The low energy operator has gained importance as a result of Americans with Disabilities Act (ADA) requirements for commercial facilities to provide access and egress for the physically disabled. Low energy door operators open the door when a lock, touch pad or similar product is activated. Unlike high energy automatic swinging door operators that make use of sensors, the low energy versions do not require guard rails, safety mats or a certified installer.
The three-hour fire rated Detex Low Energy Automatic Door Operator AO19 Series meets American National Standard requirements for Power Assist and Low Energy Power Operated Doors (ANSI/BHMA A156.19), the requirements of the American Disabilities Act and UL 325 and UL10C. It is designed for medium to high traffic applications operating doors up to 250 lbs.
The Detex AO19 Series is a motor and gearbox with clockspring design power door operator. Extending from the gearbox is the clockspring and the spindle shaft. An arm attached to the spindle shaft pushes or pulls the door to the open and closed positions when the spindle rotates. As the DC powered motor opens the door, the clockspring winds up. When the door is opened, the motor stays engaged to keep the door held open. As the door closes, the motor slows the rotational forces of the clockspring, resulting in a slow, smooth closing cycle.
To control the opening, hold open and closing cycles, the motor receives varying amounts of amperage. The amount of amperage is controlled by a potentiometer (like a light dimmer switch). The more amperage, the faster the door will swing open. The Detex AO19 can be adjusted to open a door much faster than the minimum ANSI requirement of four seconds for a low energy operator.
The less amperage, the slower the door will swing during the opening cycle as rotational resistance applied by the clockspring increases. A minimum amount of amperage is required to maintain the door in the open position. If no power is provided, the door will close because the clockspring’s rotational pressure is forcing the gears to rotate in the closing direction.
Because the gearbox, clockspring and motor low energy door operation involves significant amounts of restive forces for controllably smooth operation, the Detex AO19 was designed with a one-inch diameter spindle shaft and a heavy duty hypoid gear equipped gearbox. The spindle shaft has 19 1/8”-thick teeth around the circumference insuring that neither the spindle nor the arm assembly teeth will strip. The motor is custom for the AO19 in order to provide the specific revolutions per minute and torque required.
Speed of the opening and closing operations as well as the open time are adjustable. There are minimum times specified in ANSI/BHMA A156.19. These include a minimum of four seconds opening time, a five-second hold open time and a 4.5-second closing time (3 seconds from 90 degrees to 10 and 1.5 seconds from 10 degrees to fully closed. The size and weight of the door can affect the opening and closing times.
However, these are only the minimum times. Each application’s times are determined by the abilities and disabilities of the persons using the doorway. To accommodate the diversity of needs, the hold open time is adjustable from 0 to 60 seconds.
I was invited to observe the installation of the Detex AO19 Low Energy Automatic Door Operator and a Detex Exit Device with Latch Retraction onto a non-public, double door entry used by employees of a large facility. The inactive door is equipped with two flush bolts. The active door can be opened to a maximum of 110 degrees. The employees are the plumbers, electricians, HVAC, etc. The individuals who keep the facility operating use this door more than 600 times a day.
This exterior doorway with outswinging three-foot doors leads into a very large multi-function room. The room contains stock for some of the trades as well as a machine shop, locker room, etc. From this room, there are smaller specialized application rooms and hallways leading to other areas and exit doors within the building.
The Detex AO19 is designed for medium to high traffic applications operating doors up to 250 lbs.