IRIS P522 manual Installation of Viewing Head, Sighting of the Viewing Head

IRIS MODEL P522 APPLICATION MANUAL

detected). The 4-20mA output will still perform the same way on the high end (i.e., on a strong signal, it will saturate at the same level, slightly above 22mA).

Specifications for the analog current output signal are provided in SPECIFICATIONS Figure 13.

INSTALLATION OF VIEWING HEAD

Before beginning the actual installation, determine the best location for mounting the viewing head based upon the following factors:

VIEWING HEAD CROSS-REFERENCE

OL D NUMB ER	NEW NUMB ER
S506	S506
IRX2S	S509
IRGS	S511
IRS	S512

FIGURE 7 - VEWING HEAD CROSS-

REFERENCE TABLE

PRESSURE

The viewing head lens will withstand 5 psi. If the lens assembly is exposed to greater than 5 psi through sight pipe, then an isolation unit must be used. An IRIS isolation unit with purge air entrance is avail- able as an accessory.

TEMPERATURE

The viewing head will withstand an ambient tem- perature to 80°C (176°F). However, the case tem-

perature of the housing must not exceed 60°C

(140°F). Purge air will help reduce conducted heat through sight pipe to flange (a plastic nipple will also help), but direct radiation can cause housing case temperature to exceed limits. If the ambient heat (direct radiation) is excessive, then a fiber optic ex- tension should be used (please refer to the IRIS Model 500 Fiber Optic System manual). This sys- tem is composed of a viewing head, a fiber optic assembly, and an amplifier module.

The model S5xx series of viewing heads have in place a sensor for sensing the internal temperature of the head. To access the reading of the viewing head temperature, press the “Reset” and the “Down” arrow key at the same time. The temperature read- ing will be displayed in the four-digit readout. The reading (indicated in °C) will disappear and the nor- mal reading will continue after several seconds.

VIBRATION

Do not install the viewing head where it could be subject to vibration. A vibrating viewing head (flicker type) can simulate flame when viewing a glowing background. Provide an antivibration mount if excessive vibrations are present.

CLEARANCE

Make sure there will be sufficient room to remove the housing for servicing (see Figure 16).

SIGHTING OF THE VIEWING HEAD

In general, the sighting of the viewing head should be parallel to the center line of the burner in the di- rection of the burner flame. This applies to both the UV type as well as the flicker type. Flicker type detectors respond to the high frequency flicker of the flame; so, in order to achieve maximum dis- crimination between burners, the near portion of the primary combustion zone should be favoured – meaning the sight pipe should be mounted as close as possible to the burner center line. The sight pipe should be aimed at the root of the flame, which radi- ates the most intense, high-frequency flicker energy. Sighting along the flame rather than across it per- mits the detector to view a greater depth of the flame root, obtaining better response (see Figure 17).

When sighting for a UV viewing head, you must aim for the UV zone, which is usually at the very first part of the flame root. UV radiation from most flames is restricted to a narrow region: it starts very close to the burner nozzle and does not extend out very far from the burner nozzle. You may have to angle the sighting inward toward the flame root, as shown in Figure 18.

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