I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow rate
at atmospheric pressure, not the flow rate at the compressor's maximum
working pressure. Can someone confirm this for me?

Many thanks,

Chris

Christopher Tidy wrote:
I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow rate
at atmospheric pressure, not the flow rate at the compressor's maximum
working pressure. Can someone confirm this for me?
The volume is measured in SCFM (Standard Cubic Feet per Minute). The
"standard" means referenced to standard temperature and pressure. But,
the reading is only useful when the tank pressure is known. Single
stage pumps lose a LOT of efficiency at higher pressures, that's why
el-cheapo manufacturers give the SCFM rating at 40 PSI tank pressure.
You want the rating at 90 PSI tank pressure. A crummy punp will lose
half its volumetric efficiency at 90 PSI. A good single-stage punp
will still lose 25% or so, going from 40 to 90 PSI.

If they didn't do this, ratings would be almost impossible to compare.
One cubic foot of sea-level air would be compressed to 1/7th of a cubic
foot at 90 PSI, which is 7 atmospheres of absolute pressure. That, of
course, is neglecting any temperature effects.

Jon

If you only want to draw 40 psi you can get xx cfm. If you want to
maintain 125 psi you can only get x cfm.I have not seen one rated at
atmospheric pressure.most quote a lower pressure of 80 or 40psi then at
max working pressure.

Christopher Tidy wrote:
I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow rate
at atmospheric pressure, not the flow rate at the compressor's maximum
working pressure. Can someone confirm this for me?

Many thanks,

Chris

Christopher Tidy wrote:

I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow rate
at atmospheric pressure, not the flow rate at the compressor's maximum
working pressure. Can someone confirm this for me?

Oh, god not again. We beat this to death and then some awhile ago, much much
flames with mucho heat but very little light. I read thousands of lines of
postings and didn't understand what the gurus were saying. Typical specs are
given at 40psi and again at 90psi, but the way I read it none of this matters
somehow. It doesn't really matter about the theory, a decent 5hp 2-stage
compressor can keep up with a die grinder, that's all I really care about.

GWE

Grant Erwin wrote:
Christopher Tidy wrote:

I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow
rate at atmospheric pressure, not the flow rate at the compressor's
maximum working pressure. Can someone confirm this for me?


Oh, god not again. We beat this to death and then some awhile ago, much
much flames with mucho heat but very little light. I read thousands of
lines of postings and didn't understand what the gurus were saying.
Typical specs are given at 40psi and again at 90psi, but the way I read
it none of this matters
somehow. It doesn't really matter about the theory, a decent 5hp 2-stage
compressor can keep up with a die grinder, that's all I really care about.

Well actually I was looking at this second hand compressor:

http://www.mythic-beasts.com/~cdt22/compressor.jpg

I know it's old, but I love projects. The whole thing is 28" long and
has a motor rated at 0.75 hp at 1440 rpm. There are two small air
receivers underneath you can't see. Basically I was wondering what kind
of tools I could run off it. A few things I'm interested in are paint
spraying, a die grinder, Cengar saw (a.k.a. shark saw, as used by the
fire service) and inflating tyres. At a rough guess I reckon this
machine probably has a flow rate of 6-8 CFM at atmospheric pressure. Any
thoughts?

Best wishes,

Chris

Grant Erwin wrote:
Christopher Tidy wrote:

I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow
rate at atmospheric pressure, not the flow rate at the compressor's
maximum working pressure. Can someone confirm this for me?


Oh, god not again. We beat this to death and then some awhile ago, much
much flames with mucho heat but very little light. I read thousands of
lines of postings and didn't understand what the gurus were saying.
Typical specs are given at 40psi and again at 90psi, but the way I read
it none of this matters
somehow. It doesn't really matter about the theory, a decent 5hp 2-stage
compressor can keep up with a die grinder, that's all I really care about.

Well actually my thoughts were more pragmatic too. I was looking at this
second hand compressor:

http://www.mythic-beasts.com/~cdt22/compressor.jpg
http://www.mythic-beasts.com/~cdt22/compressor2.jpg

I know it's old, but I love projects. The whole thing is 28" long and
has a motor rated at 0.75 hp at 1440 rpm. There are two small air
receivers underneath you can't see. Basically I was wondering what kind
of tools I could run off it. A few things I'm interested in are paint
spraying, a die grinder, Cengar saw (a.k.a. shark saw, as used by the
fire service) and inflating tyres. At a rough guess I reckon this
machine has a flow rate of 6-8 CFM at atmospheric pressure. Any thoughts?

Best wishes,

Chris

Christopher Tidy wrote in
:




You can forget the spray painting and die grinder with 6-8 CFM, and
probably the saw too. Just about any die grinder will eat more like 10 CFM
(for a good one) an elcheapo may pull as much as 14-16 CFM.


--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

http://www.machines-cnc.net:81/

On Wed, 8 Jun 2005 03:57:38 +0000 (UTC), Christopher Tidy
wrote:


somehow. It doesn't really matter about the theory, a decent 5hp 2-stage
compressor can keep up with a die grinder, that's all I really care about.

Well actually my thoughts were more pragmatic too. I was looking at this
second hand compressor:

http://www.mythic-beasts.com/~cdt22/compressor.jpg
http://www.mythic-beasts.com/~cdt22/compressor2.jpg

I know it's old, but I love projects. The whole thing is 28" long and
has a motor rated at 0.75 hp at 1440 rpm. There are two small air
receivers underneath you can't see. Basically I was wondering what kind
of tools I could run off it. A few things I'm interested in are paint
spraying, a die grinder, Cengar saw (a.k.a. shark saw, as used by the
fire service) and inflating tyres. At a rough guess I reckon this
machine has a flow rate of 6-8 CFM at atmospheric pressure. Any thoughts?

Best wishes,

Chris
My old 1/2 HP gives me 2CFM @ 80-100 PSI and with 10 gal. storage I
can use a die grinder but not continuously. With minimal storage, the
one you are looking at would be cycling very rapidly and put out about
3 CFM of usable air. By adding storage capacity it might be of some
use.
Gerry :-)}
London, Canada

"Christopher Tidy" wrote in message
...
snip-----

The whole thing is 28" long and
has a motor rated at 0.75 hp at 1440 rpm. There are two small air
receivers underneath you can't see. Basically I was wondering what kind
of tools I could run off it. A few things I'm interested in are paint
spraying, a die grinder, Cengar saw (a.k.a. shark saw, as used by the
fire service) and inflating tyres. At a rough guess I reckon this
machine probably has a flow rate of 6-8 CFM at atmospheric pressure. Any
thoughts?

