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gun safe fire ratings

Discussion in 'Shooting Gear and Storage' started by staff111, Nov 6, 2018.

  1. staff111

    staff111 Member

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    A few years ago, I bought a gun safe. When I did I noticed that there is very little accurate information on fire ratings. For that reason, I thought I would write this post to share my opinion on the subject. Before I start, I have no experience testing gun safes (though I have several years experience testing electronics) however, I also do not work in the gun safe or other safe industry. With that in mind here it goes.

    The safe review guy (by the way if you are buying a gun safe read his site, it is excellent) correctly says that gun safe fire proofing can be split into three categories. The categories are drywall, ceramic fiber, and cement. He also says that cement is most effective followed by ceramic fiber with drywall being the worst. However, he uncharacteristically does not back up that opinion well likely due to the fact that little information is available. In my opinion he is correct but I would like to take the time to show this to the best of my ability. To do that I used excel to perform heat transfer modeling on all three types of safes.

    There are two basic effects which keep the inside of a safe cool in a fire. These are insulation effects (high thermal resistance or low heat transfer coefficient) and evaporative cooling. Both cement and drywall rely on both while ceramic fiber relies on only thermal resistance.

    What happens in a fire – ceramic fiber

    In a fire, assuming the safe is well sealed, the safe will quickly reach thermal equilibrium. This means that the temperature of the outside wall of the safe is the same as the fire and the interior is what it was before the fire. The temperature inside the wall of the safe (inside the ceramic fiber) is in between (at the midpoint it is half way between the fire temp and the inside of the safe temp). At this point the heat will slowly transfer through the wall and this effect can be calculated readily if the outside temp, inside temp, and thermal resistance of the insulation are known. I did this for a safe with 2.5 inches of ceramic fiber insulation and discovered that in a 1200 degree fire at ideal conditions the safe would stay under 350F for 38 minutes and at 1500 degrees for 27 minutes. If you want the details of the analysis I can provide them.

    What happens in a fire – concrete

    The concrete example is a bit more complicated. In this case the heat from the fire will attempt to heat the concrete. However, once it gets above the boiling point of water the water contained in the concrete will evaporate which will cool the concrete. This effect will continue until no more water is left. Once that happens the safe will start to heat beyond the boiling point of water far more quickly than the ceramic lines safe (since concrete does not insulate as well). To model this phenomenon I assumed that the safe had 2 inches of concrete all around would heat evenly all around. I then assumed that each infinitely thin layer of water contained in the concrete would evaporate evenly until all the layers evaporated. This results in the first layer evaporating very rapidly since there is very little insulating it from the heat of the fire. However, as more water evaporates the heat has to pass through more of the concrete which insulates the water resulting in less energy reaching it. This means each layer takes longer to evaporate as the heat penetrates further into the safe wall. This sounds complicated but it results in the average water layer being 1 inch (half way) in and I can assume all of them are. Using this logic I discovered that in a 1200 degree fire a 2 inch lined concrete safe would use up its supply of water in about 3 hours 45 minutes. After this the safe would last a few more minutes due to the insulating properties of concrete. At 1800 degrees this time drops to around 2 hours. Drywall is similar to concrete but has much less water. 4, half inch layers surrounding the safe lasted 7 minutes in a 1200 degree fire.

    How do I make my safe last longer in a fire?

    Concrete safes do not have enough insulation to benefit an there is not much that can be done inside the safe to help. This is not true with ceramic fiber lined safes. In these the contents matter greatly. This is because a fire basically causes heat energy to transfer through the safe walls and this will cause whatever is inside to heat up. This means the more stuff in there the more energy needed to heat it up and the longer the contents will last in a fire.

    One last note, it occurred to me when I was doing all this that the best fire resistant safe would have concrete on the inside and a ceramic fiber layer on the outside. This would prevent heat from getting to the concrete layer and any that did would be dissipated by the evaporative cooling of the water in the concrete. There might be issues of the water evaporating into the ceramic fiber and causing it to lose its insulating properties. If ceramic fiber was used on the inside and concrete on the outside the safe would not last much longer than the concrete alone but would have even more moderate temperatures on the inside for a while. I later found out media safes are made this way.

