Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..

"Stormin Mormon" wrote in message
...
Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.


You forgot one factor. Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

"Stormin Mormon" wrote in message
...
Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.


You forgot one factor. Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

On Dec 10, 4:56*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. *Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent..

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

On Dec 10, 4:56*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. *Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent..

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56Â*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. Â*Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56Â*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. Â*Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56Â*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. Â*Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

Joe wrote:
(snip)
Spot on, Roger. Power is not measured in watts, it is
measured in watt- hours. That's what that nice meter on
the side of your building records.

Joe

Watt-hours = watt-seconds/3600 = joules is energy.
Power = Rate of energy transfer (watts = joules/second).

Joe wrote:
(snip)
Spot on, Roger. Power is not measured in watts, it is
measured in watt- hours. That's what that nice meter on
the side of your building records.

Joe

Watt-hours = watt-seconds/3600 = joules is energy.
Power = Rate of energy transfer (watts = joules/second).

On Thu, 10 Dec 2009 16:15:41 -0500, "Stormin Mormon"
wrote:

Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.


A couple weeks ago I put my killawatt on my compressor. I noticed
that the amperage went up for a while but toward the end of the cycle
it went down. at the time I thought it might just be from things
"warming up" or perhaps I imagined it but it looks like there is
something to the idea that at sufficiently high pressure the flow
resistance drops faster then the pressure resistance increases.

On Thu, 10 Dec 2009 16:15:41 -0500, "Stormin Mormon"
wrote:

Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.


A couple weeks ago I put my killawatt on my compressor. I noticed
that the amperage went up for a while but toward the end of the cycle
it went down. at the time I thought it might just be from things
"warming up" or perhaps I imagined it but it looks like there is
something to the idea that at sufficiently high pressure the flow
resistance drops faster then the pressure resistance increases.

On Thu, 10 Dec 2009 16:15:41 -0500, "Stormin Mormon"
wrote:

Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.


A couple weeks ago I put my killawatt on my compressor. I noticed
that the amperage went up for a while but toward the end of the cycle
it went down. at the time I thought it might just be from things
"warming up" or perhaps I imagined it but it looks like there is
something to the idea that at sufficiently high pressure the flow
resistance drops faster then the pressure resistance increases.

On Thu, 10 Dec 2009 16:15:41 -0500, "Stormin Mormon"
wrote:

Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.


A couple weeks ago I put my killawatt on my compressor. I noticed
that the amperage went up for a while but toward the end of the cycle
it went down. at the time I thought it might just be from things
"warming up" or perhaps I imagined it but it looks like there is
something to the idea that at sufficiently high pressure the flow
resistance drops faster then the pressure resistance increases.

wrote in message
...

You forgot one factor. Time.

I bet if you noted the time that it took to attain the increase in
pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig
you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where
the
temperature of the air in the tank was held constant, you will find
that the
cost in power would increase for the volume/pressure of air in the
tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the
solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

Horsepower is defined:

"Common unit of power, the rate at which work is done. In the English
system, one horsepower equals 33,000 foot-pounds of work *per minute* - that
is, the power necessary to lift a total of 33,000 lbs a distance of one foot
in one minute."

So if you fail to consider the amount of time the motor is consuming a
lesser amount of Watts, you will not get the whole picture. I took issue
with the statement:

"The load on the motor is actually less at 135 PSI than it is at 100."

Think about it this way. Lets say you have a pneumatic nail gun that when
it is fed 80 psi it can shoot a 16 penny nail into a board. If you set your
compressor to turn on @ 80 psi (regulated) and shut off @100psi you could
shoot x number of nails before you consumed enough air to cause the
compressor to turn on again.

Now take the number of Watts and multiply it by the amount of time it takes
the compressor to shut off.

Now reset the compressor to turn on at 115 psi and off at 135psi and count
the number of nails you can shoot (it will be more)

Again take the Watts and multiply by the amount of time.

When you then take the number of nails driven divided into the Watt seconds
of power you expended it will give you the cost per nail driven.

I suggest that the cost will be higher per nail at the higher pressure,
because you are creating much more waste heat that does not put any air in
the tank to drive nails.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

wrote in message
...

You forgot one factor. Time.