Best wishes,

Chris


My honest opinion? It isn't worth your effort. 3/4 of a HP won't
produce enough air on a continual basis to do much for you. What Grant
said. I have a two stage 5 horse Quincy, rated 19+ CFM @ 175 PSI and it is
just adequate for running a small blast cabinet. It will run most air
tools with ease, that's not an issue. Small compressors aren't up to
much. Been there, done that. That's why I own the 5 horse Quincy. Unless
you have no prospects of a larger compressor, I'd pass on it and invest in
something that will serve you better in the long term.

Harold

Harold and Susan Vordos wrote:
"Christopher Tidy" wrote in message
...
snip-----


The whole thing is 28" long and
has a motor rated at 0.75 hp at 1440 rpm. There are two small air
receivers underneath you can't see. Basically I was wondering what kind
of tools I could run off it. A few things I'm interested in are paint
spraying, a die grinder, Cengar saw (a.k.a. shark saw, as used by the
fire service) and inflating tyres. At a rough guess I reckon this
machine probably has a flow rate of 6-8 CFM at atmospheric pressure. Any
thoughts?

Best wishes,

Chris

My honest opinion? It isn't worth your effort. 3/4 of a HP won't
produce enough air on a continual basis to do much for you. What Grant
said. I have a two stage 5 horse Quincy, rated 19+ CFM @ 175 PSI and it is
just adequate for running a small blast cabinet. It will run most air
tools with ease, that's not an issue. Small compressors aren't up to
much. Been there, done that. That's why I own the 5 horse Quincy. Unless
you have no prospects of a larger compressor, I'd pass on it and invest in
something that will serve you better in the long term.

Thanks for the opinions. It looks like this compressor would be a bit
limiting, but I'm still tempted by it. I can't afford a 5 hp compressor,
and although I have the space for it now, I'm likely to be moving and
won't in the future.

I probably should have mentioned that when I talked about spraying I
didn't mean cars or trucks, I meant small stuff which I've built.
Probably I wouldn't want to spray things larger than 18" across. I can
manage without the die grinder but the Cengar saw would be nice. I
checked the Cengar website and the saw needs 5 3/4 CFM at 75-90 psi.
Perhaps I might just manage it with this compressor, or am I pushing my
luck? I figure that inflating tyres and blowing away debris would be
fine with a little compressor like this.

I was also looking at a Broomwade compressor, which is of a similar size
but I believe it is two-stage:

http://www.mythic-beasts.com/~cdt22/compressor3.jpg

I know these machines are projects in themselves, but I don't mind that.
I like their "old school" appearance and construction.

Best wishes,

Chris

Christopher Tidy writes:

I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow rate
at atmospheric pressure, not the flow rate at the compressor's maximum
working pressure. Can someone confirm this for me?

"CFM" refers to the cubic feet of free air per minute, regardless of the
delivery pressure. It does not mean the compressed volume delivered. See
my page, "Evaluating True Horsepower and CFM Ratings of Air Compressors":

http://www.truetex.com/aircompressors.htm

"Christopher Tidy" wrote in message
...
I checked the Cengar website and the saw needs 5 3/4 CFM at 75-90 psi.
Perhaps I might just manage it with this compressor, or am I pushing my
luck? I figure that inflating tyres and blowing away debris would be fine
with a little compressor like this.



I question the CFM required to run your saw. Many manufacturers do not rate
the CFM at 100% usage so you get a poor indication of air volume needed to
run the tool.
Either way anything less than a 3 HP compressor will allow very intermittent
use of the tools you mention. I have a Porter Cable 7 HP, ( yeah right,
really about 3 HP), compressor that pretty much does all I need it to do. It
is rated at 9+ CFM at 90 PSI.. I had a real 2 HP compressor for years that
really was inadequate for much air tool use.
If you need a limited amount of air, a larger tank will get you by with a
small compressor. Keep in mind that once the tank has run down, recovery
time is very poor so you will not have air when you probably will want it!
Greg.

"Christopher Tidy" wrote in message
...
snip------
Thanks for the opinions. It looks like this compressor would be a bit
limiting, but I'm still tempted by it. I can't afford a 5 hp compressor,
and although I have the space for it now, I'm likely to be moving and
won't in the future.

I probably should have mentioned that when I talked about spraying I
didn't mean cars or trucks, I meant small stuff which I've built.
Probably I wouldn't want to spray things larger than 18" across. I can
manage without the die grinder but the Cengar saw would be nice. I
checked the Cengar website and the saw needs 5 3/4 CFM at 75-90 psi.
Perhaps I might just manage it with this compressor, or am I pushing my
luck? I figure that inflating tyres and blowing away debris would be
fine with a little compressor like this.

I was also looking at a Broomwade compressor, which is of a similar size
but I believe it is two-stage:

http://www.mythic-beasts.com/~cdt22/compressor3.jpg

I know these machines are projects in themselves, but I don't mind that.
I like their "old school" appearance and construction.

Best wishes,

Chris


I can't argue with that, Chris. As long as you don't mind using your tools
on a limited basis, there's no reason why you can't get by. You could
even sand blast with it, but not for a very long time. It's all in what you
expect. If you can get it for the right price and dedicate some time to
making it work well, using it will quickly tell you if you made the right
decision, or not. On thing is absolute------you can't have too much air at
your disposal, but you certainly can find yourself needing more than you
have. Only you will know if you're happy, or not. Good luck,
regardless of your decision. Let us hear from you and how things turned
out.

Harold

Harold and Susan Vordos wrote:
"Christopher Tidy" wrote in message
...
snip------

Thanks for the opinions. It looks like this compressor would be a bit
limiting, but I'm still tempted by it. I can't afford a 5 hp compressor,
and although I have the space for it now, I'm likely to be moving and
won't in the future.

I probably should have mentioned that when I talked about spraying I
didn't mean cars or trucks, I meant small stuff which I've built.
Probably I wouldn't want to spray things larger than 18" across. I can
manage without the die grinder but the Cengar saw would be nice. I
checked the Cengar website and the saw needs 5 3/4 CFM at 75-90 psi.
Perhaps I might just manage it with this compressor, or am I pushing my
luck? I figure that inflating tyres and blowing away debris would be
fine with a little compressor like this.

I was also looking at a Broomwade compressor, which is of a similar size
but I believe it is two-stage:

http://www.mythic-beasts.com/~cdt22/compressor3.jpg

I know these machines are projects in themselves, but I don't mind that.
I like their "old school" appearance and construction.

