A couple of points about back-check which, when fitted within a door closer, can be a very useful feature.
A door closer is designed to control the movement of a door during the closing cycle. However, door closers with the Back-check feature can also ‘dampen’ the doors movement during the opening cycle after a specified angle (approx. 75⁰)
When you open a door, without back-check, it swings in an uncontrolled movement until it is stopped. This can be by an adjacent wall, a piece of furniture, the doorframe, or perhaps even a person standing in the way. Obviously the last thing you want is for a door to start inflicting damage on the surrounding area or someone nearby.
For this reason back-check can be a very useful feature within a door closer as it can slow the door down as it approaches a set angle to prevent it hitting a wall or adjacent item.
Back-check is also very desirable on external fire doors as it can prevent a door swinging violently out of control when hit with a gust of wind, reducing the risk of strained hinges or damage to the doorframe.
Similarly, in any environment where people may be rushing through a door – a school for example – back-check can reduce accidents and injuries.
The back-check feature can come in two guises; fixed or adjustable. In short, fixed back-check begins to slow the opening action down at approximately 75°, so in normal use you would hardly know it was there. Adjustable back-check can have the deceleration of the door increased or decreased depending on the environment.
In either case, if the door is ‘flung’ or pushed open spiritedly, back-check will help catch this movement and cushion the door until it reaches the door stop or runs out of momentum.
Used correctly, the back-check feature in a door closer helps to reduce the momentum of a door as it approaches the door stop, thus minimising damage to the door , hinges and frame fixings and preventing it bouncing back sharply towards the person using the door.
However, back-check is not a substitute for a door stop, which should always be specified for any door which is at risk of hitting a wall or other item.
Unfortunately this is not always the case; back-check is quite often used where a door stop was left off the installation list, or even when someone realises the door may cause a lot of very expensive damage and use the back-check feature as a stop-gap solution.
So remember, you should only use back-check to help slow a door down as it opens and always fit a door stop to halt a door damaging the surrounding area or people nearby, but never rely solely on back-check to control how far a door opens.
Another point to remember is that back-check is not always certified (tested) on some door closers. Just because the door closer is CE marked it must never be assumed the certification includes the back-check or indeed other functions.
To meet CE standards the back-check function should have gone through a 100,000 test cycle to EN1154. However, some brands offer door closers with a CE marking and back-check – yet the back-check function may not have been part of the test. In this instance the door closer would have been tested with the back-check function disengaged.
Common problems with door closers not having a back-check function tested but engaged by the installer or user on a fire door can include; arm failure, internal piston / pinion damage – potentially stopping the unit from sealing a fire door in its frame and last but not least, any certification being invalidated.
So it’s very important that you check the manufacturer’ Declaration of Performance (DoP) and – vitally – the Construction Product Regulation (CPR) paperwork from a UKAS certification body, to ensure any door closer featuring back-check has been thoroughly tested and certified.