I bet if you noted the time that it took to attain the increase in
pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig
you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where
the
temperature of the air in the tank was held constant, you will find
that the
cost in power would increase for the volume/pressure of air in the
tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the
solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

Horsepower is defined:

"Common unit of power, the rate at which work is done. In the English
system, one horsepower equals 33,000 foot-pounds of work *per minute* - that
is, the power necessary to lift a total of 33,000 lbs a distance of one foot
in one minute."

So if you fail to consider the amount of time the motor is consuming a
lesser amount of Watts, you will not get the whole picture. I took issue
with the statement:

"The load on the motor is actually less at 135 PSI than it is at 100."

Think about it this way. Lets say you have a pneumatic nail gun that when
it is fed 80 psi it can shoot a 16 penny nail into a board. If you set your
compressor to turn on @ 80 psi (regulated) and shut off @100psi you could
shoot x number of nails before you consumed enough air to cause the
compressor to turn on again.

Now take the number of Watts and multiply it by the amount of time it takes
the compressor to shut off.

Now reset the compressor to turn on at 115 psi and off at 135psi and count
the number of nails you can shoot (it will be more)

Again take the Watts and multiply by the amount of time.

When you then take the number of nails driven divided into the Watt seconds
of power you expended it will give you the cost per nail driven.

I suggest that the cost will be higher per nail at the higher pressure,
because you are creating much more waste heat that does not put any air in
the tank to drive nails.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

wrote in message
...

You forgot one factor. Time.

I bet if you noted the time that it took to attain the increase in
pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig
you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where
the
temperature of the air in the tank was held constant, you will find
that the
cost in power would increase for the volume/pressure of air in the
tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the
solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

Horsepower is defined:

"Common unit of power, the rate at which work is done. In the English
system, one horsepower equals 33,000 foot-pounds of work *per minute* - that
is, the power necessary to lift a total of 33,000 lbs a distance of one foot
in one minute."

So if you fail to consider the amount of time the motor is consuming a
lesser amount of Watts, you will not get the whole picture. I took issue
with the statement:

"The load on the motor is actually less at 135 PSI than it is at 100."

Think about it this way. Lets say you have a pneumatic nail gun that when
it is fed 80 psi it can shoot a 16 penny nail into a board. If you set your
compressor to turn on @ 80 psi (regulated) and shut off @100psi you could
shoot x number of nails before you consumed enough air to cause the
compressor to turn on again.

Now take the number of Watts and multiply it by the amount of time it takes
the compressor to shut off.

Now reset the compressor to turn on at 115 psi and off at 135psi and count
the number of nails you can shoot (it will be more)

Again take the Watts and multiply by the amount of time.

When you then take the number of nails driven divided into the Watt seconds
of power you expended it will give you the cost per nail driven.

I suggest that the cost will be higher per nail at the higher pressure,
because you are creating much more waste heat that does not put any air in
the tank to drive nails.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

On Thu, 10 Dec 2009 19:52:54 -0500, wrote:

On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. *Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

This obviously explains why my Yamaha 9.9 hp outboard motor has a spec
for its output power measured in kilowatts. :-)

..7457 Kilowatts=1 BHP

On Thu, 10 Dec 2009 19:52:54 -0500, wrote:

On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. *Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

This obviously explains why my Yamaha 9.9 hp outboard motor has a spec
for its output power measured in kilowatts. :-)

..7457 Kilowatts=1 BHP

On Thu, 10 Dec 2009 19:52:54 -0500, wrote:

On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...





Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. *Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

This obviously explains why my Yamaha 9.9 hp outboard motor has a spec
for its output power measured in kilowatts. :-)

..7457 Kilowatts=1 BHP

On Dec 11, 5:47*am, wrote:
On Thu, 10 Dec 2009 19:52:54 -0500, wrote:
On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...

Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. *Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, *Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

This obviously explains why my Yamaha 9.9 hp outboard motor has a spec
for its output power measured in kilowatts. :-)

.7457 Kilowatts=1 BHP- Hide quoted text -

- Show quoted text -

I think there are 2 factors that effect power (power is measured in
Watts, energy is measured in Watt-hours), one is the pressure that you
measured, and the other is the FLOW which you did not measure. Power
is probably highest when BOTH pressure and flow are high. When the
compressor first comes on and is pumping air into the tank, the flow
is high and the pressure is low. As the pressure builds, the power
goes up but the flow tends to go down a bit. When you get to max
pressure, the flow is almost zero. If you want to do a science
experiment, try to arrange for a flow of air out of the compressor and
record power vs pressure AND flow.

