Technical Section

The specification for hinges is detailed in British Standards BS 7352:1990

"Specification for strength and durability of metal hinges for side hanging applications and dimensional requirements for template drilled hinges".

The following notes are taken from the above British Standard.

Notes on guidance for the selection and use of hinges

Whilst the classification adopted in this standard should ensure that properly selected hinges give reasonable service at economic cost, it is impossible to derive expected service lives in terms of the test procedures because conditions of use vary so widely, particularly in such matters as whether door closers are to be used, the degree of care in use, the number of hinges per leaf and their positions, the size of leaf, accuracy of fixing and the amount of maintenance during service. Subsequent clauses of this appendix give guidance on these and other subjects such as choice of hinges for fire doors.
It should be noted that the test rig is designed so that the total test leaf weight is carried by one hinge only during test. This increases the severity of loading during the static load tests to ensure that the hinge strength includes a factor of safety and accelerates the rate of wear during endurance testing to reduce the test times.

Use of door closers

Door closers increase the loading on door hinges and their rate of wear. For non-back check closers it is normal to allow for this by assuming the effective door weight to be about 20% greater than the actual door weight. For back check closers the effect is much greater and double the actual door weight provides a safer basis for assessing endurance.
Doors fitted with door closers should normally use three or more hinges, although some specialist door manufacturers fit very substantial hinges that provide satisfactory performance with door closers when only two hinges per door are fitted. Guidance is given in C.7 on the number of hinges to be used and their positions.
The maximum closing torque that can be exerted by a door closer is limited and varies with the size (power) of the door closer. For this reason it is important that hinges for doors to be fitted with door closers should not generate too much frictional torque. It is recommended that the maximum in-service torque for a set of three hinges when installed on such doors should be 3 N. m for classes 1 to 6, N.m for classes 7 and 8 and 5N.m for class 9. Hinges for such applications should be carefully selected and additional testing of the installed frictional torque of a set of hinges should be considered.

Types of duty associated with hinges

The degree of care in use, the possibility of accidental misuse and the frequency of operation are important factors, which affect the likely service life.
Three levels of duty can conveniently be recognized as follows:

(a) Light duty: Low Frequency of use by those with a high incentive to exercise care, e.g. by private house owners and with a small chance of accident occurring or of misuse. Examples: Doors: Internal doors in dwellings and external and external doors in dwellings, which provide access to private areas; Windows: Windows in low-rise dwellings; Cabinets: furniture for domestic use or for careful light contract situations such as hotel bedrooms.

(b) Medium duty: Medium frequency of use primarily by those with some incentive to use care, but some chance of accidents occurring or of misuse. Examples: Doors: External doors of dwellings, which provide access to, designated public areas but not generally used by the public or by the people carrying or propelling heavy objects. Windows: Windows in shops, offices, high-rise dwellings and factories. Cabinets: Furniture intended for normal contract use where careless handling or rough treatment may occur such as library bookcases, college study and school storage cabinets, and hotel reception and dining room storage furniture

. (c) Heavy duty: High frequency of use by public or by others with little incentive to exercise care, and with a high chance of accidental occurring and of misuse. Examples: Doors: Doors of shops, hospitals and of other buildings which provide access to designated public areas and which are used by the public and by people who may be carrying or propelling bulky objects: Any application where an overhead door closer is fitted: Windows: Windows in schools, hospitals and other buildings to which the public have access; Cabinets: Furniture intended for exceptionally severe contract use such as in transport termini, student common rooms and buildings for the armed services. Hinges may be selected from classes1 to 4 for light and medium uses, whereas for heavy-duty use hinges from classes 5 to 9 are more suitable.

DD 171 recognises an additional category of severe duty where doors may be subject to frequent violent usage and impact. Whilst such usage may necessitate a particularly strong construction for the door leaf and frame, heavy-duty hinges in classes 5 to 9 should be suitable for hanging the doors.

