PSS 20   "13 Mode" and "Transient" tests User facilities Mobile and small dimension sampling system   PARTICULATE SAMPLING SYSTEM Following the European directives 88/77/EEC and 91/542/EEC and a new measurement in “transient” directives, the legislation requires a partial flow dilution system for measuring particulate matter exhausted from Diesel engines. The PSS 20 represents a low cost and user-friendly system complying with annex V of this directive. Adopted by numerous car-makers, the mini dilution tunnel is the result of a joint cooperation between CONTROL SISTEM and IVECO started in 1987. It consists of a cabinet containing the dilution air system, the diluted gas system, the control unit, and a mobile trolley with the sampling system to be placed close to the engine.