# Valve to fill additional compressed air tank

On 2013-12-07, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

If the "loss" that occurs during initial pumping up is small, then the tank is slow to fill, and it means that it will not be filled fast when the system reaches pressure.
i
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So? You said you only need it for occasional "high flow" jobs. If you need it to fill faster, install a manual valve to override the restrictor when you absolutely have to, and let the pump work longer in one session. (the total pump time will _always_ be the same per cubic foot of tank capacity, so you save nothing in pump run time, either way. It either runs in 'bursts' until it's filled the big tank, or it runs continuously...total time is the same).
Again... remember that you're only drawing from that big tank when the small one can't provide the flow you need.
LLoyd
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Let me revise my comment a little.
You're a math guy. How will the big tank _ever_ fill quickly, and still not prevent you from getting full pressure quickly in the small tank?
Opening a 'pass-over' valve to the big tank once the small one is full won't do it! It'll drop the system down to system peak divided by the ratio of tank volumes the INSTANT you open it (well, within seconds). So the pump will come back on, and now run an intolerable length of time before you have enough pressure to work. You can't have 'quick' and 'full pressure' in the same formula.
Pump capacity is the limit; always. Lloyd
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On 2013-12-07, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

Very simple. The big tank would start to fill only when system pressure is above, say, 120, and stop filling if it drops below, say, 90. A valve and a pressure switch can do that.

Think some more, you will realize that what I want to do is the nicest way of doing it.
i
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If your pump cuts in at 90, then all you've done is complicate the system without improving the performance. The INSTANT your system hits 120, it'll dump _all_ your main tank capacity into the reserve until the pressure drops to 90 -- then the electric valve turns off and the pump starts to run again... it will not improve the length of time it takes to get the reserve up to pressure. That's dependent entirely on pump capacity. It matters not how you fill it, it will always take the same length of time.
Your method will NOT improve run time, or the time to reach "usable" air pressure in the main tank, except for a slight (say 10%) time. But it will increase the complexity and maintenance issues over a simpler, purely solution.
Ig... for any given solution that will work, simpler and less expensive is always better.
Lloyd
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On 2013-12-07, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

Actually, if you think about it, the compressor will run continuously from the time the pressure hits 120, until such time the reserve tank is filled. All the while, the system pressure will never drop below 90.
During filling, no energy will be lost, unlike with restricted valves.
i
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probably not. The 90-120 psi stuff is just a distraction from the real problem. you don't want to fill the large tank when there's a load on your compressor from tools. Pressure on the system doesn't truly indicate if you have a load or not.
I don't deal with air systems, maybe somebody can answer this-
do they make simple flow guages or sensors for compressed air systems?
If so connect both tanks with a check valves in a Y, allowing flow out to your load, but no flow between tanks. The connection to each tank from the compressor is with a solenoid valve in the same Y configuration. The only states are compressor connected to no tank, connected to the small tank, connected to the large tank or connected to both tanks.
back to the flow detector-
When you detect a load on your system, disconnect the large tank from the compressor. Only the small tank is connected to the compressor. It will fill quickly so nobody is standing around.
If there is no, or low tool load, disconnect the small tank from the compressor, and connect the compressor to the large tank. The air supply to your load will be from the tank with the highest pressure, which is the small one. Immediate usage needs are met.
When the pressure there (small tank) drops too much, you start the compressor and disconnect the large tank.
Add a pressure sensor to the large tank. Once it hits minimum acceptable pressure (90 in your case) leave both valves from the compressor to both tanks open. You're now using the capacity of both tanks and the fill of the large tank never interrupted with your immediate use requirements.
You need a little logic to run this, but it's nothing beyond a couple relays.
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This is completely untrue.
There is nothing wrong with filling secondary tank, and using tools at the same time, as long as the system pressure is adequate (above 90 PSI for tools).

