Quote: (Originally Posted by UWSojourner)
Hey Gilles,
Can you give us an idea of your calibration routine before you went with this "wet sensor calibration." Are your sensors stored in hot humid conditions? Or are you calibrating in an air conditioned building where humidity is kept much lower? I assume you are on Apecs? How do you perform the steps for calibration of that system?
Anything you can pass on with regard to temperature and humidity of calibration location and location where your meg is stored might be helpful.
Thanks.
Hi UWS (Couldn't find your name);
I'm glad someone finally asked for some detail.
I reside in Miri, Sarawak (Tropical jungle). The Meg is stored in a non-air-conditioned room adjascent to a moderately air-coned house . Cooling in my 2-story house is done by runnning air-cons upstairs, and sometimes 1 (of 3 available downstairs) air-con is on for the kids playroom. Meg is stored in 25-27 degC temp with plenty of ventilation (via a fan).
I've just arrived from a dive outing. I will detail the procedure I used on the boat after the days diving. This is the same procedure I used to practise in the above described room before I made this post.
Slide 1 in the attached .ppt photos my Head and calibration coupling that fits into the bottom nipple (that fits inside the scrubber cartridge). Following the air calibration, I plug in my cal-kit and I crack open the OMS flow meter to its minimum (some 0.5 L/m) of 99% O2 (slide 2). I also like to keep the head upright whilst flowing the O2 as this avoids gravity segregation of O2 and prevents the apparent slow response of an otherwise perfectly fine sensor 2. If 1 of the sensors is a bit slow, I hit cal when 2 of the sensors are at or above their theoretical mV (in this case however, all 3 have an equivalent response time).
Note also that the breathing hose port is open (no cap) when doing this to avoid any chance of building pressure.
Slide 3 details new data acquired today, and slides 4 and 5 chart it.
I also went out today to determine how long during the 1st dive it takes for the sensors to change their state. Note that I'm using a 9-hr old calibration performed some 6 days ago after a days diving.
After stopping briefly @6m with an O2 flushed loop (to readings of 1.7-1.8), I flushed and went down quickly to 40m with EAN30 dil. Flushed and started off at about 1.7, flushed every 5 minutes or so, and at 15 minutes all 3 sensors @1.5. On way up, stopped @6m and switched to bail-out. Opened the OPV, pinched the loop hose with left hand and hit the manual O2 button for a few seconds. Got readings of 1.55-1.65.
I could never achieve this before and always felt insecure (and thus dived at 1.0 all the time). I'm much more comfy now with the 1.2-1.3's!
I hope I got the right amount of detail
. Don't hesitate to ask for more.
Gilles