What Is Backcheck On Door Closer?
If you are a building owner or maintenance technician you may have heard the term "backcheck" when used in the context of door closers. But what is backcheck and how is it used? Do you need it? What are the benefits of having it? In this article we explore everything backcheck and why you should have it.
Understanding Hydraulics and Door Closers
An automatic door closer is one of the most important hardware components to any commercial door. Having a safe and smooth closing door is something that is expected in any commercial establishment. To understand how backcheck works, one must first understand how hydraulics work in commercial door closers. A door closer is comprised of a main body housing that is typically manufactured from aluminum. Inside the closer body is a spring and two gear system known as the rack gear and pinion gear. The door closer body housing is filled with a special oil substance known as hydraulic fluid. When the rack and pinion gear assembly are in place within the closer body, it divides the closer body into chambers. In order for the hydraulic fluid to travel between the chambers, small pathways are mitered into the closer body. These restricted pathways are controlled by valves, which can open the pathway for more hydraulic fluid to flow, or decrease the pathway for less hydraulic fluid to flow. Backcheck is one of these valves, which controls the restriction of hydraulic fluid. So here's how it works. When a door is pulled open, the door closer spring compresses, causing all of the hydraulic fluid to flow into chamber near the pinion gear via the small hydraulic fluid pathway. After the person passes through the door, the spring uncompresses, closing the door, and forcing the hydraulic fluid into the other chamber with the spring via the small hydraulic pathway. Standard door closers include two valves which restrict or open the hydraulic pathways. These two valves are called the sweep or closing speed valve, and the latch speed valve. A third valve is sometimes included on the door closer, and this is known as the backcheck valve.
The backcheck valve is a speed adjustment too, but unlike the closing speed sweep valve and the latch speed valve which control the speed when the door closes; the backcheck valve controls the opening speed of the door during the final 15 to 20 degrees before the door reaches the full open position.
What Are The Benefits of Backcheck?
Backcheck is a very good feature to have on any door closer. Essentially, the reduced speed right before the door reaches the full open position, allows the door to not be "slammed" open. Whether the commercial door is abused by a pedestrian pushing the door open as fast as possible, or the wind catching the door, having a door with backcheck, will allow the door to safely and smoothly swing open. Doors that use door closers with an adjusted backcheck speed last much longer than with door closers that do not have backcheck.
How To Adjust Backcheck
The backcheck valve can be adjusted by turning the valve clockwise to decrease the opening speed or counterclockwise to increase the open speed. It is important that the backcheck valve is never closed all the way. If the backcheck valve does get screwed in all the way it completely closes the pathway of the hydraulic fluid and will cause the door to completely stop and not be able to reach the full open position. Remember backcheck is used to slow down the door and should not be used as a door stop. For stopping any door, a commercial door stop or wall stop should be installed. When adjusting the backcheck consider the door application. As an example, a door closer installed in an abusive area such as school or prison, should have a much slower backcheck speed, than a chiropractor's office door.
Is Backcheck Required For ADA Standards?
Backcheck is not required in order to meet ADA compliance. According to ADA Section 404.2.8 door closers must close atleast 5 seconds from 90 degrees to 12 degrees and Section 404.2.9 requires a 5 pound maximum opening force for interior doors.
Is Backcheck Required For Fire Rated Doors?
According to NFPA 80, all fire doors are required to be self closing. This is accomplished by installing commercial door closers on fire doors. However, there is no requirement for backcheck.
When Should I Use Backcheck?
Ideally backcheck should be used on all door closers. The safety benefit of allowing the door to safely swing open is a positive aspect that should always be considered. However, since backcheck is not required, it is typically neglected. Here are great applications where doors would benefit from backcheck.
Abusive Environments Like Schools
Kids can be very hard on doors. Whether they are playing and pushing the door open too hard, or there is heavy foot traffic and hundreds of children pass through the door each day, having backcheck can save the door from slamming open and increase the door's lifespan.
If the door is in a windy environment, it is recommended to have backcheck on the door closer, so that if the wind catches the door, it will not be able to swing open at full speed.
Doors That Open Against Walls
Although a door stop is always recommended as the means of stopping the door from slamming or hitting a wall, additionally having backcheck can help reduce damage as well. Remember, if the door is opening and hitting a wall or even a door stop, there is still impact which can cause damage.
Doors that receive heavy traffic can greatly benefit from backcheck. When many pedestrians pass through the doorway at a heavy flow it is very common for the door to get bumped and pushed on even, when it is in the full open position. Having backcheck properly adjusted allows the door to never slam open when bumped or pushed on.
Why Do Backcheck Door Closers Cost More?
Backcheck door closers cost more than standard door closers that do not have backcheck, simply because the manufacturing process is much longer for backcheck door closers. A backcheck door closer has one more hydraulic fluid pathway inside of the door closer body as well as the adjustable valve, these additional components result in an increased price.
Backcheck is simply the opening speed of the door closer during the remaining 20 degrees before it approaches the full open position. The backcheck function of the door closer helps prevents the door from slamming open which could result in major damage to the door, frame, hardware, or wall. If you are in need of a door closer with backcheck we recommend Liberty Door Closers. All Liberty door closers include the option to include the backcheck function. Backcheck can increase the door closer's longevity and should always be considered on all door closer installations.
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