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Subject:
From:
Phil Bavaro <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 5 May 2000 13:29:51 -0700
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More than I should divulge about ESD Smocks and testing...I'm sure I won't
make any friends with the ESD garment industry with this post, but there
are some things that you should be aware of.......

I am assuming that you are not procurring the smocks with a quality clause
for meeting the EOS/ESD test requirements for smocks after laundering.  If
you are not familiar with these requirements, then you should start there
first.  Go find the spec and read it carefully.

If your coats are like ours, you will discover that the junctions of the
separate pieces are not connected electrically (shoulder to arm, etc)
because that costs more money to make.

You indicate a rivet is used, but is it used for each junction and is it
rusting out after laundering (I hope you aren't drycleaning them) etc.  I'm
not too familiar with how they terminate Carbon Suffused Nylon (CSN) to a
metal rivet and still ensure conductivity long term, but yours might be ok
if you were to perform the correct test on it.

If you don't have it specified in your garment procurement contract to test
the smocks after each washing, then you are getting what you are paying
for, which isn't necessarily a bad thing.

Also, I am not aware of a heel and wriststrap tester which is set up for
testing smocks cuff to cuff either because there is no pressure applied by
just connecting the snaps.

In my opinion, smocks are generally a waste of time for ESD protection
purposes, but we have always worn them because of the management aspect of
having uniformity within the plant.

We rely on our esd shoes for the dissipation of charges from the operators
which has been shown to be superior or at least equal to any other method
and always more cost effective.

The strands of conductors that you may see (usually a criss-cross pattern
of CSN) are indeed compensating for the raw garment materials which may or
may not be dissipative by itself and the cuff snaps are intended for
tightening up the sleeve opening at the wrist and not for connection to
test apparatus.

Of course, our operators wear mostly cotton clothing and no one wears
nylons, polyesters and angora sweaters in San Diego.  If they did, I might
be a lot more concerned about the quality of the smocks, testing, and the
level of protection that the smocks might provide.

Also, if it helps, our smocks are not tested by contract and they would
fail if tested per the EOS/ESD methods as well because they do not have the
pieces interconnected.

And yes, they are always yelling at me to close my smock as well.

Phil

At 12:22 PM 5/5/00 -0400, Lou Hart wrote:
>Technetters, got a question about resistance (or surface resistivity) of
>static dissipative lab coats.
>
>I've been pushing for people to keep their coats closed here, as suggested
>by several technetters a few weeks back.
>
>Now one of the operators tells me, Those lab coats don't work, I tried to
>measure the resistance and they are no good.
>
>
>So I went to our wrist and heel strap checker and found I could not get my
>cuff to cuff resistance to pass either wrist or heel check.  It failed high.
> When I checked the resistance between snaps on one cuff, using a
>multimeter, I found 10-20 megohms.  My coat is white with grey threads
>through it, the conductive nylon filaments, I guess.  It's made from 4 or 5
>or more pieces of material, like a lot of coats.  There is a metal rivet in
>each sholder where 3 pieces of fabric come together, that looks like it's
>supposed to connect the nylon from the various pieces.
>
>Can anyone comment on my experience?
>
>Lou Hart
>
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