What's the deal with sleeping bag comfort ratings?

[TLM]

leave my clothes somewhere dry

In the taiga winter there is no such place in the military. If just left outside and no snow fall it'll take some days before the clothes would be dry or at least dryer.

keep my uzi warm within the sleepingbag

Why, it should work even when cold. Actually we were told not to take AKs into the warm tent (if we had one) condensation and after that ice caused some funny situations like solidly frozen gas pistons. Not so funny if it had been war time.

In the winter a stove warmed tent has very high humidity because of the snow floor and everybody trying to dry equipment. Take a gun in from -35C to +20C and 90% humidity the gun is almost instantly thoroughly wet.

 

[Great egret]

Why, it should work even when cold. Actually we were told not to take AKs into the warm tent (if we had one) condensation and after that ice caused some funny situations like solidly frozen gas pistons. Not so funny if it had been war time.

Had nothing to do with the uzi working or not All who left it laying around found there uzi's gone the next morning... They were taken by the sergeant as a lesson to never leave your weapon laying around. Imagine telling your sergeant you lost your uzi which he already knows because he took it. That was fun for the whole platoon minus 3 soldiers

 

[TLM]

Somehow that sounds familiar. That frozen gas piston did happen. We left the guns by the tent door so they would be in as cold as possible but still visible from the inside

 

[Dan00001]

I have not this sleeping bag but I could read that is insulation is Apex Climashield 300g/m². With 200g/m² you will be a little under 0°C. So it is surely not "comfort rated" to -15°C with EN 13537: 2012.

You have a lot of "norm" about sleeping bag. In UK they used a lot BS4085 or Leeds Comfort Model. In Scandinavia THELMA. Very often military sleeping bag are rated in accordance with these norms.

For the same sleeping bag you could have for different norm :
ASTM F1720 (US) : -16°C
BS 4785 (UK) : -11°C
Thelma (No) : -10°C
EN 13537 : -4°C

This is probably the case here :

Ray Mears 3-Season Sleeping Bag - Osprey

The Ray Mears Osprey Sleeping Bag is a premium-quality 3-season synthetic sleeping bag, designed exclusively for Woodlore by Ray Mears.

www.raymears.com

I understand "SAFE" : You will surely survive at -15°C fully dressed, 4 to 6 hours sleep, if you are a young soldier according Thelma or BS 4785 (or even ASTM). But my wife would kill me after such "comfortable night".


They give us insulation information "TOG 11.8".

This is typical Leeds Norm and about -15°C. It would be approximatly "EN comfort limit : -7°C".

And if you have only underwear and the sleeping bag fit you (very often military bag are large since you are dressed) the confort would be something like -4°C according EN. If you are a cold sleeper or if the bag is large or a woman...you will be "limit" at -4°C.

Of course EN norm is "without wind and 50% humidity".
ex of an EN Test report for a sleeping bag with approximatly the same insulation of 11 Tog : https://www.valandre.com/media/pdf/aitex-EN13537-2012/Swing700.pdf


More information in "Mammut Sleep Well" here (english) : https://4sport.ua/_upl/2/1410/Mammut_Sleep_well_pt1_E.pdf

Apologies for reviving an old thread,

"For the same sleeping bag you could have for different norm :
ASTM F1720 (US) : -16°C
BS 4785 (UK) : -11°C
Thelma (No) : -10°C
EN 13537 : -4°C"

Is there a method to calculate the equivalent temp rating from one standard to another?

I noticed that Alpkit use the Leeds Comfort Model which are "interpolated to give an equivalent EN13537 rating".

Looking at different bagd from different manufacturers using different standards, it seems the the EN standard is on the conservative side of temp ratings.

Many thanks.

 

[Moondog55]

Well a starting point is simply looking at the loft of the sleeping bag and dividing by two. This gives the thickness of insulation and then you can use the tables estimated by the US army as a starting point [ AC Burton Man in a cold environment ] understanding that these insulation thicknesses are not comfort ratings but closer to survival ratings and that a fit and healthy adult can sleep naked at 24C quite well in still air conditions. Also insulation is additive and if your clothing is reasonably dry and wearing clothing doesn't compress the insulation thickness of your sleeping bag too much then wearing clothing is an easy way to add warmth, a conservative thickness of clothing might be 25mm but I've worn my Everest parka to sleep in many times when using an UL synthetic overbag and half bag and it was 75mm thick in the body and 55mm in the sleeves. Now being a climber I was heavily influenced by Gerry Cunningham and his system approach to keeping warm. I'd agree that the EN rating is conservative and the US ratings are closer to survival ratings. The difference tho is only about an inch or 25mm of insulation thickness. If your sleeping bag isn't an Expedition cut and you can't wear your down jacket inside it you simply add it over the top and gain the added thickness that way. Once the temperature drops well below freezing you may want to investigate Vapour Barrier systems; either VB clothing or VB bag liners.
Also you need to understand that all testing is done to simulate being inside shelter and real world conditions can easily need a sleeping bag ten degrees warmer than the tables tell you.

