Installing or fixing commercial door closers can be a frustrating task. You need to know what you’re dealing with – which includes the public, property managers and the hazards whoever worked on the closer before you have left behind.
There are 4 main types of door closure on commercial doors:
• Floor springs (some are very old ‘horseshoe’ springs and they come forward to modern hydraulic units)
• Transom units in the overhead of an aluminium frame
• Hinge side chain drive spring closers and
• Surface mounted hydraulic units.
There are many and varied brands and cheap China copies and while you would expect them to be interchangeable – they aren't.
In my early days the most common door mounted closer was made by Comyn Ching and they were huge barrel shaped units but they could be serviced and adjusted. (There were of course many other makes – Briton, Yale, etc). These closers were nicknamed ‘pot bellied’.
All door closers give problems. They wear and leak causing the door to slam, which is a Health and Safety issue right there. They close too quickly in the summer as the oil thins and conversely in the winter slower. The chain driven units cannot be controlled. Floor units can be full of many unpleasant body fluids, if on an outer door. They will be rusted and maybe the floor is breaking up. Transom units can be difficult to service and you have to remove the door to get to it and unless the make and model is on the door, (and that was changed by someone if they replaced the unit) you are likely to have the wrong parts. Take that with impatient staff/shoppers trying their hardest to chop your finger off, send you diving off you ladder or just swearing at you and you can find working on these things very frustrating.
The likelihood is the door closer will be a surface mount on a hollow metal or wood door
The surface mounted door closer has had significant changes in the last 70 or so years since it evolved from a 'pot belly' style of door closer. Some of the changes include aluminium body, all weather fluid, powder coated finishes, adjustable back check, delayed action, cam closers and special function arms including the track arm.
A significant change has been the development of the power adjustable door closers, which permit the spring power to be increased or decreased in an attempt to meet the needs of the opening. Power adjustable door closers range from Spring strength range EN 2-5 / EN 3-6. Of course CEN marking is compulsory on any fire door and must conform to either of the BS ENs
In Europe, most modern surface mounted door closers use a rack and pinion mechanism designed with a spring(s) to give power to close the door and hydraulics to control the speed of the door. As the door is opened, the pinion rotates, forcing the rack to move and compress the spring(s) storing energy to close the door.
To control the movement of the door, hydraulic fluid moves through the door closer body through a series of channels and valves. The two most important valves are closer speed valve and latch speed valve. When the door is released (from a maximum of 180 degrees), the door begins the closing procedure. The closer speed valve controls the fluid movement from the opened position to about 10 to 15 degrees (approximately 200mm from the closed position). At this point, the latch speed valve controls the door speed into the door frame and the lock latches.
A good video explaining this can be found at www.youtube.com/watch?v=lne5i6xu8Mw
The term ‘door closer’ is actually a misnomer. Although door closers close the door, they actually operate as door controllers, controlling the opening and closing operations. Even if a door closer is not equipped with backcheck, fluid is forced through the closer body affecting the opening speed of the door.
The surface mounted is the easiest door closer to install. Upwards of four screws secure the closer body and up to five screws secure the arm bracket. Because this type of door closer is not concealed, minimum modification or brackets are needed for the installation. Surface mounted door closers are available in four basic variations: track arm, regular arm, parallel arm and top jamb mounted.
The regular arm door closer is mounted on the upper portion (top rail) of the pull (hinge) side of the door. The arm is attached to the frame face at a right angle to the door.
The parallel arm door closer is mounted onto the push side (opposite the hinge) side of the door and the arm mounted onto the head jamb. The arm is parallel to the door, unlike the regular arm that is at a right angle to the door.
The top jamb door closer is mounted onto the push side (opposite the hinge side) head jamb. The arm is attached to the upper portion (top rail) of the push (opposite the hinge) side of the door at a right angle to the door.
The track arm door closer is mounted on either the push side or pull side of the door. When track arm closer body is mounted onto the push side of the door, the arm is mounted onto the head jamb. When the track arm closer body is mounted onto the jamb head, the track is mounted onto the upper portion of the push side of the door. When track arm closer body is mounted onto the pull side of the door, the arm is mounted onto the frame face. When the track arm closer body is mounted onto the jamb head, the track is mounted onto the upper portion of the pull side of the door.
Surface mounted door closer mountings have advantages and disadvantages. The top rail mounted closer arm is mounted onto the frame face, which means a narrow frame face does not cause any problems. The top rail mounted closer arm projects from the door at approximately a right angle. This position is easily assessable to vandalism. However, the geometry of the regular arm closer is somewhat more power efficient than a parallel arm closer.
The parallel arm closer’s forearm is mounted to the underside of the frame head using a soffit plate. The arm is relatively protected, being parallel to the door. It does not extend out like the regular arm or top jamb closers. However, the geometry of the parallel arm closer is somewhat less power efficient than a regular arm or top jamb closer.
The track arm (slide channel) closer has even more protection against vandalism, as the track, which is mounted onto the jamb, operates as the forearm. The geometry of the track arm reduces door closer power efficiency similar to that of a parallel arm. However, to compensate, door closer manufacturers developed the cam action door closer.
The cam action door closer has a linear drive mechanism with a heart-shaped cam. The cam’s shape provides lower opening resistance, while providing more favourable control and closing force. A cam action door closer with a track arm application can provide efficiency similar to a rack and pinion door closer in a regular arm application.