GRIMM Aerosol Technik Dehumidification methods from GRIMM by

GRIMM Aerosol Technik Dehumidification methods from GRIMM by Eng. Wolfgang Brunnhuber

general information Ø Moisture / humidity is the greatest problem when measuring particles in ambient air. Ø Most instruments on the market heat the probe up to about 35 -40°C to handle this problem. But at the same time they loose the semi volatile compounds (SVC). Ø We at GRIMM have decided to dry the probe instead of heating to keep the SVC. We begin to dry when humidity gets higher than 65%.

Silica GEL Dryer Nafion Dryer

EDM 165 & EDM 265

EDM 165 main parts Sample Pipe Humidity Temperature Sensor Dryer Monitor Reserve

DEHUMIDIFICATION EDM 165 Operating Principle

Silica GEL Dryer Nafion Dryer

EDM 180, EDM 365 & EDM 565

Benefits of Nafion ØNafion transfers moisture quickly Water transfers through Nafion as a first order kinetic reaction. Water transport is driven by partial vapor pressure differential. ØNafion transfers water selectively Water associates readily with sulfonic acid groups and permeates through the membrane wall. ØNafion needs no maintenance By the working principle of the Nafion it has the big advantage that it doesn’t need any cleaning and has a long life time (if used under normal ambient air conditions over 10 years) without loss of performance. ØNo loss of semi volatile compounds

Dryer flow schematic

Jorge Anjos

Sampling pipe with Nafion tube

RAW Data – 15 min average values

RAW Data – comparison to reference daily values