Best wishes,

Chris

I can't argue with that, Chris. As long as you don't mind using your tools
on a limited basis, there's no reason why you can't get by. You could
even sand blast with it, but not for a very long time. It's all in what you
expect. If you can get it for the right price and dedicate some time to
making it work well, using it will quickly tell you if you made the right
decision, or not. On thing is absolute------you can't have too much air at
your disposal, but you certainly can find yourself needing more than you
have. Only you will know if you're happy, or not. Good luck,
regardless of your decision. Let us hear from you and how things turned
out.

I'll let you know how it turns out. Thanks for all the advice and
suggestions. This compressor is cheap and only 30 miles from my home, so
there's not too much to lose if I buy it and later decide it isn't for
me. Physically it's about the largest I can accommodate (at 28" long),
but I guess I might be able to get a larger CFM rating from a more
modern machine of about the same size. I'm hoping I might be able to get
a small spray gun which will operate happily from this compressor for
little jobs. Also the saws I'm referring to were originally powered from
breathing apparatus cylinders when used by the fire service, so maybe
connecting a larger reservoir to this machine would give acceptable
performance with the saw. Also I could add a larger reservoir at a later
date. I recently spent a while restoring a vacuum pump I got free and am
very pleased with the result (perhaps I'll post some pictures here
sometime) so this is an appealing project. I'll think it over and let
you know how it works out.

Best wishes,

Chris

Christopher Tidy wrote:
Grant Erwin wrote:

Christopher Tidy wrote:

I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow
rate at atmospheric pressure, not the flow rate at the compressor's
maximum working pressure. Can someone confirm this for me?



Oh, god not again. We beat this to death and then some awhile ago,
much much flames with mucho heat but very little light. I read
thousands of lines of postings and didn't understand what the gurus
were saying. Typical specs are given at 40psi and again at 90psi, but
the way I read it none of this matters
somehow. It doesn't really matter about the theory, a decent 5hp
2-stage compressor can keep up with a die grinder, that's all I really
care about.


Well actually my thoughts were more pragmatic too. I was looking at this
second hand compressor:

http://www.mythic-beasts.com/~cdt22/compressor.jpg
http://www.mythic-beasts.com/~cdt22/compressor2.jpg

I know it's old, but I love projects. The whole thing is 28" long and
has a motor rated at 0.75 hp at 1440 rpm. There are two small air
receivers underneath you can't see. Basically I was wondering what kind
of tools I could run off it. A few things I'm interested in are paint
spraying, a die grinder, Cengar saw (a.k.a. shark saw, as used by the
fire service) and inflating tyres. At a rough guess I reckon this
machine has a flow rate of 6-8 CFM at atmospheric pressure. Any thoughts?

Best wishes,

Chris


I'll say that some compressed air is a lot better than none. When I was
a kid I had a little corn-popper compressor with about a 4 gallon tank.
I could knock 5 wheel nuts off if I loosened them all first, but if I
took three all the way off there wan't pressure enough to break the last
ones loose.. but it would air up a tire just as good as a big one..

John

JohnM wrote:
Christopher Tidy wrote:

Grant Erwin wrote:

Christopher Tidy wrote:

I've been looking at a few second air compressors. I've always
understood the volume flow rate quoted in CFM to refer to the flow
rate at atmospheric pressure, not the flow rate at the compressor's
maximum working pressure. Can someone confirm this for me?




Oh, god not again. We beat this to death and then some awhile ago,
much much flames with mucho heat but very little light. I read
thousands of lines of postings and didn't understand what the gurus
were saying. Typical specs are given at 40psi and again at 90psi, but
the way I read it none of this matters
somehow. It doesn't really matter about the theory, a decent 5hp
2-stage compressor can keep up with a die grinder, that's all I
really care about.



Well actually my thoughts were more pragmatic too. I was looking at
this second hand compressor:

http://www.mythic-beasts.com/~cdt22/compressor.jpg
http://www.mythic-beasts.com/~cdt22/compressor2.jpg

I know it's old, but I love projects. The whole thing is 28" long and
has a motor rated at 0.75 hp at 1440 rpm. There are two small air
receivers underneath you can't see. Basically I was wondering what
kind of tools I could run off it. A few things I'm interested in are
paint spraying, a die grinder, Cengar saw (a.k.a. shark saw, as used
by the fire service) and inflating tyres. At a rough guess I reckon
this machine has a flow rate of 6-8 CFM at atmospheric pressure. Any
thoughts?

Best wishes,

Chris


I'll say that some compressed air is a lot better than none. When I was
a kid I had a little corn-popper compressor with about a 4 gallon tank.
I could knock 5 wheel nuts off if I loosened them all first, but if I
took three all the way off there wan't pressure enough to break the last
ones loose.. but it would air up a tire just as good as a big one..

Thanks for another opinion, John. I'm still pondering the 3/4 hp machine
but I suspect I not going to buy it. The guy wants more than I thought,
although I'm still tempted as it looks like a nicely built machine.

By the way, can anyone summarise briefly explain the advantage of a
two-stage compressor? Do you get better performance at higher pressures?

Best wishes,

Chris

On Sat, 11 Jun 2005 23:00:26 -0400, JohnM wrote:




I'll say that some compressed air is a lot better than none. When I was
a kid I had a little corn-popper compressor with about a 4 gallon tank.
I could knock 5 wheel nuts off if I loosened them all first, but if I
took three all the way off there wan't pressure enough to break the last
ones loose.. but it would air up a tire just as good as a big one..

John
Or clean out the lint trap on the boss's automatic washer.
Gerry :-)}
London, Canada

"Christopher Tidy" wrote in message
...
snip------

By the way, can anyone summarise briefly explain the advantage of a
two-stage compressor? Do you get better performance at higher pressures?

Best wishes,

Chris

Unless you have need for the higher pressures they generate, I don't think
there are any other benefits. In my mind, it's another way to increase
storage capacity. Regardless of the size of the tank, you have more air
stored for use, so you can get more from a smaller tank. That means you
can use air longer before the compressor kicks in, but that then becomes the
limiting factor. At that point, you're limited to the capacity of the
compressor, the chief reason to not buy one that is undersized for your
needs.

Let us know how it goes, and if your decision was good for you.

Harold

Harold and Susan Vordos wrote:
"Christopher Tidy" wrote in message
...
snip------

By the way, can anyone summarise briefly explain the advantage of a
two-stage compressor? Do you get better performance at higher pressures?

