Environmental Instruments
Download
Report
Transcript Environmental Instruments
GRIMM
Aerosol Technik
Dehumidification methods
from GRIMM
by Eng. Wolfgang Brunnhuber
general information
Moisture / humidity is the greatest problem when
measuring particles in ambient air.
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).
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
EDM165 & EDM265
EDM165 main parts
Sample Pipe
Humidity
Temperature
Sensor
Dryer
Monitor
Reserve
F ei dl housnig 1 1. 65
DEHUMIDIFICATION
EDM165
Operating Principle
1 1. 07
Silica GEL Dryer
Nafion Dryer
EDM180, EDM365 & EDM565
Benefits of Nafion
Nafion transfers moisture quickly
Water transfers through Nafion as a first order kinetic
reaction.
Water transport is driven by partial vapor pressure
differential.
Nafion transfers water selectively
Water associates readily with sulfonic acid groups and
permeates through the membrane wall.
Nafion 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 10years) without
loss of performance.
No loss of semi volatile compounds
Dryer flow schematic
Model 180 Vacuumflow schematic
from
Sample Out
sample pipe
holder
sample pipe
sample pipe
holder
under-pressure
regulator
-550mbar
1.2l/min
from
room
Sample
Head
1.8l/min
CQ
vacuum
filter
Linear
Silencer
Pump
permapure
dryer
CQ
Needle-valve
1
Vakuum
meter
3
Switch
-400mbar
to meassurment chamber
protection
filter for
vacuum pump
Outlet
back
side
Jorge Anjos
Sampling pipe with Nafion tube
RAW Data – 15min average values
RAW Data – comparison to reference daily
values