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Why heavier isn’t necessarily better…

Lou Blaiotta on Monday, March 17, 2014 at 12:00:00 am

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Better Elevator Doors Columbia ElevatorSometimes in building, we automatically think of ‘heavier’ being ‘stronger’ and then being ‘better.’ Like steel entrance doors – we think if they’re heavier, they’re better. Let me tell a story:

We did a job at the bio-medical building at Yale University. The drawings were submitted, and the request was for the doors to be made out of 12 gauge steel and covered in 14 gauge stainless steel. Additionally, the two speed doors had to be 9’6” high – basically, the facility wanted to have strong doors that were protecting the people and equipment that would use it.

I had to attend a meeting with a number of people to give one of my early lessons on the job about this proposal. I told them, “We can make doors like this – yes they are ‘strong’ but they are too heavy. Plus, we have another issue: doors of that size and weight are not code compliant because of the rule on kinetic energy.” Yale’s in-house elevator specialist, the chief architect for the University, and the construction manager of the bio-medical facility wanted to have a safe environment, so they figured the heavy specifications would work.

The architect was the moderator of our code conflict and quickly saw my reasoning about why we couldn’t meet the specifications within the code rule. The 750 lb hoistway doors and car doors combined weight moving at the prescribed speed would exceed the kinetic energy of the code rule. To make it work safely, we’d have to slow down the door so much you could eat your lunch in the amount of time it would take for the door to close.

We thereby made recommendations to reduce the weight of the doors that were finally accepted.

Sometimes, people think that the more steel in a door will make it stronger and safer. However, the heavier the steel, the less fire resistant it will be because it will retain more heat in the fire.

That is why we focus on making ‘better’ doors rather than ‘heavier’ doors. Architects can always give us independent manufacturers a call, and we can talk through these specifications before drawings go out to bid.



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