{"id":8857,"date":"2018-06-18T15:08:04","date_gmt":"2018-06-18T15:08:04","guid":{"rendered":"https:\/\/www.apdiving.com\/en\/?page_id=8857"},"modified":"2018-06-18T15:18:45","modified_gmt":"2018-06-18T15:18:45","slug":"suppressible-warnings-by-martin-parker","status":"publish","type":"page","link":"https:\/\/beta.apdiving.eu\/en\/suppressible-warnings-by-martin-parker\/","title":{"rendered":"Suppressible Warnings by Martin Parker"},"content":{"rendered":"

\u00a0<\/h3>\n

\u00a0<\/h3>\n

Suppressible Warnings<\/h3>\n

by Martin Parker, AP Diving. Posted April 2016.<\/strong><\/p>\n

\u00a0<\/p>\n

Low and High O2 warnings:<\/strong><\/p>\n

Please remember: oxygen warnings, low or high are not suppressible \u2013 we expect you to add gas,\u00a0diluent or oxygen, to get the PPO2 within the normal life sustaining range (0.4 to 1.6 bar) or bailout\u00a0to open circuit.<\/p>\n

Other warnings are suppressible by pressing and holding the right button.<\/p>\n

\u00a0<\/p>\n

Cell Warnings:<\/strong><\/p>\n

Cell warnings have two levels of warnings: At 0.2 bar and 0.4 bar away from the average of the other\u00a0two. At 0.2 bar the 1st level alarm is activated. Although this alarm is suppressible for 5 mins at a\u00a0time, the appropriate action is to assess the cells: how do they react to gas addition, do they rise\u00a0when oxygen is added? \u2013 if a cell doesn\u2019t rise then it could well be current limited so start to lower\u00a0the setpoint until all the cells are acting appropriately, right down below 1.0 bar if necessary. In the\u00a0event that one cell deviated from the average of the other two by 0.4 bar, then the 2nd level alarm is\u00a0activated and cannot be suppressed. You have to do something about it \u2013 ignoring it could cost you\u00a0your life.<\/strong><\/p>\n

Lower the setpoint way down; take it to 0.7 bar if necessary. Flush with diluent, add a little\u00a0oxygen, do all three cells behave appropriately to the gas change? \u2013 The ones that do change value\u00a0appropriately are the ones to believe in.<\/p>\n

Just because two cells agree, doesn\u2019t mean they\u2019re correct.<\/p>\n

Cell warnings can occur for a number of reasons. Sometimes it can be trivial, for instance when you\u00a0instigate a big change in PPO2, one cell might react more slowly than another and you might get a\u00a0momentary alarm. An example of this would be when changing from the low setpoint to the high.<\/p>\n

But, usually it is not trivial and needs your attention.<\/p>\n

Cell warnings are the catchall. It is telling you there is something wrong and your EARLY assessment\u00a0and monitoring is required. Just ignoring or suppressing it has cost lives.<\/p>\n

The PPO2 control logic is very simple \u2013 the electronics are programmed to believe the closest two are\u00a0correct and ignores the third cell. This gives very accurate PPO2 control and it is easy for you to see\u00a0at a glance which are the closest two cells and understand what the rebreather electronics are\u00a0doing.<\/p>\n

In the event that one cell goes adrift too far, the cell warning is activated and this is where you come\u00a0in. Firstly, do NOT think that the closest two must be correct.<\/strong> It\u2019s your job to assess what is\u00a0happening and check which cells are accurate and which are not. If the closest two are 1.28 and\u00a01.31 but the third cell is rising rapidly to the maximum displayable value of 2.55 bar, you need to find\u00a0out whether that wayward cell is faulty or is it the only good cell you have?<\/p>\n

Assumption is the killer.<\/strong><\/p>\n

Please don\u2019t assume that your old favourite cell, which hasn\u2019t caused a\u00a0problem in the past, is still the best one. Please don\u2019t assume that the latest cell that you have just\u00a0fitted is the faulty one. Check it \u2013 that\u2019s the smart thing to do.<\/p>\n

