The other possibility is that your lungs are larger than the counterlung. The counterlung, not intended for underwater use, is very small. If you are a marathon runner and generally a large guy, you may be overbreathing the counterlung, and you will find that it will vent pretty much continuously. Yes, this is annoying. The other factor of course, is that at that shallow a depth, it will vent a lot with very little change in depth, it happens much less as you get deeper. Personally, my lung volume is only a tiny bit smaller than the counterlung, so I get venting at almost every depth change, usually as little as about 5 feet. This is annoying, and wastes gas, but that is what you get with a nearly free rebreather. There is a way around it, by building a larger counterlung spacer, but it takes some mold and machining experience. Sorry on the outrageous delay. jason
Mike- I'm not sure what happened, or if I actually responded, but your message did not go to my inbox- it is in some rebreatherworld backwater. Anyway, let me quickly respond, and if you are still working on this, perhaps this info will help. Two things are happening with the venting. First, there is a possibility that you have the IP set too high, and there is too much O2 going into the loop. This can only be confirmed by watching your O2 display, and if it continually creeps up, this is the cause. Of course, your O2 consumption will change between hanging out in 10 feet of water and swimming, so depending on how you want it set, this might be alright with you. Personally, I like my o2 to be at my resting level of usage, so it doesn't creep on deco, and then I let it drop while I swim, and just add as I need it. I prefer it lower than higher.
Hi Jason, My name is Mike Miller, and the reason I'm writing you is that I have been following you build, test and development of your BP60 sidemount RB. I have built one very similar using many of your ideas and experience but I have a few questions/concerns that have arisen during confined water testing of my BP60-SMS. I'm using a fixed IP modified poseidon reg with IP set at 165 psi and a CMF orfice of 0.004". My problem is that the CL OPV is venting about every 4th breath cycle while testing in a shallow (<10') pool. Is the to be expected or should I dial back the IP to 150 psi perhaps? Also I noticed that you are using a manual Dil add valve instead of the built in ADV. Is there a reason for this? So far I haven't gotten past the confined water testing stage, as soon as I'm confident that everything is right I'll move to open water testing but I was concerned about this venting issue. Any help or advice would be greatly appreciated. Thanks Mike
