Equipment and Calibration History

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View history entry 5533 for PME miniDOT sn: 1221

Date: 2021-10-20
From: Lab - none
To: Lab - none
Title: Tested
Notes: This sensor was covered in barnacles, the copper screen was falling apart and there are nicks in the coating on the window. I cleaned up the sensor and tested it side by side with miniDot sn 931528. Both sensors were suspended in a bucket of water with a bubbler in the bottom. The sensors were out of the stream of bubbles. Ice was added to the water bringing its temperature down from 20C to 0C. Then the dissolved O2 was recorded by both sensor over about 24 hours as the water returned to room temperature. The two miniDots matched each other by better then 2%. And they matched the theoretical O2 saturation of the water at about 4%. This sensor had a quailty flag of about 0.84 whereas the newer, uncompromised sensor (sn 931528) had a quality flag on 1.03. I think I'll send a photo of the window coating and these notes to PME to get their take, but I think it's okay to return sn 1221 to service.
Entered by: Joe Verfaillie