Tom Gardner wrote:
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

I got a Quincy QR25 that had a continuous-run motor and totally
pneumatic pressure controls. I swapped in the largest motor the
compressor was rated for, changed the motor pulley, and built a
microcontroller "automatic dual mode" controller for it. Once it
reaches the pressure on the pressure switch, the compressor in unloaded,
and the motor continues to run for 30 seconds. If I need air again
within that time, it just shuts off the unloader. If not, the motor is
stopped. It also unloads the compressor for motor starting, and watches
the oil pressure. See
http://pico-systems.com/aircomp.html

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.


Yeah, I've got some leaky regulators to either repair or replace.

Jon

My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.

In article ,
"Tom Gardner" wrote:

We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

30 starts an hour has got to be hard on a bunch of things.

I wonder if you might be better off with one of the 4 running a bit
slower on a smaller motor and continuously - ie - 3-4hp - and then use
the other 3 as needed when the draw is larger. Don't know for sure, but
seems more likely to be efficient to have one pumping all the time (or
nearly) than to have it pumping and unloaded and pumping with a bigger
motor.

I am prone to overcomplicate things at times, but a setup where you had
that, and then as that started to be overcome you switched in a 7.5, and
when/if the pair got to pressure you shut down the smaller one and let
the 7.5 carry the larger load, unless/until it was unloaded for a long
period of time, when you'd switch it off and go back to the smaller one
when the pressure dropped again...

Seems like something that a PLC could manage for you most efficiently.

Getting the leaks should help, certainly - that's just money out the
window.

--
Cats, coffee, chocolate...vices to live by

On 2007-10-31, Tom Gardner wrote:
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

I think that it is awfully stressful for a continuous duty motor to
start up every 2 minutes. I would look into continuous run or I would
get a drive or a soft start.

Can you get a bigger compressor? And sell all this hodgepodge of
compressors to pay for a bigger one?

i

On Wed, 31 Oct 2007 20:10:48 GMT, "Tom Gardner"
wrote:

My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.

If they aren't already, I would first connect all the tanks as common
storage. That will increase your cycling time.

--Andy Asberry--
------Texas-----

"Tom Gardner" wrote in
et:

My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can
usually carry the load. It come on at 90 and runs to 120, or there
about. If the demand is bigger, another Quincy gets put on line. I
also have a 10 hp. Hydrovane as a back-up. I have yet another Quincy
in reserve. I hate not having air! We're looking at #1 that seems to
be about 50% duty cycle with just less than 1 minute off time. We're
wondering if we would be better off financially running the motor
continuously and unloading the valves at high pressure.

One of my ideas was for the lowest mechanic to catalog every air leak
and repair them...they add up quick. It seems we can go about a year
before they become an issue.



A small plc brick could rotate cycling of the 3 the quincy's, so that you
aren't wearing out 1 compressor. This gives the motors time to cool
between cycles. I would also have it control the unloaders. As someone
else stated all the tanks should be tied together.
We do this on the 4 compressors at the plant (3-400 hp, 1-250 hp Sullair
screw compressors).

--
Anthony

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

Remove sp to reply via email

What the others said about managing the load.

But how about rethinking the load? Sounds like the smallest (the 7.5 hp
Quincy) only runs half time for normal loads. How about repowering that
unit with a 5 hp motor and slightly lower compressor speed? That should
get it to almost 100% on time. Easier on the compressor, MUCH easier on
the motor.

Tom Gardner wrote:
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.

Ignoramus1192 wrote:

On 2007-10-31, Tom Gardner wrote:
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

I think that it is awfully stressful for a continuous duty motor to
start up every 2 minutes. I would look into continuous run or I would
get a drive or a soft start.

Can you get a bigger compressor? And sell all this hodgepodge of
compressors to pay for a bigger one?

i

VFD, a pressure sensor and a microcontroller to throttle back the motor
speed (within limits) to match the air demand?

On 2007-11-01, Pete C. wrote:
Ignoramus1192 wrote:

On 2007-10-31, Tom Gardner wrote:
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

I think that it is awfully stressful for a continuous duty motor to
start up every 2 minutes. I would look into continuous run or I would
get a drive or a soft start.

Can you get a bigger compressor? And sell all this hodgepodge of
compressors to pay for a bigger one?

i

VFD, a pressure sensor and a microcontroller to throttle back the motor
speed (within limits) to match the air demand?

