Air compressor for hull cleaning
 

Am wondering if anyone has set up a small air compressor rig, 110V,
similar to the ones used by divers for hull cleaning services. I assume
just a small oil-less compressor and couple it directly to a stock dive
regulator? I only need it dockside in a marina with 30A seervice.

THANKS for any input

Air compressor for hull cleaning: MMC, this one is yours.
 

BajaJim wrote:
Am wondering if anyone has set up a small air compressor rig, 110V,
similar to the ones used by divers for hull cleaning services. I assume
just a small oil-less compressor and couple it directly to a stock dive
regulator? I only need it dockside in a marina with 30A seervice.

THANKS for any input


So you are saying that you want to set up a surface supplied diver air
system?
In other words ya want to breath the stufff pumped out of the
compressor?

Common Air Breather Bob

Air compressor for hull cleaning: MMC, this one is yours.
 

I've been using a system like this for 14 years - an invaluable tool.
Here are the details:
http://www.yandina.com/hints.htm#Compressor

Air compressor for hull cleaning: MMC, this one is yours.
 

Dave wrote:
On 20 Apr 2006 12:47:53 -0700, "Bob" said:

the stufff pumped out of the
compressor?

It's called "air," Bob.


Wellll......... somtimes its air. Sometimes there is a bunch of other
stuff too.

Lets see. CO, oil, smoke, teflon tape, bits and pieces ???
Bob

Air compressor for hull cleaning: MMC, this one is yours.
 

Dave wrote:
On 20 Apr 2006 15:31:01 -0700, "Bob" said:

CO, oil, smoke,

Better take another look at the original post, Bob. Hydrocarbon powered
engines are not usually described as "110 Volt."


Good point.... and attention to detail.

I agree. I guess I needed to be more specific about the source of the
CO, oil, and smoke...................

What about the exhaust from another source introduced into the system
because the operator does not have the training, kowledge, experience,
to know where to position the air intake. I do not thiink most of the
Ace hardware oiless compressors come with 30' CP hose for the air
intake.

That bar-b-q shure smells good the guy in the next slip is cooking.

So there I was driving a boat with a sea and wind on my STB aft
quarter. The same place where my exhaust was located. After about 5
hours I was ready to barf.

Oh, and then there is always lipoid pnumonia as another posted
mentioned earlier.

Many think ya can just go out and fill your pockets with rocks and grab
the garden hose.

Personally........................ I prefer a snorkle and mask. But I
think the post a month or so ago decribed how-to free dive.

Bob

Air compressor for hull cleaning
 

BajaJim:

Let's try to ignore all of the irrelavent BS that was recently posted to
this topic. An oil less air compressor is perfectly safe to use with a
simple filter to trap any particles that get through.

But your stock dive regulator won't work. It is designed to work with about
200 psi air supply. A typical Home Depot oil less compressor won't supply
enough pressure.

You need a "hookah" regulator that will work with about 25-50 psi supply
air. I bought mine from an outfit that sells equipment for small scale gold
mining. Google around and you should find one.

David

Air compressor for hull cleaning
 

Am wondering if anyone has set up a small air compressor rig, 110V,
similar to the ones used by divers for hull cleaning services. I assume
just a small oil-less compressor and couple it directly to a stock dive
regulator? I only need it dockside in a marina with 30A seervice.

The diver that cleans my boat does it that way and I know of one other in
this area.


Leanne

Air compressor for hull cleaning: MMC, this one is yours.
 

Dave wrote:
On 20 Apr 2006 17:32:37 -0700, "Bob" said:

Personally........................ I prefer a snorkle and mask. But I
think the post a month or so ago decribed how-to free dive.

I spent three years as a hardhat diver, diving to several hundred feet. Your
parade of horribles is just that.

Hi Dave:
Yea.... yea. I've heard that bilge before. But most likley I've
****ed more salt water than you've been on.

When you were som mud duck hoping to breakout I was a saturation diver
making bell jumps to 1000s of feet. I worked for a Mexican outfit. Of
course it was the best abd bigest and fastest etc.... Then it
happened.......................... We were working at 1,200 feet when I
just finished a riser clamp. My bell tender's last words were,
"Bob......the adobe is failing!"
Bob
DIT 107/80

Air compressor for hull cleaning
 

The compressor might work, but I would use a dive tank.
Cheaper, easier, claener air, more reliable.
You can get a new one for under $100, a used one for half of that.
One air fill will last you hours when you stay as shalllow as the hull
of a boat. If you like the setup with th long hose, use it and leave
the tank on board.
You are going to buy 90% of a full set of scuba gear anyway, why stop
at the tank?

