--===============8666431353813871573==
--000000000000148d5c05c9488a98
1. What really controls how much a comperssor can generate, ie. SCFM?
Mostly the amperage of the motor and the design of the pump. You can ignore
the HP ratings for the most part and just look at the current draw assuming
you are looking at the same voltage (e.g., 220VAC). Some pumps are more
efficient, but mostly the power of the motor will determine what size pump
and how fast you can spin it, which will determine the CFM.
2. What controls how long your compressor can supply air before having to
start
the motor to refill the tank? I realize that some air tools use a LOT more
air, but
I'm speaking for any given tool, not compairing something like spray
painting to
undoing 5 lugnuts on a car.
Here it is just the storage capacity of the tank minus the continuous draw
of the tool. Larger tanks will require less frequent pump cycling with the
same amount of draw than would a smaller tank.
3. Why is a bigger tank better? After the compressor's pressure switch
kicks on,
doesn't it take longer for the compressor to reach the shut off pressure
with a
larger tank?
See above, but the larger the tank, generally the longer the motor off
cycles against a similar load. Think of it like a battery in a cordless
drill. the larger the battery, the longer it will run before it needs to be
recharged. The same metaphor works for the pump and the tank.
4. How can a 1.7 hp compressor deliver a peek of 175 psi and a regulated
155 psi
when my 5 hp can only charge to 125 psi. I realize part of that is due to
the
pressure switch, mine is 110 on - 125 off, but really. Can I put a
pressure switch in mine and 175 psi. I don't really think so. Is this
more advertising hype like
when they were rating compressors at their starting current vs running
current for
hp? They could get 7hp of of a 110V motor - NOT!
Most compressors with a 175 psi rating are dual stage, a primary and a
secondary piston or sets of piston. The first piston compresses the air to
125 psi and the second one to 175 psi. Most single stage pumps are limited
to 125 -135 psi. One advantage of a two-stage pump is that by compressing
the air to 175 psi, you increase the amount of compressed air stored in a
given size tank. One achieves about 40% more stored compressed air in a
tank if the pump is capable of 175 psi vs. 125 psi. The single stage pumps
generally are lower cost than the dual stage pumps.
You should not try to increase your psi rating by changing the limit
switch, The psi rating is determined by the design of the pump.
Again, the best rating for the power of the motor is the continuous
amperage rating. The start-up amperage will be significantly higher. Ignore
the HP rating for the most part.
best ,
Doug
On Tue, Aug 10, 2021 at 7:58 PM John T. Blair <jblair1948@cox.net> wrote:
> At 02:59 PM 8/10/2021, Mark Andy wrote:
>
> >If I were buying a compressor today and the air requirements were modest,
> I
> >would be looking HARD at one of the super quiet compressor types that are
> >available now.
>
> Again thanks to everyone. Mark mentions the harbor freight compressor:
>
>
> https://www.harborfreight.com/26-gallon-175-psi-ultra-quiet-vertical-shopauto-air-compressor-57336.html
>
> Looking at it's basic specs, it is only rated at 4.5 SCFM @ 90PSI. My
> compressor
> is rated at 9.3 SCFM @ 90 PSI. I've have used my compressor for
> everything
> from painting cars, sanding, impact hammers, die grinders, and both media
> blasting
> cabinets & pressure blasting. And I'm always running out of air and
> stopping to let
> the compressor catch up.
>
> So that brings up more questions:
>
> 1. What really controls how much a comperssor can generate, ie. SCFM?
>
> 2. What controls how long your compressor can supply air before having to
> start
> the motor to refill the tank? I realize that some air tools use a LOT
> more air, but
> I'm speaking for any given tool, not compairing something like spray
> painting to
> undoing 5 lugnuts on a car.
>
> 3. Why is a bigger tank better? After the compressor's pressure switch
> kicks on,
> doesn't it take longer for the compressor to reach the shut off pressure
> with a
> larger tank?
>
> 4. How can a 1.7 hp compressor deliver a peek of 175 psi and a regulated
> 155 psi
> when my 5 hp can only charge to 125 psi. I realize part of that is due to
> the
> pressure switch, mine is 110 on - 125 off, but really. Can I put a
> pressure switch in mine and 175 psi. I don't really think so. Is this
> more advertising hype like
> when they were rating compressors at their starting current vs running
> current for
> hp? They could get 7hp of of a 110V motor - NOT!
>
> John
>
>
>
> ------------------------------
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>
> John T. Blair WA4OHZ email: jblair1948@cox.net
> Va. Beach, Va Phone: (757) 495-8229
>
> 48 TR1800 48 #4 Midget 65 Morgan 4/4 Series V (B1106)
> 75 Bricklin SV1 (#0887) 77 Spitfire 71 Saab Sonett III
> 65 Rambler Classic
>
> Morgan: www.team.net/morgan
> Bricklin: www.bricklin.org
>
> If you can read this - Thank a teacher!
> If you are reading it in English - Thank a Vet!!
