There are four basic types of standard hinges: full mortise, half mortise, full surface and half surface.
The Four Types of Hinges
The full mortise hinge is the most frequently used type of hinge today. It can be used on aluminum, hollow metal and wood doors and frames. It was formerly referred to as a “butt hinge” because the two leaves of the hinge are pressed together when the hinge is closed. It is used for medium to heavy weight doors that are subjected to low to high frequency use. When the door is closed, the barrel is the only part of the hinge that is visible.
The half mortise hinge is generally used on hollow metal doors with channel iron frames that experience medium to high frequency use.
The full surface hinge is for medium weight tubular steel doors and kalamein wood doors with channel iron frames under medium to high frequency service
The half surface hinge is for regular weight hollow metal or wood composite doors with hollow metal frames that see medium to high frequency use.
Special Hinges
There are also some special types of hinges sometimes used with emergency exit doors. One of these is the continuous hinge, also called a continuous geared hinge or a traditional piano hinge. This hinge distributes the weight of the door along the full height of the door frame, and allows smooth operation and longer life for the door opening. Continuous hinges are great options on all openings, but especially high-use doors. And adding full length continuous hinges to exterior doors means that an intruder must cut the hinge the entire length of the door, which, while possible, requires much more time and effort.
Another special type of hinge is the swing clear hinge. Swing clear hinges are generally used on ADA swing doors, since they are designed to swing completely clear of the frame when opened, which creates a wider opening for maximum access.
An electric hinge is a special type of hinge that allows electrical current to pass from a door frame to a door. This allows the use of electronic hardware on doors, such as electric locks, electrified exit devices, access control systems, or monitoring devices without use of visible wiring.
There are also specific hinges for security applications of emergency exit doors.
Choosing A Hinge
There are a few factors that should be considered when choosing which type of hinge should be used, including the weight of the door, the frequency of use and the environment. Obviously, the correct choice of hinge depends on the application.
Interior doors usually have two hinges, while heavier exterior doors usually have three.
Concealed hinges are used when the design mandates that the hinge not be visible. A knuckle hinge is the exact opposite of a concealed hinge, in that it is intended to be seen and admired.
High-use doors, such as employee entrances and main entrances, might require heavy weight, ball bearing hinges in a finish that can endure the weather and elements. Bearings offer the highest levels of durability and ease of operation.
Medium-use doors, such as trash removal or receiving doors, might require a medium weight, standard 5-knuckle hinge in a durable finish.
Light-duty doors, such as emergency exit doors, may require three or even four hinges.
To help ensure the door provides trouble free operation, the height, width and weight of the door should be considered when choosing the type of hinge and the number of hinges.
