PURPOSE: To suppress the level fluctuation of noise signals in a fine-particle detector that detects fine particles by eliminating noise signals resulting from molecules of air.
CONSTITUTION: An orifice pipe 5, having the appropriate length lo and a small diameter o as compared with the bore n of the shell of an injection nozzle 22, and adapted to reduce internal pressure by increasing the flow velocity of air A, is provided for insertion into the inlet of the injection nozzle 22. The velocity-increased air A is supplied to the injection nozzle A, and diffused at the shell 22a to lower its velocity, and is uniformly injected from an opening 22c without fluctuating. Therefore noise signals are eliminated and detecting errors are avoided, so enhancing the detecting performance of a fine-particle detector.
SHINPO SENJI
SUZUKI TSUNEKIYO
