Brixon latches are designed to operate under a wide variety of conditions with a variety of options available to suite particular purposes. The user must insure that the latches are appropriate for the particular application. Any questions regarding model selections should be referred to the factory.
It is recommended that the latch release force be adjusted prior to mounting when the internal components are visible. The pressure setting should allow the latch to open at an internal pressure slightly higher than that encountered under normal operation circumstances. Caution: Factory Mutual Global requires that latches open at a maximum internal pressure of 50 lbs/ft2 (244.1 kg/m2), while NFPA (National Fire Protection Association) recommends 30 lbs/ft2 (146.5 kg/m2): in general, the lowest practical setting should be used.
The appropriate release pressure is obtained by the following calculations. (The formula assumes a hinged door with the latches mounted on the edge opposite the hinges.)
NOTE: Divide door area by 2 if door is hinged. Divide by 1 if not hinged. (Ex: Blow out panel).
Note: Precise pressure adjustment is not possible due to the location of the strike, the amount of gasket compression, friction, etc. The listed values are a guide only, and if the release pressure is critical, the pressure must be measured directly at the door after installation for more accuracy. The estimated variance is plus or minus 2 full turns.
To adjust, have the latch in the door closed position (see illustration above), wherein one rivet which holds the laminated cam together is exposed.
Turn the adjusting screw counter-clockwise to its loosest position, making sure that the square nut does not come off the ball pin and the nut has full thread engagement. Using the Latch Release Force Adjustment Chart (above) as a guide, tighten the adjusting screw clockwise a half turn at a time until the desired pressure setting is reached. It should be possible to feel the adjusting screw slipping into the relaxed position at each half turn. For example, if you wanted 107 lbs. pressure setting on a #4 latch, you would tighten the adjusting screw 10 half turns (10 x 4.935) + (58 lbs. min.) = 107 lbs.
If the latch is mounted, adjustment can be made by turning the adjustment screw to its tightest position and backing off to the desired setting. Latches can be factory adjusted upon request for additional cost. For example, if you wanted 107 lbs pressure setting on a #4 latch, you tighten the adjustment screw clockwise to its maximum position. Then you would loosen the adjustment screw counter-clockwise 36 half turns {285 lbs max. - (36 x 4.935)} = 107 lbs
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