Component 06 of 10 · Ironmongery

Door closer

Controlled door closing device. The discipline.

An open fire door is just a door. The closer is required to reliably return the leaf into its closed position from any angle, every time, and into its latch where one is fitted, without anyone deciding to do it. It is what makes the rating true in use rather than on paper. Switch to the cutaway to see what is doing the work: a spring wound up by opening the door, and hydraulic fluid pushed through valves on the way back.

Key facts

Function: Returns the leaf to fully closed, and latched where a latch is fitted, unaided
Specification: Power size 3 (18 Nm) minimum on a fire door. Closing speed, latching action and usually backcheck are adjustable
Materials: Typically a cast or extruded aluminium body running in hydraulic fluid, with a steel arm. Surface mounted on the pull or push side, transom mounted, concealed in the frame or the leaf, or a floor spring
Critical tolerances: Must overcome the seals, air pressure and the latch where fitted, from any opening angle
Standards: CE/UKCA marked to BS EN 1154. Hold-open and free-swing devices conform to BS EN 1155; where connected to a fire detection and alarm system, the electrical control, interface and release arrangements follow BS 7273-4
Role in fire: Ensures the fire door is closed, the only state in which any rating exists
Where it sits: Head of the leaf or frame, pull or push side per the evidence

Compliance

Manually released mechanical hold-open devices should not be used on fire doors: they inhibit closing. Where a door must stand open, or swing freely for accessibility, use an electrically powered hold-open or free-swing device conforming to BS EN 1155, connected to the fire detection and alarm system with the control, interface and release arrangements to BS 7273-4, so it releases on detection or power failure. BS 7273-4 governs that connection, not the device itself. A wedge defeats every other component on this page.

Did you know

The humble door wedge is the most common point of non-compliance on UK fire doors. A certified fire door with a wedge under it provides precisely zero minutes of protection.

On the model

Closer body: Spring and hydraulic fluid in one casing
Spindle: The arm bolts to this and drives the mechanism inside
Scissor arm: Main arm and forearm, jointed at the knuckle
Arm shoe: The bracket the forearm fixes to
BS EN 1154 mark: Power size 3 (18 Nm) minimum on a fire door
Closing spring: Opening the door winds this up
Hydraulic fluid: Forced through valves as the piston moves
Rack and pinion: Turns the spindle against the spring
Adjustment valves: Closing speed, latching action, backcheck

What inspectors check

Work through the checklist with the door closed, then in motion. Every line here is a recordable outcome for a Fire Door Inspector.

Release from 90 degrees and from a few degrees: it must close fully from both, and latch where a latch is fitted
Check every fixing is present, tight and into sound material
Check the closing speed, then the latching action, as separate things
Look for fluid on the body, the arm and the face of the door below it
Check the fixing position against the manufacturer's instructions
Confirm the power size suits the leaf in the position it is fitted
Look for wedges, and for hold-open devices not connected to the alarm

Common defects

Fixings missing, loose or into the wrong material
Does not close fully onto the stop, or does not overcome the latch where fitted
Under-powered for the leaf, or turned down until it is
Slamming: closing or latching speed set too fast
Fluid weeping from the body or the arm
Closer not compatible with the leaf it is fitted to
Fitted in a position the evidence does not cover
Arm disconnected, bent or seized
Unlinked hold-open devices or wedges in use

Go deeper

Types of closing device

The model here is a surface mounted overhead closer, the most common kind and one type among several. Where it is mounted, and which side of the door it is on, changes how much closing power you actually get.

Pull side, commonly called Fig 1: Body on the door, arm to the frame, on the side the door opens towards you. The standard arrangement and the most efficient: this is where a closer delivers its rated power.
Transom mounted, commonly called Fig 61 or Fig 6: Body on the frame above the door, arm down to the push face. May be used where the door opens outward and the closer needs protecting from the elements, for example.
Parallel arm, push side, commonly called Fig 66: Body on the door with the arm running parallel to it, back to a bracket on the frame. The other push-side option.Push-side fixings do not deliver the same power as the pull side. A closer that achieves power size 3 in the Fig 1 position may not achieve it in Fig 66. The manufacturer states the size for each position, and on a fire door that number has to still be 3 or above.
Free swing: The door behaves as though it has no closer at all until the alarm sounds or power is lost, at which point the device takes over and closes it. The accessibility answer for doors people would otherwise wedge.
Concealed: Morticed into the leaf, the frame head or the jamb so nothing shows when the door is shut. A lot of timber comes out to fit one, so the fire evidence and any intumescent protection supplied with it need consideration.
Floor springs: The closing mechanism sits in a box in the floor. Common on heavy and double-action doors, and usually paired with floor pivots rather than hinges.

Power, force, and the three adjustments

A closer has to be strong enough to shut the door against its seals and the air pressure in the building, and to overcome a latch where one is fitted, and weak enough that a person can open it. Those two pull in opposite directions, and that tension is most of what goes wrong.

The BS EN 1154 power table: Power size runs 1 to 7 against leaf width and mass. Size 1 suits a leaf up to about 750 mm and 20 kg, size 3 about 950 mm and 60 kg, size 4 about 1100 mm and 80 kg, up to size 7 at about 1600 mm and 160 kg.
Size 3 (18 Nm) is the floor for a fire door: BS EN 1154 does not consider closers below power size 3 suitable for fire doors: the closing moment is too low, particularly beyond 90 degrees. A power adjustable closer must be capable of size 3 or more, and must actually be set there on site rather than left where it left the factory.
Opening force, Approved Document M: On an accessible route the opening force at the leading edge should not exceed 30 N from closed to 30 degrees, and 22.5 N from 30 to 60 degrees. This is why closer efficiency matters: a poor closer meets one requirement only by failing the other.The wrong fix is turning the power down until the door opens easily. A closer set below what the door needs will not close it onto the stop, and a fire door that does not close is not a fire door.
Closing speed: The main sweep, from fully open down to roughly the last 15 degrees. Set too fast and the door slams; set too slow and it hangs open while smoke moves.
Latching action: The last few degrees, deliberately quicker, giving the push that drives the door home against seal pressure and, where a latch is fitted, drives the bolt into the keep. A door that closes beautifully and then stops short usually has latching action set too low.
Backcheck: Cushions the door towards the end of its opening arc so it cannot be thrown back into a wall or caught by wind. It is a protection feature, not a closing one, and it adds significantly to the load the hinges carry.

When a closer is not required

A self-closing device is important, but it is not universally required. Fitting one where it is not needed is a waste, and recording its absence as a defect where none was needed is simply wrong.

Doors kept locked shut: A fire door to a cupboard, riser, plant space or store that is kept locked is held closed by the lock. It is not standing open, so there is nothing for a self-closing device to correct. These doors are normally signed “fire door keep locked” rather than “keep shut”.
What to check instead: On a door like that the question is whether it is actually kept locked, whether the signage matches how it is managed, and whether the lock is the one the evidence covers. A closer would add nothing.
Where it is not optional: On doors in daily use, protecting escape routes and circulation, the closer is the component that makes the rating real. Everything else on the door only works when the door is shut, and the closer is what makes sure it is.

Fire Door Anatomy is an introduction to fire doors, not the whole subject. Always defer to the fire door’s certification, its test evidence and a competent inspection.