On 9 Oct 2003 08:32:10 -0700, someone who calls themselves
(Shawn Lin) wrote:

I don't have an air compressor yet, I know nothing about them, and
don't know anyone in person that owns one, but I was thinking about
getting one for running an impact wrench, air ratchet wrenches, and
occasional painting.

After some Google searches, I came across a few threads about air
compressor tanks exploding. It was sometimes caused by corrosion,
sometimes a bad relief valve, or bad pressure switch, or any
combination of the 3. I've also read that bad welds, a weak tank, or
other problems can contribute to a potentially fatal explosion.

Keep the tank drained well - every time you use it, drain it. No
water, no rust. (Well, almost.) If you like gadgets or have people
using the system that can't be bothered to drain it manually, you can
get automatic drain valves for stationary compressors that do the
draining every time the motor cycles.

And I sincerely doubt that any ASME Inspectors have been within a
thousand miles of any Harbor Fright factory... If you want the
insurance on the shop building to stay in force, you'll need a
compressor with an ASME certified tank, and the paperwork on file.

I was originally going to buy the Harbor Freight 47065 "4-1/2 HP"
vertical compressor for about $150. It's oil lubed, so I thought it
would be a much better (and cheaper) alternative than picking up a
cheap oil-free compressor from Wal-mart. This would be for light
occasional use anyway, so I'm not too concerned about full cast iron
pumps or belt drive. My other alternative is to drop $400 on an oil
lubed Craftsman or Campbell-Hausfeld.

However, we all know Harbor Freight products are Made In China which
is not a country known for making high-quality products. If I buy a
cheap Chinese compressor, do I risk poor welds on the tank? A weak
tank made with poor grade iron? A pressure relief or pressure switch
that's likely to fail? If I'm risking my life by going cheap, I'd
definitely spend the extra money. If the HF compressor is perfectly
safe, then I'd rather buy it and save the money. Anyone have
experience with the HF compressor? I know compressor tank explosions
are few and far between, but I'm a very safety-oriented person.

Consider any complex hand or power tools from Harbor Fright
(including their air compressors) to be disposable. {If} ^w strike
that... /When/ they break, getting replacement parts and service are
going to be a problem, and it'll often be cheaper to throw it away and
get another.

Although they are tempting to have around as a backup for your good
tools, or as a "beater tool" - the one that gets used when working in
a mud pit, at the edge of a cliff or on a boat on the water, where a
tool can go "oops" and disappear forever.

I have their throwaway angle grinder with the grinding wheel for
welding cleanup, and the good DeWalt with a knotted wire wheel for
prep - if the HF grinder goes belly-up on me, I can start using the
DeWalt for both and switching wheels between uses.

Use a Harbor Fright compressor for portable jobsite work where if it
gets stolen or wrecked you're not out much, and get the good
compressor for permanent install at your shop.

Also, a quick question about compressors - when the compressor is not
being used, do most people leave the tank pressurized at all times and
the compressor plugged in, or do most people unplug them and bleed the
pressure out of the tank?

Moisture drained-off but still pressurized (you've already spent for
the electricity to compress it) and turned off unless there's a reason
to leave it on, like a hose left at the driveway for filling the
bicycle and car tires.

IMPORTANT SAFETY NOTE: If you plumb a compressor permanently in the
shop do NOT use any sort of PVC plastic pipe for the air lines. When
it breaks, it grenades, and that can be just as deadly as it sounds if
you're in the wrong place at the wrong time. Use copper pipe
(soldered or brazed), black iron or galvanized pipe, with a piece of
hose as a vibration isolator between the compressor and plumbing.

-- Bruce --
--
Bruce L. Bergman, POB 394, Woodland Hills CA 91365, USA
Electrician, Westend Electric (#726700) Agoura, CA

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