Experts:
I need your opinions on the following.
I am having a 'discussion' with an NRTL on a product that I can't show you a
picture of but here is a description:
* the base of the unit is 20" w x 26" l x 29" hf
* the base of the unit is mounted on caster/leveling feet devices that when
positioned for use, the leveling feet are lowered and the casters come off the
ground, and the leveling feet are sufficiently rated for more than 4x the load
of each corner
* in the middle of the top of the base there is a robot mast for the Z
axis, and it measures roughly 4" square and is 41" tall
* the whole product weighs 220 lbs
The stability requirements in 61010-1 are as follows, and I highlighted the
text of interest:
Equipment and assemblies of equipment not secured to the building
structure before operation shall be physically stable.
If means are provided to ensure that stability is maintained after the
opening of drawers, etc. by an OPERATOR, either these means shall be automatic
or there shall be a warning marking to apply the means.
Each castor and support foot shall be RATED to support a load of at least
4 times its normal load, or the castors and support feet shall be tested
according to d) and e), below.
Conformity is checked by inspection and by carrying out each of the
following tests, if applicable, to ensure that the equipment will not
overbalance. Containers contain the RATED amount of substance which provides
the least favourable conditions of NORMAL USE. Castors are in their least
favourable position of NORMAL USE. Doors, drawers, etc. are closed unless
otherwise specified below.
1.
1. Equipment other than HAND-HELD EQUIPMENT is tilted in each
direction to an angle of 10° from its normal
2. Equipment which has both a height of 1 m or more and a mass of 25
kg or more, and all floor-standing equipment, has a force applied at its top,
or at a height of 2 m if the equipment has a height of more than 2 The force is
250 N, or 20 % of the weight of the equipment, whichever is less, and is
applied to all surfaces in directions which could cause the equipment to
topple. Stabilizers used in NORMAL USE, and doors, drawers, etc., intended to
be opened by an OPERATOR, are in their least favourable positions.
3. Floor-standing equipment has a force of 800 N applied downwards at
the point of maximum moment to:
+ all horizontal working surfaces;
+ other surfaces providing an obvious ledge and which are not
more than 1 m above floor
Doors, drawers, etc. are closed, except that those intended to be
opened by an OPERATOR are in their least favourable positions.
When the force was applied at the top of the robot mast, it unit started to
topple at 38 lbs, which is less than the required 44 lb force according to the
standard.
The case I presented why this test was not applicable was:
* because the robot mast is located in the center of of the unit, and not
flush with the sides, that it did not represent the same situation as a
bookcase, filing cabinet, or other product which if someone were to bump into
it, they would not be contacting the robot mast to due to the location in the
center of the top.
* the robot mast is part of a component and not part of the structure of
the product, and so the test should be done at the top of the base unit, and no
higher.
* there is text in the user manual that says not to push on the robot mast
when moving the product to new location
* and, if absolutely necessary, we an add do not push labels at the top
sides of the robot mast
The NRTL rejected my rationale so I am looking to you to get your thoughts on
this before I press on with them.
Do you think the test is applicable?
You can respond here publicly or privately, or at
[email protected] mailto:stevenb@prduct
Thanks in advance,
Steve Brody
[email protected] mailto:[email protected]
C - 603 617 9116
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