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Show -6- If a flare ,pilot. is co~str~cted with only a simple retention-type nozzle, it is likely to ~e extinguished In high crosswinds. An effective windshield, the length of which should be 1 ~3rd the total length of the pilot flame, will prevent this probI~ m. ~rope~ly de~lgned and manufactured to 180-9001 quality standards, a pilot windshield will protect a pilot flame and keep it lit, despite the worst on shore or offshore conditions. Why Constant-Burning Pilots? constant-burning flare pilots are needed to guarantee effective ignition of waste gas streams. Typically, flare pilots have flames that are approximately 18" (450mm) long. To maintain optimum flame stability and reliability, an inspirating or venturi-type gas burner is used in a flare pilot. A small gas jet, installed in the venturi tube at the base of the pilot, will introduce a gas/air mixture for a stable, fast burning flame and deliver that flamefront to the pilot tip. Pilot flames become unstable or tend to blowout if they are plugged by foreign material or dirt in the pilot gas stream. To insure proper pilot operation, it is necessary to keep pilot lines clean*. Retractable pilots, conveniently accessible from grade level, will simplify periodic inspection, cleaning and any readjustments. Because pilot flames are not visible to the eye in daylight, a thermocouple should be used to monitor pilot operation. A well-designed and thoroughly proven thermocouple is a reliable, convenient method of detecting a pilot flame. However, a thermocouple mounted on a pilot without an effective windshield will react erratically in high winds. Wind shear will tend to blow the pilot flame away from the thermocouple, resulting in an inaccurate "readings," thus causing false alarms and necessitating unnecessary EPA paperwork. To prevent these problems, while minimizing wind or rain intrusion, the thermocouple should be located inside a Fluidic Windshield. Other Pilot Design Parameters For an inspirating flare pilot burner, the mixture tube length may be several hundred feet. By contrast, mixture tube lengths for the "regular" inspirating pilots of process burners are usualty in the order of 2 to 6 ft. The influence of ·Our experience shows that when a new,flare or pilot is p~aced in service, ~" lines mU,st be ~Iown out before commissioning. Use of a strainer on fuel gas lines to keep the lines clean IS deSirable, as is a liquid trap or knockout pot to, re~ove liquid from the ga~ stream, A strainer s,hould not be placed in a flamefront line because It Will prevent the propagation of a flame to the pilots, |