From: John Downey
Subject: Fwd: Particle sampling issue found
Date: Tue, 6 Nov 2018 14:00:29 -0700
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Big thank you to Ed!
> Begin forwarded message:
>=20
> From: Ed Leon
> Subject: Particle sampling issue found
> Date: November 6, 2018 at 1:58:32 PM MST
> To: John Downey
> Cc: kaike pan
>=20
> Gentlemen,
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> I did find that the outside sampling tube had been left disconnected =
from the last service.  This explains the low counts - sorry. =20
>=20
> I did perform the side by side experiment with the hand held particle =
counter.  Web page displays counts per 0.1cubic ft and the hand held =
displays counts per 1.0 cubic ft.  Sampling flow rate is the same for =
both units (0.1cubic ft per minute).
> F.Y.I.
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> With the long sampling tube:
> 		hand held	web page
> 0.3um	128990		4493
> 1.0um	    3380		  156
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> With the short sampling tube:
> 0.3um	127600		9285
> 1.0um	    3510		  221
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> Samples above were taken within 5 minutes of each other.
>=20
> The experiment is VERY uncontrolled so I doubt any correlations can be =
made from these two samples.  The service counters are on a 5 minute =
cadence so a controlled experiment would require software support to =
bring the experiment inside.  Suffice to say that the particle counters =
(not the hand held) are calibrated yearly.  The count data can only =
provide relative (compared to historical) information at best.
>=20
> Ed Leon
> Apache Point Observatory
> 2001 Apache Point Road
> Sunspot,  NM 88349
>=20
> 575-437-0552
>=20
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Big thank you to Ed!Begin =
forwarded message:From: =
Ed Leon <eleon@apo.nmsu.edu>Subject: =
Particle sampling =
issue foundDate: November 6, 2018 at 1:58:32 PM MSTTo: =
John Downey <jdowney@apo.nmsu.edu>Cc: kaike pan <kpan@apo.nmsu.edu>Gentlemen,I did =
find that the outside sampling tube had been left disconnected from the =
last service.  This explains the low counts - sorry.  I did perform the side =
by side experiment with the hand held particle counter.  Web page =
displays counts per 0.1cubic ft and the hand held displays counts per =
1.0 cubic ft.  Sampling flow rate is the same for both units =
(0.1cubic ft per minute).F.Y.I.With the long sampling tube:		=
hand held	=
web page0.3um	128990		=
44931.0um	    3380		=
  156With the short sampling tube:0.3um	=
127600		=
92851.0um	    3510		=
  221Samples above were taken within 5 minutes of each =
other.The =
experiment is VERY uncontrolled so I doubt any correlations can be made =
from these two samples.  The service counters are on a 5 minute =
cadence so a controlled experiment would require software support to =
bring the experiment inside.  Suffice to say that the particle =
counters (not the hand held) are calibrated yearly.  The count data =
can only provide relative (compared to historical) information at =
best.
Ed =
LeonApache Point Observatory2001 Apache Point RoadSunspot,  NM =
88349575-437-0552
=
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