Q: Yesterday I was injured by a chain/spring contraption at a local coffee shop. I was wondering if you can tell why it came down and hit me. It all happened very quickly. I heard a loud "pop" sound and the next thing I knew something smashed into my face. The store may have taken the part that failed away, I am not sure what it looked like before it broke. I have attached photos my son took of the apparatus. Thanks for your help!
A: Where you entering or exiting to coffee shop?
Q: I was exiting the coffee shop. I heard a loud popping sound and the next thing I knew, the coffee cup in my right hand went flying and something smacked me in the head.
A: There is an automatic door operator above the door. do you allow that unit to open the door or did you manually push the door open?
Q: I manually opened the door.
A: There is certainly more involved than I can glean from the 2 - photos you supplied but must admit I have never seen two crash chains installed on a single door which tells me the addition of the second crash chain is intended to compensate for an unusual condition or unusual usage.
There is an automatic door operator installed on the door activated by a hardwired or radio frequency switch plate. These are costly units. The door in your image swings out on an exterior wall. The two crash chains installed are there to limit the degree of door opening to prevent the door from swinging too far open, which would damage the costly door operator, damage the door and frame and the balance of the hardware and certainly be potentially dangerous to people. The door swinging too far open would be caused from wind and use (people pushing the door open too far over and over) and possibly to automatic operator simply opening the door to the limit point of the crash chains. This outline, for me, accounts for the unusual condition and application. I am unfamiliar with the door operator so cannot comment as to what "on board" provisions the unit has to prevent the door from swinging too far open, but can tell you the crash chains are meant to limit the door degree. I can also tell you - these items fail. Plain and simple. Crash chains break and in my opinion is proof positive they are used beyond the engineered and designed application for a crash chain. The standard use and abuse these crash chains encounter work towards them to a potential point of failure. Generally the screws will rip from the door (and there is evidence of the screws becoming loose and possible ripped from the face of the door) on the failed unit.
Why are there two chains, I cannot say except to conclude the hardware applied, the environmental conditions they had to contend with, operator abuse tells me there was an intent from the coffee shop to eliminate damage to people and property by including these two (and not just one) crash chain. I might add there are better, possibly more appropriate, devices to control a doors degree or opening (because again - crash chains fail) but would also state these devices called, Overhead Stops, are not the "path of least resistance" when approaching an installation to an existing door (these need to be considered when the door is originally installed).
In conclusion, yes there is a loud and startling "pop" when these brake and the chain is suddenly freed from the tension. In all the story's related to me, it is the shock of the sound that is most firefighting but yours is the first and only account of harm done to a person physically from the chain. As you stated you were exiting. The door would be open at 90° and you are at that moment on the opposite side of the direction the chain would initially travel. In order for you to have been hit in the face or head I conclude you would have had to turn back around and possibly travel back towards the door opening. The chain is 25" or so in length and the door, lets assume it is 36" wide. I you have left the store with the door closing behind you, I ask how it is possible you were physically hit by the chain? I am a hardware guy and do not give permission for the use of my conclusion to be used in any attempt to implicate others but based on your account the obvious fact is this: The crash chain failed at some point when you were using the door and were startled to the point when you dropped your coffee after the sound and hit. the answer is for the coffee ship to alter the hardware set to prevent a future potential reassurance.
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Q: Hi, Can you please advise if the "Heavy Duty Crash Chain" is capable to withhold on door leaves weighing up to 800 kg (1763 lbs)? Our subject heavy doors are currently having a Dorma-TS93B door closer. However, the door closer is breaking when the doors are subjected to 40-50 mph wind-speed hits the door and cause damages on the door closer and on the backside wall as well. Therefore, we want to install heavy duty crash chain to save the door closers from breaking and stop the doors at approx. 90degress so the opening force created by the strong winds won’t reach to the door closer and break it. How should we attached the chain plate to the frame and to the door leave i.e. if the chain needs to be through-bolted to the door with a backer plate and fastened to the frame with multiple tap and die machine screws (as opposed to self-tapping), can you please advise what type of bolt, screw will work with your chain system? In short, we have about 67 exterior doors which some of them (almost half of 67 doors) are very heavy as mentioned above and they are subjected to 40-50 mph wind speed, therefore their door closers break and this cause damages on the backside wall. We want to stop the door at somewhere 90 degrees so the door closer arm does not receive any load comes from swinging door by the wind. The door is 1000 mm wide. Some doors are manufactured from 6 mm thick metal sheet. Some doors are hollow metal which they are about 1.5 mm thick galvanized steel. Attached the typical drawings of the doors:
Download File
Can you please inform what length of chain can fit on these doors and advise on how to attach the chain to the doors considering their weigh and wind speed that will create an additional force on the chain mechanism… Pls, contact me via my email below for any clarification. Ali Poland
A: Happy to help. But first - Are you sure your weight calculation is accurate?