On Sun, 08 Dec 2013 17:51:42 -0600, Ignoramus3322
wrote:

On 2013-12-08, wrote:
On Sun, 08 Dec 2013 10:07:29 -0600, Ignoramus3322
wrote:

On 2013-12-08, wrote:
On Fri, 06 Dec 2013 19:47:58 -0600, Ignoramus5722
wrote:

I have a strange sounding idea. I want to have an extra compressed air
tank in my system. I have a bunch of tanks at this moment to choose
from. This way, I could run air hungry tools like breakers, etc,
intermittently but longer.

So far, so good, and nothing complicated. I have a whole bunch of
tanks right now, and thought to do something nice for my shop and have
an extra tank.

Examples of tanks I have a

http://igor.chudov.com/misc/ebay/tmp/Marengo/186.jpg
http://goo.gl/PdkzbM (Tank with "QT-15" lettering on left)

However, I also realize that with a big extra tank, it will take so
much longer for the air system to come up to pressure. This will be my
wasted money, as people will be waiting longer to use compressed air.

So, I thought, can I have a valve, that would not fill the tank, until
system pressure reached 120 PSI. And then it would shut off again if
the pressure ever falls to below 90 PSI.

To use the accumulator tank to supply air, another pipe would be used
with a check valve.

This setup makes sense to me, as

1) I would get the system to reach pressure quickly and
2) I would eventually get a supply of air in the accumulator,
without ever dropping the system pressure below 90 PSI.

I do realize that I can accomplish what I want, with a electric
pressure switch and a normally open pneumatic valve. But I thought,
perhaps, there is a purely pneumatic valve that does this? What would
it be called?

Here is what I would use. The 60cfm model.

http://www.airtekltd.com/valves.htm#LOAD_GENIE

It will open and allow flow to the secondary tank at 120psi and block
the flow when the primary tank drops to 90psi. A parallel line with a
check valve to allow flow from the secondary to the primary would
allow both tanks to supply the system below 90psi.

Interesting. There are several items listed. Do you mean item "NLG-1"?

i

Yes, NLG-1. With this and the check valve, there is no need for
electrical power to operate it.

OK, couple more question.

1. For my application, I need to simply connect my compressed air
system to the inlet, cap the "outlet" connection, and connect tank to
the muffler connection. Right?

2. Is it piloted or does it get pressure from the input line?

i

Compressor output to inlet.
Outlet to primary tank.
Exhaust to secondary tank.
Plug the throttle port.

Second line between tanks with check valve blocking flow from primary
to secondary.

Startup of morning - secondary tank will be empty until primary is at
120. Then flow goes to secondary until primary drops to 90. Secondary
will fill in increments. If primary usage keeps pressure below 90, no
air will go to secondary.

Your pressure switch should be set 5psi higher than the unloader
pressure so the pump doesn't turn off every time the unloader cycles.
When the pump does turn off, both tanks will be at the same pressure
and with usage, will bleed down together.