That could work if he added a fan to cool the motor. at low speed.

i

suggestion - buy a VFD and an analog ( variable resistance) pressure gauge.
follow the VFD circuit example to have a "reference" pressure - the VFD will
then act as a servo amp of sorts and as the pump comes to the ref pressure
it will slow it down, and if it exceeds it, it will slow it more - so it
will keep running, but stay near the ref pressure. this will save lots of
wear and tear and also save you the wasted energy (and noise) of an unloader
dumping air into the, well, "air" making lots of hissing noises. your cost
will be modest, any VFD supplier can help you choose a suitable control




"Tom Gardner" wrote in message
et...
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle
with just less than 1 minute off time. We're wondering if we would be
better off financially running the motor continuously and unloading the
valves at high pressure.

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.




--
Posted via a free Usenet account from http://www.teranews.com

"Tom Gardner" wrote in message
et...
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle
with just less than 1 minute off time One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.


We had a 25 hp Quincy where I used to work. When we were doing a
system blowdown, it could barely keep up as long as we kept the
blowdown pressure under 40 psig. During a normal process run, it would
cycle at about 45 second intervals. In talking with our
service company, anything that cycles more than 15-20 times an hour
needs to run in unloader mode. We reset it to unloader mode and
it ran cooler and cut our power consumption by a significant amount.

As to ganging the compressors, set the 7.5 to a 95-120 split, unloader
mode, and the second one to a 90-115 split, on-off mode. That way if
you sag below 95, the second
one comes on to boost capacity. If you watch your power consumption
prior to setting the 7.5 to unloader and then after, you will be
definately suprized at the savings, especially
if you are on a peak demand pricing contract for power.

Craig C.

wrote in message
oups.com...


"Tom Gardner" wrote in message
et...
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If
the
demand is bigger, another Quincy gets put on line. I also have a 10
hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate
not
having air! We're looking at #1 that seems to be about 50% duty cycle
with just less than 1 minute off time One of my ideas was for the
lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year
before
they become an issue.


We had a 25 hp Quincy where I used to work. When we were doing a
system blowdown, it could barely keep up as long as we kept the
blowdown pressure under 40 psig. During a normal process run, it would
cycle at about 45 second intervals. In talking with our
service company, anything that cycles more than 15-20 times an hour
needs to run in unloader mode. We reset it to unloader mode and
it ran cooler and cut our power consumption by a significant amount.

As to ganging the compressors, set the 7.5 to a 95-120 split, unloader
mode, and the second one to a 90-115 split, on-off mode. That way if
you sag below 95, the second
one comes on to boost capacity. If you watch your power consumption
prior to setting the 7.5 to unloader and then after, you will be
definately suprized at the savings, especially
if you are on a peak demand pricing contract for power.

Craig C.


The fact that your service company cited 15-20 cycles per hour is what I was
looking for. I think we'll try unloader mode for a few months and check our
power bills. Very, very seldom do we need more than #1 running. I replaced
my 40 hp blower with a bunch of 1 hp dust collectors and saved $300/month on
our power bill.

"Tom Gardner" wrote in message
et...

wrote in message
oups.com...


"Tom Gardner" wrote in message
et...
My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can
usually
carry the load. It come on at 90 and runs to 120, or there about. If
the
demand is bigger, another Quincy gets put on line. I also have a 10
hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate
not
having air! We're looking at #1 that seems to be about 50% duty cycle
with just less than 1 minute off time One of my ideas was for the
lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year
before
they become an issue.


We had a 25 hp Quincy where I used to work. When we were doing a
system blowdown, it could barely keep up as long as we kept the
blowdown pressure under 40 psig. During a normal process run, it would
cycle at about 45 second intervals. In talking with our
service company, anything that cycles more than 15-20 times an hour
needs to run in unloader mode. We reset it to unloader mode and
it ran cooler and cut our power consumption by a significant amount.

As to ganging the compressors, set the 7.5 to a 95-120 split, unloader
mode, and the second one to a 90-115 split, on-off mode. That way if
you sag below 95, the second
one comes on to boost capacity. If you watch your power consumption
prior to setting the 7.5 to unloader and then after, you will be
definately suprized at the savings, especially
if you are on a peak demand pricing contract for power.

Craig C.


