Pivot hinges (pivots) are installed along the heel edge (hinge side) of the door in openings in or on the floor and at the top of the frame. Pivots permit the door to pivot (rotate). Unlike butt hinges, pivots support the door from the floor, not the frame. A pivot set includes both the top and bottom pivots. A pivot set can support very heavy doors.
There are two types of pivots, offset and center hung. A center hung pivot supports the weight of the door from directly beneath. A door supported by a center hung pivot set can be double acting. Center hung pivot sets can provide full concealment by mounting them within the body of the door.
Offset pivots have the door offset from the center of the pivot. Offset pivots are available with the pivot point located ¾” from the heel edge and either ¾” or 1-1/2” from the face of the door. Most offset pivots are handed. For offset pivot applications, there are intermediate pivots to assist with the pivoting of heavy doors.
Pivots are available in different sizes and configurations to accommodate the varying door widths, heights, thickness and traffic flow.
For fire rated openings, the intermediate offset pivot is available for power transfer. Most intermediate electric power transfer pivots have a 20- minute label. The Marray Intermediate offset pivot, part number PVT, is manufactured from stainless steel, is UL 10C Listed and rated for three hours. Bottom offset pivots are available having up to a three hour label. If the pivot is manufactured of brass or similar material, the fire rating maximum is 20 minutes. Pivots manufactured of steel and stainless steel can have a fire rating of up to three hours.
For fire rated or labeled opening applications, only power transfer pivots bearing the UL Mark, or other recognized listing agency mark, should be considered listed for fire rated door applications. All of the pivots installed onto the Fire Listed assembly must meet the minimum fire rating requirement. Pivots must be installed according to the manufacturer’s installation instructions in order to maintain their listing status.
The continuous hinge takes the attributes of the butt hinge and expands the leafs to the full height of the door/frame. The continuous hinge distributes the door’s weight along the entire length of the frame.
Continuous hinges are available as geared or pin and barrel. The pin and barrel continuous hinge leafs are a longer style of the butt hinges, also known as piano hinges. The geared continuous hinge leafs have geared ends in place of the knuckles. In place of the pin, the geared ends are held in place and able to swing since they are connected to the gear cap.
As the geared hinge opens and closes, the gear teeth engage and disengage, keeping the two leafs connected. The design keeps each leaf in alignment, minimizes lateral wear because the door swings evenly along the entire height.
Continuous hinges are available in aluminum, steel and stainless steel in a variety of finishes. They are available as Full Mortise, Half Mortise, Half Surface and Full Surface. Some continuous hinges are reversible. Depending upon the manufacturer, continuous hinges are available to accommodate a four-foot by ten-foot door that weighs in excess of 500 pounds.
Continuous hinges are available for fire rated openings. For most continuous hinges, there are basically two fire ratings, 1-1/2 hour (90 minutes) and 3 hours. Depending upon the manufacturer, fire pins may be required for the continuous hinge to maintain the fire rating. Most Select Product continuous hinges can be UL rated for up to 3 hour, without fire pins, using a patented process that incorporates intumescent material in specific areas of the hinge. Intumescent material swells as a result of heat exposure filling the void. This poor conductor of heat protects the surrounding materials.
Continuous hinges must be factory prepped for electrical transfer and monitoring. The electrical prep options include concealed thru wires, electrical power transfer cutout, removable panel and access panel. For monitoring applications, the prep options include concealed magnetic switch and exposed monitor switch.
The location of the UL Mark in fire rated continuous hinges can vary by manufacturer and the hinge model. Full and half surface hinges can have the UL Mark located beneath the door cover.
Continuous hinges must be installed according to the manufacturer’s installation instructions in order to maintain the UL rating. To install the hinge, all of the provided fasteners must be used in their respected locations. Failure to do so will void the UL rating. Alterations to the hinges in the field, other than cutting the hinge to a required length if necessary will void the UL rating.
Note: If the door does not properly fit the opening, continuous shim stock up to 1/8” maximum thickness, can be installed on the frame side beneath the hinge.
Continuous hinges are available in many configurations, some for specialized applications and configurations including a full wrap edge guard that protects the door edge.
There is a great deal more information regarding hinges and pivots. Contact the manufacturers engineering or technical services departments.
The following is a partial list of butt hinges, continuous hinges and pivot manufacturers and modifiers:
Hager Companies, www.hagerhinges.com
PBB Hinges, www.pbbinc.com
S & S Hinge Company, www.sandshinges.com
Select Hinges, www.select-hinges.com
Stanley Works, www.stanleyworks.com
For a more complete list, go to www.locksmithledger.com, click on the online buyers guide or the 2009 Locksmith Ledger Security Register.