Bushcraft accidents research
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Tepid water is water that is slightly warm, ie not icey and nowhere near body temp.
I then used the word 'ambient' to describe a specific event, which I think is relevant when the ambient air temp at the time was almost 50 degrees C !!!
I then used the word 'ambient' to describe a specific event, which I think is relevant when the ambient air temp at the time was almost 50 degrees C !!!
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Tepid water is water that is slightly warm, ie not icey and nowhere near body temp.
I then used the word 'ambient' to describe a specific event, which I think is relevant when the ambient air temp at the time was almost 50 degrees C !!!
Apparently we are also taught very different definitions of tepid.
That aside, the ambient air temperature is very, very rarely the same as the ambient water temperature (apart from shallow bodies of surface water)
.....I then used the word 'ambient' to describe a specific event, which I think is relevant when the ambient air temp at the time was almost 50 degrees C !!!
50c is roughly 122f. Heatstroke can occur when the body's core temp reaches 105f. Do you seriously expect me to believe that you can cool that body temp back down to a safe level using water that's 17 degrees warmer than the safe body temp? The reality is that the water temp was much cooler than the air temp (see post immediately above)
Sorry, but it ain't my first rodeo.
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The cooling in that situation is due to evaporation not to the temperature of the water you use.
Evaporation is more dependent on humidity than temperature. "Swamp coolers" only work I arid environments. And only marginally so there.
Use that same technique with alcohol instead of water though, and you'll get very good results in any environment (other than a flameable one)
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bambodoggy
Bushcrafter (boy, I've got a lot to say!)
At the risk of ruining a good argument, I think you've misunderstood what Bluffer was saying...I read it as he was in a place where the air temp was around 50c...say somewhere like.....oh I don't know, say somewhere like Afganistan and was dealing with a job that had somebody who was over heating (amount over normal not specified) when he used water out of say...a ditch or a water bottle to cool somebody that he'd got under the shade of a tarp...not that somebody's internal body temp was 50c!!!! That would be really scary! Certainly over here "tepid" means only very slightly warm water.....contrast this with an air temp of 50c and you are both saying the same thing chaps
Seems a perfectly sensible thing for him to have done. Anyway, hope that helps you guys a bit
(Bluffer, if that wasn't what you meant then I read it wrong too lol)
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At the risk of ruining a good argument, I think you've misunderstood what Bluffer was saying...I read it was he was in a place where the air temp was around 50c...say somewhere like.....oh I don't know, say somewhere like Afganistan and was dealing with a job that had somebody who was over heating (amount over normal not specified) when he used water out of say...a ditch or a water bottle to cool somebody that he'd got under the shade of a tarp...not that somebody's internal body temp was 50c!!!! That would be really scary!
Seems a perfectly sensible thing for him to have done. Anyway, hope that helps you guys a bit
(Bluffer, if that wasn't what you meant then I read it wrong too lol)
No. I read it the way you did. That was my point. If the water was the same temp as the air (50c) then it would actually be warmer than the body temp. Therefore it would not have any cooling effect. If anything, it would have further elevated the body temp.
IF! he was using tap water, or water from a deeper source, or flowing water, then it would be cooler than the air temp by quite a bit. And in that situation, yes it would help; but not nearly as well as an ice pack in strategic places or an ice bath.
And yeah, I probably wrote it badly.
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But it isn't the temperature of the water that has the cooling effect, it's the evaporation of that water. Unless you have extremely high air humidity the water will evaporate and cools in the process. Get someone wet and move the air over their skin to speed evaporation and it helps to cool them. As Santaman2000 says, if you can add some alcohol it's even more effective.
bambodoggy
Bushcrafter (boy, I've got a lot to say!)
No...you've missed it again...he's not saying air and water where the same temp, he's saying air was about 50c and water was tepid...say (and guessing this relative to my kids baths) 23 to say 25c
Does that make a bit more sence?
Lol....I'm a Master at being misunderstood and misinterpreted on forums lol It's a wonder anybody speaks to me at all lol
Does that make a bit more sence?
Lol....I'm a Master at being misunderstood and misinterpreted on forums lol It's a wonder anybody speaks to me at all lol
The same here. That said, for water to feel slightly warm it must/needs be slightly warmer than the instrument feeling it. Being as that's normally a human hand or finger, it would be slightly warmer than normal body temp. Any cooler than that and it would feel cool. Ergo tepid = normal body temp or there-about.
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Not in my experience. At a normal humidity level (anywhere from 40% - 70%) evaporation just isn't going to be particularly useful. In an arid environment, yes (below 30%)
No...you've missed it again...he's not saying air and water where the same temp, he's saying air was about 50c and water was tepid...say (and guessing this relative to my kids baths) 23 to say 25c
Does that make a bit more sence?
Lol....I'm a Master at being misunderstood and misinterpreted on forums lol It's a wonder anybody speaks to me at all lol
As am I unfortunately. And yes I agree the water would be cooler than the air; that was rather my point.
Just did some quick converting. 23c - 25c is about 77f -80f. That would actually feel cool at first. That's the normal temp of our swimming waters in Summer. Just had a look at the weather on the coastline; air temp in Destin was 92f (about 33c) and sea temp was 80f (about 26.7C)
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bambodoggy
Bushcrafter (boy, I've got a lot to say!)
Bingo! So you and Bluffer where agreeing
LOL. Apparently so.
TurboGirl
Bushcrafter (boy, I've got a lot to say!)