The fact that your service company cited 15-20 cycles per hour is what I
was looking for. I think we'll try unloader mode for a few months and
check our power bills. Very, very seldom do we need more than #1 running.
I replaced my 40 hp blower with a bunch of 1 hp dust collectors and saved
$300/month on our power bill.
That sounds good, although using a smaller motor and running the compressor
at a slower speed is also a good suggestion, if that slower speed will
satisfy demand most of the time. Do you participate in a demand reduction
program? Energy Curtailment Specialists is installing free demand interval
meters at our facilities. They aggregate demand reduction and sell it to the
NYISO grid. It's a nationwide company, they might offer something in your
area.

http://www.ecsny.com/

On Oct 31, 1:10 pm, "Tom Gardner" wrote:

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.

When I visited the Starrett tools factory, the apprentice who gave me
a tour said that each department was being held accountable for its
air leaks. The average department found about 30-40, with the worst
offenders having over 100 leaks. When they fixed all the leaks, they
found they saved about $10000 a year in terms of running their 300 HP
air compressor less.

On Wed, 31 Oct 2007 20:10:48 GMT, "Tom Gardner"
wrote:

My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle with
just less than 1 minute off time. We're wondering if we would be better off
financially running the motor continuously and unloading the valves at high
pressure.

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.

I once worked on a project with Ingersoll Rand. They'd found that a
significant consumer of energy in many or most factories is ... leaks!
Some of those facilities had energy cost of over $1 million per year
just for compressing air. There's one consultant, don't recall his
name, who makes a very good living finding ways to save a few percent
of that.

Don Foreman wrote:

I once worked on a project with Ingersoll Rand. They'd found that a
significant consumer of energy in many or most factories is ... leaks!
Some of those facilities had energy cost of over $1 million per year
just for compressing air. There's one consultant, don't recall his
name, who makes a very good living finding ways to save a few percent
of that.


At a previous job, I found a guy with an air hose fixed up to blow air at
himself for personal cooling. I asked him if he realized how expensive that
trick was and he replied he asked for a fan and the supervisor said we
couldn't afford it.

Just an example of shop logic, economics and pushback.

Wes

On Nov 1, 2:51 pm, Wes wrote:
Don Foreman wrote:
I once worked on a project with Ingersoll Rand. They'd found that a
significant consumer of energy in many or most factories is ... leaks!
Some of those facilities had energy cost of over $1 million per year
just for compressing air. There's one consultant, don't recall his
name, who makes a very good living finding ways to save a few percent
of that.

At a previous job, I found a guy with an air hose fixed up to blow air at
himself for personal cooling. I asked him if he realized how expensive that
trick was and he replied he asked for a fan and the supervisor said we
couldn't afford it.

Just an example of shop logic, economics and pushback.

Wes

Many tool companies advertise "no power required, just hook it to
your air supply". Most people do not realize that operating an air
tool costs twice as much in power as operating an electric tool for
the same job. We have two 75 hp Gardner -Denver screw compressors
with a couple 50 hp screws as backup. With regular oil and filter
changes one of the 75 hp compressors has an operating time of 143000
hours on the machine without any repairs - other than a solenoid valve
in the control circuit. That is what I call a reliable machine.

"Don Foreman" wrote in message
...
On Wed, 31 Oct 2007 20:10:48 GMT, "Tom Gardner"
wrote:

My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle
with
just less than 1 minute off time. We're wondering if we would be better
off
financially running the motor continuously and unloading the valves at
high
pressure.

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.

I once worked on a project with Ingersoll Rand. They'd found that a
significant consumer of energy in many or most factories is ... leaks!
Some of those facilities had energy cost of over $1 million per year
just for compressing air. There's one consultant, don't recall his
name, who makes a very good living finding ways to save a few percent
of that.


After we shut down at night and before the air tank has bled down, I walk
through the plant and cry listening to the hissing air leaks. I need to
bump it up to top priority.

If you put a stopwatch to the bleed down time, you should be able to get
a good idea of how much of your power bill is going toward leaks.

Tom Gardner wrote:
"Don Foreman" wrote in message
...
On Wed, 31 Oct 2007 20:10:48 GMT, "Tom Gardner"
wrote:

My air supply is in stages. One 7.5 hp 3-phase 230v Quincy can usually
carry the load. It come on at 90 and runs to 120, or there about. If the
demand is bigger, another Quincy gets put on line. I also have a 10 hp.
Hydrovane as a back-up. I have yet another Quincy in reserve. I hate not
having air! We're looking at #1 that seems to be about 50% duty cycle
with
just less than 1 minute off time. We're wondering if we would be better
off
financially running the motor continuously and unloading the valves at
high
pressure.

