rEvo User Newsflash..7th May 2012
Official Newsletter From rEvo Rebreathers HQ, Belgium – 7th May 2012
1 - Warning on curved or shrinked mushroom valves
2 – Update for rMS users: new software coming soon
3 – Correct use of the gag strap
1 Warning on curved / shrinked mushroom valves
We have been notified by some users that they discovered curved mushroom valves in their breathing loop when taking the hoses off. There was no incident, but they stated that they would never have noticed this, if the hoses were not removed. This picture shows you an extreme example:
We also got some people mentioning shrunk valves, in that way that the valve did not cover the spider completely anymore: this was detected in a normal ‘stereo check’ as gas passed trough the valve in the wrong direction.
So how do we know if our mushroom valves are functioning correctly, without each time removing the hoses from the DSV?
A mushroom valve works correctly if it closes off completely, even with only a very small differential pressure over the valve, or when breathing with very low RMV on the loop.
The same mushroom valve must still close off, when a higher pressure is applied on the valve.
So it becomes clear that it is very important/critical, how the ‘stereo check’ (checking the mushroom valves) is performed: all curved valves will always close if you blow/suck hard on the DSV/hose end. On the other hand, if you only blow with a very low flow, heavily curved valves will not close and let gas pass trough in the reverse way.
So from now on, this is the way the valve check should be done:
When you perform the ‘stereo check’ on your mushroom valves, before mounting the hoses on the rebreather: check the valves with a very low flow/low pressure and with a normal overpressure: the valve should not leak under any condition! If you are not sure, then remove the hose, check the valve, and if not ok, replace it.
Remember: mushroom valves are very thin and flexible items: they do not withstand any aggressive cleaning or disinfecting product: the only approved cleaning product is fresh water, no chlorine, and the only approved disinfecting product is Virkon S, 1 tablet in 0.5l cold water, and for max 10 minutes. Then rinsing with fresh water again.
It is also important to rinse the hoses the correct way: just pouring water in the hose from inhale side to exhale side is not the right way: the mushroom valves will fold in the direction of the flow, and the side of the valve facing the exhale hose, will not be cleaned. For correct cleaning, pour water in both hoses with the DSV closed, shake the hoses, holding the connector ends up, and then pour out the water. Do this twice.
In case of doubt, ask your instructor!
2 Update on the rMS: new software coming soon!
The rMS on the rEvo has become very popular, and thanks to the feedback of many users, we can soon announce an update on the rMS software that will contain a lot of improvements. Some major are: -
- for the first time in sport diving, the user can enter biometric parameters, gender and weight, into his/her computer model: this allows a better match between the scrubber prediction model and the physiology of the diver: depending on gender and body weight, the calculated RST and RCT will be more realistic for the light weight and/or female diver.
- allowance to see/check the real temperatures in the scrubber (in surface mode) to better understand the ‘warming-up’ of the scrubber, and to make trouble shooting easier
- some users reported short interruption of communication with scrubbers and/or solenoid/O2 boards over the CAN-bus: this has now been corrected in the communication protocol
- some smaller, lighter divers reported difficulties to get a full warm up of the scrubber. (related to the very low RMV of some people): this also is covered in the new software
The release of the new software is planned in the next weeks: we will notify all users.
3 Correct use of the gag strap on the rEvo mouthpiece.
We notice that some people hesitate on using the gag strap on the DSV that comes with each unit.
The gag strap is an essential part in the safe use of a rebreather, and should always be used: in the event of an unconscious diver, when correctly used, the mouthpiece attached with the gag strap will keep the water out of the loop and the divers lungs, as 99% of the diving fatalities is due to … breathing water!
The gag strap can always be worn on top of the mask strap, as during diving you have no intention to take off your mask for drills: in that case it will not slide up or down, but just stay in place.
The strap also has ‘levers’ to release the tension of the strap when you want to take it off.
The tension on the strap should just be high enough that, when in water, it keeps the mouthpiece in place without the need to bite on the bite piece, so that there is no jaw fatigue in longer dives.
When correctly used, it is absolutely not a ‘PITA’, but a dream to use , I have been using it for years, and would never dive without.
If you’re not comfortable, please ask your instructor for correct advise in how to use it.