KISSing a Russian Chest...

KISSing a Russian Chest . . .

. . . mounted Rebreather

By Jay Harding



Russian IDA-59s are inexpensive. Alright, let’s face it, they’re downright cheap. But, unless you subscribe to the Russian military diving standards for ppo2 exposure and flowrates, most recreational Rebreather divers wouldn’t dive them in stock configuration below about 25 fsw. This, of course, only utilizes them as a pure o2 unit and wastes the potential of the diluent cylinder and beautiful ADV. Not to mention that for those of us that don’t speak or read Russian, even just understanding the actual function of the stock system can prove problematic. Additionally, there appears to be little information available about them and even what is available is sometimes conflicting. CCR or SCR? Some claims have been made that it is both depending on depth. Maybe it’s semantics or how the individual describes SCR (some people will argue that the KISS is a low flow rate SCR). I’m not going to get into that. I’m just going to tell you what I did to overcome the issue of making the unit produce a known, stable O2 rate so that it could be dived recreationally as a mCCR.


Step 1
Snag a unit off of eBay. I got one, unused, for $150 plus shipping.

The stock unit looks like this:



Step 2
Call up your friend who has a massive stock of Russian rebreather detritus, bang heads together and then sweet talk him out of an IDA-71 oxygen cylinder. Big shout-out to Dave. Thanks, man, great minds do think alike. I’ll explain why I grabbed a -71 cylinder off him in a little bit.


Step 3
Remove the -59’s O2 cylinder and regulator from the chassis. Get it up on the workbench with the -71 cylinder and compare the two. If you look you will see that the two are virtually identical except for a couple little details: 1) The -59 valve/regulator obviously is mated to the CMF metering device (I say CMF for a reason that I will explain in a bit) and 2) it is a mirror image of the -71 cylinder’s valve/regulator.


The picture shows both cylinders in comparison with the IDA-59 cylinder above and the IDA-71 cylinder below. Aside from that, there may be some little differences in connections, tee-pieces, etc. From what I can ascertain, these little differences can be attributed to the year they were made and the factory they were made at. Essentially, however, if you were to remove the CMF unit from the -59 cylinder, the result would be the same: a cylinder with a combination valve and regulator.


Step 4
Notice one key thing: the -59 cylinder’s first stage has a blanking cover over the valve spring housing (it has already been removed in the picture). This is what convinces me that the -59 uses CMF. The -71 cylinder has a similar cover, but it is ported to allow water into the spring housing. So, what do we do? We take the cover from the -59 reg and fit it to the -71 reg. The result: the -71 cylinder is now essentially a fixed IP gas supply!!!



Step 5
Mate the newly modified, fixed intermediate pressure IDA-71 cylinder/valve/reg to an O2 metering device like a Hydrogom valve, KISS valve, or needle valve. Adjust the IP, set the flowrate, and the O2 gas supply is done.


Step 6
Make up some short hoses (or use stock ones, your choice) and rig the connection to the counterlung. I chose to remove the original connection from the counterlung and make up a dedicated replacement from readily available parts so that I didn’t have to modify the original.



Step 7
Add the PPO2 monitoring of your choice. There’s a lot of individual preference and decision making involved here, so use whichever method you want (i.e. – cut hole for p-port, add housing in hose path, etc.). And it’s done. I haven’t added monitoring yet. I’m still working on my monitor, I just couldn’t wait to share the mechanical mod. Here’s a pic of the almost finished product.


The diluent cylinder and ADV can be left alone to function as normal. Just fill it with your dil of choice. What we have now is a virtually stock MCCR IDA-59. I realize that there are some pros and cons to this rig (WOB, non-purge DSV, possibility of caustic cocktails, potential problems filling cylinders, etc) but it gives us a simple way to make a nice little, cheap MCCR without recreating the wheel. Plus, if you are a nerd like I am, it’s just fun to study and build stuff!

Please note that this is my method. I chose to grab a -71 cylinder and cap it because I had access to one and didn’t want to get crazy with modifying the original -59 cylinder unit. Not to mention that the connections on the -59 cylinder were so tight that you would swear they were swaged. I didn’t want to damage them so, I’ll keep it for study. Others may want to do things differently depending on your resourcefulness and what you have on hand or have access to.

Stay tuned as updates will follow. The next installment will address PPO2 monitoring and a modification to the ADV to allow use as an intentional manual bypass for diluent addition/flushing.

Happy and safe diving,

Jay


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Necessary Disclaimer This article is not a “how-to” tutorial. It’s a “how-I-did-it” showcase. It’s likely very stupid and may kill me. This article is for study purposes only and I do not in any way endorse your attempting to do this yourself. If you have to ask how I did something that I described in this article, you are likely not prepared to modify any piece of diving equipment and should NOT do it. If you choose to modify, play around with, or dive the IDA-59 or any other rebreather, commercial, modified, or homebuilt, you do so at your own risk. I take no responsibility for your decisions or your safety. That’s your job. We all know that rebreathers can and do kill without warning, so make your decisions independently and accordingly.