General Rebreather Care and Maintenance

General Rebreather Care and Maintenance

Keeping your unit in Tip Top condition.

It’s important to keep your rebreather in tip top condition, this includes keeping up with routine maintenance and care. If you take the time to keep up with day to day maintenance then you will reduce the possibilities of failures, but also help to make it work more efficiently and extend its life.

Below, are some tips on how to keep your rebreather in good order.

Proactive Rebreather Care

Its good practice to wash off and disinfect your unit after each day’s diving. Also open the unit up and allow the head to dry naturally, dry out the inside of the canister from any moisture build up. If you are going to reuse the scrubber, then place it in a drybag or seal in the canister with a canister lid if your unit has one. Do NOT try and dry the CO2 absorbent or repack it and keep it out of direct sunlight

Keep a close eye on the condition of the O-rings

Whenever you are assembling and disassembling, always check the condition of the O-rings and keep them clean and lubricated. Always be careful when removing O-¬rings and avoid using sharp tooth picks to remove them. If you are struggling to feel the condition of the O-¬ring due to cold hands etc... then run your tongue along it and you will find any tiny imperfections.
When applying lubricant, put a small amount between your finger and thumb and then rub together along the whole length of the O-ring. Never apply too much lubricant and wipe away any excess.

Storing your unit.

If you are going to store your rebreather in a garage that does not have heating, then keep the head in the house in normal room temperature and during the cold months cover the unit in a thick blanket when stored below room temperature.
Try to avoid keeping your unit in your car over night when the conditions are freezing, as this will only cause small leaks as the O-rings become brittle.
Clean any spilt CO2 absorbent from the canister and scrubber, as this can be difficult to remove when its dry. It will also remove the anodizing from any aluminium canister.
If you are in a location where small bugs etc could enter the rebreather, then take care to make sure all the possible entry points are sealed.

Looking after your Oxygen cells and annual replacement.

The oxygen cells in your rebreather should not be used for more than 12¬15 months from date of manufacture. I’m a strong believer in following an Oxygen Cell rotation approach to replacing them. This means that every four months you will replace one of the cells. In this way you will never have
the problem of three cells having been exposed to the same amount of oxygen through their life span. It also means that it will be unlikely to have two cells from the same manufacturing batch. Therefore, any production problems, would not be on all three cells.
Using this method also means that you will not have to keep a spare cell, as the cell you have taken out becomes your spare cell, as it has been working fine before it was removed.
If you were to rotate all three cells each year and also buy a fourth as a spare. You would never know if the spare worked until you took it out the bag, at which time it is now too late to find out it doesn’t function.
It’s important to watch the MV of each cell when you are calibrating the unit, this information is critical to assessing the health of the cell. In air the oxygen cell should read between 9¬11mv and in 100% oxygen it should read between 46¬54mv. This may vary on the manufacturer of the cell. Always make a note of the readings from each cell, then if you see that the readings are starting to degrease, this could be a sign that the cell is becoming current limited. To check if a cell can read higher mv you can carry out an Oxygen flush at 6m to see if the cells are able to reach 1.6PPO2. A cell checker can also be used to check this.
If you are not sure that the cell is working correctly, then ask your instructor for advice.

Take Care of Your Solenoid

During your user level rebreather course, you will have learnt how to deal with a solenoid failure in the open or closed position. Although this is a skill we must master, it is always better to try and prevent a problem in the first place.
Most solenoids are not user maintainable or serviceable, so always try and keep any moisture or contaminants from entering it and causing corrosion to the steel parts or any other damage.
To avoid this moister entering through the first stage always replace the first stage cap when it’s not connected to a cylinder. If there is a possibility that water could find its way to the solenoid feed hose or into the solenoid itself, then cap them off when not connected. Remember that there may be open water divers at a dive centre using a hose pipe and have little or no knowledge of the damage they could cause.

Disinfection of Your Rebreather

Whilst you are breathing from your rebreather, the breathing loop and counterlungs become an extension of your body. This means that any bacteria in the loop and counterlungs could cause a lung infection. With this in mind, it is important that we keep them in disinfected state.
Its good practice that in between dives of the same day, that we remove the exhaust loop hose and remove any fluid, also check that there is no fluid in any water trap. Of course, if you do this, you must perform another Negative and Positive check when the unit is reassembled following your normal checklist.
At the end of each days diving, it’s advisable to disinfect your breathing loops, counterlungs and DSV/ BOV. A suitable disinfectant would be either ChemGene HLD4L rebreather disinfectant or Virkon S Broad Spectrum disinfectant.

Other Equipment

Don't forget to keep all other equipment in full working condition, including wing, drysuit, bailout regulators, suit inflation system and all cylinders.

Further information

For further information follow your unit specific rebreather manual which will explain about the care and maintenance of your unit. You can also consult your instructor or the manufacturer to see when your rebreather should be serviced.
You can also attend a unit specific maintenances course with your instructor. This way if you are at a dive site and have an issue, you will be able to repair it yourself.

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