>
> From Dennis Prager - The American Trilogy:
> e pluribus Unum, "from many, one."
> In God We Trust
> Liberty - the power of choosing, thinking, and acting for
> oneself; freedom from control or restriction
>
>
> _______________________________________________
>
> Shop-talk@autox.team.net
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>
>
--000000000000148d5c05c9488a98
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><br style=3D"font-size:medium"><span style=3D"font-size:me=
dium">1. What really controls how much a comperssor can generate, ie. SCFM?=
</span><div><br></div><div>Mostly the amperage of the motor and the design =
of the pump. You can ignore the HP ratings for the most part and just look =
at the current draw assuming you are looking at the same voltage (e.g., 220=
VAC). Some pumps are more efficient, but mostly the power of the motor will=
determine what size pump and how fast you can spin it, which will determin=
e the CFM.<br style=3D"font-size:medium"><br style=3D"font-size:medium"><sp=
an style=3D"font-size:medium">2. What controls how long your compressor can=
supply air before having to start</span><br style=3D"font-size:medium"><sp=
an style=3D"font-size:medium">the motor to refill the tank?=C2=A0 I realize=
that some air tools use a LOT more air, but</span><br style=3D"font-size:m=
edium"><span style=3D"font-size:medium">I'm speaking for any given tool=
, not compairing something like spray painting to</span><br style=3D"font-s=
ize:medium"><span style=3D"font-size:medium">undoing 5 lugnuts on a car.=C2=
=A0</span></div><div>Here it is just the storage capacity of the tank minus=
the continuous draw of the tool. Larger tanks will require less frequent p=
ump cycling with the same amount of draw than would a smaller tank.<br styl=
e=3D"font-size:medium"><br style=3D"font-size:medium"><span style=3D"font-s=
ize:medium">3. Why is a bigger tank better?=C2=A0 After the compressor'=
s pressure switch kicks on,</span><br style=3D"font-size:medium"><span styl=
e=3D"font-size:medium">doesn't it take longer for the compressor to rea=
ch the shut off pressure with a</span><br style=3D"font-size:medium"><span =
style=3D"font-size:medium">larger tank?</span></div><div>See above, but the=
larger the tank, generally the longer the motor off cycles against a simil=
ar load. Think of it like a battery in a cordless drill. the larger the bat=
tery, the longer it will run before it needs to be recharged. The same meta=
phor works for the pump and the tank.=C2=A0<br style=3D"font-size:medium"><=
br style=3D"font-size:medium"><span style=3D"font-size:medium">4. How can a=
1.7 hp compressor deliver a peek of 175 psi and a regulated 155 psi</span>=
<br style=3D"font-size:medium"><span style=3D"font-size:medium">when my 5 h=
p can only charge to 125 psi.=C2=A0 I realize part of that is due to the</s=
pan><br style=3D"font-size:medium"><span style=3D"font-size:medium">pressur=
e switch, mine is 110 on - 125 off, but really.=C2=A0 Can I put a pressure =
switch in mine and 175 psi.=C2=A0=C2=A0 I don't really think so.=C2=A0 =
Is this more advertising hype like</span><br style=3D"font-size:medium"><sp=
an style=3D"font-size:medium">when they were rating compressors at their st=
arting current vs running current for</span><br style=3D"font-size:medium">=
<span style=3D"font-size:medium">hp?=C2=A0 They could get 7hp of of a 110V =
motor - NOT!=C2=A0</span></div><div><span style=3D"font-size:medium"><br></=
span></div><div>Most compressors with a 175 psi rating are dual stage, a pr=
imary and a secondary piston or sets of piston. The first piston compresses=
the air to 125 psi and the second one to 175 psi. Most single stage pumps =
are limited to 125 -135 psi. One advantage of a two-stage pump is that by c=
ompressing the air to 175 psi, you increase the amount of compressed air st=
ored in a given size tank.=C2=A0 One achieves about 40% more stored compres=
sed air in a tank if the pump is capable of 175 psi vs. 125 psi. The single=
stage pumps generally are lower cost than the dual stage pumps.</div><div>=
<br></div><div>You should not try to increase your psi rating by changing t=
he limit switch, The psi rating is determined by the design of the pump.=C2=
=A0</div><div>Again, the best rating for the power of the motor is the cont=
inuous amperage rating. The start-up amperage will be significantly higher.=
Ignore the HP rating for the most part.</div><div><br></div><div>best ,</d=
iv><div>Doug</div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" cla=
ss=3D"gmail_attr">On Tue, Aug 10, 2021 at 7:58 PM John T. Blair <<a href=
=3D"mailto:jblair1948@cox.net";>jblair1948@cox.net</a>> wrote:<br></div><=
blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-l=
eft:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<font size=3D"3">At 02:59 PM 8/10/2021, Mark Andy wrote:<br><br>
