maintenance

[marc.collin]

hi

do you change your o-ring every year?

 

[DA Aquamaster]

The short answer is "at least every two years". KISS, for example, recommends a two year interval, but it's really a guideline as with heavy use, and/or salt water and/or sandy conditions, 2 years may not be nearly enough.

The long answer is that a CCR is composed of different sub systems that may have different maintenance requirements and schedules, and maintenance needs will vary greatly depending on use and conditions.

Dust from the sorb tends to find it's way into cracks and crevices inside the unit as does sand. O-rings and sealing surfaces will last longer if you clean the unit periodically to remove the caustic buildup and any dirt or sand that finds its way into the o-ring grooves and seating surfaces.

I seldom go more than about 30 hours before thoroughly cleaning the unit and then cleaning and re-lubricating the O-rings. If I've been diving really sandy and silty side mount passages, or making entries in areas with sand silt or mud, this interval ends up being shorter. If you dive in salt water, that will add the additional need to thoroughly soak and rinse the parts exposed to salt water. If you flood the unit, that will also shorten the interval between thorough cleaning.

I've also found that the O-rings in my DSV won't last nearly as long as the O-rings in the unit itself. That's partly due to the reality that most of the O-rings in the DSV are dynamic O-rings (they move or rotate, versus just sitting in a static condition), and that's aggravated by the ability of sand to infiltrate between the moving parts and potentially score the sealing surface of the o-ring, and in extreme cases the sealing surfaces on he DSV. A year is about the maximum I've ever gotten from a set of DSV O-rings and then only with disassembly and cleaning of the DSV on a more frequent basis.

The internal O-rings are generally static, or are subject to minimal and very sporadic rotation in use and if you keep the unit clean and disassemble it now and then for a full cleaning, you should be able to get 2 years out of the static or mostly static O-rings.

Properly drying the CCR is also important. Obviously putting the loop hoses or counter lung away wet will encourage mildew and storing it near a source of ozone will cause weather checking and dry rot of the rubber components. However, less obviously leaving the head and associated wiring wet will promote corrosion of the small wires used to connect the sensors to the controller or computer(s). They are not perfectly sealed at the soldered connections in the wires or in the connectors. Leaving them wet over night between dive days, rather than letting the head dry, will greatly decrease their useful life.

The manual add valves for the O2 and diluent also need to be kept clean, and dry. You should ensure you have check valves in the proper places to prevent water or condensation from entering from the CCR unit. Post dive you should flush O2 through a leaky valve/MAV or MAV to ensure that any water that may have gotten into a filter or orifice is blown out and the item suitably dried.

The diluent and O2 regs also need to be serviced at their proper intervals, and again that interval can be shorter under harsh conditions. I also replace my low pressure hoses on the O2 and diluent regs every 2 years or 200 hours. When you consider the sorb, sensors and gasses you use over a 2 year or 200 hour interval, replacing the hoses very inexpensive insurance.

 

[happy-diver]

Haven't found anything as concise in any of the factory manuals
Thank you.