Best wishes,

Chris


Unless you have need for the higher pressures they generate, I don't think
there are any other benefits. In my mind, it's another way to increase
storage capacity. Regardless of the size of the tank, you have more air
stored for use, so you can get more from a smaller tank. That means you
can use air longer before the compressor kicks in, but that then becomes the
limiting factor. At that point, you're limited to the capacity of the
compressor, the chief reason to not buy one that is undersized for your
needs.

I decided to pass on the small compressor, even though it was rather
nice. If it won't run a die grinder or Cengar saw, I won't find it too
useful. I'm not in any hurry so I'll look out for something which can
supply around 10 CFM, is nicely built and is on a trolley/can be fitted
to a trolley. We'll see what turns up.

I did also see a big twin cylinder BroomWade pump on eBay which I
thought I might be able to build into a decent compressor:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388266578

I need to keep it fairly compact, which probably means a smaller air
receiver than average. I'll keep a look out and think it over.

Thanks for the advice!

Chris

"Christopher Tidy" wrote in message
...
Harold and Susan Vordos wrote:
"Christopher Tidy" wrote in message
...
snip------

By the way, can anyone summarise briefly explain the advantage of a
two-stage compressor? Do you get better performance at higher pressures?

Best wishes,

Chris


Unless you have need for the higher pressures they generate, I don't
think
there are any other benefits. In my mind, it's another way to increase
storage capacity. Regardless of the size of the tank, you have more air
stored for use, so you can get more from a smaller tank. That means
you
can use air longer before the compressor kicks in, but that then becomes
the
limiting factor. At that point, you're limited to the capacity of the
compressor, the chief reason to not buy one that is undersized for your
needs.

I decided to pass on the small compressor, even though it was rather
nice. If it won't run a die grinder or Cengar saw, I won't find it too
useful. I'm not in any hurry so I'll look out for something which can
supply around 10 CFM, is nicely built and is on a trolley/can be fitted
to a trolley. We'll see what turns up.

I did also see a big twin cylinder BroomWade pump on eBay which I
thought I might be able to build into a decent compressor:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388266578

I need to keep it fairly compact, which probably means a smaller air
receiver than average. I'll keep a look out and think it over.

Thanks for the advice!

Chris


I can't help but think you made the right decision, Chris. I started out
with a small compressor and grew to hate it the moment I put it to serious
use. In a sense, I was lucky. One fine day the reed valve started
leaking, providing the push I felt necessary to get me to purchase a serious
compressor. I've never regretted my decision. Even if you must use a
small receiver, the compressor may very well have the capacity to run your
choices directly. That's the most important feature, at least to me.

The one on ebay looks like it has some possibilities----although I'm not
familiar in the least with that particular machine. Strangely, Chris, it
bears a strange resemblance to the Quincy (at least in color). I noticed
it has unloading valves, a very good sign of a quality compressor.

Good luck, should you bid. Let us know if you get it.

Harold

Harold and Susan Vordos wrote:
"Christopher Tidy" wrote in message
...

Harold and Susan Vordos wrote:

"Christopher Tidy" wrote in message
...
snip------


By the way, can anyone summarise briefly explain the advantage of a
two-stage compressor? Do you get better performance at higher pressures?

Best wishes,

Chris


Unless you have need for the higher pressures they generate, I don't

think

there are any other benefits. In my mind, it's another way to increase
storage capacity. Regardless of the size of the tank, you have more air
stored for use, so you can get more from a smaller tank. That means

you

can use air longer before the compressor kicks in, but that then becomes

the

limiting factor. At that point, you're limited to the capacity of the
compressor, the chief reason to not buy one that is undersized for your
needs.

I decided to pass on the small compressor, even though it was rather
nice. If it won't run a die grinder or Cengar saw, I won't find it too
useful. I'm not in any hurry so I'll look out for something which can
supply around 10 CFM, is nicely built and is on a trolley/can be fitted
to a trolley. We'll see what turns up.

I did also see a big twin cylinder BroomWade pump on eBay which I
thought I might be able to build into a decent compressor:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388266578

I need to keep it fairly compact, which probably means a smaller air
receiver than average. I'll keep a look out and think it over.

Thanks for the advice!

Chris



I can't help but think you made the right decision, Chris. I started out
with a small compressor and grew to hate it the moment I put it to serious
use. In a sense, I was lucky. One fine day the reed valve started
leaking, providing the push I felt necessary to get me to purchase a serious
compressor. I've never regretted my decision. Even if you must use a
small receiver, the compressor may very well have the capacity to run your
choices directly. That's the most important feature, at least to me.

The one on ebay looks like it has some possibilities----although I'm not
familiar in the least with that particular machine. Strangely, Chris, it
bears a strange resemblance to the Quincy (at least in color). I noticed
it has unloading valves, a very good sign of a quality compressor.

I've done a little more research on the Broomwade compressor on eBay.
It's rated at 41 CFM (one site says 32 CFM) at 150 psi. It needs a 10 hp
motor so I think it's a bit big for me, especially as I only have a
single-phase supply. I had a thought about driving it from one of those
12 hp two-cylinder Petter diesel engines, but really I don't have the
space, and I don't want to noise either. Pity though because it looks nice.

I think Broomwade were one of the top makes in the UK until they were
taken over by CompAir. Not sure what they're like now though.

I've also spotted a 2 hp / 100 psi B.E.N. compressor on eBay. I believe
B.E.N. later became Broomwade. It probably has a 100 litre tank. Do you
think I would get reasonable performance from a die grinder and shark
saw with this? I know it's a project in itself, but like I said, I enjoy
restoring equipment.

Best wishes,

Chris

we
"Christopher Tidy" wrote in message
...
Harold and Susan Vordos wrote:
snip-----

I've done a little more research on the Broomwade compressor on eBay.
It's rated at 41 CFM (one site says 32 CFM) at 150 psi. It needs a 10 hp
motor so I think it's a bit big for me, especially as I only have a
single-phase supply. I had a thought about driving it from one of those
12 hp two-cylinder Petter diesel engines, but really I don't have the
space, and I don't want to noise either. Pity though because it looks
nice.

Indeed, a pity! But that is pretty large. Assuming you had the space, and
the proper electrical service to handle it, it would be an excellent choice,
for it would handle most anything you might desire to run, including a nice
blast cabinet, but it presents some serious issues for home use. I'm not up
to speed on how things are wired in the UK, but here in the States, it would
be a tough one to run without 3 phase power. Running it on diesel could
prove to be a serious nuisance, and would be quite expensive as well. I
agree----you should seek something smaller, 5 horse max, in my opinion.

