American Safe Room manufactures these pre-hung blast resistant doors that are engineered to protect your shelter from the high pressure blast waves produced by a large conventional or nuclear detonation.
They also are designed to protect against malicious people and fires. The door features four inches of concrete that resists structural fires, cutting torches, and has a UL level 8 ballistic rating - multiple hits with a 7.62 NATO round with no penetration.
The standard frame is designed to bolt to the wall with high strength concrete wedge anchors. If you choose the assault resistant cam latch option, you also get the wall capture brackets which give you the security of a poured in place door with the ease of installation of a bolt on door.
Sizes - standard and custom
The standard sizes are 32 by 72 inches and 36 by 80 inches. These dimensions are the outside of the frame lips that insert into the opening in the wall. You need to make your wall opening a little larger that these dimensions - see the manual for more information. We have built many custom sized doors. If you have an existing opening that needs a blast door, please contact us.
This is a 38 by 80 inch door with a bolt-on frame and a stepover threshold. It features assault resistant cam latches, a wide angle viewer, an inset deadbolt, and the differential pressure gauge will mount just below the viewer.
Certified load rating
These doors are certified by a professional engineer to withstand a 50 PSI (3 bar) blast load in the seated condition and 14.5 PSI (1 bar) rebound load in the unseated condition.
The door has been engineered to withstand the "negative pressure" force (less than atmospheric) that sucks the door outward right after the blast wave passes over. A detonation blasts all the atmosphere outward, leaving little or no atmosphere for a very short amount of time. This "negative pressure" has energy and can be as deadly as the high-pressure blast wave. That is why our blast doors have the rebound load rating and our automatic blast valves are double acting for both pressure and vacuum.
How blast doors stop detonations
The energy from a detonation must first overcome the static inertia of the mass of the concrete. Once this inertia is overcome and the door begins to move, it flexes inward, acting as a bridge between the frame from side to side. The blast load puts the concrete fill under a compression load that transfers the blast load to the inside skin. The inside steel skin is put under a tension load as it stretches. Engineers use concrete for applications that require a high compression strength and steel for applications that require a high tensile strength.
Steel envelope construction
We put the steel right where it does the most to resist blast pressures. The concrete is contained inside the steel envelope where it cannot escape. Even if it cracks or disintegrates, it's mass stays inside the door leaf where it transfers the blast load to the inside steel skin.
Install before filling
The 3/16 inch steel envelope is filled with concrete after you hang it in place. This keeps the door relatively light for installation, but puts a lot of dense mass between you and whatever threats are outside your shelter. A 36 x 80 inch door will be about 650 pounds without concrete and about 1700 pounds when filled with concrete.
The massive hinges have one and a half inch shafts captured by bronze bushings that are press fit into steel blocks and are packed with grease - and they feature grease zerks so that you can keep them lubricated for smooth, effortless opening. The hinges alone weigh 30 pounds per leaf.
The cam latches are rotating handles on the inside of the door leaf that engage a cam welded on the frame. They operate in opposite directions in case the door is subject to violent movements by a detonation - one may loosen, but the other one will tighten, holding the door in place.
As you turn them, they draw the door leaf into the frame, compressing the door seal.
The picture above shows the latch in the closed position. Note the bracket on the door leaf above the latch that allows you to lock your latches in the open position with a paddle lock. The hole in the bracket correspond with the hole in the cam latch handle. The picture below shows the latches in the open position over these brackets. Most machinery and large tools have a "lock out" function for maintenance. This duplicates that function in case you have to give someone access to your shelter who may try to lock you out. We incorporated this feature on all doors after a customer with a teenage son inquired about a way to ensure he was not locked out of his shelter.
These doors are made to be as difficult as possible to penetrate from the outside. Calling the fire department to extract someone who locks themselves in your shelter is not a good way to keep your preparations hidden. And, the fire department would have a difficult time breaching this door. They would not forget the experience. The concrete filled door leaf is impervious to cutting torches, 7.62 NATO rounds only make it half way through, the assault resistant security latches hold the door in place if the hinges are cut off, and the wall capture brackets hold the frame in place if the outside fasteners are removed.
The cam latches are fabricated from plasma cut and formed quarter inch steel plate and feature adjustable tension bolts that keeps the handle in whatever position you leave it.
This shows the upper cam latch and the upper assault resistant cam latch with the viewer port between them. Note the steel plate welded on the outer edge of the door leaf. It gives a firm stop to the door with steel to steel contact between the door leaf and the frame so the seal is not compressed too much, breaking it down over time.
