¾-1/2” Red. Union

3/8”OD

ACSM Inlet Configuration

0.1 lpm to ACSM with PM1 passing thru aerodynamic lens

2.9 lpm to external Pump*

Sheath Flow

6 lpm dry air

¼” OD

OUT

1/8” NPT

Rotameter

Needle Valve

ACSM Pivot

Splitter

½” OD thin wall ss-Tubing PD-50T-24SS 1/8” OD ss-Tubing

¾-1/2-3/8” Reducing Unions

Inside Shelter

PM2.5 at 3 lpm on platform ~5 mag

Goose neck connection to top of cyclone

1/4” NPT

3/8” OD flex Tubing

½”OD

Qty 2: ¼” to 1/8 NPT Connect.Qty 2: ½” to ¼ NPT ConnectorTube-Fittings needed:

¼” ODIN

*) Pump needs to be installed outside in order to reduce heat and vibration near ACSM inside

Perma Pure Nafion Dryer (ND) for ACSM Sample

PD-50T-24SS

AmbientSample

3 lpm

Dry sheath~6 lpm

Operating PD-50T-24SS at 3 lpm generates a pressure drop of 0.403 psid or 11.2” water, delivering sample air with a dew point of -11 oC; see chart.

In SEARCH it is standard to provide sheath flow at about twice the rate of the sample flow, using a heatless dryer model from Perma Pure; see next slide for details. Operating ND with Sample In and Sheath Out at approximately the same absolute pressure lessens the need for leak-tight connections, thus preventing potential twisting of the membrane tubing and damage.

¾-1/2” Red. Union

3/8”OD

SEMS (DMA-CPC) Inlet Configuration#

0.36 lpm to CPC

9.6 lpm to external Pump*

Sheath Flow

¼” OD IN

¼” OD

OUT

1/8” NPT1/8” Union

Rotameter

Needle ValveBMI

Splitter½” OD thin wall ss-Tubing PD-200T-24SS

1/8” OD ss-Tubing

¾-1/2-3/8” Reducing Unions

Inside Shelter

BGI-1.829 for PM1 at 10 lpm on platform ~5 mag

½” O-ring seal

1/4” NPT

3/8” OD flex Tubing½”OD

Qty 2: ¼” to 1/8 NPT Connect.Qty 2: ½” to ¼ NPT ConnectorTube-Fittings needed:

*) Pump needs to be installed outside in order to reduce heat and vibration near ACSM inside.

#) When not sampling ambient aerosol, the SEMS is used in combination with an atomizer to calibrate the ACSM response with 300 nm NH4NO3 particles of different concentrations. After initial set up, this calibration procedure needs to occur daily or weekly before reducing it to a quarterly schedule once in routine operation mode.

Perma Pure Nafion Dryer (ND) for SEMS Sample

PD-200T-24SS

Sambien Sample 10 lpm

Dry sheath

~20 Lpm

Operating PD-200T-24SS at 10 Lpm generates a pressure drop of 0.336 psid or 9.3” water, delivering sample air with a dew point of -12 oC; see chart.

In SEARCH it is standard to provide sheath flow at about twice the rate of the sample flow, using a heatless dryer model from Perma Pure; see next slide for details. Operating ND with Sample In and Sheath Out at approximately the same absolute pressure lessens the need for leak-tight connections, thus preventing potential twisting of the membrane tubing and damage.

Perma Pure Heatless Dryer (HD)

HD-2000-06-110 (7 “ Dryer, 110 VAC) provides ND sheath flow at ~6 lpm for the ACSM (~20 lpm for DMA-CPC) and ambient pressure. HD dryers consist of two chambers filled with highly adsorbing molecular sieve 4A desiccant. One chamber dries the gas stream while the opposite chamber is regenerated (purged). Purge air is a small portion of dried air taken from the drying chamber, expanded to atmospheric pressure and flowing countercurrent through the regenerating (wet) chamber. Wet purge air is released from an exhaust port in the vapor state so that no drain is required. Purge air volume is controlled with an orifice housed within the unit and is vented directly into the surrounding atmosphere.

HD units have been operating very reliably for the SEARCH network, consistently generating dry air with less than 10% RH at total flow rate of up to 60 lpm.

Possible reasons to fail: i)desiccant needs replacing, ii)solenoid valve stops switching, iii)circuit board fails due to lightning strikes or power delivery issues.

ZA/DA System at ATL site

HD-2000-06-110 (7 “ Dryer, 110 VAC) can provide <10% RH or -40oC DP dry air of up to ~60 lpm at ambient pressure. With currently only 26 lpm used to dry the combined ACSM and SEMS (DMA-CPC) sample air flows, at least another 30 lpm can be provided before maximum capacity is reached.

Running the compressor’s duty cycle consistently above 60 % will reduce the lifetime of the working components and risk the need for replacement before the end of the 2-year study. Mfg-suggested Reflux or Split Sample methods may be considered as alternative solution (see Mfg manual).

Using chart from slide #2, and assuming operation of same model PD-200T-24SS at (up to) 20 lpm generates a pressure drop of 0.672 psid or 18.6” water, delivering sample air with a dew point of -8 oC.

ZA for ACSM and SEMS cal

6Lpm ACSM-spl

20Lpm SEMS-spl

<20Lpm DMA-sheath