Air compressor for hull cleaning
 

BajaJim writes:

Am wondering if anyone has set up a small air compressor rig, 110V,
similar to the ones used by divers for hull cleaning services. I assume
just a small oil-less compressor and couple it directly to a stock dive
regulator?

Yes, we do this in our swimming pool. I run an old ScubaPro regulator 2nd
stage ($25 on eBay) off 90 psig shop air from a standard piston/oil type
compressor. Despite all the dire warnings (from people just reciting
paranoia they've heard, who've never tested for oil or tried it), the air
should be OK if your compressor doesn't consume oil such as from bad piston
rings. And the pressure is fine for feeding a 2nd stage.

The fear of "any oil in air will harm you" is silly. First, it is mineral
oil, which is non-toxic. Second, if were that bad, a whiff of 2-cycle
exhaust would kill you. I run this compressor for hours and hours,
thousands of cubic feet, and it loses only tiny amounts of oil, most of
which condenses in the tank.

I suppose an oilless compressor would eliminate even the possibility of
entrained oil. Although they're hideously noisy. You would want at least
a 2 cfm compressor rating, since you typically breathe about 1 cfm. But 2
cfm at 90 psi is only about a 1/2 (true) horsepower unit.
But see my essay http://www.truetex.com/aircompressors.htm on horsepower
ratings.

You need an adapter from the SAE scuba fitting to NPT pipe thread and
thence to a shop air quick-connect, which all then goes on your regulator
second stage hose where it would have connected to a first stage. You now
have a scuba regulator that terminates in an air tool quick-connect. I
made my own threaded adapter on my machine shop lathe. The only source for
such a part otherwise that I can think of is the adapters made for buoyancy
compensator connectors to shop air for filling tires or running tools from
scuba tanks (although this is the opposite direction of adaptation, it
might have the critical SAE-fitting-thread to NPT-pipe-thread conversion).
You could do it by simply splicing hoses with a hose barb if you were
willing to cut up the regulator feed hose.

Here is my drawing of the adapter essentials:

http://www.truetex.com/scuba_lp.pdf

Shallow water hookah diving is easier than most open water scuba diving.
The dive gear industry makes everything but this year's model sound like
it's going to kill you. The old 2nd stage regulators were very simple and
easy to repair yourself. They too were once the thing you had to have and
all the old models would kill you.

If anyone wonders if this is unreliable and therefore hazardous, I would
only use it for shallow diving, like working or practicing diving in a
swimming pool, or working on a boat hull, and I would insist on having a
trustworthy person for a topside tender. Being suddenly out of air is not
a problem with some simple training; we as tenders routinely disconnect the
air unexpectedly to our diving family members to help them practice the
drill (a habit I got from my first scuba instructor in the 1970s, who liked
to turn off your main valve when you weren't expecting it).

To anyone suggesting you just go full scuba instead of improvising a
topside compressor, I would say that full scuba is absurdly cumbersome and
expensive compared to hookah for shallow diving on a fixed location, and in
my opinion, no improvement in risk.

Of course this is diving, which takes training and recent diving experience
to minimize risks.

Air compressor for hull cleaning
 

MANY Thanks to Richard Kinch and Bryan Combs for some great replies, it
was clear that they understood I am only going down 6 to 8 feet and
just need a little compressor, similar to those used for small paint
sprayers. I will also have 30A dock service to plug into.

This was my first post and participation and, while I love a little
humor as much as the next guy (see my book The Baja Bash), it was a
little hard finding the worthwhile posts while sifting through others
from people who clearly feel a need to reply to anything and
everything, under the assumption that they know all and should
therefore pass on their pearls of wisdom.

Air compressor for hull cleaning
 

So I got the regulators and hoses from this outfit.

http://www.akmining.com/diving.htm

Really the hoses could be any compressor hose from Home Depot but it
was nice to have all the fitting match.

I got a small 12volts compressor that I run off the battery. I may
need to get a bigger one though because It can't quite keep up with
me.