    Hopefully this helps someone but if anyone wants more details or has questions I’ll answer them as best I can.
     
  2. Walkalong

    Walkalong Moderator

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    Very interesting. How would the "ceramic wool" in a Sturdy gun "safe" react to heat?
     
  3. staff111

    staff111 Member

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    Thanks for asking

    To be clear by ceramic fiber I meant ceramic wool so the sections on ceramic fiber partially cover this. Also, that section describes how any insulator will act (though the time to failure of the safe will be different depending on how effective the insulator is). However, I will expand on that a bit here.

    In a fire the temperature of the outermost layer exposed to the heat would be at the temperature of the fire. The innermost layer would be at the temperature inside the safe. The layer half way between the outside and inside of the safe would be at the average (mean) temperature of the fire and inside of the safe. This matters because the ability of ceramic wool to insulate is affected by the temperature it is at. Check out the following product information sheet.

    http://www.lynnmfg.com/wp-content/uploads/2015/09/DATA-TC-514-205.pdf

    It shows the thermal conductivity of various ceramic fiber blankets. Higher means more heat is conducted and the higher the temperature the higher the thermal conductivity. Also, the products here are 8 pounds per cubic foot which is what sturdy uses.

    The heat distribution mentioned in the second paragraph of this post is why they can use fiberglass as the inner layer even though it is only good to 1000 degrees. Since the inside layers will stay cooler no need to use expensive ceramic wool (in theory at least).
     
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  4. EMT40SW

    EMT40SW Member

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  5. staff111

    staff111 Member

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    Neat product but I don't believe these would do anything to protect a safe in a fire. Assuming it was put inside the safe the plastic outer shell would melt and then it would spill its contents all over the safe. Since the fire suppressant is ammonium phosphate this would create a highly corrosive environment in the safe even if the fire did not heat the contents to the point of damaging them. If it was put outside the safe it might prevent things around the safe from burning but in a major fire I believe the effect would be short lived and the safe would be exposed to a similar heat profile.

    All that being said please let me know if you have some other way of using these that I did not consider.
     
  6. earlthegoat2

    earlthegoat2 Member

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    I like older antique safes that used asbestos as fire proofing.
     
  7. Englishmn
    • Contributing Member

    Englishmn Member

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    Recently saw the contents of a gun safe that went through a fire. I don't know the specifics but temp didn't get hot enough to melt plastic or char wood.
    Everything steel in the safe was surface rusted from the heat and moisture from the drywall insulation.
     
  8. staff111

    staff111 Member

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    According to engineering toolbox, asbestos does not insulate as well as fiberglass or ceramic wool (though it is unclear to me exactly what type of asbestos engineers toolbox was referring to). In addition, asbestos derives its insulation properties in the same way as fiberglass or ceramic wool. This is by creating static air pockets within the insulation's structure which are the real source of insulation. Overall, while I was unable to find much information on the insulating properties of asbestos during my quick search I don't think it would work as well as ceramic wool due to its inferior performance as an insulator unless it has something in it which will melt when heated (I did not find any type which did).
     
  9. staff111

    staff111 Member

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    I don't have the experience you do but I believe it. A safe of steel and drywall would heat up to 212 F in seconds and start releasing water into the safe (actually it would release water before that but I won't go into why that is here).
     
  10. Varminterror

    Varminterror Member

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    Great objective analysis of these insulators. I’d be interested to see the work, and especially interested to see if any accommodations were made for the common interruptions in the safe shell - electrical ports and doors. I’ve incorporated intumescent seals into my own safes to accommodate these infiltration points.

    Additional considerations:

    • The structural integrity, let alone the integrity of the fireproofing materials, can be compromised by structural yielding of the home around it. For example, if an above floor falls onto your safe, or if/when your safe falls through a floor as the fire weakens the home structure beneath/around it.

