Preventive Maintenance

Nitrogen-phosphorus detector (NPD)

Caution

Caution

Reinstallation

1.Reinstall the jet in the detector base (using a 1/4•inchnut driver). Make sure that the threads are clean and free of burrs that could cause damage. If there is any binding, the cause should be determined and corrected before proceeding. If a torque wrench is available, no more than 1 Nm (newton meter) of torque should be used to install a new jet.

Do not overtighten the jet! Overtightening may permanently damage the jet, the detector base, or both.

2.Cleaning and reassembly of the collector/collector assembly is as follows:

Powdery deposits may be removed from the interior of the collector by gently blowing out the loose material with low•pressurecompressed air or nitrogen.

Do not attempt to clean out the inside of the collector by inserting objects such as wires or brushes•to do so may damage the active element.

Inspect the collector assembly to make sure that the active element is centered in the tube and is not shorted to the side and that it is positioned horizontally.

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