Instruction Manual

748332-F April 2003

Model NGA2000 NDIR

4-8 FLOW SENSOR REPLACEMENT

See Figure 4-5 on page 4-5 for Flow Sensor location. To replace Flow Sensor, remove all connecting hardware and undo connections to the sample line.

Open Analyzer Module front panel

Access the oscillator tune value in the Primary Variable Parameters menu.

Adjust oscillator tune knob to its maximum setting and then turn it counterclockwise to 80 % of that maximum setting.

4-9 CASE TEMPERATURE SENSOR REPLACEMENT

Case Temperature Sensor is attached to the motor source assembly. To replace this sensor, cut the Ty-Rap binder and disconnect the sensor connector. Reverse these instructions by reconnecting the new sensor and attaching with a new Ty-Rap.

4-10 THERMAL FUSE REPLACEMENT

Disassemble and reassemble the Detector block according to Figure 4-7 on page 4-7 to replace the Detector Thermal Fuse.

4-11 OSCILLATOR TUNE/SOURCE BALANCE SHUTTER ADJUSTMENT

The Analyzer Module is calibrated, tuned and balanced at the factory. If the diagnostic values for oscillator tune and detector signals are within ±5 % of the factory settings in Primary Variable Parameters and Modulation Check menus), no adjustment is necessary. If not, see Figure 4-5 on page 4-5 and Figure 4-6 on page 4-7 for Oscillator Tune and Source Balance Shutter adjustments, and do the following:

Open Platform front panel, if present.

CAUTION

HAND INJURY HAZARD

Do not place hands or fingers in Platform front handles when the front panel is open. Dropping front panel while hand or fingers are inside either handle can cause serious injury.

Access the detector signal value in the Modulation Check menu.

Flow zero gas (nitrogen) through the sample cell until the display reading stabilizes.

CAUTION

DELICATE COMPONENTS

The shutter is a delicate component with only a six-degree rotation. Take care when making the required adjustments.

Using an appropriate screwdriver that will fit through the Source Balance Adjustment Screw Holes (see Figure 4-5 on page 4-5), rotate the sample shutter adjust screw until a minimum reading on the display is obtained. (A typical reading is 0.2 through 0.5.)

Add 0.5 V to the value obtained in Step 7 by adjusting the sample shutter adjust screw clockwise. (If this reading exceeds 1.2 V, then a cell cleaning is necessary; see Section 4-12 on page 4-8.)

Rotate the shutter adjust screw clockwise until the display reads the value obtained in Step 8.

Reassemble the Analyzer Module and, if appropriate, the Platform.

4-6 Maintenance and Troubleshooting

Rosemount Analytical Inc. A Division of Emerson Process Management