    • Water and any extinguishing chemicals can be incredibly damaging to safe contents after a fire. Even if your fireproofing is successful, flooding of the safe can and does happen.

    • I’m assuming the mathematical model described above assumes a constant fire temperature on the outside - but any time I look at this topic, I’m reminded of something the department training lead for our rural department used to say: “the best way to survive a fire is to not be in one.” Isolating your safe away from combustible materials will greatly reduce the temperature and duration of exposure. For example - I know a career firearms instructor who has his safe in his reloading room, with his powder magazine organized on top of his safes, surrounded by a wooden shelving set up. You might imagine his safes won’t fare as well in a fire as they might without 150lbs of highly combustible material in the immediate vicinity.
     
  11. Armored farmer

    Armored farmer Member

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    Very interesting.
    I am currently un the market for a new large safe. 60-80 gun.
    Any recommendations?
    We intend to store other valuables and important documents ad well as guns.
     
  12. staff111

    staff111 Member

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    Thanks for the questions and comments.

    I made no accommodations for either electrical ports or doors. The reason for each omission (besides the difficulty in calculating this) is as follows.

    door seal.
    Assuming the door seal is good, the insulation usually is included both behind the door and in the door jam leaving little gap. That being said, if the door seal is bad the safe will heat up rapidly and none of the other factors here matter.

    electrical port.
    I ignored it due to its small size though assuming air could flow through it I would guess it would not effect the safe much in a fire (unless the cord caught fire and spread into the safe). The reason for this is that during a fire the air in the safe will expand causing air to leave the safe through the hole and thus preventing heat from entering through it (I assume anyway). If air can't flow through it it will act like an insulator and would not increase heat input greatly. I don't remember where I heard this but I've heard of safes surviving fires which had contents around the electrical port undamaged suggesting the safe did not experience large heat inflows from that area.

    as a side note, I calculated the effect of a half inch steel bolt and in the large (40X72X27 inch) safe I modeled I calculated that each one increased heat transferred to the safe by about 1.5% for the ceramic wool lined safe.

    Agree with your point that if the safe is hit hard enough, flooded, or hit with water from a high pressure hose your stuff is likely to be damaged.

    The model assumed the safe was suspend in air and that the air temperature was instantly heated to full temperature and held there for the duration of the test. Agree that there are many other things that would affect the safe in a fire.
     
  13. Varminterror

    Varminterror Member

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    At that size, it’s generally getting close to cheaper to simply poor a reinforced concrete room with a vault door.
     
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  14. staff111

    staff111 Member

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    Give some of the stuff on this site a read.

    https://gunsafereviewsguy.com/

    Lots of good info IMO
     
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  15. Armored farmer

    Armored farmer Member

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    This will be in our 1881 built farm house.
    I am concerned about the floor joists.
    If i were building a new house, the reinforced door/safe room is an awesome idea. My buddy built a house with one in his basement. Its a fortress. Storm cellar, gun vault, safe room.
     
  16. Varminterror

    Varminterror Member

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    At my last house, also a turn of the last century home, we cut down beside the foundation and poured sub-grade. Put an apparent built-in shelf on a caster track in front of the door, so going downstairs, the basement didn’t look inconsistent with the 1st floor floor plan.

    Moving in there, I was concerned, like you, about putting so much point load on the floor structure. Running the numbers and resale value, PLUS the foundation repair and drainage improvement opportunity, AND loving the idea of NOT hauling multiple 48-64 gun safes down then back out of the basement AND having the opportunity to improve the ventilation for humidity mitigation down there... it worked out very well to do a simple foundation expansion and buy a vault door. And renting the mini-ex and doing the finish work ourselves obviously made a big difference).

    My biggest problems, of course, with 60-80gun safes is the size to install, the single point protection (read single failure for full access) AND the fact no safe is ever big enough, and growing 60-80 by 10% means s lot of new space required.
     
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  17. CapnMac

    CapnMac Member

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    Sixty guns? A bit boggling. Lessee, figure a 9" x 6" x 48" volume.
    Just raw foot print is 54 x 60, or 3240 square inches (22.5 square feet).

