Honeywell C7015A manual Operation Installation, Tory, Cell Construction, Basic Requirements

C7015A

OPERATION • INSTALLATION

Operation

OPERATION OF INFRARED DETECTORS

Infrared detectors can be used with gas, oil, coal, or dual- fuel flames. Since more than 90% of the total flame radiation is infrared, these detectors receive ample radiation and can detect weak fkunes as well as flames of higher intensity.

The lead sulfide cell used in the detector cannotdiitin- guish between the infrared radiation emitted by hot refrac- tory and the infrared radiation from a flame. Therefore, the infrared detection system includes an amplifier that re- sponds only to the flickering characteristic of flame radiation and rejects the steady radiation characteristic of hot refrac-

tory.

Unfortunately, smoke or fuel mist within the combustion chamber can intermittently reflect, bend, or block the hot

refractory radiation, thus making it fluctuate. This fluctuating action can simulate the flickering radiation from a flame, and infrared radiation may be present even after the refractory has visibly stopped glowing. Therefore, be very careful when applying an infrared detection system to be sure it responds only to flame.

CELL CONSTRUCTION

,The photosensitive material used in the infrared detector is lead sulfide. The electrical resistance of lead sulfide de- creases when exposed to infrared radiation. If a voltage is applied across the lead sulfide photocell, current flows when the cell is exposed to infrared radiation.

Installation

WHEN INSTALLING THIS PRODUCT.. .

1.Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condi- tion.

2.Check the ratings given in the instructions and on the product to make sure the product is suitable for your applica- tion.

3.Installer must be a trained, experienced flame safe- guard control service technician.

4.Afterinstallationiscomplete,checkoutproductopera- tion as provided in these instructions.

A! CAUTION

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1.Disconnect power supply before beginning in- stallation to prevent electrical shock and equip- ment damage, there may be more than one disconnect.

2.All wiring must be NBC Class 1 (line voltage).

3.Use the C7015A only with Honeywell lead sulfide photocells (part no. 104662D) and flame signal amplifiers specified, (see Table 6).

Proper flame detector installation is the basis of a reliable flame safeguard installation. Refer to the burner manufac- turer instructions and instructions below. Carefully follow instructions for the best possible flame detector application.

BASIC REQUIREMENTS

Because all flames produce infrared radiation, a C7015A Infrared (lead sulfide) Flame Detector can be used to prove the presence of a flame in a combustion chamber. The detector is mounted outside the combustion chamber. Screw themountingcollartooneendofasightpipeinsertedthrough the wall of the combustion chamber. The lead sulfide photo- cell in the detector sights the flame through the sight pipe.

When a flame is present, the lead sulfide photocell detects the infrared radiation generated. The C7015A pro- duces an electric signal that is sent to the amplifier in the flame safeguard control. The amplified signal pulls in the flame relay in the flame safeguard control to allow proper operation.

Because it is necessary for the detector to actually see the flame, it is best to locate the detector as close to the flame as physical arrangement, temperature, and other restrictions permit. These restrictions are described in detail below.

DETERMINE THE LOCATION

Before beginning the actual installation, determine the best location for mounting the flame detector. Carefully consider the factors discussed in this section before establish- ing the location.

TEMPERATURE

The sensitivity of the lead sulfide cell decreases as its temperature increases. Up to 125’ F [52’ Cl, the loss in sensitivity is negligible, but temperatures above this point must be avoided. Under normal temperature conditions (be- low 125” F [.52’ Cl, the life of the lead sulfide cell should be unlimited. The quickest check for excessive temperature is simply to grasp the detector-it should not be too hot to hold comfortably in your bare hand.

Several methods are available for cooling the lead sulfide photocell including ventilating the sight pipe and installing a pipe nipple, seal-off adapter, and/or heat block between the sight pipe and the detector. Refer to Installing Accessories, page 8.

SIGHTING

The infrared detector must continually sight a stable portion of the flame being detected. The detector is com- monly applied to detect both the gas pilot and main gas flame, or thegaspilot and main oil flame.ln either case, the detector must be carefully aimed at the intersection of the pilot and muinflame. A Swivel Mount (Honeywell part no. 118367A)

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