Door Gaugegreenspun.com : LUSENET : Elevator Problem Discussion : One Thread
Hi Guys, I recently ask my boss for a guage that dover had when i first got in the business. This Gauge (though probably not very accurate) had a torque and kinetic energy scale. He doesn't know what I'm talking about. (imagine that!) Has anyone out there know what i'm talking about or if it even exists anymort?
-- William J. Bunch (email@example.com), September 15, 2004
Yes I do.
Unfortunately, it was realized that the device could not produce accurate kinetic energy readings, since the Code requires that the AVERAGE speed be used and any such gage could only give a reading based on the speed at the moment the reading was taken. Therefore, it is necessary to determine the time to travel the code specified distance, convert that to feet per second to determine the average speed and then compute the KE from the formula, which is:
Where M is the Mass of the doors and V is the speed we just computed. (The conventional "weight" must be divided by 32.2 to determine the Mass ). Then, some factor must be added to account for the rotating masses of the operator.
-- John Brannon (firstname.lastname@example.org), September 15, 2004.
your spending way to much time behind a desk with nothing to do. all of the manufacturers of door equipment today incorporate some sort feedback to tell what position the doors are in and adjust torque accordingly. about all you have to do today to meet the code is adjust the doors 1 foot per second, with no slamming in the open or close and everything with be within the code.
-- (email@example.com), September 16, 2004.
the door guage your talking about is available from adams, wittur and a few other vendors. trust me that if someone is manufacturing a door operator, all this " torque and kinetic energy " bullshit is incorporated into it, and it has been an accepted standard complying to code. it is also pre-set to a lower default setting than the maximum close speed and torque allow. most of the equipment i've worked on has some sort of a built in " fail safe " that will prevent the doors from closing too hard or too fast. the gauge you talk about is fine, unless john shows up with his slide rule and protractor.
-- (firstname.lastname@example.org), September 16, 2004.
Well, Kick, you are entitled to an opinion.
I have an Adams door gauge. It reads force, not kinetic energy.
Even 1 fps closing speed could be too fast with very heavy doors, at least theoretically. Also, this would be unnecessarily slow in many cases and thus hamper efficiency.
I spend as much or more time in the field as I do behind a desk. Your apparent contempt for anyone with a little knowledge is interesting. If you think the extremely simplified information I provided is all that big a deal, I can see no one need have contempt for you on that score.
-- John Brannon (email@example.com), September 16, 2004.
Thanks so much for the resourceful information. Kick is just an example of a temp mechanic that doesn't know why he does things, he just does what the support person on the other end of his phone tells him to do. Regretfully, about 70% of the elevators operating out there are not closed loop nor do they have feedback for position other than a door open limit or closed limit. Some door operators actually require you to adjust a resistor band or move a cam, not turn a potentiometer.
The purpose of this meesage board is to provide help to fellow elevator men, and discuss issues that are important to our industry. Keep up the good work John.
-- John (firstname.lastname@example.org), September 17, 2004.
guess youve never worked on a DMC or an OTIS product during the last 15 years, eh ? what do you think the pulse count is ? GAL even has it their stuff. ive been in this business since 1974 and i do know which resistor band to move, my only point is - why are you trying to re- invent the wheel ? both of you john's must be on the same committee, making a bunch of horse shit out of nothing, trying to make yourselves invaluable to the company your working for when all it is is a waste of everyone's time. the door gauge works just fine, i wouldn't set a door above 25 pounds with it, but it works just fine.
-- (email@example.com), September 17, 2004.
For "Kick" --
While I do not customarily engage in working on elevators personally, it has been my privilege to work with many highly qualified engineers, mechanics and adjusters and to witness their work first hand during a half century in the elevator business. I know what a pulse count is - I'd like to hear your explanation.
It is manifestly obvious that you do not understand the difference between force and energy. The A17.1 code has requirements for BOTH. Force is limited to 30 lbf per rule 22.214.171.124.3. Kinetic energy is limited to 7.37 ft-lbf by rule 126.96.36.199.1.