They make these little compressors for trucks tires that run of the
battery. If you only going to use it in a marina, then 110v is great.

I would use an oil less model though. Why take a chance.

Been cleaning the bottom no problems. Even had to use it to dive down
30 feet to retrieve a pot that I dropped overboard.

Jeannette AA6JH
Bristol32
S/V 'Con Te Partiro'
http://www.eblw.com/contepartiro/contepartiro.html

On 20 Apr 2006 12:29:35 -0700, "BajaJim" wrote:

Am wondering if anyone has set up a small air compressor rig, 110V,
similar to the ones used by divers for hull cleaning services. I assume
just a small oil-less compressor and couple it directly to a stock dive
regulator? I only need it dockside in a marina with 30A seervice.

THANKS for any input

Air compressor for hull cleaning
 

Hello:

Okay, I appologize for that my sarcastic remarks earlier. However,
after a long run I am much more relaxed.

For the "I wanat to go diving" folks who were asking for air supply
advice.

But for real try this........................

Oregon State University DIve Ops guy, Jim Washburn used an old USN hand
operated diver air supply pump to guide a new lilght weight v3resion
for shallow water applications.

I am not talking about the big two person pump designed put a Mark V
down, rather somthing much smaller.

The shallow water pump weighs about 25 pounds and is pumped by one
person. The diver uses a "special" low preasure demand stage for the
regulator.

The pump is prettey cool. Stone age technology. Maybe four moving
parts. And the beauty is that only one person is needed topside to work
the pump.

Where do you get one??

Jim was cosidering manufaturing and sell the pumps. But because of
libility issues decided to shelve the idea.

However.......... if you are interested call Oregon State University
and ask for Jim Washburn, College of Oceaneering. I have a set of plans
but Jim is there to do just that. Help the tax payers benfit from tax
paid research projects.

Two bighest problems with this set up:
1) limited to about 20' depth
2) need a person topside to operate the manual hand pump.

The advatges:
1) No fuel,oil,noise
2) Stone age relibility, simplicity, light, CHEEP

Helpful Bob.

Air compressor for hull cleaning: MMC, this one is yours.
 

Actually I stole the idea from Andina who used to be my "dockmate" at CBYC
about 100 years ago.
How are you and Lea? Sure was good seeing you last month.
MMC

"Andina Marie" wrote in message
oups.com...
I've been using a system like this for 14 years - an invaluable tool.
Here are the details:
http://www.yandina.com/hints.htm#Compressor

Air compressor for hull cleaning: MMC, this one is yours.
 

Mud divers get shot at too! Be careful out there!
MMC (EOD/DV/PJ- usetobe)

"Dave" wrote in message
...
On 20 Apr 2006 20:45:09 -0700, "Bob" said:

som mud duck hoping to breakout

Hardly. Just hoping to do my duty to country (sort of an old-fashioned
idea)
without getting shot at.

Air compressor for hull cleaning
 

Dave writes:

Your post made me wonder whether somebody doesn't make a civilian
version of what we used to call a "Jack Brown" rig--mask that covers
both nose and mouth, and with a continuous feed of air through the
mask from a surface compressor.

There are scuba full-facemask regulators, but they cost multiples of the
conventional type.

Air compressor for hull cleaning: MMC, this one is yours.
 

Dave:

As my Polish grandmother Magda always said, If you can not say anything
good about a person Its best to not say anything.

Its nice to know you got some dolphins Dave.

Dobra Notes
Bed Time BOb

Air compressor for hull cleaning
 

BajaJim wrote:
MANY Thanks to Richard Kinch and Bryan Combs for some great replies, it
was clear that they understood I am only going down 6 to 8 feet and
just need a little compressor, similar to those used for small paint
sprayers. I will also have 30A dock service to plug into.

This was my first post and participation and, while I love a little
humor as much as the next guy (see my book The Baja Bash), it was a
little hard finding the worthwhile posts while sifting through others
from people who clearly feel a need to reply to anything and
everything, under the assumption that they know all and should
therefore pass on their pearls of wisdom.


Jim,

I believe that the warnings you received about "oil" based compressors
are based on the concern that you might be exposing yourself to what are
admittedly small amounts of toxins but over long periods of time, all
while working underwater - an environment where one would like to avoid
encountering breathing issues.

