The Cambustion DMS500 now includes a 2 stage dilution system. This will allow sampling of most aerosols without any additional hardware. The dilution system is integrated with the instrument interface and the dilution ratio can be automatically corrected for in the instrument output.

The primary dilution system comprises a mass flow controller which supplies a measured quantity, automatically controlled to the desired proportion of the sample flow, of filtered dilution air into the sample stream at the sample point. It provides dilution ratios up to 5:1 and reduces the humidity and temperature of some samples such as internal combustion engine exhaust. If the optional heated sample line is used, the primary dilution air may be heated up to 150°C. Use of the primary diluter requires a supply of 10slpm of compressed air.

The secondary diluter is a rotating disc type and is mounted inside the DMS500. It provides dilution ratios from 20:1 to 500:1, to increase the dynamic range of the instrument and reduce the need for cleaning. Compared with other rotating disc diluters, the Cambustion system is designed for minimum residence time to preserve the time response of the instrument and reduce diffusive particle losses.

Raw sample enters the diluter and the majority passes through the holes in the rotating disc and through a HEPA filter. The clean carrier gas passes back through the dilute sample ports in the disc. A small fraction of the sample is transported by the rotation of the disc directly from the raw sample port to the dilute output and constitutes the fraction of the sample which is measured by the instrument.

The dilution ratio is determined in real time from measurement of the filtered sample flow and the rotation speed of the disc, and accounted for in the instrument output.

High ratio diluter (pdf 160kB)

For many applications, only the secondary diluter is required. For example sampling engine exhaust from a CVS system (dilution tunnel) or engine plume sampling. For high concentration, humid, samples, such as raw exhaust gas, the two stage system should be used.

add specs from brochure.

Contact Cambustion for more information and prices.