>If I were buying a compressor today and the air requirements were
modest, I<br>
>would be looking HARD at one of the super quiet compressor types that
are <br>
>available now.<br><br>
Again thanks to everyone.=C2=A0 Mark mentions the harbor freight
compressor:<br><br>
<a href=3D"https://www.harborfreight.com/26-gallon-175-psi-ultra-quiet-vert=
ical-shopauto-air-compressor-57336.html" target=3D"_blank">
https://www.harborfreight.com/26-gallon-175-psi-ultra-quiet-vertical-shopau=
to-air-compressor-57336.html</a>
<br><br>
Looking at it's basic specs, it is only rated at=C2=A0 4.5 SCFM @
90PSI.=C2=A0 My compressor<br>
is rated at=C2=A0 9.3 SCFM @ 90 PSI.=C2=A0 I've have used my compressor
for everything <br>
from painting cars, sanding, impact hammers, die grinders, and both media
blasting <br>
cabinets & pressure blasting.=C2=A0 And I'm always running out of a=
ir
and stopping to let<br>
the compressor catch up.<br><br>
So that brings up more questions:<br><br>
1. What really controls how much a comperssor can generate, ie.
SCFM?<br><br>
2. What controls how long your compressor can supply air before having to
start <br>
the motor to refill the tank?=C2=A0 I realize that some air tools use a
LOT more air, but<br>
I'm speaking for any given tool, not compairing something like spray
painting to <br>
undoing 5 lugnuts on a car.=C2=A0 <br><br>
3. Why is a bigger tank better?=C2=A0 After the compressor's pressure
switch kicks on, <br>
doesn't it take longer for the compressor to reach the shut off pressur=
e
with a <br>
larger tank?<br><br>
4. How can a 1.7 hp compressor deliver a peek of 175 psi and a regulated
155 psi <br>
when my 5 hp can only charge to 125 psi.=C2=A0 I realize part of that is
due to the <br>
pressure switch, mine is 110 on - 125 off, but really.=C2=A0 Can I put a
pressure switch in mine and 175 psi.=C2=A0=C2=A0 I don't really think
so.=C2=A0 Is this more advertising hype like <br>
when they were rating compressors at their starting current vs running
current for <br>
hp?=C2=A0 They could get 7hp of of a 110V motor - NOT!<br><br>
John<br><br>
</font><div id=3D"gmail-m_8777314284171356316DAB4FAD8-2DD7-40BB-A1B8-4E2AA1=
F9FDF2">
<br><br>
<hr style=3D"border:none;color:rgb(144,144,144);background-color:rgb(176,17=
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style=3D"color:rgb(61,77,90);font-family:Calibri,Verdana,Arial,Helvet=
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This email has been checked for viruses by
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</tbody></table>
<br>
<a href=3D"#m_8777314284171356316_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" wid=
th=3D"1" height=3D"1"> </a></div></div>
<br>
<div>John T. Blair=C2=A0 WA4OHZ=C2=A0=C2=A0=C2=A0=C2=A0 email:=C2=A0
<a href=3D"mailto:jblair1948@cox.net"; target=3D"_blank">jblair1948@cox.net<=
/a></div>
<div>Va. Beach,
Va=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0
Phone:=C2=A0 (757) 495-8229</div>
<br>
<div>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 48
TR1800=C2=A0=C2=A0=C2=A0 48 #4 Midget=C2=A0=C2=A0=C2=A0 65 Morgan 4/4
Series V (B1106)</div>
<div>=C2=A0=C2=A0=C2=A0=C2=A0 75 Bricklin SV1 (#0887)=C2=A0=C2=A0=C2=A0
77 Spitfire=C2=A0=C2=A0=C2=A0 71 Saab Sonett III</div>
<div>
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0
65 Rambler Classic</div>
<br>
<div>Morgan:=C2=A0=C2=A0=C2=A0
<a href=3D"http://www.team.net/morgan"; target=3D"_blank">
www.team.net/morgan</a></div>
<div>Bricklin:=C2=A0=C2=A0=C2=A0=C2=A0
<a href=3D"http://www.bricklin.org/"; target=3D"_blank">www.bricklin.org</a>
</div>
<br>
<div>If you can read
this=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0
- Thank a teacher!</div>
<div>If you are reading it in English - Thank a Vet!!</div>
<br>
<div> From Dennis Prager - The American Trilogy:</div>
<div>=C2=A0=C2=A0=C2=A0=C2=A0 e pluribus Unum, "from many,
one."</div>
<div>=C2=A0=C2=A0=C2=A0=C2=A0 In God We Trust</div>
<div>=C2=A0=C2=A0=C2=A0=C2=A0 Liberty - the=C2=A0 power=C2=A0 of=C2=A0
choosing,=C2=A0 thinking,=C2=A0 and=C2=A0 acting=C2=A0 for=C2=A0 </div>
<div>
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0
oneself; freedom=C2=A0 from=C2=A0 control=C2=A0 or=C2=A0
restriction=C2=A0 </div>
<br>
<br>
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