This filter is used in motor testing applications especially with diesel engines or FSI engines where you have high particles in the exhaust gas. The built in solenoid valve is protecting the whole analyzing system during the flushback cycle against high flashpressure. In this time, the valve is switching to room air. Another solenoid valve is switching the pressure air for flushing the filterelement. The built in titan filter element is very easy to replace and also easy to clean.