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tamorgen · 28th April 2008, 09:04

Hi all,
I bought my VR3 last year when I bought my Dolphin to use it to monitor FO2. I have the C9 code (External O2 Sensor), as well as up through C4(CCR & Trimix) I've never had a lot of luck of getting an accurate reading of the FO2, but I went out this weekend for the first dive trip of the season, with brand new sensors, and this has got to take the cake.

I hooked up the new sensor, and I went to calibration mode. First off, please note I am using it in semi-closed mode, so Xo2 and XDec are both on. Apparently, it took me a little while to figure out, but this sets the VR3 into calibrating the sensor as per CCR mode. Is this what everyone else has noticed?

When I tried calibrating it, I thought it was supposed to calibrate off of air. Well, I tried doing this, and after calibration, it was reading air as 32%. Doesn't quite seem right, does it? I would turn my mix on (38%), and the VR3 would read around 50%. Definately not right. I tried a different, brand new sensor, and I got the same result. I turned off XDec and dove it as table inspiration, and got off the boat.

That night, I was reading the manual, and it occured to me to that CCR wants to calibrate via 100% O2 (it tells me to Flush with my calibration mix). So, one of the guys I was diving with had his 13 cu ft O2 bottle for his Optima, so I hooked up the sensor to his bottle, and started the calibration processs all over. The VR3 started calibrating the O2 at 161%, but then I told it to calibrate, it reverted down to 100%, and I thought I was good to go. I stopped flushing, pulled it away (after all calibrated), and it said 21% (air), so I thought I was good to go.

Yesterday morning I go out to the boat, and hook up everything, and I think everything is good to go. I plug my VR3 back in to my Dolphin, and it's reading 9% FO2 off of my 37% mix. At this point, I'm like WTF!? So, I again turn off XDec and dive it via the tables.

Two things: 1) Can anybody tell me what I'm doing wrong? 2) Can the folks at VR3 kindly write the manual to explain to us using the VR3 in semi-closed mode that you may have to calibrate it via CCR calibration mode? I just about wanted to through the computer over the side this weekend. It was extremely frustrating. Keep in mind that I tried two different, brand new sensors, and got the exact same results.

28th April 2008, 09:04	#1 (permalink)
tamorgen Gadget guru extrordinaire Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Apr 2006 Location: Columbia, MD Posts: 183	Calibrating the VR3 O2 Sensor Hi all, I bought my VR3 last year when I bought my Dolphin to use it to monitor FO2. I have the C9 code (External O2 Sensor), as well as up through C4(CCR & Trimix) I've never had a lot of luck of getting an accurate reading of the FO2, but I went out this weekend for the first dive trip of the season, with brand new sensors, and this has got to take the cake. I hooked up the new sensor, and I went to calibration mode. First off, please note I am using it in semi-closed mode, so Xo2 and XDec are both on. Apparently, it took me a little while to figure out, but this sets the VR3 into calibrating the sensor as per CCR mode. Is this what everyone else has noticed? When I tried calibrating it, I thought it was supposed to calibrate off of air. Well, I tried doing this, and after calibration, it was reading air as 32%. Doesn't quite seem right, does it? I would turn my mix on (38%), and the VR3 would read around 50%. Definately not right. I tried a different, brand new sensor, and I got the same result. I turned off XDec and dove it as table inspiration, and got off the boat. That night, I was reading the manual, and it occured to me to that CCR wants to calibrate via 100% O2 (it tells me to Flush with my calibration mix). So, one of the guys I was diving with had his 13 cu ft O2 bottle for his Optima, so I hooked up the sensor to his bottle, and started the calibration processs all over. The VR3 started calibrating the O2 at 161%, but then I told it to calibrate, it reverted down to 100%, and I thought I was good to go. I stopped flushing, pulled it away (after all calibrated), and it said 21% (air), so I thought I was good to go. Yesterday morning I go out to the boat, and hook up everything, and I think everything is good to go. I plug my VR3 back in to my Dolphin, and it's reading 9% FO2 off of my 37% mix. At this point, I'm like WTF!? So, I again turn off XDec and dive it via the tables. Two things: 1) Can anybody tell me what I'm doing wrong? 2) Can the folks at VR3 kindly write the manual to explain to us using the VR3 in semi-closed mode that you may have to calibrate it via CCR calibration mode? I just about wanted to through the computer over the side this weekend. It was extremely frustrating. Keep in mind that I tried two different, brand new sensors, and got the exact same results.
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