 

[Dan00001]

Well a starting point is simply looking at the loft of the sleeping bag and dividing by two. This gives the thickness of insulation and then you can use the tables estimated by the US army as a starting point [ AC Burton Man in a cold environment ] understanding that these insulation thicknesses are not comfort ratings but closer to survival ratings and that a fit and healthy adult can sleep naked at 24C quite well in still air conditions. Also insulation is additive and if your clothing is reasonably dry and wearing clothing doesn't compress the insulation thickness of your sleeping bag too much then wearing clothing is an easy way to add warmth, a conservative thickness of clothing might be 25mm but I've worn my Everest parka to sleep in many times when using an UL synthetic overbag and half bag and it was 75mm thick in the body and 55mm in the sleeves. Now being a climber I was heavily influenced by Gerry Cunningham and his system approach to keeping warm. I'd agree that the EN rating is conservative and the US ratings are closer to survival ratings. The difference tho is only about an inch or 25mm of insulation thickness. If your sleeping bag isn't an Expedition cut and you can't wear your down jacket inside it you simply add it over the top and gain the added thickness that way. Once the temperature drops well below freezing you may want to investigate Vapour Barrier systems; either VB clothing or VB bag liners.
Also you need to understand that all testing is done to simulate being inside shelter and real world conditions can easily need a sleeping bag ten degrees warmer than the tables tell you.

Thank you. I understand that the tests are flawed relative to real world conditions and that the temperature ratings only give a basic guide to work off of.

But it's of little help comparing one bag from one manufacturer to another bag from another manufacturer when testing standards show different results.

For example, the Rab Neutrino 600 with 600g of 800 fill down has an EN comfort rating of -5C and the Alpkit Pipedream 600 with 600g of 750 fill down has an (interpolated) EN comfort rating of -10.5C. How do they even calculatethe EN equivalent of the Leeds Comfort Model? I guess the size/volume of the sleeping bag also has an effect and the Alpkit bags do come smaller than Rab but I can't see it having a big effect as 5C difference.

 

[Dan00001]

Another odd thing I noticed, and maybe it's a typo, but the Rab Neutrino 600 with 600g of 800 fill down has an EN comfort rating of -5C and the Rab Neutrino 700 with 700g of 800 fill down has an EN comfort rating of -4C. Both bags are identical in size/shape.

Somebody asked recently, in a Facebook group, for recommendations for a 4 season sleeping bag to which I replied that I use a Rab Neutrino 700 and somebody pointed out that it's only rated to -4C. I also have an Oex Fathom Ev300 which I bought for £35 from Go Outdoors which Go Outdoors state 'will keep you comfy down to -5°C!'

 

[TLM]

Is there a method to calculate the equivalent temp rating from one standard to another?

In this case I don't think there is, estimates could exist.

Heat insulation testing on real world equipment (in contrast to flat test panels) is always standard dependent. It is not so easy to estimate which std best follows "nature", not to include real world outside conditions (wind, radiation losses, moisture in insulation etc.) As a best guess I would take the most "pessimistic" value and use that, one can always open the zipper a bit but only fully close it.

 

[Moondog55]

OK If bag shape is different; say very slim cut compared to a similar but more generously cut bag and both have the same level and quality of down fill then the skinny bag will be warmer because it will loft higher. Usually. More zip? Less warm
Also mistakes happen with copywriters and maybe it's a typo with the Rab bags
This is why I use insulation thickness as my guide to temperature rating. And I add an inch to the US army tables to get a reasonable comfort level.
Also I only look at bags that have been EN tested as that test to me seems to be the most reliable.
It isn't perfect but it's betterer than it was 50 years ago, but only personal experience really works . I've always needed a much warmer bag than my mates and by the same token warmer static layers too. But I just googled the Rab bags and the EN rating is -4C for females and -10C for males for the 700 as you say so maybe you could message Rab and ask for the difference to be explained? As the main difference I could see was the use of different Quantum shell fabrics and my take on QuantumPro is that is it warmer shell because of its superior windproofing and should be the warmer of the 2 bags.
I do wish Rab still made their half bag and the Topside bags

 

[TLM]

It is not the total weight of insulation but thickness that matters. Also down flattens almost totally underneath but hollow fibers a lot less. In practice your mat is more important the colder it gets.

