Rebreather World - View Single Post

tamorgen · 28th April 2008, 14:01

Quote: (Originally Posted by Dinspiration)

Hi

For OC/SCR calibration of VR3 the calibration gas is always AIR and can not be changed.

To calibrate the VR3 for SCR you will need to switch the VR3 into OC mode and do the calibration as outlined within the manual with air. The Xdec function has no impact on the calibration at all.
After the calibration in air you can connect the O2 cell holder to your SCR breathing loop, Fill it using the bypass valve and the display should give you the correct reading.

Very often the SCR users did not set and activate the correct gas on the VR3. E.g. If you have a SCR and use a NX 50 with the standard flow rates you will have a NX 45 in your breathing loop. This means you have to set the active gas to a NX 45 and this should be the only active gas on your VR3. Xdec and Xfunc will then calculate the cell reading for you decompression and display it as FO2. If you don’t set the active gas near to the calculated FO2, you can get an “X Check” or “Check FO2” message on the display. To set the gas near your calculated FO2 is more important, if you are playing around with different flow rates. E.g. using a NX 40 with the NX 50 dosage etc.

DINspiration

Hi Dinspiration,
As I mentioned, I did try per the manual. I set the XFunc to Xo2, and began the calibration process. As you said, XDec shouldn't matter, but I attempted both methods.

When I have XFunc set to Xo2, and my VR3 in open circuit mode, I switched the right button to o2, give it a long push, and that brings me to the sensor screen, as expected. I hold down both left and right buttons to go into calibration mode, and it immediate tells me "FLUSH CAL GAS". This is not outlined in the manual, except in CCR mode. I believe if you have bought the CCR pin, the VR3 will only calibrate the o2 sensor in CCR mode. Next it tells me to "EQUALISE", then "STABLE READING?" This is precisely the method for CCR.

The Open circuit method skips both "FLUSH CAL GAS" and "EQUALISE", as illustrated on page 50 & 51 of my manual (2004 V3.0) When I have a stable reading, I should simply be able to give a short push of both switches and it will calibrated to air.

So, if I'm not diving CCR, how do I properly calibrate the unit if it doesn't give me an OC option?

28th April 2008, 14:01	#6 (permalink)
tamorgen Gadget guru extrordinaire Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Apr 2006 Location: Columbia, MD Posts: 183	Re: Calibrating the VR3 O2 Sensor Quote: (Originally Posted by Dinspiration) Hi For OC/SCR calibration of VR3 the calibration gas is always AIR and can not be changed. To calibrate the VR3 for SCR you will need to switch the VR3 into OC mode and do the calibration as outlined within the manual with air. The Xdec function has no impact on the calibration at all. After the calibration in air you can connect the O2 cell holder to your SCR breathing loop, Fill it using the bypass valve and the display should give you the correct reading. Very often the SCR users did not set and activate the correct gas on the VR3. E.g. If you have a SCR and use a NX 50 with the standard flow rates you will have a NX 45 in your breathing loop. This means you have to set the active gas to a NX 45 and this should be the only active gas on your VR3. Xdec and Xfunc will then calculate the cell reading for you decompression and display it as FO2. If you don’t set the active gas near to the calculated FO2, you can get an “X Check” or “Check FO2” message on the display. To set the gas near your calculated FO2 is more important, if you are playing around with different flow rates. E.g. using a NX 40 with the NX 50 dosage etc. DINspiration Hi Dinspiration, As I mentioned, I did try per the manual. I set the XFunc to Xo2, and began the calibration process. As you said, XDec shouldn't matter, but I attempted both methods. When I have XFunc set to Xo2, and my VR3 in open circuit mode, I switched the right button to o2, give it a long push, and that brings me to the sensor screen, as expected. I hold down both left and right buttons to go into calibration mode, and it immediate tells me "FLUSH CAL GAS". This is not outlined in the manual, except in CCR mode. I believe if you have bought the CCR pin, the VR3 will only calibrate the o2 sensor in CCR mode. Next it tells me to "EQUALISE", then "STABLE READING?" This is precisely the method for CCR. The Open circuit method skips both "FLUSH CAL GAS" and "EQUALISE", as illustrated on page 50 & 51 of my manual (2004 V3.0) When I have a stable reading, I should simply be able to give a short push of both switches and it will calibrated to air. So, if I'm not diving CCR, how do I properly calibrate the unit if it doesn't give me an OC option?
(Offline)