Mark

On Dec 11, 5:47*am, wrote:
On Thu, 10 Dec 2009 19:52:54 -0500, wrote:
On Thu, 10 Dec 2009 15:59:27 -0800 (PST), Joe wrote:

On Dec 10, 4:56*pm, "Roger Shoaf" wrote:
"Stormin Mormon" wrote in message

...

Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.

You forgot one factor. *Time.

I bet if you noted the time that it took to attain the increase in pressure
when you saw the apparent dip in watts consumed between 90 and 100 psig you
would find that the total load (power consumption)increases.

I suspect if you were also to apply the gas laws to the equation where the
temperature of the air in the tank was held constant, you will find that the
cost in power would increase for the volume/pressure of air in the tank.
--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

Spot on, Roger. Power is not measured in watts, it is measured in watt-
hours. That's what that nice meter on the side of your building
records.

Joe

No power is watts. Also known as power dissipation, *Power
CONSUMPTION is watt hours.
Horsepower is also a power rating, and is an INSTANTANEOUS
measurement. - A snapshot in time.

This obviously explains why my Yamaha 9.9 hp outboard motor has a spec
for its output power measured in kilowatts. :-)

.7457 Kilowatts=1 BHP- Hide quoted text -

- Show quoted text -

I think there are 2 factors that effect power (power is measured in
Watts, energy is measured in Watt-hours), one is the pressure that you
measured, and the other is the FLOW which you did not measure. Power
is probably highest when BOTH pressure and flow are high. When the
compressor first comes on and is pumping air into the tank, the flow
is high and the pressure is low. As the pressure builds, the power
goes up but the flow tends to go down a bit. When you get to max
pressure, the flow is almost zero. If you want to do a science
experiment, try to arrange for a flow of air out of the compressor and
record power vs pressure AND flow.

Mark

wrote:
On Fri, 11 Dec 2009 02:06:37 -0800, "Roger Shoaf"
wrote:

When you then take the number of nails driven divided into the Watt
seconds of power you expended it will give you the cost per nail
driven.

I suggest that the cost will be higher per nail at the higher
pressure, because you are creating much more waste heat that does
not put any air in the tank to drive nails.

--

That gets back to what I said a long tome ago, the compressor is less
efficient at higher pressures, as another poster said, it can't
exhaust the air into a tank full of pressure but that also means the
motor is not working as hard as evidenced by the amps drawn

That does make some sense. It would only occur as the air delivered approaches
zero. The air in the cylinder is compressed, but can't go anywhere, so it just
pushes the piston back down, speeding up the crankshaft so it doesn't work so
hard going up the next time.

On Fri, 11 Dec 2009 14:37:58 -0500, wrote:

On Fri, 11 Dec 2009 09:32:19 -0800 (PST), Mark
wrote:

I think there are 2 factors that effect power (power is measured in
Watts, energy is measured in Watt-hours), one is the pressure that you
measured, and the other is the FLOW which you did not measure. Power
is probably highest when BOTH pressure and flow are high. When the
compressor first comes on and is pumping air into the tank, the flow
is high and the pressure is low. As the pressure builds, the power
goes up but the flow tends to go down a bit. When you get to max
pressure, the flow is almost zero. If you want to do a science
experiment, try to arrange for a flow of air out of the compressor and
record power vs pressure AND flow.

Mark

Just from standing there taking the pictures, I can say that last 30
pounds took a lot longer than the first 30. It is clear, according to
mr Boyle, that the flow is less.
It is also clear that if the flow increases the preasure will drop.
To maintain the same pressure with higher flow the pump needs to turn
faster - which WILL require more power.

I hear yah. Takes forever to boyle a kettle of water for my
oatmeal. The last couple degrees take forever before it
reaches boyling point.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


wrote in message
...
On Fri, 11 Dec 2009 09:32:19 -0800 (PST), Mark

wrote:


Just from standing there taking the pictures, I can say that
last 30
pounds took a lot longer than the first 30. It is clear,
according to
mr Boyle, that the flow is less.