Instrument Updates

Nephelometer Updates

TSI will cease production of the 3563 at the end of this calendar year. They plan to support the instrument for another 7 years. If you are looking to add to your TSI nephelometer collection - order one soon! It is good to know that TSI will not abandon the instrument service anytime soon. This provides a multi-year window for the decision on whether to upgrade from 1G or 2G motors to the 3G motors.

Continuous Light Absorption Photometer (CLAP) updates

CLAP failure issues

As reported in the last newsletter, CLAPs have been deployed at almost all stations in the federated network. Over the past several years there have been a few common problems with the CLAP which have been solved as they arose.

First, the voltage regulator inside the instrument overheated and eventually failed. The symptom of this was that the instrument appeared to not be getting power (the flow readout was blank and the instrument was not talking to the aerosol software) even though the external power supply was fine. The solution to this problem was to have the NOAA aerosol group's engineer (Jim Wendell) added a heat sink to the voltage regulator to help dissipate heat. If your station's CLAP hasn't been sent back to NOAA for this repair [EC: 10.002 (AI1), 10.006(ETL), 10.017(WHI); ARN: 10.021; BEO: 10.022] don't be surprised if this issue comes up for your instrument sometime in the next year! We're also happy to fix the instrument pre-emptively if there's a convenient time to be without CLAP measurements for a bit (expect a 2-4 week turn around).
Note: the overheating is caused by running the voltage regulator at 24 V which is what the solenoids require. There are now solenoids that operate at 12 V so at some point we will transition to those. This will have the added benefit of allowing the CLAP to be run at 35 C which was the original design temperature.

Second, some solenoids have begun to leak (there are 10 solenoids in each CLAP - one for each sample spot plus the two reference spot solenoids). We are in the process of developing a kit which will allow you to quickly and easily check the status of your CLAP's solenoids. We are unsure of the cause of this of the solenoid leakage - one hypothesis is that it could be heat-related; another hypothesis is that bits of filter or other 'gunk' might fall into the holes when the filter is being changed. When a CLAP filter is being changed - be careful to clean any filter residue sticking to the instrument in such a way that it does not fall into the holes.

Thermo-denuder study using CLAPs

NOAA is currently in the middle of a second run of 10 CLAPs. The idea is that these new CLAPs will be run with a thermo-denuder in front of them to remove volatile species. Running a normal CLAP and a CLAP with a thermo-denuder inlet side-by-side will provide information on artifacts/interference of volatile species on the measurement of aerosol absorption. Kondo et al. (2009) provide an example of the type of experiment we are planning. If you are interested in participating in a tandem CLAP study please contact John Ogren and Pat Sheridan.

Tri-color Absorption Photometer by BMI

Don't forget - Brechtel Manufacturing Inc (BMI) is now making an off-the-shelf version of the CLAP. They call it the Tri-color absorption photometer or TAP. Contact BMI for more information.
 
CLAP and TAP side-by-side.