To compound this further you will be most likely be exerting yourself
enough to raise your respiration rate which would increase any toxin
absorption rate. Also, because of the "partial pressures" of breathing
gases in increased atmospheres, the percentage of toxin absorbed by your
body goes up dramatically as you go deeper.

If you can avoid using an oil based compressor I would strongly suggest
doing so, especially since inexpensive alternatives exist.

Cheers,

Robb

Air compressor for hull cleaning
 

On 20 Apr 2006 12:29:35 -0700, "BajaJim" wrote:

Am wondering if anyone has set up a small air compressor rig, 110V,
similar to the ones used by divers for hull cleaning services. I assume
just a small oil-less compressor and couple it directly to a stock dive
regulator? I only need it dockside in a marina with 30A seervice.


I've been using a diaphram type compressor for about 28 years. I think
they call them "pancake" compressors now. Totally oilless, using a
rubber diaphram. About 30 PSI max. It came with a 117 VAC motor, belt
driven. I replaced the motor with a 12 VDC wheel chair motor for
live-aboard use (take off the gear box and fit a pulley).

Get an "old" regulator. Take off the 1st stage and disable the 2nd
stage so you get free-flow. I bought some fittings/adapters so I use
regular water hose as an air hose.

If one wants to go this route, and have it run at 12 volts, a good
"motor" to drive it is an original VW bug GENERATOR. Not an
alternator. Connect the F (Field) terminal to the B (Battery)
terminal. This is the +. The - goes to the case or ground terminal.
This will draw about the same current as the wheel chair motor, about
10A, and give plenty of power.

Rick


------------------------------------------------
Absolute safety is a concept promoted by those
without the guts to live in the real world.
------------------------------------------------

Air compressor for hull cleaning
 

Rick Morel wrote:
On 20 Apr 2006 12:29:35 -0700, "BajaJim" wrote:

------------------------------------------------
Absolute safety is a concept promoted by those
without the guts to live in the real world.
------------------------------------------------


I think Absolute safety is a great goal. Most times not relaistic
but.......
Personnaly, I follow this:

"Its the second mouse that gets the cheese."

Observe.............anticipate.................... improve and
innovate.
Relationships with friends and coworkers tend to be longer this way

Bob

Air compressor for hull cleaning
 

Good post Robb.
The toxins are minute until the compressor pistons rings get worn (or do not
fit right from the beginning) and allow oil to enter the cylinders. With the
heat that's generated by compressing air, the oil will partially burn and
create carbon monoxide which coats the red blood cells and prohibits the
transfer of oxygen to those cells and further to the other cells in the
body.
Absolutely right about the oil free compressor!
MMC
"AMPowers" wrote in message
...
BajaJim wrote:
MANY Thanks to Richard Kinch and Bryan Combs for some great replies, it
was clear that they understood I am only going down 6 to 8 feet and
just need a little compressor, similar to those used for small paint
sprayers. I will also have 30A dock service to plug into.

This was my first post and participation and, while I love a little
humor as much as the next guy (see my book The Baja Bash), it was a
little hard finding the worthwhile posts while sifting through others
from people who clearly feel a need to reply to anything and
everything, under the assumption that they know all and should
therefore pass on their pearls of wisdom.


Jim,

I believe that the warnings you received about "oil" based compressors
are based on the concern that you might be exposing yourself to what are
admittedly small amounts of toxins but over long periods of time, all
while working underwater - an environment where one would like to avoid
encountering breathing issues.

To compound this further you will be most likely be exerting yourself
enough to raise your respiration rate which would increase any toxin
absorption rate. Also, because of the "partial pressures" of breathing
gases in increased atmospheres, the percentage of toxin absorbed by your
body goes up dramatically as you go deeper.

If you can avoid using an oil based compressor I would strongly suggest
doing so, especially since inexpensive alternatives exist.

Cheers,

Robb

Air compressor for hull cleaning
 

MMC wrote:
Good post Robb.
The toxins are minute until the compressor pistons rings get worn (or do not
fit right from the beginning) and allow oil to enter the cylinders.
Absolutely right about the oil free compressor!

Thanks for adding your ideas here. Finally some advice based on
training, experince, and still here to give it. Unlike the other past
posts that simply said, "Ive been doing it this way for years and never
had any porblems."