I think Broomwade were one of the top makes in the UK until they were
taken over by CompAir. Not sure what they're like now though.

I've also spotted a 2 hp / 100 psi B.E.N. compressor on eBay. I believe
B.E.N. later became Broomwade. It probably has a 100 litre tank. Do you
think I would get reasonable performance from a die grinder and shark
saw with this? I know it's a project in itself, but like I said, I enjoy
restoring equipment.

Best wishes,

Chris

Unfortunately, I'm not familiar with the shark saw of which you speak, so I
don't have an opinion, but I can't imagine you couldn't run a die grinder,
at least intermittently, with a 2 horse compressor. Frankly, I would
think that your choices begin with a 2 horse compressor, and get more
reasonable as they approach a 5 horse, so you're likely on the right track.
Perhaps someone with a 2 horse could chime in and relate their experiences.

Harold

Harold and Susan Vordos wrote:

snip-----


I've done a little more research on the Broomwade compressor on eBay.
It's rated at 41 CFM (one site says 32 CFM) at 150 psi. It needs a 10 hp
motor so I think it's a bit big for me, especially as I only have a
single-phase supply. I had a thought about driving it from one of those
12 hp two-cylinder Petter diesel engines, but really I don't have the
space, and I don't want to noise either. Pity though because it looks

nice.

Indeed, a pity! But that is pretty large. Assuming you had the space, and
the proper electrical service to handle it, it would be an excellent choice,
for it would handle most anything you might desire to run, including a nice
blast cabinet, but it presents some serious issues for home use. I'm not up
to speed on how things are wired in the UK, but here in the States, it would
be a tough one to run without 3 phase power. Running it on diesel could
prove to be a serious nuisance, and would be quite expensive as well. I
agree----you should seek something smaller, 5 horse max, in my opinion.

I think Broomwade were one of the top makes in the UK until they were
taken over by CompAir. Not sure what they're like now though.

I've also spotted a 2 hp / 100 psi B.E.N. compressor on eBay. I believe
B.E.N. later became Broomwade. It probably has a 100 litre tank. Do you
think I would get reasonable performance from a die grinder and shark
saw with this? I know it's a project in itself, but like I said, I enjoy
restoring equipment.

Best wishes,

Chris


Unfortunately, I'm not familiar with the shark saw of which you speak, so I
don't have an opinion, but I can't imagine you couldn't run a die grinder,
at least intermittently, with a 2 horse compressor. Frankly, I would
think that your choices begin with a 2 horse compressor, and get more
reasonable as they approach a 5 horse, so you're likely on the right track.
Perhaps someone with a 2 horse could chime in and relate their experiences.

Sorry, forgot the link. This is the 2 hp compressor I was looking at:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388671359

I've just had a nasty thought about it though. The seller says it has a
2850 rpm 2 hp motor. Is there any chance a 1 hp 1425 rpm motor could
have been replaced with a 2850 rpm 2 hp motor to increase the output?
I've never seen a compressor with a 2850 rpm motor before. Apparently
this machine is 2 cylinder and each cylinder is 2" bore by 2" stroke.
Also the receiver looks a little rusty, but the machine is cheap. Might
want to get a hydro test on it?

I'll think about the big Broomwade compressor. I have no problem with a
5 kW welding set in our workshop, so I might get away with a 10 hp
compressor. It would have to have a small receiver though. Will think it
over. Fortunately I'm not in a hurry...

By the way, the saws are made by www.cengar.co.uk and are cheap because
the fire service are selling loads. They need 5 3/4 cfm at 75-90 psi.

Best wishes,

Chris

Sorry, forgot the link. This is the 2 hp compressor I was looking at:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388671359

I've just had a nasty thought about it though. The seller says it has a
2850 rpm 2 hp motor. Is there any chance a 1 hp 1425 rpm motor could
have been replaced with a 2850 rpm 2 hp motor to increase the output?
I've never seen a compressor with a 2850 rpm motor before. Apparently
this machine is 2 cylinder and each cylinder is 2" bore by 2" stroke.
Also the receiver looks a little rusty, but the machine is cheap. Might
want to get a hydro test on it?

Thinking about it again this morning I think I'll pass on this one too.
Looks a bit too dodgy even for me!

Chris

Sorry, forgot the link. This is the 2 hp compressor I was looking at:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388671359

I've just had a nasty thought about it though. The seller says it has a
2850 rpm 2 hp motor. Is there any chance a 1 hp 1425 rpm motor could
have been replaced with a 2850 rpm 2 hp motor to increase the output?
I've never seen a compressor with a 2850 rpm motor before. Apparently
this machine is 2 cylinder and each cylinder is 2" bore by 2" stroke.
Also the receiver looks a little rusty, but the machine is cheap. Might
want to get a hydro test on it?

Thinking about it again this morning I reckon I'll pass on this one too.
It looks just a bit too dodgy, even for me!

Chris

"Christopher Tidy" wrote in message
...
Harold and Susan Vordos wrote:
snip-

Unfortunately, I'm not familiar with the shark saw of which you speak,
so I
don't have an opinion, but I can't imagine you couldn't run a die
grinder,
at least intermittently, with a 2 horse compressor. Frankly, I would
think that your choices begin with a 2 horse compressor, and get more
reasonable as they approach a 5 horse, so you're likely on the right
track.
Perhaps someone with a 2 horse could chime in and relate their
experiences.

Sorry, forgot the link. This is the 2 hp compressor I was looking at:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388671359

I've just had a nasty thought about it though. The seller says it has a
2850 rpm 2 hp motor. Is there any chance a 1 hp 1425 rpm motor could
have been replaced with a 2850 rpm 2 hp motor to increase the output?
I've never seen a compressor with a 2850 rpm motor before. Apparently
this machine is 2 cylinder and each cylinder is 2" bore by 2" stroke.
Also the receiver looks a little rusty, but the machine is cheap. Might
want to get a hydro test on it?

You certainly have a good point. I looked to see if the driven pulley was
evident in the picture, and it isn't. Makes one think it very well could
have been replaced with a smaller one, or it has, indeed, had a faster motor
installed. I have no idea how you would know unless you could find a like
compressor, or literature pertaining to it.

A hydro would probably be a good idea for any pressure vessel that is old,
although I'm not following my own thoughts. I have never pressure tested my
tank, and it's over 35 years old now. Shame on me! They are known to
fail catastrophically, although not routinely.


I'll think about the big Broomwade compressor. I have no problem with a
5 kW welding set in our workshop, so I might get away with a 10 hp
compressor. It would have to have a small receiver though. Will think it
over. Fortunately I'm not in a hurry...