The door gauge measures force and is fine for that purpose. You can measure the force right up to the maximum with such a device. Basically, this is a measure of how much force a blocked door exerts in attempting to continue to close. The weight of the doors is not a factor here.
There is no gauge that I know of that measures kinetic energy. Accordingly, it must be calculated, as I explained. The calculations have been pre done and are available in chart form. One source is GAL (http://www.gal.com/downloads/kinetic/single%20speed.pdf). If this is so unnecessary as you contend, why do you think GAL (and others) publish such charts? Kinetic energy represents the impact doors would make in striking someone or something in the act of closing. Thus (even) you should easily see that BOTH the weight (M) and the speed (V) contribute to that impact. If you don't like my explanations, perhaps you'd prefer GAL's (http://www.gal.com/downloads/kinetic/overview1.pdf)
It is the many experts who write the Code (over 40 on the Standards Committee alone) who are "making a bunch of horse shit out of nothing" according to your way of thinking. No one is "reinventing the wheel". These considerations have always existed and always will. The Code does not "invent" anything. It addresses the safety issues that arise as a natural consequence of using the machines necessary for the operation of elevators.
As to an attempt to "make myself invaluable to the company I work for," I am in business for myself now and have for a number of years.
-- John Brannon (firstname.lastname@example.org), September 17, 2004.
what i'm trying to say is... At the Mechanic's and Adjuster's level, and even the Service Mechanic's level, torque and kinetic energy has been " childproofed " by R & D, the engineer's, the Code Jurisdiction, and such, and unless grossly mal-adjusted, you should be able to maintain an acceptable level according to Code unless you have 10 wraps on a spirator, or a door closer with its spring tension maxxed out. john- you have to admit, there are mechanic's out there that can't wind a wrist watch, do you really think a manufacturer would put something in the field that had the potential to be that absurdly dangerous in the wrong hands ? from what you've said, being a business owner, you can't say incompetance hadn't crossed your mind a few times in the past. all of this is engineered into the product LONG before it presents itself in the field or YOU wouldn't have been in business for very long.
-- (email@example.com), September 17, 2004.
Further message for "Kick" -
First, you might try to say "what I'm trying to say" without demeaning and insulting others.
We are now far afield from the original question - which, as I recall, was about a particular gauge made many years ago. I happened to be intimately familiar with that one because it was designed by a very dear friend of mine (now deceased, may he RIP), at the time the force and KE limitations were added to the Code. The rest of that story I've already told.
It is very easy indeed to misadjust even the most modern of operators such that the force or KE or BOTH are exceeded. In my capacity as a consultant and inspector, I have encountered MANY cases of this. Not too long ago I ran into one (a modern closed loop design) that bottomed my gauge and compressed it so hard that the imprint of the spring inside was visible on the stainless steel tube forming the case. Prior to that experience, I would never have thought that an operator would be capable of exerting that much force.
There are incompetent people in every line of work and ours, regretfully, is no exception. Even the most competent ones cannot "child proof" the equipment against them. As one wise old engineer told me about forty or more years ago "we may be able to make 'em foolproof, but we can't make 'em idiot proof".
Also, perfectly capable people make mistakes and there are component failures, changing conditions over time and other factors to consider.
This is why we have standards and why someone must check to insure they are complied with, by whatever means are necessary. Don't let all that big, bad math scare you, Kick. Me and some of the other egg heads will take care of it for you.
-- John Brannon (firstname.lastname@example.org), September 18, 2004.
We still use the gauges here in Portland. They are probably available from Vertex. My personal experience is that they tend to be very unstable and inaccurate. After a GAL operator slams into them well over the 7flbs code-allowed KE, the spring goes South and what used to be 23lbs force is now 18lbs. Good luck with that! I have checked my old style pressure gauge against those of various State Inspectors and it's still accurate after all those years. The TKE stick failed after the 2nd use.
-- Richard Orr (email@example.com), September 18, 2004.