Here is my question for you MMC:

A few comments earlier in this discssion I described a hand pump that
supplied diver air to about 20'. Did you ever run into anything like
that in the service? They were a little (maybe 25 lbs.) two cylinder
thing with a five foot handle that a person push-pulled too operated
the pump. The guy who made the new prototype said he got the idea from
one he saw in an old USN Dive Manual.

Thanks,
Bob

Air compressor for hull cleaning
 

MMC writes:

The toxins are minute until the compressor pistons rings get worn (or
do not fit right from the beginning) and allow oil to enter the
cylinders. With the heat that's generated by compressing air, the oil
will partially burn and create carbon monoxide which coats the red
blood cells and prohibits the transfer of oxygen to those cells and
further to the other cells in the body.

You are confusing heat and temperature, because compressing air does not
generate heat. The existing heat is concentrated into a smaller volume,
raising the temperature, but this does not rise to ignition at 90 psi.
Perhaps you are thinking of scuba tank compressors at many 1000s of psi.

If what you say were true, then working with compressed air in a closed
shop would be even more hazardous, since the air is recycled over and
over through the compressor as it is exhausted into the room. But there
is no CO or oil vapor to be concerned with in those situations.

Mineral oil is not toxic in itself.

You are breathing oil-contaminated air all the time, over a cooking
stove or around 2-cycle engines. No one thinks much of it, because it
isn't a hazard.

Air compressor for hull cleaning
 

:
MMC writes:

The toxins are minute until the compressor pistons rings get worn (or
do not fit right from the beginning) and allow oil to enter the
cylinders. With the heat that's generated by compressing air, the oil
will partially burn and create carbon monoxide which coats the red
blood cells and prohibits the transfer of oxygen to those cells and
further to the other cells in the body.


Richard J Kinch wrote
You are confusing heat and temperature, because compressing air does not
generate heat.

Way big mistake..........! Please consult Charles Law

The existing heat is concentrated into a smaller volume,
raising the temperature, but this does not rise to ignition at 90 psi.
Perhaps you are thinking of scuba tank compressors at many 1000s of psi.
If what you say were true, then working with compressed air in a closed
shop would be even more hazardous, since the air is recycled over and
over through the compressor as it is exhausted into the room. But there
is no CO or oil vapor to be concerned with in those situations.

Mineral oil is not toxic in itself.

Now that depend on where you are breathing a contaminated gas mix that
includes Mineral Oil present. The term that MMC used is worth
researching: Partial Preasure.

You are breathing oil-contaminated air all the time, over a cooking
stove or around 2-cycle engines. No one thinks much of it,

Uhh. I do!

because it isn't a hazard.

Did I just bit on a troll?
This has got to be a troll.

If not........... for anyone wanting to breath compressed air please do
not belive anything posted here.
Bob

Air compressor for hull cleaning
 

Bob writes:

You are confusing heat and temperature, because compressing air does not
generate heat.

Way big mistake..........! Please consult Charles Law

Charles's Law relates pressure and temperature. Not heat. Learn the
difference.

Air compressor for hull cleaning
 

Richard J Kinch wrote:

Charles's Law relates pressure and temperature. Not heat. Learn the
difference.

Dear Richard:

Please explain the relationship between pressure and heat and
temperature. I think temperature and heat might be similar. But how?
That is BTU = Degrees Fahrenheit. So what is missing?
We can get into a discussion about pressure-heat - volume when the sun
is up.

Ignorant Bob.

Air compressor for hull cleaning
 

How often are you planning on using this? I just use a scuba tank
with a 40' hose to do all my maintenance.... no worries about maint or
worn rings or electricity.

If you use it a lot, contact brownies third lung. They make a safe
electic unit as well. Sure it costs a few more bucks but we are
boaters... If you can't right the checks, stay on the dock!!!!!





Bob wrote:
Rick Morel wrote:

On 20 Apr 2006 12:29:35 -0700, "BajaJim" wrote:


------------------------------------------------
Absolute safety is a concept promoted by those
without the guts to live in the real world.
------------------------------------------------



I think Absolute safety is a great goal. Most times not relaistic
but.......
Personnaly, I follow this:

"Its the second mouse that gets the cheese."