One of my ideas was for the lowest mechanic to catalog every air leak and
repair them...they add up quick. It seems we can go about a year before
they become an issue.
I once worked on a project with Ingersoll Rand. They'd found that a
significant consumer of energy in many or most factories is ... leaks!
Some of those facilities had energy cost of over $1 million per year
just for compressing air. There's one consultant, don't recall his
name, who makes a very good living finding ways to save a few percent
of that.


After we shut down at night and before the air tank has bled down, I walk
through the plant and cry listening to the hissing air leaks. I need to
bump it up to top priority.

On Fri, 02 Nov 2007 07:14:53 GMT, "Tom Gardner"
wrote:
"Don Foreman" wrote in message
.. .

I once worked on a project with Ingersoll Rand. They'd found that a
significant consumer of energy in many or most factories is ... leaks!
Some of those facilities had energy cost of over $1 million per year
just for compressing air. There's one consultant, don't recall his
name, who makes a very good living finding ways to save a few percent
of that.

After we shut down at night and before the air tank has bled down, I walk
through the plant and cry listening to the hissing air leaks. I need to
bump it up to top priority.

Brazed heavy L copper pipe, lots of good ball shutoff valves
everywhere, lots of padded supports and bracing so it can't vibrate.

For large outfits it's worth the extra effort to set the main line
up as a "ring main" in a loop around the room, with three or four
shut-offs (or more) around each loop in a logical pattern. That way
you can shut down one zone to work on it during the day, while leaving
the rest of the plant with air pressure and running. Ball valves are
cheaper than lost time for a shutdown.

All take-off tees pointed up, so the condensate in the ring main
stays in the ring main, and finds it's way to the drain legs placed at
the low spots. But you still put drip-legs and drains at each
machine.

Buy the materials and keep them on site - call your friend the
Plumber and ask about the "Special rate for slow days".

20' lifts of pipe means less joints on long runs.

-- Bruce --

RoyJ wrote:

If you put a stopwatch to the bleed down time, you should be able to get
a good idea of how much of your power bill is going toward leaks.


If Tom does a bleed down time he will have a baseline to check if leaks are
larger or smaller over time.

Wes

sparky wrote:

Many tool companies advertise "no power required, just hook it to
your air supply". Most people do not realize that operating an air
tool costs twice as much in power as operating an electric tool for
the same job. We have two 75 hp Gardner -Denver screw compressors
with a couple 50 hp screws as backup. With regular oil and filter
changes one of the 75 hp compressors has an operating time of 143000
hours on the machine without any repairs - other than a solenoid valve
in the control circuit. That is what I call a reliable machine.


We have a couple of G-D's in the 50 - 75 hp range. We only have 40,000+ on
them. Glad to know they will be still be there after I retire.


I worked at a place that ran 2 75 hp Ingersol-Rand air cubes for 23 or so
years. Biggest issue was with cracked reed valves every 4 or so years but
that was generally a quick fix if you had done it before. The tip was the
intercooler pressure being up above 20 sumpthing psi iirc. It has been a
while.

Why is it that air compressors, boilers and switch gear tend to get
shoehorned into the same area?

Wes

To the OP, i saw some decent screw compressors (40 and 100 HP) sell
for 750, and 1,000 dollars respectively. I think that both were
LeRoi's. They had about 20k hours on them.

i

In article , Wes
wrote:

Why is it that air compressors, boilers and switch gear tend to get
shoehorned into the same area?

....cause the architect wrote "Utilities" on that part of the plans? They
don't have to work on the stuff. Being close to the switchgear keeps the
wiring to the motors short, but being near the boiler sure won't help
anything.

--
Cats, coffee, chocolate...vices to live by

In article ,
Ignoramus28555 wrote:

To the OP, i saw some decent screw compressors (40 and 100 HP) sell
for 750, and 1,000 dollars respectively. I think that both were
LeRoi's. They had about 20k hours on them.

i

If a single 7.5 HP is enough air compressor most of the time, I doubt
that a 40HP screw is going to cut Tom's power bill, Iggy. He'll do much
better getting the leaks fixed.

--
Cats, coffee, chocolate...vices to live by