These doors features a synthetic rubber seal between the door and the frame allowing for the use of a positive pressure NBC filtration system inside the shelter. The inside cam latches draw the door into the seal as they are rotated. This puts the seal under compression between the door leaf and the frame. The strict tolerances we hold allow us to use a closed cell EPDM foam seal - not the bulb (automotive type) seal commonly used when manufacturers can't hold the tolerance necessary for a solid seal. This seal is expertly applied without stretching it and the corners are cleanly chamfered to seal out airborne toxins.
As an option, you can get a second, fire rated seal applied outside of the primary seal.
It is a 1/2” wide bulb seal that would have to fail before the main seal is compromised by a thermal event.
Tested in accordance with NFPA (National Fire Protection Association) standards 105 and 252, this seal also meet ASTM E283, E90, and E413. UL classified for use on hollow metal and steel-covered composite-style fire doors rated up to and including three hours. Meets UL 10B, UL 10C, and UL 1784.
There are four different frame options to handle any type of threshold you have:
Three inch concrete step over
Five inch concrete step over
Frame step over
This inward swinging door has a flat threshold with an adjustable sweep, a deadbolt lock, and an inset pull handle so that an outward swinging wooden door can be mounted over it to hide the shelter entrance. There is no extra cost for any of these threshold options. See page seven of the manual for detail drawings of these thresholds.
We asked one of our industrial customers that had a door installed in a FLEX building at a nuclear power generation plate in Missouri to test the force required to open a door. This particular door was a 36 by 80 inch door, but the thickness was sized to resist a certain spectra of missile threats. It featured a 5/16 inch skin thickness (compared to 1/4 inch on a normal door) and a 6.5/8 inch total door leaf thickness (compared to 4.3/8 inches on a normal door). The weight of the door leaf after filling was about 2,300 pounds (compared to about 1,700 pounds on a normal door). Here is their test results:
We did the test on the American Safe [Room] personnel doors that you requested. All testing was performed on the Plant South Door. We did the test 3 times and got consistent results on all 3 tests. There was no break away force needed to get the door swing started and the force was consistent throughout the travel to 45 degree OPEN. See below for equipment used and force observed:
Dillon Model GL Digital Force Gauge (0 – 100 lbs.)
M&TE number DYN2038MT
Cal. Due Date: 10/11/15
1. Unlatched door
2. Observed 20 lbs. of initial force to OPEN door
3. Continued to apply 20 lbs. of force through travel to 45 degree OPEN
It took just 20 pound of force to open a 2,300 pound door. This is due to our bronze bushings, grease zerks, and how straight we can keep the door leaf and frames because we form the steel using a press brake - which keeps the hinges and latches from binding.
Inward swinging blast doors
Blast doors normally open outward to carry the load in the seated condition. The blast load transfers directly from the door leaf to the frame and wall, not through the hinges and latches.
Certain installations require an inward swinging door and we offer it as an option. This is one of our cam latches secured shut on an inward swinging door. We mount the cams on risers and widen the face flange of the frame. This picture shows an inward swinging door cam latch secured under the cam which is mounted on a riser to clear the door leaf thickness.
We purposely made this door as nondescript as possible because nothing says "valuables inside" like a blast door that looks like a bank vault. It is shipped to you with a primer finish so you can paint it to blend in with whatever is around your shelter entrance.
The doors are shipped by LTL freight. We can specify that the delivery truck has a drop gate so the delivery is on the ground exactly where you want it. You must ensure that there is adequate turn around room.
These are two solid steel doors we built for the FLEX building at the Prairie Island Nuclear Generation Plant in Minnesota. The free opening is 75 by 85 inches and the door leaf is 2.5 inches of solid steel.
After the 2011 problems at the Fukushima nuclear power plant in Japan, the Department of Energy mandated that all nuclear power plants in the US have install a secure building to store their emergency equipment in. These buildings had to resist the impacts of a variety of missiles (telephone poles, automobiles, etc.). American Safe room was hired to design, engineer, and build doors for many of these nuclear power plants.
The hinges and latches were engineered to handle the 5,100 pound door leaves. Note the cam latch operators on the outside and the deadbolt lock by the outside pull handle. That lock engages a rod on the inside that prevents the cam latches from being operated to provide access control.
These doors are installed and in operation right now.
We've placed a lot of these doors in industrial applications: chemical plants, foundries, ordnance storage magazines, ordnance testing ranges, refuge chambers, and even a rhinoceros enclosure at a zoo. If you have an application that needs to protect from, or to contain a detonation, please contact our Sales Manager at 541-459-1806 or sales@AmericanSafeRoom.com
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Gallery of blast doors
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