Observe.............anticipate.................... improve and
innovate.
Relationships with friends and coworkers tend to be longer this way

Bob

Air compressor for hull cleaning
 

Richard J Kinch wrote:
MMC writes:


The toxins are minute until the compressor pistons rings get worn (or
do not fit right from the beginning) and allow oil to enter the
cylinders. With the heat that's generated by compressing air, the oil
will partially burn and create carbon monoxide which coats the red
blood cells and prohibits the transfer of oxygen to those cells and
further to the other cells in the body.


You are confusing heat and temperature, because compressing air does not
generate heat.

Nonsense. The "compression of air", i.e. the volume change alone, does
not change heat content(enthalpy), however mechanically "compressing
air" always does. Any mechanism that compresses air does work on the
system (consider all the frictional components), and that work is
reflected in increased temperature and enthalpy.

The existing heat is concentrated into a smaller volume,
raising the temperature, but this does not rise to ignition at 90 psi.

Ignition temperatures are not required, however, to generate volatilized
oxidation components. CO is not likely to be an issue without
ignition-high temps, but I'd just as soon not breath contaminated oil vapor.

Perhaps you are thinking of scuba tank compressors at many 1000s of psi.

If what you say were true, then working with compressed air in a closed
shop would be even more hazardous, since the air is recycled over and
over through the compressor as it is exhausted into the room. But there
is no CO or oil vapor to be concerned with in those situations.

Hardly the same context given the dilutional differences. A "closed"
shop is *not* a sealed shop.

Mineral oil is not toxic in itself.

In the gut, no. In the lungs, yes. Coat your alveoli with it and see
how long you last. The lungs have mechanisms for clearing particulates,
but not oils. And let's not forget that the oil has lots of other
charming things in it (like heavy metals from wear surfaces) by the time
it gets to your lungs.

You are breathing oil-contaminated air all the time, over a cooking
stove or around 2-cycle engines. No one thinks much of it, because it
isn't a hazard.

Well, I'd suggest that most people think more about it than you do. And
in most of those situations, you're getting particulates, not
volatilized oil. You're also breathing through your nose, which is
designed as a filter (i.e. impingement on mucosal linings of the nasal
and sinus passages), which you will not be doing underwater, unless
using a full face mask.

Using an oil sealed compressor to supply breathing air is just stupid,
unless you care nothing for your health.

Keith Hughes

Air compressor for hull cleaning
 

Keith Hughes writes:

You are confusing heat and temperature, because compressing air does
not generate heat.

Nonsense. The "compression of air", i.e. the volume change alone,
does not change heat content(enthalpy), however mechanically
"compressing air" always does.

I correctly responded to a misstatement of your "does not". Your
"always" is irrelevant.

I'd just as soon not breath contaminated oil vapor.

Then you better not cook over a stove or grill.

Hardly the same context given the dilutional differences.

So you must agree. Some oil is OK. How much? And what shred of
evidence do you have that a shop compressor exceeds that?

Mineral oil is not toxic in itself.

In the gut, no. In the lungs, yes.

Aspiration hazards are not toxicity hazards. By your logic, water is
toxic since too much of it in your lungs will kill you.

You are breathing oil-contaminated air all the time, over a cooking
stove or around 2-cycle engines. No one thinks much of it, because
it isn't a hazard.

And in most of those situations, you're getting particulates, not
volatilized oil.

So you must think a particulate oil fog is OK when a vapor isn't? That
cooking or running a 2-cycle or fogging for bugs isn't generating a lot
of oil vapor? Come on.

Using an oil sealed compressor to supply breathing air is just stupid,
unless you care nothing for your health.

Calling something a hazard when you have absolutely no data on the
levels, and where the oil consumption suggests negligible levels, and no
standards for permissible exposure, is what is ... I don't want to say
"stupid", but let's call it California style environmentalism.

OSHA PEL for mineral oil mist is 5 mg per cubic meter. Show that this
is exceeded in shop air at the delivery point. Don't just timidly
speculate.

Air compressor for hull cleaning
 

Dave wrote:
On 23 Apr 2006 03:24:48 -0700, "Bob" said:


I think temperature and heat might be similar. But how?
That is BTU = Degrees Fahrenheit.

Sorry, Bob. You're dead wrong on this one.


Hi Dave:
Okay........... I agree, most likely wrong. Im not sure about the dead
part, although I felt like sunday morning. Thats what I was wondering.
Let try this: How is BTU related to Degrees Fahrenheit?

