I have used an Aladdin Uwatec Air X for several years and recently upgraded to an Air OX. I like the Air X better and use it more often. Well I had the Air X on loan to a dive buddy for about a year while I played with the Air OX. She mentioned to me that the air pressure reading seemed low compared to the other divers fills when she used it. It was also on that same trip that she got DCS "rash and soreness in her breasts The instructor did not properly identify the problem and she continued to dive the entire trip. With the problem getting worse the whole trip. Her DCS symptoms of itchy burning and soreness would temporarily go away when diving. But would return with even greater intensity day after day. She told me that she did dive at the bottom of the group but was well within the safety limits as displayed by the computer. I could go into greater detail as to the symptoms of her DCS but I am quite convinced that is what it was.
Later that summer we went diving in a local lake and as she purchased her own computer I had my Air X back. I too noticed the lower pressure reading and non-linear consumption it displayed when diving. The lake is a cold fresh water lake and we rarely dive below 30ft. However this year I had my new dry suit and was diving to 60-100ft and having a good time. Half way thru the year "the 2nd or 3rd trip I decided to check out this computers readings. I know I should of verified the readings first thing but I had called Uwatec after she told me about the pressure discrepancy and Uwatec told me the pressure differences was because of the thermal compensation built into the transmitter. So I dismissed the problem. I decided to wear both of my computers at the same with two different transmitters so I could compare the two computers. I was amazed to find pressure differences of 500-700 lbs. I then when out of the water I paired the air X computer to the Air OX transmitter and found the fault was with the transmitter. I had 3 transmitters so I compared them all to discover that the Air X transmitter was defective. I sent it in for service and the technician called me back and told me it was a bad battery and it would cost me 50.00 to get it fixed.
I got the unit back and it was a new unit. I called to talk to a technician after I got the unit back because I had concerns about this type of problem happening again. I was nervous about using the computer and wanted to find out exactly what had happened. After a bit of cornering he told me that once and a while they get a transmitter that does this and it is not a battery problem. I continued to drill him about the subject and he said that he notices that maybe a half dozen transmitters a year come in with this problem. I also asked if this problem could cause problems with the diving profile as these computers calculate air consumption as part of the compartment half lives. He said, Yes it could cause a problem but was very rare that the transmitters fail this way.
So what does this mean to you? If you dive on a hose less air integrated computer you have to make sure that transmitted pressure is accurate. If you notice short fills while everyone else has full ones check it out with a different computer that is not air integrated! I would also recommend intermittent comparisons against other systems on the same tank. If the integrated computer records pressure as low and calculates your air consumption as low as a result you could be diving beyond your tables and be a risk of DCS!
I will always verify my pressure-sending unit on a regular basis now. In my opinion there should be some type of annual inspection where the unit is calibrated and verified accurate. I think my problem was a slow creeping one that took a few years to get to the point it was at but when the computer calculates air consumption as part of your profile you had better make sure the pressure sending unit is accurate!
I love the hose-less computer systems but I wonder if an old style pressure gage would be a better idea.
Later that summer we went diving in a local lake and as she purchased her own computer I had my Air X back. I too noticed the lower pressure reading and non-linear consumption it displayed when diving. The lake is a cold fresh water lake and we rarely dive below 30ft. However this year I had my new dry suit and was diving to 60-100ft and having a good time. Half way thru the year "the 2nd or 3rd trip I decided to check out this computers readings. I know I should of verified the readings first thing but I had called Uwatec after she told me about the pressure discrepancy and Uwatec told me the pressure differences was because of the thermal compensation built into the transmitter. So I dismissed the problem. I decided to wear both of my computers at the same with two different transmitters so I could compare the two computers. I was amazed to find pressure differences of 500-700 lbs. I then when out of the water I paired the air X computer to the Air OX transmitter and found the fault was with the transmitter. I had 3 transmitters so I compared them all to discover that the Air X transmitter was defective. I sent it in for service and the technician called me back and told me it was a bad battery and it would cost me 50.00 to get it fixed.
I got the unit back and it was a new unit. I called to talk to a technician after I got the unit back because I had concerns about this type of problem happening again. I was nervous about using the computer and wanted to find out exactly what had happened. After a bit of cornering he told me that once and a while they get a transmitter that does this and it is not a battery problem. I continued to drill him about the subject and he said that he notices that maybe a half dozen transmitters a year come in with this problem. I also asked if this problem could cause problems with the diving profile as these computers calculate air consumption as part of the compartment half lives. He said, Yes it could cause a problem but was very rare that the transmitters fail this way.
So what does this mean to you? If you dive on a hose less air integrated computer you have to make sure that transmitted pressure is accurate. If you notice short fills while everyone else has full ones check it out with a different computer that is not air integrated! I would also recommend intermittent comparisons against other systems on the same tank. If the integrated computer records pressure as low and calculates your air consumption as low as a result you could be diving beyond your tables and be a risk of DCS!
I will always verify my pressure-sending unit on a regular basis now. In my opinion there should be some type of annual inspection where the unit is calibrated and verified accurate. I think my problem was a slow creeping one that took a few years to get to the point it was at but when the computer calculates air consumption as part of your profile you had better make sure the pressure sending unit is accurate!
I love the hose-less computer systems but I wonder if an old style pressure gage would be a better idea.
