Within the same week, I received several questions about the timing for low-energy automatic operators…

What is the required speed for the opening cycle of a low-energy automatic operator?

Is there a minimum closing speed?

How long should a low-energy automatic door stay open?

Are there any code requirements for sequential operation?

The answers to most of these questions are found in BHMA A156.19 – Standard for Power Assist and Low Energy Power Operated Doors.  The model codes and accessibility standards do not include detailed requirements for automatic operators but require low-energy power-operated doors to comply with A156.19, so this standard includes a lot of important information that is needed for a code-compliant installation.  If you don’t have a copy of A156.19, it can be purchased through BHMA’s website (if you’re an Allegion employee, you can download it from Techstreet).

In the standard, Table I includes the minimum opening time from backcheck to 80 degrees (whichever occurs first) and the minimum closing time from 90 degrees to latch check or 10 degrees (whichever occurs first).  The opening and closing times in Table I range from 3 seconds to 5.5 seconds, and the minimum time depends on the door width as well as the door weight.  For example, a 3-foot-wide door weighing 125 pounds must open to 80 degrees/backcheck in no less than 3.5 seconds, and close from 90 degrees to latch check/10 degrees in no less than 3.5 seconds.

Table II shows the total opening time to 90 degrees, which depends on the degree of opening where backcheck begins.  For example, for backcheck at 70 degrees, the minimum opening time to 90 degrees is the opening time from Table I plus 1.5 seconds.  The total minimum closing time is the applicable time from Table I plus 1.5 seconds (Section 4.4).

When powered open automatically (not opened manually), Section 4.3 requires the door to remain at the fully-open position for at least 5 seconds.  The exception to that requirement is when the door is operated by a pushing or pulling motion rather than a wall-mounted actuator or other knowing act.  With push-pull activation, the door must remain in the fully-open position for at least 3 seconds.

Given the original example of a 3-foot wide door weighing 125 pounds, with backcheck at 70 degrees, operated by a wall-mounted actuator, the total cycle time would be (3.5 seconds + 1.5 seconds = 5 seconds total opening time) + (5 seconds hold-open time) + (3.5 seconds +1.5 seconds = 5 seconds total closing time) for a grand total of 15 seconds.

There is one more thing in the standard about time delay – related to the position of the actuator.  Appendix A includes supplementary recommendations, including the location of the actuators.  The preferred location is within 1-5 feet of the door, and if located more than 12 feet from the center of the door, the appendix recommends adding a longer time delay to accommodate for the required time to travel from the switch to the door.  The additional time delay should be a minimum of 1 second for each additional foot of distance (>12 feet).

Sequential operation describes a situation where there are two doors in sequence, usually in a vestibule, and operating one door with a knowing act operates the second door a few seconds later.  With this application, building occupants do not have to stop in the vestibule to push another button before moving through the second door.  I did not see any requirements or recommendations in A156.19 regarding sequential operation (correct me if I missed something), so each door would have to comply with the requirements for individual doors as described above, and the time delay between the initiation of the first and second doors would be dependent on the distance and speed at which building occupants travel.

For more information, consult A156.19, and if you have questions, you can leave them in the reply box.

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