C7. Door dimensions, number of hinges per door and their positions:

BS 4787: Part 1 applies to doors up to 2040mm high by 926mm wide of different listed types. The standard specifies that three hinges per leaf be fitted, the upper and lower hinges being equally disposed about the centre line of the door, and the middle hinge being fitted on the centre line. The spacing between the middle hinge and the upper and the lower hinges are 770mm from mid-point to mid-point.

BS 1245 includes similar requirements of three hinges symmetrically situated about the centre line of the door.

PD 6512: Part 1 recommends that for the taller doors the middle hinge be at mid height, with the upper and lower hinges positioned 250mm from the top and bottom of the door.
A central position for the third hinge is especially beneficial in resisting possible warping of the door leaf, thereby reducing potential difficulties in latching or locking and also reducing draughts. Lightweight doors are particularly likely to warp and, additionally, fully glazed doors with narrow stiles are subject to whip, i.e. lack of rigidity in the frame.
When a door is first hung it is inevitable that the load will not be equally split between the three hinges. This leads to relatively rapid initial wear of the hinge which is carrying the greatest load, but as this hinge wears, the bigger proportion of the load is gradually transferred to the others until eventually it is fairly evenly distributed over all three hinges and their rates of wear become more equal.
Fitting three hinges reduces the eventual loading per hinge, and the classification in table 1 is based on the use of three hinges per leaf. In situations where only hinges per leaf are fitted, the maximum mass of leaf supportable should be reduced by one third.
If warping is not expected to be a problem there are good reasons for fitting the third hinge just below the top hinge, particularly for heavy doors.
This is because the weight of the door sets up a bending moment, which tends to lever the top hinge out of the doorjamb, whereas the bottom hinge is pushed inwards against its rebate in the jamb. The bending moment on a centrally -fitted hinge is zero. If the third hinge is fitted just below the top hinge (200mm is a typical spacing) it is able to resist part of the outwards bending moment and so reduces the tendency of the door to sag in service.
For these reasons, if load carrying is expected to be the major requirement for the door hinges, they should be fitted with two hinges high up and one low down, whereas equally spaced hinges should be used for the doors where resistance to warping or whipping is expected to be more important.
It should be noted that there is an opinion held by some users and supported by some manufacturers that large or heavy doors in situation with heavy traffic should be hung in such a manner that the bottom hinge carries very little load, acting mainly as a pivot to control the location and movement of the door. In such situations the maximum mass of leaf supportable should be reduced by one third to compensate for the lack of support normally provided by the bottom hinge.
For door widths greater than 950mm the increased bending movements should be allowed for by a reduction in the maximum mass of leaf supportable by each class of hinge. For widths above 1250mm the advice of the manufacturer or specialist supplier should be sought.
For doors of height above about 2100mm it is advisable that a fourth hinge should be fitted. Equal spacing gives maximum resistance to warping, whereas if the four hinges are fitted with two high and two low this achieves the best results of load carrying ability.
However many hinges are used, it is important that they be fitted accurately with the axis of the pins as nearly as possible in line with each other. Any errors will cause the hinges to be strained as the leaf rotates, making operation of the door or window more difficult. More rapid wear of the bearing surfaces or loosening of the fixings is likely to result. Squeaking of hinges is commonly due to inaccurate alignment. Rising butt door hinges were originally introduced to improve the clearance between a door and carpets fitted up to it's opening. Later, the self-closing effect came to be regarded as beneficial, particularly for doors for toilets and shower cubicles. For the self-closing action to be effective a certain minimum door weight is necessary to overcome the friction in the hinges.

Corrosion Protection

Approximately two thirds of hinges are supplied in self-colour mill finish for use in situations where the door leaf and its hinges are to be painted in situ as part of a decoration scheme after installation and where it is expected that redecoration will take place from time to time. No special corrosion protection is necessary for these hinges.
A variety of decorative and/ or corrosion resistance treatments is applied to other hinges. Exposure conditions in increasing order of severity range from dry interiors where dampness or condensation are common to external exposure in unpolluted atmospheres and, finally, to external exposure in atmospheres polluted by chemicals, including salt in marine situations. The rate of corrosive attack may vary by a factor of about ten times according to the conditions of exposure and different surface treatments differ n their resistance to different environments. The exposure conditions for window hinges are, in general, more severe than for door hinges because condensation occurs more frequently and exposure to external atmospheres is the norm.

