Instruction Manual

HAS60E-IM-HW

June 2007

NGA 2000 CLD

4-7 DETECTOR DISASSEMBLY

Refer to figure 4-3.

a.Reaction Chamber Removal

Disconnect the stainless steel tubing lines at the fittings. Remove the (4) nuts holding the Detector Assembly to the chassis. Disconnect the plug from connector J1 on the Signal Board and remove the assembly from the chassis.

NOTE

Care should be taken to avoid getting heatsink compound on optical surfaces. If this substance is removed during the disassembly process, a zinc- oxide-filled, silicone grease (e.g. Dow Corning 340 or EG & G Wakefield Engineering´s Series 120 Thermal Joint Compound) be reapplied in the reassembly of this component.

Although the heater and thermostat can be removed to facilitate handling, contact with the white heatsink compound can be minimized by leaving these items in place. Remove the (2) screws holding the top plate of the De- tector, and move the plate along the wires and away from the Detector.

Remove the (2) screws holding the tube assembly in place. Hold the tubing with one hand while inverting the Detector Housing with the other, allowing the Reaction Chamber O-ring and window to be removed from below.

b.Reaction Chamber Installation

To reinstall, hold the housing in the inverted position while sliding the Reaction Chamber O-ring and window into position and the tubing into the slot in the housing. Hold the Reaction Chamber in place while rotating the housing upright. Replace the hold-down screws.

NOTE

The procedure described above is for the purpose of maintaining the relative positions of windows and O-ring to the Reaction Chamber during instal- lation.

Replace the top cap and screws. Reverse the removal procedure to reinstall the Detector Assembly into the Analyzer Module.

c.Photodiode Removal

Remove the Detector Assembly as described above. Invert the housing to access the mounting bracket. Remove the (3) screws and shoulder washers from the bracket, insulating disk and bottom plate as a unit to minimize the spread of the heatsink compound.

Remove the (2) screws holding the lower section of the Detector Housing, then slide the section along the cable and remove.

Remove the (2) screws holding the socket, thermistor and photodiode in place, being careful not to lose the washers that are used as shims.

Grasp the socket and photodiode base while slowly rotating to separate the photodiode from the housing. Some friction will be felt as an O-ring is used around the photodiode as a seal.

d.Photodiode Installation

To replace the photodiode, carefully remove the diode from the green socket, and replace with a new one. Before mounting the new diode, the top cap of the enclosure should be temporarily removed and the (2) screws holding the Reaction Chamber loosened about two turns.

This allows air which is trapped between the O-ring seals to escape when the diode is inserted. It also maintains the position of the O-ring and window in the upper com- partment.

The new photodiode should be slowly inserted into the housing while gradually rotating the body. This allows the O-ring to properly seat. Continue replacing screws, wash- ers, thermistors, etc., with the thicker shim (washer) on the opposite side of the socket from the thermistor.

Replace the lower section of the housing, then the bottom cover, insulator and bracket with the shoulder washers and screws.

Re-tighten the screws in the Reaction Chamber (upper section). Replace the top cap and its screws.

To reinstall in the Analyzer Module, reverse the procedure for removal as indicated above.

Emerson Process Management GmbH & Co.OHG

Maintenance and Service 4 - 5