1. How do I know my Dust Sentry is reading correctly?

The best way to maintain confidence in the performance of your Dust Sentry is to carry out regular field maintenance checks such as a zero calibration, flow check, leak check and filter replacements at frequencies recommended in the User Guide. Factory Calibration of the optical engine should be undertaken every two years.

2. What is the difference between a zero and span calibration?

A zero calibration involves delivering particle free air to your Dust Sentry and adjusting the Dust Sentry to read zero. A span calibration involves exposing the Dust Sentry to a known concentration of particulate matter and adjusting the response of the instrument so that it reports the correct concentration.

3. What is the difference between field and factory calibration?

Field Calibration involves either a zero or span calibration of the Dust Sentry in a real outdoor environment whereas Factory Calibration involves removing the optical engine from the Dust Sentry and returning it to us for calibration and servicing. Factory Calibration is necessary to ensure that the optical path, laser and detector are in good condition, and any drift in the response of the detector is accounted for.

4. How do I zero calibrate my Dust Sentry?

The Dust Sentry can be zero calibrated by installing a particle filter on the Dust Sentry inlet and adjusting the Dust Sentry reading to zero. A zero calibration will take you only a few minutes. For complete instructions on zero calibration please refer to the User Guide.

5. How often do I need to zero calibrate my Dust Sentry?

We recommend performing a zero calibration once every month.

6. How do I span calibrate my Dust Sentry?

If you require a higher level of accuracy from your Dust Sentry, you may wish to perform a field span calibration. To do this you will need suitable reference monitoring equipment that uses the gravimetric method or reference Beta Attenuation method. A full list of reference method equipment can be found by clicking here. The Dust Sentry must be placed in close proximity to the reference instrument for a period of at least one day. The data from the reference instrument must be made available and used to correct the response of the Dust Sentry. For complete instructions on span calibration please refer to the User Guide.

7. How often do I need to span calibrate my Dust Sentry?

The recommended frequency of a field span calibration depends on the availability of reference equipment and the required accuracy of the measurement application. For most of our industrial customers, field span calibration is not required for the acceptable level of accuracy, provided Factory Calibration is undertaken as recommended.

8. How do I factory calibrate my Dust Sentry?

Factory Calibration involves removing the optical engine from your Dust Sentry and sending it to us for calibration and servicing. The optical engine will be returned to you with a new factory calibration certificate. You will need to re-install the optical engine and enter the unique calibration parameters from the calibration certificate using the Aeroqual software. To send your optical engine for Factory Calibration please contact us for a RMA number.

9. How often do I need to factory calibrate my Dust Sentry?

We recommend Factory Calibration of the optical engine once every two years. To send your optical engine for Factory Calibration please contact us for a RMA number.

10. What is the expected lifetime of the optical engine?

With Factory Calibration and servicing every two years it is possible for the optical engine to last indefinitely. In order for the optical engine to be properly calibrated it may be necessary to replace some high performance components such as the laser, detector or solenoid inside the engine. If required these parts can be replaced multiple times, ensuring the long life of the optical engine.

11. What is the fiber span and how often should I use it?

Use the fiber span to test that the laser and detector in the optical engine are working correctly. The fiber span uses a small length of optical fiber which collects light from the laser and guides it directly to the detector which produces a high instrument response. The fiber span procedure takes approximately 5 minutes and should be performed once every month.

12. How do I read the Dust Sentry calibration certificate?

For a visual aid to reading your Dust Sentry calibration certificate please click here.