Fastenings

Hinges have to be fixed to a wide variety of different materials including softwoods, hardwoods, particle boards, extruded aluminium profiles, sheet metals and plastics extrusions (which may also be reinforced with other materials)
Conventional wood screws are suitable for fixing to timber, but it is advisable that properly dimensional pilot holes should be provided in all cases and are essential for some hardwoods. When woodscrews made from stainless steel, aluminium, brass, bronze or other relatively soft materials are used, the risk of breaking such screws is reduced if a conventional woodscrew of the same dimension is fitted first to 'size' the hole before finally fitting the softer screw.
Unplated steel screws should only be used when the installation is to be painted in situ. Otherwise the screws should be protectively treated, e.g. zinc plated and passivated, or should be of materials inherently more resistant to corrosion such as stainless steel, brass or aluminium.
Contact between dissimilar metals in damp environments can initiate electrolytic corrosion, which abnormally increases the rate of attack. This behavior is discussed inPD6484. The document tabulated pairs of metals using a rating system, which indicates how much the rate of attack is increased, from which undesirable contacts can be seen, e.g. brass screws should not be used with aluminium hinges. The holding power of threaded fasteners in different materials depends on the thread form and special thread forms have been developed to suit particle boards, aluminium extrusions, unreinforced plastic extrusions and reinforced plastics extrusions. Even in timber the holding power can be improved by using recently developed fully threaded twin-start thread designs. Proper selection of fastenings reduces the risk of loosening of hinges.

Maintenance

Loosening of hinges is usually caused by poor alignment or by incorrect choice of screws. Loose screws should be tightened and if possible the problem should be eliminated by realigning the hinges or by replacing the screws with a more suitable type.
Fitters who find it difficult to avoid transferring oily marks to doors and windows usually supply hinges dry by manufacturers because there are objections to oily hinges. The great majority of cases oiling immediately after installation and from time to time during service significantly reduces wear. The exceptions are special situations, such as very dusty locations in which a mixture of oil and grit can act as a grinding paste which accelerates wear, or public toilet rooms which may be regularly hosed down or washed with detergent solutions which remove oil. For such situations specialist dry film lubricants may be used.
Whilst squeaking of hinges is a sign of lack of lubrication, if it occurs frequently misalignment should be expected.

Fire Door Applications

The integrity of a fire door is entirely dependent on the ability of the hinges to withstand temperatures reached and stresses, which occur during a fire. Detailed specialist advice can be found in ABHM Code of Practice for Hardware Essential to the Optimum performance of Fire Resisting Timber Doorsets' 1) and in 'Code of Practice. Architectural Ironmongery Suitable for Use on Fire Resisting Self-closing Timber and Emergency Exit Doors' 2). Such a degree of detail is beyond the scope of this British Standard and these publications should be consulted. They list the following factors of major importance.

(a) The melting point of the materials used. Low melting point materials such as aluminium alloys, zinc base die casting alloys, and plastics are not suitable. Building Regulations require a minimum melting point of 800 Degrees Centigrade.

(b) The number of hinges fitted. Three hinges equally spaced resist leaf deformation best, but the increasing use of in tumescent seals is making this requirement less important.

(c) The use of rising butt hinges to provide self-closing action is not allowed by some authorities and is only permitted by some authorities in defined situations. In all cases conformity with Building Regulations is essential.

(d) The size of the hinge being used, particularly the width of the leaf in relation to the door thickness and the amount of timber remaining as a fire resistant barrier between the edge of the hinge rebate and the edge of the door.

(e) The position of screw holes and the length and type of screws used can affect holding power during a fire.

(f) Types of hinges, which allow easy removal of a door. E.g. loose pin, snap in or lift off hinges, are not allowed by some authorities because of concern that fire doors should not easily removable.~

Wherever possible, hinges and doors which are known to have been fire tested together as a system should be used for fire door applications, because apparently insignificant changes to assembly or the way in which heat transference occurs, and so alter the way the door behaves during a fire.

