Water temp effect on scrubber performance

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igoRluse

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Scuba Instructor
Divemaster
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Location
Perth, Western Australia
# of dives
200 - 499
Hi all,

I have just been reading the doc from Dräger discussing the scrubber time increase from 70 mins to 110 mins of the Ray scrubber. I have put it in the resources section of my site for reference.

Basically the test data is as follows:

If the physical work is reduced to the following test criteria:
- water bath temperature : 4 (-2)°C
- breathing rate : 20 strokes/min. x 1.5 L/stroke = 30 L/min.
BTPS*
- simulated oxygen consumption : 1.33 L/min. STPD**
- interruption criterion : 0.5 % by vol. CO2 in the inhaled gas
- CO2 supply : 1.2 L/min. STPD**
the CO2 absorption increases from 70 minutes to 110 minutes.

Now this shows that under normal levels of exertion a recreational diver would have to handle with, the scubber duration goes to 110 mins, but this is in water at -2°C !!!

Myself I would pretty much never have to deal with water under 16°C even in the midst of winter so how will that affect the scrubber performance? Does anyone know of any test run on this?
 
igoRluse:
Hi all,
I have just been reading the doc from Dräger discussing the scrubber time increase from 70 mins to 110 mins of the Ray scrubber. I have put it in the resources section of my site for reference.
Now this shows that under normal levels of exertion a recreational diver would have to handle with, the scubber duration goes to 110 mins, but this is in water at -2°C !!!

I cant get your site up so can't fully comment. However it may turn out that this is a typo. The test water temperature is normally 4 degrees Centrigrade with a tolerance of plus or minus 1 deg C Its problerbly the +/- bit thats the typo.
However I wouldn,t mind seeing the detail if you could post or email the full spec.

What you have posted looks a bit slight on the other factors.
C02 injection in the bag is normally 1.6 litres per minute in the test, injecting only 1.2 l/min will of course increase the scubber chemical lifetime for a given C02 loading.
0.5% breakout is the same on both tests.

Again the oxygen simulated absorbsion is normally tested by removing 1.78 l/min from the exhaled gas simulator.
Your figure of 1.2 l/min is again light. Also BTPS (Body Temperature Pressure Saturated) figures are very low.
It may sounds like breathe less to last longer!! but a least you have some proper test data to work from.
 
Strange, site seems to be up. Anywho, I attached the doc in question.
 
https://www.shearwater.com/products/teric/

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