Finding the appropriate motor would be my only concern under that
circumstance. You'd never regret having the large compressor, of that I'm
quite sure.

By the way, the saws are made by www.cengar.co.uk and are cheap because
the fire service are selling loads. They need 5 3/4 cfm at 75-90 psi.

Best wishes,

Chris


Armed with that information, I can't imagine a 2 horse wouldn't power it
well, although the compressor may have to work almost full time. My 5
horse is rated @ 19+ CFM @ 175 PSI. Assuming it would produce 2/5 of the
output mine does, it would be well within specs. Still, overall, you'd be
happier with the larger head, long term. Besides, if you like to restore
old things, you'd really enjoy a blast cabinet. It's one of the better
ways to remove rust or old paint. I use mine routinely for such things.
I've owned a blast cabinet for something like 35 years and wouldn't be
without one. I use either glass beads, or aluminum oxide, each of which
does an outstanding job, depending on what I'm trying to accomplish.

Nice looking saw, by the way. Very much like the Milwaukee Sawzall, only
it's electric instead of air.

Harold

"Christopher Tidy" wrote in message
...
Sorry, forgot the link. This is the 2 hp compressor I was looking at:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388671359

I've just had a nasty thought about it though. The seller says it has a
2850 rpm 2 hp motor. Is there any chance a 1 hp 1425 rpm motor could
have been replaced with a 2850 rpm 2 hp motor to increase the output?
I've never seen a compressor with a 2850 rpm motor before. Apparently
this machine is 2 cylinder and each cylinder is 2" bore by 2" stroke.
Also the receiver looks a little rusty, but the machine is cheap. Might
want to get a hydro test on it?

Thinking about it again this morning I think I'll pass on this one too.
Looks a bit too dodgy even for me!

Chris


I'm cheering for the 10 horse unit, Chris, if you think you can make it
work.

Harold

On Tue, 14 Jun 2005 20:25:54 +0000 (UTC), Christopher Tidy
wrote:



The one on ebay looks like it has some possibilities----although I'm not
familiar in the least with that particular machine. Strangely, Chris, it
bears a strange resemblance to the Quincy (at least in color). I noticed
it has unloading valves, a very good sign of a quality compressor.

I've done a little more research on the Broomwade compressor on eBay.
It's rated at 41 CFM (one site says 32 CFM) at 150 psi. It needs a 10 hp
motor so I think it's a bit big for me, especially as I only have a
single-phase supply. I had a thought about driving it from one of those
12 hp two-cylinder Petter diesel engines, but really I don't have the
space, and I don't want to noise either. Pity though because it looks nice.

I think Broomwade were one of the top makes in the UK until they were
taken over by CompAir. Not sure what they're like now though.

I've also spotted a 2 hp / 100 psi B.E.N. compressor on eBay. I believe
B.E.N. later became Broomwade. It probably has a 100 litre tank. Do you
think I would get reasonable performance from a die grinder and shark
saw with this? I know it's a project in itself, but like I said, I enjoy
restoring equipment.

You can always run a large pump more slowly with a smaller motor
pulley or maybe a jackshaft. Larger pumps running more slowly tend
to be more efficient, providing that friction and leaks aren't
excessive.

The 41 CFM is probably displacement, the 32 CFM delivered SCFM at
rated pressure. This could be a nice unit with a 3 to 5 HP motor.
5 hp 220-volt single-phase motors are readily available. Even with 3
HP I think you'd have puhlenty of air with the Broom & Wade.

Lower speed operation is also usually quieter.

On Wed, 15 Jun 2005 06:18:48 +0000 (UTC), Christopher Tidy
wrote:

Sorry, forgot the link. This is the 2 hp compressor I was looking at:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=4388671359

I've just had a nasty thought about it though. The seller says it has a
2850 rpm 2 hp motor. Is there any chance a 1 hp 1425 rpm motor could
have been replaced with a 2850 rpm 2 hp motor to increase the output?
I've never seen a compressor with a 2850 rpm motor before. Apparently
this machine is 2 cylinder and each cylinder is 2" bore by 2" stroke.
Also the receiver looks a little rusty, but the machine is cheap. Might
want to get a hydro test on it?

Thinking about it again this morning I think I'll pass on this one too.
Looks a bit too dodgy even for me!

A 2850 RPM compressor will drive you bonkers with its noise.

"Don Foreman" wrote in message
...
On Tue, 14 Jun 2005 20:25:54 +0000 (UTC), Christopher Tidy
wrote:



The one on ebay looks like it has some possibilities----although I'm
not
familiar in the least with that particular machine. Strangely, Chris,
it
bears a strange resemblance to the Quincy (at least in color). I
noticed
it has unloading valves, a very good sign of a quality compressor.

I've done a little more research on the Broomwade compressor on eBay.
It's rated at 41 CFM (one site says 32 CFM) at 150 psi. It needs a 10 hp
motor so I think it's a bit big for me, especially as I only have a
single-phase supply. I had a thought about driving it from one of those
12 hp two-cylinder Petter diesel engines, but really I don't have the
space, and I don't want to noise either. Pity though because it looks
nice.

I think Broomwade were one of the top makes in the UK until they were
taken over by CompAir. Not sure what they're like now though.

I've also spotted a 2 hp / 100 psi B.E.N. compressor on eBay. I believe
B.E.N. later became Broomwade. It probably has a 100 litre tank. Do you
think I would get reasonable performance from a die grinder and shark
saw with this? I know it's a project in itself, but like I said, I enjoy
restoring equipment.

You can always run a large pump more slowly with a smaller motor
pulley or maybe a jackshaft. Larger pumps running more slowly tend
to be more efficient, providing that friction and leaks aren't
excessive.

The 41 CFM is probably displacement, the 32 CFM delivered SCFM at
rated pressure. This could be a nice unit with a 3 to 5 HP motor.
5 hp 220-volt single-phase motors are readily available. Even with 3
HP I think you'd have puhlenty of air with the Broom & Wade.

Lower speed operation is also usually quieter.

Absolutely! One of the things I really hated about my first compressor was
the fact that it ran fast and was terribly noisy.. It was more noisy at
3/4 hp than the 5 horse Quincy. Slow is definitely better.

Harold

I've used Broomwade compressors in the past and found them very reliable.
If the price is good enough, you could replace the motor on the compressor
with one that is as big as you can power, then adjust the speed of the
compressor by selecting pulleys to load the motor fully. As long as you
have sufficient speed to pump the lubricating oil, it will last for ever at
the lower speed. ( It will also be quieter than a high speed compressor)
You might try getting onto Compair and ask them for the minimum speed and
horsepower requirements at that speed.