If air is compressed doesn't it get hot? If so, how measure it? But I
guess what caught my eye was when a previous post said that compressing
air does not create heat. But I may be pretty ignorant about the term
HEAT.

Confused Bob

Air compressor for hull cleaning
 

On 24 Apr 2006 14:55:29 -0700, "Bob" wrote:


Hi Dave:
Okay........... I agree, most likely wrong. Im not sure about the dead
part, although I felt like sunday morning. Thats what I was wondering.
Let try this: How is BTU related to Degrees Fahrenheit?

If air is compressed doesn't it get hot? If so, how measure it? But I
guess what caught my eye was when a previous post said that compressing
air does not create heat. But I may be pretty ignorant about the term
HEAT.

Confused Bob

If I remember correcty from chem class 35 years ago:

PV=NRT

pressure * volume = moles * R * Temperature

I don't really remember the units, but I think moles is a measure of
mass, R is a constant (.082?), temperature = degrees kelvin.
Google "ideal gas law" for better info. But solve for T and you get

T=PV/NR

The rest is left as an exercise for the student :-)

__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

Air compressor for hull cleaning
 

Glen "Wiley" Wilson wrote:
On 24 Apr 2006 14:55:29 -0700, "Bob" wrote:

If I remember correcty from chem class 35 years ago:
PV=NRT
pressure * volume = moles * R * Temperature
I don't really remember the units, but I think moles is a measure of
mass, R is a constant (.082?), temperature = degrees kelvin.
Google "ideal gas law" for better info. But solve for T and you get
T=PV/NR
The rest is left as an exercise for the student :-)


Oh no.... not moles !!!

That is almost as helpful to me as Avogadro's Number.

I think I will stick with the brick analogy......................... I
can understand bricks.

I new a Wiley Wilson in Ballard, WA in the early 1980s. Same person?
Bob

Air compressor for hull cleaning
 

On 25 Apr 2006 09:00:21 -0700, "Bob" wrote:


Glen "Wiley" Wilson wrote:
On 24 Apr 2006 14:55:29 -0700, "Bob" wrote:

If I remember correcty from chem class 35 years ago:
PV=NRT
pressure * volume = moles * R * Temperature
I don't really remember the units, but I think moles is a measure of
mass, R is a constant (.082?), temperature = degrees kelvin.
Google "ideal gas law" for better info. But solve for T and you get
T=PV/NR
The rest is left as an exercise for the student :-)


Oh no.... not moles !!!

That is almost as helpful to me as Avogadro's Number.

I think I will stick with the brick analogy......................... I
can understand bricks.

I new a Wiley Wilson in Ballard, WA in the early 1980s. Same person?
Bob

I remember studying Avogadro's Number. It goes like this: If Jane has
8 avogadros and she makes guacamole from 1/2 of them, what is the
number of avogadros she has left?

Must have been a different guy in Ballard. I didn't get to that part
of the country till about 2002.


__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

Air compressor for hull cleaning
 

Glen "Wiley" Wilson writes:

If I remember correcty from chem class 35 years ago:

PV=NRT

T is for temperature. Temperature is not heat. Chemistry is not
thermodynamics.

Air compressor for hull cleaning
 

Dave writes:

And the significance of this distinction between Chemistry and
thermodynamics is ...

The study of physics involving temperature, pressure, heat, work, etc., is
called "thermodynamics". Chemistry as such does not answer such questions,
although chemists use thermodynamics.

It is kind of like the old quarrel over whether chemistry is a branch of
physics, or physics of chemistry.

In any case, PV = nRT presumes zero heat transfer (denoted Q in
thermodynamics).

Air compressor for hull cleaning
 

On Tue, 25 Apr 2006 19:50:59 -0500, in message

Richard J Kinch wrote:

Dave writes:

And the significance of this distinction between Chemistry and
thermodynamics is ...

The study of physics involving temperature, pressure, heat, work, etc., is
called "thermodynamics". Chemistry as such does not answer such questions,
although chemists use thermodynamics.

It is kind of like the old quarrel over whether chemistry is a branch of
physics, or physics of chemistry.

In any case, PV = nRT presumes zero heat transfer (denoted Q in
thermodynamics).

