RG-UF/M Custom Commercial DSV

RG-UF/M Custom Commercial DSV
By Dan Dunfee


For several months I've tried to find and buy, vs make, a DSV that can conveniently be integrated into the heavily modded RGU rig that I’m working up. I found the big-bore hoses & DSVs (eg Dolphin) much bulkier than I want for my little close-coupled chest-pack, at least during this phase of the project. I considered the IDA family of DSVs, but could find none that were within this projects budget, and heard many complaints on their low gas throughput and added WOB and weight. I finally found one by going back to a website that I had visited several times, several months ago. The site is www.nva-militaria.de or email Medi-Leipzig@online.de. Its the old East German NVA Militaria site, run by Martin Klokosch. No one there speaks /writes english. They use Babelfish to translate e-mails, so communications are a bit slow for us one-language folks. but they try to be responsive. They have lots of RGU kits and individual parts (and a substantial inventory of Draeger parts). The customized RGU DSV / mouthpiece assy must be a new product for them. They've advertized it some on EBay. It sells for less than 100 USD + S&H. I just got the DSV, and haven't leak tested or torn it down yet, so comments here are first preliminary observations.


The DSV is made by taking a stock RGU mouthpiece shell and inserting a custom spool directly into the shell, with machining for the lever & vents. As normally delivered, the DSV assy consists only of the shell, DSV spool and lever, and a new mouthpiece... no non-return valves or hose end fittings. They obviously assume that you already have these... but they're probably available at added cost. When assembled into my loop, it fits and works quite well. The new, smaller, mouthpiece is comfortable for me . Couch breathing tests indicate that , surprisingly, it doesn't add perceptibly to the loop WOB.


I've not torn it down yet, but it appears to have one potentially disconcerting feature..no apparent o-ring or gasket sealing of the spool. The new spool is made of POM Polyascetal, same as Draeger uses for mouthpeices / DSVs. They've apparently extended the european philosophy of metal-on-metal sealing, to plastic-on-plastic. The spool appears to be split longitudinally thru the breathing slot, so that it spring-loads itself radially against the stock housing and forms a surface-contact seal when rotated to the shut-off 'surface' position. An innovative approach.... it'll be interesting to see how well it stands up to use... or not. With its MolyKote 111 lubrication, the spool rotates without undue force needed.


The custom RGU DSV will serve my purposes well, at least during the next phase of my little program. I'll report on how it performs in repetitive / extended service later on.

Given the difficulties I had getting a DSV to fill my immediate wants / needs, I thought there might be other RGU divers who might find it interesting, maybe worthwhile. Also it might be worthwhile to IDA divers who are using the smaller-bore stock hoses, but don't like the heavy brass IDA DSVs with their reportedly small gas breathing port to the mouthpiece, low gas throughput, and higher WOB.

More later

Dan

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