Tom


"Harold and Susan Vordos" wrote in message
...
we
"Christopher Tidy" wrote in message
...
Harold and Susan Vordos wrote:
snip-----

I've done a little more research on the Broomwade compressor on eBay.
It's rated at 41 CFM (one site says 32 CFM) at 150 psi. It needs a 10 hp
motor so I think it's a bit big for me, especially as I only have a
single-phase supply. I had a thought about driving it from one of those
12 hp two-cylinder Petter diesel engines, but really I don't have the
space, and I don't want to noise either. Pity though because it looks
nice.

Indeed, a pity! But that is pretty large. Assuming you had the space,
and
the proper electrical service to handle it, it would be an excellent
choice,
for it would handle most anything you might desire to run, including a
nice
blast cabinet, but it presents some serious issues for home use. I'm not
up
to speed on how things are wired in the UK, but here in the States, it
would
be a tough one to run without 3 phase power. Running it on diesel could
prove to be a serious nuisance, and would be quite expensive as well. I
agree----you should seek something smaller, 5 horse max, in my opinion.

I think Broomwade were one of the top makes in the UK until they were
taken over by CompAir. Not sure what they're like now though.

I've also spotted a 2 hp / 100 psi B.E.N. compressor on eBay. I believe
B.E.N. later became Broomwade. It probably has a 100 litre tank. Do you
think I would get reasonable performance from a die grinder and shark
saw with this? I know it's a project in itself, but like I said, I enjoy
restoring equipment.

Best wishes,

Chris

Unfortunately, I'm not familiar with the shark saw of which you speak, so
I
don't have an opinion, but I can't imagine you couldn't run a die grinder,
at least intermittently, with a 2 horse compressor. Frankly, I would
think that your choices begin with a 2 horse compressor, and get more
reasonable as they approach a 5 horse, so you're likely on the right
track.
Perhaps someone with a 2 horse could chime in and relate their
experiences.

Harold

Tom Miller wrote:
I've used Broomwade compressors in the past and found them very reliable.
If the price is good enough, you could replace the motor on the compressor
with one that is as big as you can power, then adjust the speed of the
compressor by selecting pulleys to load the motor fully. As long as you
have sufficient speed to pump the lubricating oil, it will last for ever at
the lower speed. ( It will also be quieter than a high speed compressor)
You might try getting onto Compair and ask them for the minimum speed and
horsepower requirements at that speed.

Tom

I gave CompAir a call and they were very helpful. They sent me a full
specification sheet for the BroomWade AC41 compressor. The minimum
acceptable speed is 460 rpm, whereas the normal speed is 710 rpm. Using
the table in the specification sheet I would need 5.3 hp to drive it at
460 rpm with a delivery pressure of 120 psi. This would give me 15.7
cfm. Probably I would need a 7 hp motor to be safe.

I think unfortunately 7 hp is pushing it from our single phase supply.
At the absolute maximum we can get 230 V 45 A. I know this is about 10
kW but I suspect the motor will overload the supply when starting. My 5
kW welding set makes the lights go dim in the house. I also spoke to a
helpful guy at a local compressor repair shop who thought I'd be pushing
my luck to drive this machine from a single phase supply. If I had a
three phase supply I'd jump at it because it would be a cheap way to get
a big compressor, but I think the only way I could power it here is with
a diesel engine. If I'm going to have a diesel compressor I might as
well buy a jackhammer compressor and have the convenience of being able
to tow it around. Unfortunately it seems just a bit too big!

I did spot this Bristol compressor on eBay which looks nice though, and
I've e-mailed the seller for a few more details:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=7980508669

This compressor is probably a more manageable size, but it's a pity it
isn't vertical.

I think I'm probably needing a compressor in the 2-4 hp range. Harold,
I'm interested in your suggestion about a blast cabinet. I probably
can't afford one now but would be interested in buying one in the
future. How much air does a small blast cabinet need? I've also always
wanted to have a go at hot riveting using an air hammer (hot riveted
benches and chassis look so nice), so you can see I'm thinking of more
uses for a compressor all the time. I also found an Ingersoll-Rand die
grinder which apparently consumes 43 cfm! This is probably extreme, but
I see your point about lots of air being useful.

Thanks for all the suggestions.

Best wishes,

Chris

Just another quick question. On the Bristol compressor I spotted on eBay
I see a pipe leading from the crankcase to the cylinder.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=7980508669

Anyone know what this is for? Is it for pressure lubrication or does it
mean the compressor is double-acting? Just curious.

Best wishes,

Chris

Christopher Tidy wrote:
Just another quick question. On the Bristol compressor I spotted on eBay
I see a pipe leading from the crankcase to the cylinder.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=7980508669

Anyone know what this is for? Is it for pressure lubrication or does it
mean the compressor is double-acting? Just curious.

Best wishes,

Chris

something to do with the shutoff, mine has the same

On Fri, 17 Jun 2005 19:33:31 +0000 (UTC), Christopher Tidy
wrote:

Just another quick question. On the Bristol compressor I spotted on eBay
I see a pipe leading from the crankcase to the cylinder.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=7980508669

Anyone know what this is for? Is it for pressure lubrication or does it
mean the compressor is double-acting? Just curious.

No, that looks like a single-stage compressor. The line might be a
simple gear pump to squirt oil up under the piston skirt, or it might
be for a centrifugal unloader. When the motor gets up to speed and
the oil pressure comes up in the compressor, the oil pressure allows
the intake valve to close and then it starts pumping.

One post up in the thread, Christopher wrote:

I think unfortunately 7 hp is pushing it from our single phase supply.
At the absolute maximum we can get 230 V 45 A. I know this is about 10
kW but I suspect the motor will overload the supply when starting. My 5
kW welding set makes the lights go dim in the house.

A 240V single-phase 45A service in the UK would translate to a bit
smaller than the USA small residence service for a old house, where
you get 120/240V at 50 to 70 amps or so. Definitely NOT enough to run
any sort of home shop equipment from at the same time there are
residence-type loads being run.

Let the Missus ;-) start doing a few loads of laundry (washer,
dryer, iron), start lunch (toaster) and run the air conditioning, and
when the 5-HP motor for the air compressor kicks on out in the garage
you are going to pop the Main.

You might have to break down and do a service upgrade on your house,
or if you are renting you might have to find a new house with a more
modern service. Or talk the landlord of your existing rental house
into doing the service upgrade, and you figure out an equitable split
of the electrician's bill with him - you get the extra power to use
while you are living there, and it is an improvement that will raise
the property value.

