109 Maintenance and Cleaning

Overview

Maintenance and Cleaning

CHAPTER

7

Overview

The maintenance and cleaning chapter discusses how to care for the following items:



Care and cleaning with the PID sensor



PID cleaning kit

(optional accessory, part number 074-080, see “ Customer Service ” or email

[email protected]

for details.)



Optical Engine : maintenance and cleaning



Impactor care



Gravimetric cassette and filter paper

PID Sensor

The following section explains basic installation, maintenance of the PID sensor, and cleaning the lamp.

 NOTE : The PID cleaning kit is sold as an accessory. For technical support,

see “ Customer Service ” or call TSI at 1-800-680-1220 (USA) or

(651) 490-2860.

The Photoionization detection (PID sensor) is used to measure airborne pollutants. As it is measuring and detecting for Volatile Organic Compounds (VOCs), the gases freely diffuse in and out of the sensor chamber which is formed by the filter, housing walls, and a UV lamp opening (window). It is important to keep the UV lamp clean and the electrode pellet (lid placed over the lamp housing) clean.

 NOTE: Regarding PID and performance : with the PID sensor and humidity sensitivity, this uses the fence electrode technology to minimize humidity.

EVM Series User Manual

110 Overview

Removing and Installing PID Sensor

Removing and Installing PID Sensor

If you ordered a PID sensor with your instrument, it will be shipped with an installed PID sensor that was factory calibrated. The following procedures explain how to remove and install the PID sensor.

1.

Verify the EVM is powered off and the external power supply is unplugged.

2.

Remove the sensor bar by unscrewing the two screws. Next, gently remove the sensor bar, by titling the front and lifting up. (The rubber gasket may stick a little as you lift the sensor bar off.)

Place the sensor bar to the side.

3.

A black bar (called the manifold) will be placed over the sensors. Remove this by pulling it out of the housing and set aside.

4.

Placing your fingers on the middle sensor (PID sensor), gently tilt the front of sensor up as you pull the sensor out with your thumb and index finger. Place to the side.

Sensor bar

Manifold

Screw 2

Screw 1

PID sensor (located in the middle of the sensor housing)

Figure 7-1: Removing and inserting PID sensor

5.

To insert the PID sensor, line the pins up to the circuit board and lower it vertically down and gently push it into the sensor cavity. It will fit snug.

6.

To reassemble, place the manifold over the sensor housing and then place the sensor bar on top

of the manifold and sensor housing. Tighten down the two screws. (See the Calibration section to

perform a calibration with the newly installed sensor).

EVM Series User Manual

111 Overview

Maintenance and Cleaning Overview of PID

Maintenance and Cleaning Overview of PID

Periodic maintenance is encouraged to ensure accurate VOC measurements. If you are in an environment with high concentrations of VOCs with aerosols and high particulates, you will want to check the calibration frequently and clean the components. When the PID loses sensitivity, you will want to change the electrode pellet.

 NOTE : Due to the increased sensitivity of the PID ppb sensor, it is recommended to replace this

pellet more often. (See Appendix A Accessories and adapters for details.)

The following are three recommended maintenance/cleaning benchmarks , recommended by

Ion Science.

1.

After performing a zero calibration, the baseline climbs. (You should replace the electrode pellet).

2.

Under highly humid conditions, replacement of the electrode is needed.

3.

If the baseline is unstable or shifts when you move the PID, then cleaning is needed.

Cleaning PID Sensor

Cleaning of the PID sensor requires removing the plastic, intelligent sensor casing, removing the electrode pellet, and removing the lamp. Once removed, the lamp is cleaned off with the cleaning kit

(available as an optional accessory). The flowing procedures explain how to clean the PID sensor components.

 Removing and Cleaning the sensor

1.

Remove the PID sensor (follow steps outlined in, “ Removing and Installing PID Sensor .)

2.

Using a flat-head screwdriver, gently pry open the plastic, intelligent sensor casing where the small rectangle crevice is on the backside of the housing. Using some force, lift the top off (the bottom section is glued in.)

Remove intelligent sensor casing

Figure 7-2: Removing intelligent-sensor casing with PID

EVM Series User Manual

112 Overview

Cleaning PID Sensor

3.

Using the pellet removal tool (displayed below), insert into the side crevices and place your thumb over the black pellet.

 NOTE: Once you squeeze the pellet removal tool, the lid will pop off with the lamp. In order to prevent it from popping out, it is important to place your thumb over the black pellet first.

Electrode Pellet removal tool

Figure 7-3: Removing the lamp with removal tool

4.

Set the electrode pellet and lamp to the side.

 NOTE : Use a paper towel, or a cloth without fibers, when handling these pieces to prevent oils from your hands transferring to the lamp or pellet.

Electrode Pellet

The lamp twists onto this pellet cover

Lamp

PID sensor

Displayed without the (plastic) Intell-sensor casing

Figure 7-4: Remove/insert PID sensor with lamp & pellet

5.

Using the PID cleaning kit ( optional accessory ), open the alumina oxide polishing compound and insert a cotton swab.

 In a circular motion, polish the lamp until an audible squeaking sound is heard (about

15 seconds). DO NOT touch the lamp window with your fingers. Remove any residuals of the compound with a cotton swab.

Caution

The cleaning compound, alumina oxide, should not be inhaled and can be an irritant to your eyes. Be cautious when handling the powder compound

Figure 7-5: PID sensor cleaning kit

(optional accessory)

EVM Series User Manual