Latch Mounting & Operation

Correct mounting is essential to ensure the reliable engagement and release of your safety latch. Testing your Brixon latches after mounting, adjustments, and initial installation will help ensure safety during operation and prevent potential errors or damage.
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The latch and strike assembly must be securely mounted so that the cam is centered on the strike roller and the assembly is perpendicular to the door-frame line. The distance between the latch and strike housing will vary based on the style of the model. For Brixon latch models #1 (no longer for sale) and #91, the distance should be 1/16” to 3/32”. For the #2 model, the distance between the latch and strike should be 1/8” to 5/32”. #3, #83, #93, #4, #84, and #94 latches and strikes should be spaced 1/8” to 3/16” apart.
 
LATCH/STRIKE SPACING
 
LATCH/STRIKE SPACING

NOTE: IF THE STRIKE IS MOUNTED TOO FAR FROM THE LATCH,
THE LATCH CANNOT OPERATE PROPERLY.

 
Brixon latches should be tested for proper operation after adjustment or installation. Ensure that the roller forces the latch cam into the open position when the door is opened and that the opened cam will contact the roller and be forced into the closed position as the door is closed. Failure to do so may cause an unanticipated rebound, as the latch and strike will not engage upon closing. Misalignment of the latch and strike may also cause this rebound. Hinges must be strong and securely fastened to avoid horizontal and vertical misalignment. Additionally, the strike mounting must be sufficiently rigid so the strike does not bend or twist upon closing. If the body moves toward the hinges, the latch can close incorrectly, as shown below in Illustration #3, resulting in very high and unsafe pressure.
 
Cam in wrong position from improper strike mounting
(#3) Cam in wrong position from improper strik mounting

This is most likely to happen when the door is slammed (excessively) and/or the latch mechanism is dirty or corroded. In this event, the door may be more difficult to open, either by hand or in the event of an explosion. It is also a warning that maintenance is required and that a hazardous situation exists.Because of the rather large tolerances involved in casting, each latch/strike combination must be individually aligned, and alignment must be rechecked whenever latches are replaced to avoid possible malfunctions as listed below.

In mounting the 3H, 83H, 93H, 4H, 84H, 94H or 4HD latches, it may be found that the handle stops interfere with the mounting nuts, when studs are used. If you intend to use studs, consult the manufacturer for information on modifications that may be necessary.
 

OPERATION

The Brixon latch operates in a manner similar to a toggle switch. When the door and latch are in the closed position, the latch will hold the door closed unless enough pressure is applied to compress the spring sufficiently to cause tripping of the cam into the open position. When the cam is in the open position, the door is free to open.
Closing is essentially the reverse of the above, with the force to reset the cam being supplied by the closing door.

The forces required for operation depend upon the settings of the latch- The higher the setting and the larger the latch, the greater the required force.
The recommended procedure for closing a door equipped with the 3H, 83H, 93H, 4H, 84H or 94H latches is to fold the handle back immediately prior to closing or, better, to first open and then close the handles. When folding the handles back, the cam should remain in the “open” position (illustration #4). If for any reason the cam is in the “closed” position (illustration #5) while the door is open, the latch and/or its mounting is defective, and the door would rebound open instead of latching.
Cam in open vs closed position
In the event of an explosion, the latch will begin to open when the internal pressure equals the setting of the latch. However, due to inertia in the latch-door system, there will be a slight delay between application of pressure and the opening of the door (See NFPA No. 68). This might allow a considerable pressure build-up, depending upon the oven size, type, and amount of material exploding, and the time lag involved. In the event of an explosion of maximum violence, the effectiveness of the latches is reduced. However, most explosions are not of maximum violence (FM Global Approval Guide, 1998 8-1).
 

SUMMARY AND CAUTIONS FOR OPERATORS

  1. Violent slamming is potentially hazardous and must be avoided.
  2. For reasons listed above, the door may not latch when closing; beware of rebound.
  3. Krep clear of the arc of the door.
  4. Keep clear of the operating parts of the latch and handle, particularly the laminated cam, strike roller, both ends & handle stop of the heavy duty handles, and the stops for standard 3H, 4H, 83H, 84H, 93H, & 94H handles.