Point Four Systems MBD075 User Manual page 6

REPAIRING DIFFUSERS
Cracks and Fractures:
Occasions do arise when the diffusers' ceramic cracks or fractures due to physical
abuse or over pressurization. In many cases the diffusers can be repaired. We
recommend that the diffusers are returned to Point Four for repair. There are cases
where it might be advantageous to repair at the customer's or distributor's site.
Here are the guidelines to follow:
What's fixable and what's not!
If the crack is lengthwise down the middle or along the side of the diffuser, it is virtually
impossible to do a successful repair.
If it is a short crack across the width of the diffuser, or across a corner, then repairs are
usually successful.
Procedure:
 correctly locate the crack by drawing a line along it with a pencil while the diffuser
is submerged and you can follow the line of bubbles.
 completely dry out the diffuser (place under a heat lamp or similar), do not
attempt to glue the broken parts when the ceramic is wet.
 cut a V shaped or U shaped groove approx. 5/16" deep along the crack. Cutting
the V/U shaped grove along the crack can be done with small "Dremel"
grindstone. If this is not available, drill a series of 1/8" to 3/16" holes side by side
along the crack, then break out the bits in between with a sharp tool such as a
gyproc or tile cutter. The groove should go as deep as possible without breaking
through the bottom of the plate. It is not enough to just make a superficial repair;
the broken parts of the plate must be fully joined at the crack.
 clean out grove properly with compressed air. Groove should be dry and free of
dust.
 Mix two part epoxy available in most hardware shops - do not use the fast setting
brand - the epoxy must have time to seep into the ceramic before it sets. Poor
liquid epoxy into groove and allow to set. If the temperature is too cold then place
diffuser under a lamp but the curing temperature should not exceed 40̊ C.
 test under water and observe the bubble pattern
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