As I understand the EN std measures quite well heat conduction/convection through the bag. Don't remember how temp underneath is defined.

The structure of the bag walls matter more after some use because it takes some time for the insulation to bunch up if it has a tendency. A bit like how the bag is stored.

 

[Paul_B]

Late to this thread. The minus 15C can only be an extreme rating considering the woodlore website calls it a 3 season bag. Extreme ratings are survivable temperatures. You will not sleep, you will feel very cold and be shivering badly. Think edge of hypothermia territory. That's if sheltered from any airflow. As the OP has no protection from wind under the tarp he will cool quicker

I once had a calculator produced for my company decades ago to advise industry on lagging stacks. We would be provided with hot face, average outer temp, required max cold face temp (below 60C if humans can access it) and typical design airflow outside. An increase of just 1mph often made out so much easier to insulate stacks. It made a huge difference.

It is terrible wording on the woodlore website bordering dangerous. If someone buys based on the -15°C figure and uses it in that with a cooling airflow it could result in hypothermia. I'm not a fan of even mentioning extreme temps with sleeping bags. I think it is potentially dangerous.

Insulation in sleeping is more efficient than that in clothing. This means you want your bag Insulation to loft up to its greatest amount possible. If the inside is cramped whether by a big fella or a normal person wearing clothing or is possible that you lessen the bag loft and Insulation provided. Sometimes it is warmer wearing less inside you bag. Similarly throwing a coat over the top can create a lower level of insulation than without it. That I learnt from someone in the industry.

We all run at different temps when sleeping. Plus food affects it. Loads of factors that out pays to go overboard a little

 

[Moondog55]

I agree with you Paul B to a certain extent but practical experience with wearing clothing inside a sleeping bag or layering a parka over the top tells me it works, otherwise it would not be recommended by Canadian and Alaskan guides and mountaineers such as Andy Kirkpatrick . There is a "However". You need to plan out your sleeping system and use an appropriately sized sleeping bag, the "Expedition cut type", generally plan on using not much more than a 25mm thick clothing layer and not compromise the loft of a down sleeping bag by using a very heavy outer layer on it. This naturally precludes the use of a thick woollen blanket weighing a couple of kilos over the top but a LW down parka will have negligible effect on a sleeping bags loft and even a relatively heavy parka will add more warmth than it detracts unless you are using an ethereal down fill such as 1000+FP Polish or Hungarian down and shell fabrics with very low weights like 22GSM .
Camping below -18C needs a bit more planning and a bigger budget and a realistic understanding of your own level of fitness, stamina and ability to tolerate cold.
My general rule of thumb is to look at the average temperatures for the region being visited, then look at the extremes for time and then add a safety margin of at least 10 degrees Celsius to that and remind myself that ground insulation has to equal or better the sleeping system rating.
Sleeping systems for places like an Alaskan/Scandinavian winter and Everest/Denali or Antarctica are not cheap and even at best are heavy and bulky and best handled by double bags and the possible use of VB clothing and sleeping bag liners. However the coldest I have ever slept was -35C so I have no experience with deep cold

 

[Dan00001]

Will read through replies when I'm less busy, but I sent an email to RAB questioning the temperature rating for the Neutrino 600 vs 700 and received this reply.. So basically, EN ratings a very loose guide that can alter from one test to the next even on the exact same bag.

[Equipuk] Re: Rab Neutrino Sleeping bags

H​

Harley (Rab)
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[COLOR=var(--textSecondary,#6e6e6e)]Mon 18/11/2024 08:58[/COLOR]

##- Please type your reply above this line -##​ ​ ​ ​ Harley (Rab UK) Nov 18, 2024, 08:58 GMT Hello Daniel, Thank you for getting in touch with your question. We would recommend using the Rab Sleep Limit for the basis of your purchase as this uses the EN test results in addition to supplementary laboratory, test team and athlete testing. This is because In some instances, the EN testing can return different results when testing at different test facilities and sometimes even with the same sleeping bag at the same facility. The EN standard also works 'backwards' in some cases whereby closer fitting bags perform worse than looser fitting ones due to the manikin configuration. Any tight spots around this will result in the insulation getting compressed and the bag testing as colder than it is in real-world conditions. The same thing would happen in 'real world' use however a human would pull their arms in closer to their body if they are cold curl up, making themselves smaller and reducing the compression of the insulation around them. As the 700 uses 100g more down, it will be warmer than the 600. If you have any questions, please let me know and I will be happy to help. Kind regards, Harley ​ ​ ​

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