Ensure your diluent flush technique is adequate.<\/strong><\/p>\n

While looking at the display, hold the exhale\u00a0counterlung\u2019s dump valve open and press the diluent inflator for at least 10 secs.<\/p>\n

Tip: to eliminate\u00a0buoyancy change, ensure the dump valve is at the highest point \u2013 achievable when upright when\u00a0using the over the shoulder counterlungs or by lay horizontally when using the rear mounted\u00a0counterlungs. This will change the gas over the sensors very quickly. Of course you will be fighting against the oxygen controller, which will be trying to add gas so you need to be robust, add lots of\u00a0diluent. With the gas changing rapidly it allows you to see which sensors are reacting properly and\u00a0which are not.<\/p>\n

Then add some oxygen, the cells should rise. The cells that don\u2019t rise are potentially current limited.\u00a0If you are shallow enough to do an oxygen flush this is best-achieved upright, venting from your\u00a0mouth around the outside of the mouthpiece and pressing the manual oxygen inflator.<\/p>\n

Lower the setpoint to 1.1 bar \u2013 do all three cells now react appropriately to gas change? Lower the\u00a0setpoint as low as is needed.<\/p>\n

If you are in doubt, lower the setpoint until all three cells are within the normal life supporting\u00a0range.<\/p>\n

Understanding how the oxygen controller works and what affects the displayed cell values is much\u00a0more important than trying to remember drills.<\/p>\n

CO2 and Tempstik warnings:<\/strong><\/p>\n

CO2 sensor and Tempstik warnings have two alarm levels, the first at approximately 5 mbar, which is\u00a0suppressible, and the 2nd warning at approximately 10 mbar which isn\u2019t suppressible. The Tempstik\u00a0warnings only work properly with Sofnolime 797 and only work properly when the correct amount\u00a0of sodalime is used: 2.4 kg on Inspiration XPD and EVP; 2.0 kg on Inspiration EVO (Evolution). Do not\u00a0over or under fill.<\/p>\n

CNS:<\/strong><\/p>\n

CNS and other warnings are suppressible for 20 minutes at a time. We often get asked to remove\u00a0the CNS warning by divers doing long decompression dives. I have refused these requests for the\u00a0following reasons:<\/p>\n

a) When you suppress the warning, it is suppressed for 20 mins at a time. It is no hardship to\u00a0have your attention brought back to the handset 20 mins later, check to see what the\u00a0display is saying then suppress it again if that is what you believe to be appropriate.<\/p>\n

b) if they don\u2019t know that they can suppress a CNS warning, then what else don\u2019t they know?\u00a0They are clearly not as expert as they think they are. Do they really know what levels of CNS\u00a0are safe for them? Of course they don\u2019t, none of us do, they are just pushing their luck.<\/p>\n

c) For us to not warn would be irresponsible.<\/p>\n

If you bailout to OC and change the rebreather setting to OC, CCR specific warnings are\u00a0automatically suppressed.<\/p>\n

\u00a0<\/p>\n

Martin Parker, AP Diving. April 2018<\/strong>.<\/p>\n<\/div><\/div><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"

\u00a0\u00a0Suppressible Warningsby Martin Parker, AP Diving. Posted April 2016.\u00a0Low and High O2 warnings:Please remember: oxygen warnings, low or high are not suppressible \u2013 we expect you to add gas,\u00a0diluent or oxygen, to get the PPO2 within the normal life sustaining range (0.4 to 1.6 bar) or bailout\u00a0to open circuit.Other warnings are suppressible by pressing and [Read More …]<\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-8857","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/pages\/8857","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/comments?post=8857"}],"version-history":[{"count":1,"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/pages\/8857\/revisions"}],"predecessor-version":[{"id":8858,"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/pages\/8857\/revisions\/8858"}],"wp:attachment":[{"href":"https:\/\/beta.apdiving.eu\/en\/wp-json\/wp\/v2\/media?parent=8857"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}