If the sensor appears corroded, it should be replaced. If the sensor is damaged or even slightly bent, it can show increased response to moisture. The bias and sensing electrodes are two sets of “fingers” in the MiniRAE 2000 sensor. These fingers should be straight and parallel. The bias electrode is easy to see when the bottom of the sensor is inspected. However, the sensing electrode should be blocked from sight (and the UV light from the PID lamp) by a Teflon mask. If the sensing electrode can be seen because the fingers are Cleaning the PID Sensor Cleaning the lamp and sensor surfaces using the lamp cleaning kit with cotton swabs is not good enough to remove humidity response. In fact, cotton swabs can leave behind fibers that continue to cause moisture issues after cleaning. An ultrasonic cleaning bath MUST be used. Ultrasonic cleaners are available from laboratory suppliers. Alternatively, a jewelry 3 RAE Systems Inc. 3775 N. First St., San Jose, CA 95134-1708 USA Phone: +1.888.723.8823 Email: raesales@raesystems.com Web Site: www.raesystems.com
Page 1: Addressing PID Sensor Moisture Sens
Page 5: Technical Note TN-163 rev 5 ab.05-0

PIDs As HazMat Response Tools

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