Date: Mon, 20 Jan 2020 13:03:48 -0000
Subject: Re: [sloan-25mlog 4894] 2.5m obslog 20200119 (SJD 58868)
From: "Dmitry Bizyaev"
Good morning,
the same problem was reported on October 5, 2019.
That time it was recommended to notify Ed Leon
in addition to 2.5m engineering staff.
CC-in Ed.
That time Russet commented:
>It's not uncommon for the TSL sensors to freeze when the dewpoint is higher
>than 0 C.  By "freeze" I mean physically, with ice buildup.  There is a
>procedure for unfreezing it but no one on the night staff is trained in that
>procedure.
Dmitry
>                           Sunday January 19, 2020
>                                   (SJD 58868)
> (1) We are concerned that the humidity sensors may be indicating that it is
> safe
> to open when it is not. Is there a way to check the accuracy of the dew point
> sensors to make sure they are reading properly? See log for details.
> NOTE:
> -----
> The past few nights the humidity has not been registering very high on the APO
> Weather Status page but is clearly seen with frost on the ground, seeing one's
> breath, and feeling moisture on surfaces.
>
> We closed at 5:31Z after noticing high humidity and condensation outside; we
> attempted to reopen at 07:15Z (the dewpoint depression was >8C) but
> frost/condensation was clearly visible on several surfaces outside (rails near
> ops building, walls of the plug lab, rails along the apron, enclosure doors).
> There were several times tonight when the dew point depression indicated it
> was
> very safe to open, but conditions outside indicated that it was not.