Security

Where the risk of burglary is significant, the use of face fixed hinges or hinges with the loose pins that may easily be removed should be avoided.
Resistance to violent impact may be improved by selecting doorsets or hinges that have been tested to the heavy duty or severe duty requirements of the heavy body impact test described in 4.5 and A.9 of DD 171: 1987.

Additional notes by Basta Parsons.

Fire resisting doors

Extract from Building Regulations 1992 Fire Safety Approved Document B Appendix B Clause B5.

Unless shown to be satisfactory when tested as part of a fire door assembly any hinge on which a fire door is hung should be made entirely from materials having a melting point of at least 800 degrees centigrade.

The hinges Basta Parsons Supply in Steel, Stainless Steel and Brass have minimum melting points in excess of 800 degrees centigrade.

The Melting points of component materials are:

Aluminium 650 Degrees, Stainless Steel 1371 Degrees, Phosphor Bronze 900 / 912 Degrees, Steel 1371 Degrees, and Brass 900/ 920 Degrees.

Quality of Hinges

The choice of material for the hinge, pin and washer is dependent upon the environment in which the hinges are to be fitted. Washered hinges are of a high grade and recommended for medium to heavy-duty applications.
Ball bearing hinges are of a high grade and recommended for use with door closers and in heavy-duty applications.

Hinges are supplied in various materials as follows:

Steel with:
Steel Pin and Steel Ball Bearing
Steel with Bronze Bush and Hardened Steel Pin.

Stainless Steel with:
Stainless Steel Pin and no Washers.
Stainless Steel Pin and Stainless Steel Washers.
Stainless Steel Pin and Steel Ball Bearings.

Extruded Solid Brass with:

Brass pin with no Washers.
Brass Pin and Bronze Cams
Brass Pin with Double Phosphor Bronze Washers.
Phosphor Bronze Pin with Steel Ball Bearings
Stainless Steel Pin with Double steel Washers
Stainless Steel Pin with Steel Needle Roller Bearings.
Stainless Steel Pin with Double Stainless Steel Washers
Stainless Steel Pin and Steel Ball Bearings

Extruded Aluminium with:

Stainless Steel Pin and Stainless Steel Washers
Mild Steel Pin and Zinc Plated Steel Cams
Aluminium Pin and Double Nylon Sleeve Washers.

Nylon with:

Stainless Steel Pin and no Washers.

Selection and use of washered hinges

Washered hinges provide improved performance over plain bearing hinges by incorporating washers made from different hard wearing material between each knuckle section. They can be either single or double washered type, both of which are available from Basta Parsons.
On the single washered type the washer is free to rotate about the hinge pin. Single washers used on brass hinges are made from phosphor bronze and on aluminium hinges from nylon. On double washered hinges the washers are secured to the knuckle to ensure that any movement is confined to the washer faces. The only exceptions to this are the double stainless steel washers used on the stainless steel hinges, which are free to rotate about the pin.
On Aluminium hinges there are two types of washer used; one is stainless steel, the other molybdenum disulphide impregnated nylon. The nylon needs no lubrication, whereas stainless steel provides a greater durability and can be finished with powder coatings in the assembled form.
Brass hinges are available with phosphor bronze, stainless steel or mild steel washers. Phosphor bronze has better wear properties and can be plated, whereas mild steel and stainless steel cannot. Stainless steel has resistance to corrosion and can therefore be used in external applications, but the wear properties are not as good as phosphor bronze or mild steel. Mild steel is the most price competitive, followed by phosphor bronze and then stainless steel.

Technical Specification

Determining the width of the correct hinge.
The width of the hinge on fire doors is of great importance.
It is recommended that the backset should be not less than 14mm thick. This will allow an uninterrupted in tumescent strip to be fitted to the door.
If a door is to open beyond 90 degrees then the width of the hinge should be determined by:
Door thickness, less the backset, plus inset, multiplied by two, plus clearance.
If not a standard size then use next size larger.