    Just configuring in my head, 6 deep is about 36", but 10 wide would be an impractical 90" wide.
    Double height might make sense (other than needing 96" inside height), but 6 deep by 5 wide would be 36" x 45" wide.

    In RSC calculus, of course, 60 would be like 52" x 39" x 72" and would really only fit about 28-32 at best--but, that's just how RSC companies are.

    Which is why many folk will advise to just gin up a solid CMU "closet" with a stout door instead.
     
  18. FAS1

    FAS1 Member

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    I read your analysis when you posted it and some things seemed to be contradicting. I wanted to see if anyone else interpreted the statements the same way that I did and I don't think anyone questioned them so I wasn't sure if I was understanding them correctly.

    The above statement seems to indicate that you believe ceramic insulation is superior to concrete fill. Does that concrete fill properties also include what AMSEC uses in their proprietary fill?

    This statement above seems to me shows that the concrete fill far exceeds the ceramic insulation.

    While in my mind I think ceramic insulation would work well and certainly better than drywall, I also think there are a lot of variables that can make a bit of difference when it's installed. Air gaps, etc. How can it seal well in all the corners and is it used in conjunction with any type of fireproof caulk to seal it to all the seams and corners? Seems like this is one area that ceramic insulation falls short compared to the concrete liner. The other that I think of has nothing to do with fire protection, but the strength of the safe itself. The concrete layer adds to security where the ceramic liner does not.

    That being said, I do believe that safes made of thicker steel, like the Sturdy Safes in conjunction with the ceramic insulation option do make a great combination in security and fire protection overall. Just my thoughts and I know very little about the subject of fire protection. Thanks for the write up!
     
  19. oldfortyfiveauto

    oldfortyfiveauto Member

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    From another blog I follow:

    As a former volley FD member and truck captain, I can assure you that there aren’t any good locations for a fire safe.
    All end up in the basement....period it’s just a matter of time before they end up there if they were not there in the event of a fire.
    When I crank up the fire engine rollin a 1500gpm pump pushin water to 4 lines your basement will be a pool in short order.
    Ive never seen firearms survive in a fire safe before. All end up in the basement flooded and ‘quenched’.
    With today’s lightweight construction most houses are near the 15 mins or less to full engulf. 3-4 for safe egress.

    Modern Homes & Increased Fire Risk | Safeco Blog

    Factor in that typical response time in a city is 5 mins or so to arrive leaves very little time to save the house. Odds are dramatically reduced the further from town you are.
    As others have stated they are theft deterrent devices at best.
     
  20. staff111

    staff111 Member

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    Thanks for the questions.
    In my last statement I was in no way saying that a concrete lined safe is worse than ceramic wool. What I was saying is that whether there is one gun or 50 in the safe the concrete will protect the contents for 3.75 hours (according to my model). On the other hand, a ceramic lined safe will do a much better job protecting 50 guns than one gun (by better job I mean protect them longer). The reason why is briefly explained above but if you want more details or a better explanation I can provide it.

    I looked up the moisture content and density of a standard concrete on the internet to do my analysis. The density of standard concrete is about 150 lb per cubic foot. This is far heavier than what amsec is using (can be calculated by estimating the volume of concrete in their safe based on dimensions and subtracting out the weight of the steel from the listed weight of the safe). Doing a calculation of how well the amsec would perform wold require more information then they would likely ever share. That being said, I believe it would perform worse than a true concrete lined safe but better than a ceramic wool lined safe.
     
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  21. Shimitup

    Shimitup Member

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    I wonder if boiler refractory cement has ever been considered for safes. This came to mind because in years past I had built forms to cast tongue and groove slabs to stack inside a 4,000,000 BTU heating boiler to replace the failing refractory. Once it cured during a test firing the firebox side refractory was a nice bright orange glow and though quite hot I could place my hand on the outside of the refractory. Very unscientific method but it seemed it could be very effective especially when used in conjunction with ceramic wool and heavy inner plate to absorb heat.
     
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