(I'd make sure the lease has enough time to run that you get your
investment back through usage, or agree on a pro-rated buy-out of your
part of the investment if he wants to terminate a lease or a
month-to-month rental agreement before three to five years pass.)

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

"Christopher Tidy" wrote in message
...
snip----

Harold,
I'm interested in your suggestion about a blast cabinet. I probably
can't afford one now but would be interested in buying one in the
future. How much air does a small blast cabinet need? I've also always
wanted to have a go at hot riveting using an air hammer (hot riveted
benches and chassis look so nice), so you can see I'm thinking of more
uses for a compressor all the time. I also found an Ingersoll-Rand die
grinder which apparently consumes 43 cfm! This is probably extreme, but
I see your point about lots of air being useful.

Thanks for all the suggestions.

Best wishes,

Chris


My cabinet isn't real large----20" deep and 31" wide. It has a small gun
with a carbide nozzle, which I recommend highly. Ceramic nozzles have a very
short life span, especially when blasting with aluminum oxide. Much better
life with glass beads, however. This small cabinet keeps my 5 horse
compressor running almost continually when I have my regulator set at
approximately 100 PSI. (For your convenience, the compressor is rated @
19+CFM @ 175 PSI). Using that as a guide, I'd suggest you not go under a
serious 4 horse compressor unless you don't mind blasting for a while, then
allowing your tank to recharge. You'd likely use air faster than you could
provide it. Search your soul well and decide how large you can possibly
accommodate, and make sure you can buy a single phase motor to power it.
Large single phase motors can be a serious problem, both in current demand,
and in availability. You reach a point where 3 phase becomes almost
mandatory.

Harold

"Christopher Tidy" wrote in message
...
Just another quick question. On the Bristol compressor I spotted on eBay
I see a pipe leading from the crankcase to the cylinder.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=7980508669

Anyone know what this is for? Is it for pressure lubrication or does it
mean the compressor is double-acting? Just curious.

Best wishes,

Chris


I can't imagine it's for a double action, but I can't see a good reason for
it, either. Smaller hydraulic lines typically run to unloading valves, but
I can't see how this one would work in that capacity, although it could have
some strange internal porting. I'd be interested in learning what
purpose it serves.

Harold

Bruce L. Bergman wrote:
On Fri, 17 Jun 2005 19:33:31 +0000 (UTC), Christopher Tidy
wrote:


Just another quick question. On the Bristol compressor I spotted on eBay
I see a pipe leading from the crankcase to the cylinder.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=7980508669

Anyone know what this is for? Is it for pressure lubrication or does it
mean the compressor is double-acting? Just curious.


No, that looks like a single-stage compressor. The line might be a
simple gear pump to squirt oil up under the piston skirt, or it might
be for a centrifugal unloader. When the motor gets up to speed and
the oil pressure comes up in the compressor, the oil pressure allows
the intake valve to close and then it starts pumping.

One post up in the thread, Christopher wrote:


I think unfortunately 7 hp is pushing it from our single phase supply.
At the absolute maximum we can get 230 V 45 A. I know this is about 10
kW but I suspect the motor will overload the supply when starting. My 5
kW welding set makes the lights go dim in the house.


A 240V single-phase 45A service in the UK would translate to a bit
smaller than the USA small residence service for a old house, where
you get 120/240V at 50 to 70 amps or so. Definitely NOT enough to run
any sort of home shop equipment from at the same time there are
residence-type loads being run.

To clarify, the 45 A supply is for the workshop only. However, the 45 A
is drawn from a 100 A supply in the house.

Best wishes,

Chris

Harold and Susan Vordos wrote:
"Christopher Tidy" wrote in message
...
snip----

Harold,

I'm interested in your suggestion about a blast cabinet. I probably
can't afford one now but would be interested in buying one in the
future. How much air does a small blast cabinet need? I've also always
wanted to have a go at hot riveting using an air hammer (hot riveted
benches and chassis look so nice), so you can see I'm thinking of more
uses for a compressor all the time. I also found an Ingersoll-Rand die
grinder which apparently consumes 43 cfm! This is probably extreme, but
I see your point about lots of air being useful.

Thanks for all the suggestions.

Best wishes,

Chris



My cabinet isn't real large----20" deep and 31" wide. It has a small gun
with a carbide nozzle, which I recommend highly. Ceramic nozzles have a very
short life span, especially when blasting with aluminum oxide. Much better
life with glass beads, however. This small cabinet keeps my 5 horse
compressor running almost continually when I have my regulator set at
approximately 100 PSI. (For your convenience, the compressor is rated @
19+CFM @ 175 PSI). Using that as a guide, I'd suggest you not go under a
serious 4 horse compressor unless you don't mind blasting for a while, then
allowing your tank to recharge. You'd likely use air faster than you could
provide it. Search your soul well and decide how large you can possibly
accommodate, and make sure you can buy a single phase motor to power it.
Large single phase motors can be a serious problem, both in current demand,
and in availability. You reach a point where 3 phase becomes almost
mandatory.

Thanks for the information. I reckon 4 hp is the most I can power from
my supply. I'm tempted by that Bristol compressor on eBay. It's cheap
and the seller seems pretty knowledgeable. He said he bought it with the
intention of fitting a single phase motor, but never found a suitable
motor. Apparently he tried a 3/4 hp motor but it wasn't big enough. The
receiver is 150 litres, so I'm guessing it might need a 2 hp motor? In
terms of dimensions I don't want anything much larger than this, but
maybe I should keep searching for a vertical machine. Will keep thinking...

Thanks for the help,

Chris

"Christopher Tidy" wrote in message
...
snip-----

Thanks for the information. I reckon 4 hp is the most I can power from
my supply. I'm tempted by that Bristol compressor on eBay. It's cheap
and the seller seems pretty knowledgeable. He said he bought it with the
intention of fitting a single phase motor, but never found a suitable
motor. Apparently he tried a 3/4 hp motor but it wasn't big enough. The
receiver is 150 litres, so I'm guessing it might need a 2 hp motor? In
terms of dimensions I don't want anything much larger than this, but
maybe I should keep searching for a vertical machine. Will keep
thinking...

Thanks for the help,

Chris


Don't confuse receiver size with horsepower requirements, Chris. What
matters is the power it takes to spin the compressor at a given speed.
Receiver size dictates how long the compressor will run to build turn-off
pressure, nothing else. By cautious when making your choice.

Harold