Delta CS64A User Manual download pdf (Page 15)

8. Recalibration

The LEDs have a typical operating life of 100,000 hours or about 10 years of continuous

operation.

The intensity of LEDs varies with temperature and aging due to the properties of the

semiconductor materials used. The CS64A sensors use feedback circuitry to maintain

amplitudes over a wide range of temperature and to compensate for LED aging.

The automatic compensation will not eliminate 100% of the variation, so calibration

should be checked regularly. The recalibration period depends on the application. In

many cases, every three to six months or more may suffice, while in very critical

applications, it may be necessary to check every week or every shift.

To check, place the calibration material in the sensing area at the typical sensing distance

and monitor the outputs with a voltmeter or your data acquisition system.

Typically, if any change is needed, you will only need to change one or two gains

slightly. (See Adjustments section for details). If other adjustments seem to be needed,

make certain that you have the proper calibration material and the sensor window and

sensing area are clean before adjusting.

Unless you are using narrow thresholds on the NIR amplitudes, we do not recommend

readjusting all outputs to compensate for small variations in amplitude. Calculate the

ratios, and adjust only to compensate for intensity degradations that affect the ratios.

If practical, we recommend that either a provision be made for adjusting the gains in

software, or that gain adjustment capabilities be built into the analog circuitry to which

the CS64A is connected. The gain adjust pots on the CS64A can be used if no other

adjustment point is available.

9. Maintenance

Cleaning: Under normal conditions, the CS64A requires little or no maintenance other

than keeping the window and sensing area clean. Use only water and cleaning materials

compatible with polycarbonate, such as isopropyl alcohol.

In dusty conditions, an automated air nozzle can be used to help keep the window clean.

The ratio calculations will compensate for signal strength degradation down to about 75%

of normal signal. Beyond that, performance will start to suffer. Once the window and

viewing area are cleaned, the ratio calculations will automatically readjust to the clean

conditions.

If the window becomes scratched or damaged, it should be replaced. Order from Delta:

Part No: CS64A-Window.

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Delta CS64A User Manual Page 15