UL923 Microwave Cooking Appliances -Door Assembly Tests
40 Door Assembly Tests
40.1 Door operation
40.1 .1 The door assembly shall withstand the forces expected
during intended usage without affecting the seal to the extent
that the equivalent plane wave power density of microwave radiation
emitted exceeds 5 mW/cm 2 at any point 5 cm or more from the
external surface of the enclosure when subjected to the test
in Microwave Radiation Emission Test, Section 34, with all
interlocks in the circuit. The door shall remain intact and in
place after each applicable test.
40.1 .2 To determine compliance with 40.1 .1 , a complete sample is
to be subjected to the applicable tests described in 40.2.1 –
40.5.7 and the microwave radiation emitted then measured as
described in 34.2.1 – 34.5.3 after each procedure. Following
the appropriate series of impact tests, on inner and outer
viewing screen barriers and door seals, the appliance shall be
examined for compliance with 5.9. A new sample may be used for
each procedure or the same sample may be used with the applicable
tests performed in the sequence given. If an unacceptable
result occurs on any subsequent test after the first test on a
given sample, the test is to be repeated on a new sample and
if the results are acceptable, the series of tests
continued until all the required tests have been completed or
another unacceptable result occurs.
40.1 .3 When applying the requirements of 40.3.1 and 40.4.1
consideration is to be given to the effect of different
installation arrangements (counter-top supported, built-in, and the
like), recommended by the manufacturer, upon the maximum force
that can be applied to the door without tilting the appliance.
40.2 All doors
40.2.1 Starting at a point midway between the fully open and closed
position, the door is to be moved to its fully open position
by means of a force equal to 1 .5 times the force necessary to open
the door from its closed position, 1 5 lbf (66 N) minimum,
applied to the inside surface of a hinged door at a point 1
in (25.4 mm) from the free edge, or to the handle of a sliding
door in the direction of intended travel. The opening
operation is to be performed ten times on a household appliance and
50 times on a commercial appliance.
40.2.2 Starting at a point midway between the fully open and closed
position, the door is to be moved to its fully closed position
by means of a force equal to two times the force necessary to close
the door to its fully closed and latched position, 20 lbf (89
N) minimum, applied to the outside surface of a hinged door at
a point 1 in (25.4 mm) from the free edge or the handle of a
sliding door in the direction of intended travel. The closing
operation is to be performed ten times on a household appliance and
50 times on a commercial appliance.
40.2.3 In performing the tests described in 40.2.1 and 40.2.2 the
force for opening and closing the door is to be obtained by
means of a spring scale or equivalent having a spring constant of 6
lbf/in (1 .05 N/mm).
The force is to be applied to the designated location on the door
with a restraining force applied opposite and collinear with
the actuating force. The restraining force is then removed to allow
the door to complete its opening or closing by means of the
spring-applied impulse.
40.3 Side-hinged doors
40.3.1 A side-hinged door is to be moved to its fully open position
and then closed with a force equal to 50 lbf (222 N), or the
maximum force that can be applied to the door without tilting the
appliance,whichever is smaller, supported at the free edge of the
door. The opening and closing operation is to be performed
five times for a household appliance and ten times for a commercial
appliance.
40.4 Bottom-hinged doors
40.4.1 A bottom-hinged door of a counter- or table-supported
appliance is to be subjected for 1 5 min to a force of 50 lbf
(222 N) or the maximum force that can be applied without tilting
the appliance, whichever is smaller, applied to the inside
surface of the open door at a point 1 in (25.4 mm) from the free
edge. For a floor-supported household appliance, the applied
force is to be 1 00 lbf (445 N) or the maximum weight the
appliance can support without tilting, whichever is smaller. For a
floor-supported commercial appliance the applied force is to
be 1 50 lbf (667 N) or the maximum force that can be applied
without tilting, whichever is smaller.
40.4.2 A bottom-hinged door is to be closed as far as possible with
a 3/8-in (9.5-mm) diameter hardwood dowel placed between the
lower inside surface of the door and the mating surface of the
enclosure below the oven cavity. The dowel is to be oriented
in the position that will cause the most adverse effect.
The closing force is to be 20 lbf (89 N) for a household oven
and 30 lbf (1 33 N) for a commercial oven and is to be applied
to the door handle for 5 s.