Actually PV = nRT is just an equation of state for an ideal gas that
would be equally at home in either a thermo or a chem text book. It
doesn't presume a lack of heat transfer, it simply tells you that if
you increase the temperature by adding heat, then either the volume or
the pressure will increase.

One equation in three variables is not enough to fully describe a
problem.

Ryk


--
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Air compressor for hull cleaning
 

Ryk writes:

it simply tells you that if
you increase the temperature by adding heat, then either the volume or
the pressure will increase.

No variable in the equation expresses heat. It does not tell you
*anything* about heat or its relationship to the variables it does express.
It does *presume* that Q = 0. If Q happens to be non-zero, then the
equation still holds while the values change, but the equation tells you
*nothing* about an unexpressed Q relating to T, any more than it tells you
there are unexpressed forces changing V, or a leak in the container
changing n, or radioactive decay changing n, or any other physical
principle you can imagine.

An equation must express a quantity to "say" (predict) anything about it.

An equation may be affected by unexpressed quantities, but the equation
literally does not say anything about unexpressed quantities.

Air compressor for hull cleaning
 

Ryk writes:

Actually PV = nRT is just an equation of state for an ideal gas that
would be equally at home in either a thermo or a chem text book.

If there are any meaningful definitions of "chemistry", "thermodynamics",
and "physics" anymore, then PV = nRT belongs in the second, which is a
branch of the third. But this is a philosophical quarrel that we'll not
solve here.

All I know is, there ain't no oil in my raw shop air, hot as it may be.
And certainly not compared to proximity to my 2-stroke outboard, 2-stroke
chain saw, 2-stroke string trimmer, or 2-stroke Weber charcoal grill.

Air compressor for hull cleaning
 

Salty Bob,
Man, that is an old set up! I remember pictures like that from the period
before those wiley divers hooked a new fangled gasoline engine to a
compressor!
The Navy used various models, without much change in design, of the Mk 5 hat
from the 1840s to the 1980s.
As I remember (got an old dive manual around here somewhere, hell if I know
where) the handle was like on the old manual rail cars, you know the ones 2
guys would stand on and pump the handle from the ends, up and down for
moving down a rail to perform maintanence?
Didn't John Wayne have a rig like that in "Wake of the Red Witch"?
As I remember a Mk 5 diver would be conscious for something like 6 minutes
if he lost his air supply, so if the supply flow replaced the air in the
suit every 2-3 minutes he'd be fine. Running a compressor like that directly
to a hat or mask, would only require a 2-3 cfrm and about 15 psi over bottom
pressure? Add depth and add cfm.
MMC
"Bob" wrote in message
oups.com...

MMC wrote:
Good post Robb.
The toxins are minute until the compressor pistons rings get worn (or do
not
fit right from the beginning) and allow oil to enter the cylinders.
Absolutely right about the oil free compressor!

Thanks for adding your ideas here. Finally some advice based on
training, experince, and still here to give it. Unlike the other past
posts that simply said, "Ive been doing it this way for years and never
had any porblems."

Here is my question for you MMC:

A few comments earlier in this discssion I described a hand pump that
supplied diver air to about 20'. Did you ever run into anything like
that in the service? They were a little (maybe 25 lbs.) two cylinder
thing with a five foot handle that a person push-pulled too operated
the pump. The guy who made the new prototype said he got the idea from
one he saw in an old USN Dive Manual.

Thanks,
Bob

Air compressor for hull cleaning
 

Hey, if we adapt this train of thought we can do away with diving related
illnesses like nitrogen narcosis and embolism! Oh, happy day!
Could it be that the rings in your compressor aren't shot? Breathe the
exhaust of any of the other items you list at depth and under pressure and
let me know what you find out.
MMC
"Richard J Kinch" wrote in message
. ..
Ryk writes:

Actually PV = nRT is just an equation of state for an ideal gas that
would be equally at home in either a thermo or a chem text book.

If there are any meaningful definitions of "chemistry", "thermodynamics",
and "physics" anymore, then PV = nRT belongs in the second, which is a
branch of the third. But this is a philosophical quarrel that we'll not
solve here.

All I know is, there ain't no oil in my raw shop air, hot as it may be.
And certainly not compared to proximity to my 2-stroke outboard, 2-stroke
chain saw, 2-stroke string trimmer, or 2-stroke Weber charcoal grill.