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Re: Preventing a REALLY expensive mistake. / Ground and static control in an operating room. Awful long post.
Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <uncadoc-at-juno-dot-com>
Hi Christopher. Let me give you my experience with grounding systems in
hospital operating rooms, perhaps some of this can be used or reverse
engineered to suit your new H.V. lab. , since this was used to prevent
any type of static discharge which could result in an explosion of
flammable gases within the operating room, and the very nature of the
operating room design is quite similar to a "Faraday Cage", I am not
telling you to do this, I only forward my knowledge to you as a reference
that , perhaps, some small part will help you with your high voltage lab.
O.K. , here goes; The latest designed operating rooms: Utilize
locking steel "v" channel steel metal pan concrete support both above and
below each floor level(metal steel locking continuous channel supports
the concrete flooring laid upon it). Each concrete slab flooring
division incorporates a thick(8 or 10 gauge) steel core flooring lath
with a 4", 6" or 8" center, bond welded(factory) at each cross point of
the steel lath, (maybe your proposed lab already has some of this in
place). This metal grid lath will be centered between each concrete
pour. (Hey, it wouldn't hurt to get a glimpse of the original blueprints
of your proposed site to see if some of this is already in place!). All
floor lath joints are joined by #10 gauge steel wire looped and twisted
between adjoining particles of lath. The entire room is surrounded by a
metal "v" style structural steel vertical studding (similar to the open
roof supports in all the new mall and home supply depots) and the top and
bottom of the studding are connected to a heavy grounding grid via the
steel building support beams using #2 or better welding cable. The doors
and jambs are steel. The small window insert in the room entrance doors
is steel diamond wire impregnated glass. All walls consist of heavy
gauge steel diamond lath overlapped and tie bonded to each vertical metal
stud support surface to support the plaster coats upon the vertical
walls, the ceiling structure will also consist of iron "u" channel that
will support a steel lath and is floated from the metal "v" channel above
with hanger wires of #10 gauge steel wire which thereupon creates a
working human 'crawl' space for access to the operation room lighting
fixtures and anesthesia/oxygen/vacuum piping. The #2 or better welding
cables are compression lug bolted directly to the steel girder framing
members of the building in the vicinity of the operating suite. These
grounding girders connect to the steel load bearing beams which terminate
below earth ground level and are bonded to a set of rebar grid network
that is buried beneath the ground and attached to each caisson supporting
pile of the buildings foundation as a continuous grid beneath the
operating room suite. Each new operating room has a 100 amp 3 phase
service which(laser, computerized tomography, x-ray, catherization,
heart/lung machinery, lighting and power outlet support) is feed into a
isolation transformer bank that feeds the lighting, power and service
outlets in the operating room. I will also note that the older operating
rooms utilized a floor tile that was impregnated with a copper grid which
was sandwiched between the center of each vinyl floor tile. This copper
grid was used to carry away any residual static charge. This copper
impregnated floor tile is rarely, if ever, used anymore. I remember
having to 'meg' out each operating room in the older suites to check for
conductivity in the flooring once a week and check each corner of the
room with a sling psychrometer for relative humidity wet and dry bulb
content in the older masonry only portions of the operating rooms; that
was a bugger of a job. The newer steel grid shielded and grounded
operating rooms do not require megging, but we still keep a concerned eye
on humidity content from the air handling system and strive for 45 to 55%
relative humidity. Hope this helps somewhat. Oh, yes, one other note,
we use Teflon/RHW coated wire exclusively in all new work. Geeks rule!
Al.
On Wed, 21 Feb 2001 11:40:01 -0700 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: "Christopher Boden by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <chrisboden-at-hotmail-dot-com>
>
> Over recent years I have learned that the most terrifying words you
> can say
> to a sysadmin are "Tesla Coil" (next to "What's THIS button do?").
> Now we
> have an interesting situation.
>
> We have a 20,000 sqft building at the Sigma-6 complex that we have
> to cram
> the High Voltage Lab, the Computer Labs (Hardware, Software,
> Security, AND
> BeoWulf cluster) and the main offices into.
>
> 1. The building is fed with 1-P 240VAC, and will be upgraded to 3-P
> 480VAC
> (for the elevator of doom), should I keep the 1P service as well? or
> just
> have the landlord upgrade from one to the other?
>
> 2. Will a system of 10 seperate 8-10' ground rods driven vertically
> around
> the buildings exterior and all laced together for a massive ground
> system be
> an good enough protection for the computers and other electronics?
> Is there
> a better way?
>
> 3. What are all the steps I CAN take to ensure the safety of our
> computer
> systems? I have to assume that the computers will be operating at
> the same
> time as the coils (and other HV gear), since as we all know, all
> Micro$oft
> NT-5 systems maintain 99.999% uptime and are virtually error
> free.....at
> least that's what the slicks tell us. 'Course, if you believe that
> I've got
> a great deal on some property in Florida for you, the everglades,
> perhaprs
> you've heard of them?
>
> 4. I remember reading about garage coilers who have had discharges
> through
> the roof, can this happen on a solid concrete structure? (There will
> be
> classrooms under the H.V.L.)
>
> 5. I've heard of coils being mounted inverted from the ceiling. How
> is this
> done? Why? What are the advantages of this setup? Can it be used to
> make
> near vertical discharges to the floor?
>
> 6. Will the operation of large amounts of HV gear cause a
> signifigant rise
> in the static electricity of the entire building? I'm worried about
> the
> hardware labs, static and CMOS devices aren't exactly friendly with
> each
> other.
>
>
> Thanks guys!
>
> Have fun!
>
> Christopher A. Boden Geek#1
> President / C.E.O. / Alpha Geek
> The Geek Group
> www.thegeekgroup-dot-org
> Because the Geek shall inherit the Earth!
>
>
>
>
>
>
> _________________________________________________________________
> Get your FREE download of MSN Explorer at http://explorer.msn-dot-com
>
>
>
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