Sauron
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Hoods, Hoods, Hoods: New, Used, or DIY?
I am about to acquire a large (2 meter wide, 85 cm deep) fume hood with scrubber and matching base cabinet.
This system, new, locally made and installed, is a faily serious investment at about $7000 US
Attached is the brochure from my supplier.
There are two possible alternatives: I could buy a used hood of similar size in US, ship it to Thailand, import it with consequent duty and VAT
liabilities plus transport and broker fees, and maybe save a little, but, it will probably be wrong voltage and so I will likely need to replace motor
for blower and some or all of the electricals.
The final option would be to take the plans for a hood found in the forum library, modify them for automatic bypass, if not already there, and submit
them to a good cabinetmaker for a quotation. I recall that manuals of design for lab hoods and benches recommend teakwood tops, well, we have teak in
this country if not aplenty at least still available. Teak repels water due to its high oil content, and that is probably the basis for the
recommendation. However I am not really in mood for another DIY project, I sold all my cabinetmaking machinery a couple years ago and my eyes are not
so good, I quit that hobby while I still had all my fingers attached!
Marble or granite tops are also common or were when I was a student. Presently benchtops appear to mostly be various sorts of plastic or composits. If
obliged to use such a top I would obtain a SS tray an inch or two deep of same size as the interior of the hood, line it with PTFE and feel pretty
confident.
I can go to a 2, 2.5 or 3 HP motor and still be within limitations of 220V 1 Ph 15 amp or at most 30 amp circuits. The former are normal household
mains circuits here, the latter are used for larger appliances such as air conditioning. So far so good.
The sash is 6mm safety glass or tempered glass.
The hood has all usual services (vacuum, water, gas and electrical) and fluorescent lighting totalling 80W. The ducting is 5 or 10 inch diameter.
The scrubber design looks OK.
Comments are solicited.
[Edited on 20-7-2007 by Sauron]
Attachment: hood.pdf (346kB)
This file has been downloaded 644 times
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Magpie
lab constructor
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I built a hood of aluminum, much smaller than what you are contemplating, however. Then again my installed final cost including ducting and ss outlet
plenum is ~$2000. You can read the details in this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=4777&a...
It's hard to see where you could go wrong buying a hood of that large size from an established, proven supplier.
You say the ducting is 5 or 10" diameter. I think 5" is your typo, as the brochure says 8 or 10". I have 8" for my hood and I think 10" is standard.
5" wouldn't cut it.
I also built a ss (304) tray for the bottom of my hood. I'm glad I did as it has taken some hard use but is holding up quite well.
The single most important condition for a successful synthesis is good mixing - Nicodem
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chemrox
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We have relationships with a couple of HV vendors -so our plan is to make best use of the space we have available by custom fitting. I want downward
as well as updraft circulation to pull heavy vapors off the bottom sides. I want the trays Sauron describes as well. I plan to construct from steel
sheeting. My countertops are going to be stone of some kind. I haven't figured out how to counterweight the sash but that will not be a big deal.
Since you have more space you might be best off doing as you are. I bought one from LabX and never had it delivered as my building deal fell through
before I had arranged shipping. I'm sorry I didn't get it out here. It was $35 plus shipping. Maybe you should check LabX for a few months first.
Depends whose money...
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Sauron
International Hazard
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When I import lab equipment I generally get away with duty of 3 to 5% on the CIF (value plus transport) and then 7% on top of that. For example I just
imported 1200 kg of HPLC equipment by ocean, and it cost me a total of about $2000 US including freight, broker fees, duty and VAT on a declared value
of about $6000.
Unfortunately fume hoods and base cabinets, especially if they are fiberglass, may be taxed at 20 to 40% duty on CIF, and Customs may be very
reluctant to accept a declared value of $35!! So, my cost landed in Thailand from USA may be thousands, even if I get the hood etc for cheap.
I went through this when I imported my Labconco (fiberglass) glove box. I got lucky on that one and didn't have to pay a huge duty but it could have
gone the other way. I got into the glove box on LabX for about $350, paid almost that much to truck it from Missouri to SF CA, to my warehouse, then
paid almost $1000 to truck it to San Pedro to upload to a freighter, and then paid hundreds to import it here a few weeks later. So my $350 glove box
cost me so far about $2200, and I still need a $500 pair of gloves because the the ones than came with it have a few tears back near where they mate
to the flanges and get steel-clamped and O-ringed on airtight.
Furthermore, I'd have a voltage problem and so would need to change out the blower motor and perhaps electricals in the hood; I'd have to buy ducting
and pay someone competent to install, and I still would need to buy a scrubber and integrate it, the scruvver is about 1/2 the price of the
hood/base/blower&motor or 1/3 the total installed system cost.
All in all, buying used in USA may be a chancey way to save $$$ and a general pain in the ass.
This way I get a warranty and after sales service.
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Sauron
International Hazard
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I went and looked at LabX fume hood section and there was not a single auction going. There were ads for new hoods, ads for used hoods generally
without prices posted. An ad for a Labconco warehouse sale.
No obvious bargains.
Also looked at Suplus Lab, from whom I have bought a lot. Fume hoods (used) ranged up to $13,000. Ouch.
I may take a gander at HiTechTrader with whom I have also done business but usually those guys are not as much of a bargain zone as SL or LabX.
Anyway nothing so far to make me change my mind about buying a new locally fabricated hood.
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