IRIS MODEL P522 APPLICATION MANUAL
tion is present). Its output is
The very narrow spectral response of the UV tube makes this type of detector ideal for discriminating between flame, glowing refractory, and other burn- ers. However, because of its response to only the very short wavelengths, problems can occur because this radiation is easily absorbed and masked by un- burned fuel or other impurities in the coal (i.e., with pulverized coal). Sour gas (H2S) will readily absorb these short 200 nm wavelengths, as well as other waste fuels resulting in a dropout of the flame sig- nal. Even standard glass will absorb this wavelength; therefore it is necessary to use a quartz lens with this viewing head.
In general, the S506 viewing head will work well on natural gas flames. It will respond to oil flames, but with a lower signal level. The sighting should be parallel to the axis of the burner and aimed at the foot of the flame. Photographs of gas and oil flames using visual- and
S506 SELF-CHECKING
VIEWING HEAD
The
The UV tube used in the S506 is a different type of tube, having an anode and cathode instead of the
experienced a runaway condition with this tube only once, with a tube that had been subjected to such a significant shock that the electrodes inside were clearly bent.
Why use
Each time the shutter closes, the flame signal is blocked, resulting in a cessation of pulses. This is interpreted by the P522 as a normal condition (no pulses during the dark period) and the flame relay is kept energized. If this does not occur, the P522 will go into a lockout state, causing the flame relay to
S509 VIEWING HEAD
As explained in the S509 product brochure, this view- ing head employs a
The electromagnetic spectrum, or spectral range, for the Si element is 350 nm to 1100 nm; for the PbS element it is 1100 nm to 3000 nm. The Si element will detect all incandescent type flames such as oil, pulver- ized coal, and most waste fuels. It will not see natural gas or propane fuels at all. The PbS element will detect all flames, including natural gas and propane.
For this reason, the S509 viewing head will exhibit stronger signals for oil and pulverized coal than for natural gas, providing both the Si and PbS
An important characteristic that must be explained is the nonlinearity of the Si channel on “bright” sig-
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