I would be fascinated to see the original survey, even if you have your quota, Julia
And as so many have said, just can't wait to see your extrapolated results. Can you share some of the stories and scenarios, I appreciate they might have to be 'anonymised'?! Can I just say... gal, since you've come onto this forum, you've contributed some top threads, always interesting and enjoyably written. Top lass
Actually, evaporative cooling is one of the most ideal ways of managing hyperthermia. It is also one of easiest and non-invasive methods.
The human body is constantly utilizing evaporative cooling, which is the reason a human being is secreting sweat in a warm environment.
Evaporation requires energy which, in turn, means cooling. The amount of cooling is primarily dependent on the rate of evaporation, but each kilogram of water which is evaporated has transferred about 2260 kJ of energy.
According to the reference materials I have on hand (Wyndham, et al., 1959) the level of cooling achieved by evaporative cooling can amount to 0.3 degrees celcius pr minute.
Submerging the person in ice water carries a certain risk of systemic shock and is furthermore only half as effective as the evaporative cooling with a cooling capacity of about 0.15 degrees celcius pr minute. (Wyndham, et al., 1959; Plattner, et. al., 1997; McDermott, et al., 2009)
Contrary to belief ice packing is actually not especially effective - primarily due to vasoconstriction. Whole Body ice paking reduces core temperature with about 0.03 degrees celcius pr minute (Erickson, et al, 2004), whereas strategic ice packing only manages a cooling effect of about 0.02 to 0.03 degrees pr minute. (Erickson, et al, 2004)
BTW, the wording "tepid" in conjunction with medical procedures is normally associated with a temperature around 15 degrees celcius.
//Kim Horsevad
Sources:
Erickson TB, Prendergast HM. Procedures pertaining to hyperthermia. In: Roberts JR, Hedges JR, Chanmugan AS, et al. Clinical Procedures in Emergency Medicine. 4th ed. WB Saunders; 2004:1358-70
Wyndham CH, Strydom NB, Cooke HM, Maritz JS, Morrison JF, Fleming PW, et al. Methods of cooling subjects with hyperpyrexia. J Appl Physiol. Sep 1959;14:771-6.
Plattner O, Kurz A, Sessler DI, Ikeda T, Christensen R, Marder D, et al. Efficacy of intraoperative cooling methods. Anesthesiology. Nov 1997;87(5):1089-95.
McDermott BP, Casa DJ, Ganio MS, Lopez RM, Yeargin SW, Armstrong LE, et al. Acute whole-body cooling for exercise-induced hyperthermia: a systematic review. J Athl Train. Jan-Feb 2009;44(1):84-93.
The human body is constantly utilizing evaporative cooling, which is the reason a human being is secreting sweat in a warm environment.
Evaporation requires energy which, in turn, means cooling. The amount of cooling is primarily dependent on the rate of evaporation, but each kilogram of water which is evaporated has transferred about 2260 kJ of energy.
According to the reference materials I have on hand (Wyndham, et al., 1959) the level of cooling achieved by evaporative cooling can amount to 0.3 degrees celcius pr minute.
Submerging the person in ice water carries a certain risk of systemic shock and is furthermore only half as effective as the evaporative cooling with a cooling capacity of about 0.15 degrees celcius pr minute. (Wyndham, et al., 1959; Plattner, et. al., 1997; McDermott, et al., 2009)
Contrary to belief ice packing is actually not especially effective - primarily due to vasoconstriction. Whole Body ice paking reduces core temperature with about 0.03 degrees celcius pr minute (Erickson, et al, 2004), whereas strategic ice packing only manages a cooling effect of about 0.02 to 0.03 degrees pr minute. (Erickson, et al, 2004)
BTW, the wording "tepid" in conjunction with medical procedures is normally associated with a temperature around 15 degrees celcius.
//Kim Horsevad
Sources:
Erickson TB, Prendergast HM. Procedures pertaining to hyperthermia. In: Roberts JR, Hedges JR, Chanmugan AS, et al. Clinical Procedures in Emergency Medicine. 4th ed. WB Saunders; 2004:1358-70
Wyndham CH, Strydom NB, Cooke HM, Maritz JS, Morrison JF, Fleming PW, et al. Methods of cooling subjects with hyperpyrexia. J Appl Physiol. Sep 1959;14:771-6.
Plattner O, Kurz A, Sessler DI, Ikeda T, Christensen R, Marder D, et al. Efficacy of intraoperative cooling methods. Anesthesiology. Nov 1997;87(5):1089-95.
McDermott BP, Casa DJ, Ganio MS, Lopez RM, Yeargin SW, Armstrong LE, et al. Acute whole-body cooling for exercise-induced hyperthermia: a systematic review. J Athl Train. Jan-Feb 2009;44(1):84-93.
bambodoggy
Bushcrafter (boy, I've got a lot to say!)
Both methods (ice baths and evaporative cooling) work on the same principle (heat transfer)
Yes. Evaporative cooling transfers heat (energy, as you said) by using it to do the evaporating. It only works IF! the water will evaporate. That won't happen in high humidity
Ice baths transfer heat (energy) by using it to melt the ice. That works no matter what the humidity.
Even in low humidity, do you really think you can evaporate a kilogram of water (about a gallon) quickly enough to do any good? Possibly if the victim is suffering Heat Exhaustion; but not if they're suffering Heatstroke. In either case, definitely not if the humidity is even as high as 50% (which is fairly low)
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