Operating principle

The primary dilution takes place within the perforated tube, where the raw sample mixes with dilution air forced through small pores in the perforated tube wall. The perforated tube is housed within the primary diluter body, which can be heated or cooled. The dilution ratio of the primary dilution stage can be adjusted by changing the dilution airflow into the primary diluter.

The secondary dilution stage is an ejector pump, which draws the sample from the primary dilution stage and dilutes it further. The diluted gas exiting the ejector diluter is always at ambient pressure and temperature regardless of the initial raw sample gas characteristics. Ejector diluter dilution ratio has three options, low, medium or high. 

Dilution temperatures and pressures are measured in real-time by a control unit enabling second-by-second dilution ratio calculation, which takes changes in raw sample properties directly into account. The dilution air flows are regulated with a valve unit which contains critical orifices for accurate and repeatable control. Each FPS-4000 is individually calibrated by gas flow measurements which span all operating conditions.

The dilution ratio calculation result is saved in real-time along with temperature and pressure data in an easily accessible form for post-processing of the data. Analog output of the dilution ratio is also available for easy integration into existing data logging systems.