Whatever you describe, is not hard to do with pressure switches and relays.
i
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have at it.
you solved your own problem in the most clever way possible. it's brilliant. job well done.
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"Ignoramus31823" wrote in message

<snip>

With a little additional programming, the pressure transducer information could be used to get a little more run time at pressure. For example you could measure the rate of pressure change when the compressor is running but no air is being used. The rate of change for the compressor can be compared to current rate of change of air usage. If air is being used as fast as or faster than what the compressor can keep up, you can turn in on before 90 PSI to give you more run time at pressure than you'd get waiting until 90 PSI to turn it on. Not sure that it would help you much but set points that vary with demand can give you more air.
RogerN
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I do not think that I can get more run time with that, and I definitely do not see the benefit worth diong software, adding computer etc.
i
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"Ignoramus3322" wrote in message wrote: <snip>

About the run time, let me see if I can explain it better. For example, let's say your sandblaster needs at least "X" psi to operate correctly. Now if your sand blaster drains your tanks at 15 PSI per minute, and your compressor adds 10 PSI per minute, then with the compressor on, you have a loss of 5 PSI per minute. So if you could detect usage rate > compressor rate, and turn on the compressor at 120 PSI instead of 90 PSI, you get 6 minutes of usage at a loss of 5 PSI per minute, from 120 to 90 PSI. With the compressor off, you get 2 minutes from 120 to 90 PSI.
I understand at this point the computer idea sounds too complicated / expensive but that's kind of like your EMC experience. Sounded like too much unfamiliar territory but you took it step by step, solved one problem at a time, and ended up with a system that you can repair without high \$\$ parts and labor. And you added a 4th axis + knee?, that may not have even been an option with the original control.
If anything like this ever seemed practical, options include a micro PLC with analog input or something like an Arduino board, \$30, has analog inputs, free software, screw terminal add on for around \$8. The 5V output from the microcontroller can be used on AC or DC solid state relays to control valves and/or magnetic contactors. So it's actually nothing like using a PC and trying to interface to a compressor. Or perhaps some of you scrap deals could have a controller in them that could be reprogrammed for other tasks.
RogerN
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I considered similarly overengineering a computerized draft regulator for my woodstove, with inputs from firebox, stack and outdoor air temperature and the draft vacuum, all of which I was monitoring. It would be fun and a considerable accomplishment to tune it properly. I've designed relay-ladder controls for industrial production test and burn-in stations and wired/programmed simulations of the rest of the system for circuit board test and calibration fixtures.
For the woodstove I decided instead to add a remote thermocouple temperature display above this computer's monitor, so I know at a glance to go down and attend to it when it has reached operating temperature or needs more wood. A second channel tells me when a pot on the stove is nearing boil.
When I sandblast with an inadequate compressor I hang a large pressure gauge on the wall nearby and attack a new area with hammer and chisel until the pressure recovers enough to continue.
I've learned to be cautious of designing complex things for other people's use that only the designer can fix. jsw
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"Jim Wilkins" wrote in message

I wired an Allen Bradley PLC 5 to a Brinkman Gourmet Electric Smoker. Had a PanelView 550 for operator interface. A RTD probe for the meat and another for the temperature inside the smoker. The meat set point temperature ramped up over 12 hours as the smoker temperature was kept within limits. After the temperature was reached, it was held for a period of time to allow it to even out, then brought down to a set point of 140 degrees for "keep warm". It worked great but was a pain to drag out & set up then put back up. I need to mount the controller in a box and use plugs for the temperature probes and power. It was done for fun but made pretty good BBQ, need an automatic smoke wood feeder!
Next step I could use some actuators for the air inlets and control my Weber Smokey Mountain smoker!
PLC 5's are a bit old but their cards are cheap since the 1771 racks date back to PLC 2's. The downside is the programming software but I have it on my work laptop.
RogerN
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What is OK for an outdoor smoker, is not OK for an indoor wood fired stove, a much more dangerous device.
i
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"Ignoramus3322" wrote in message wrote: <snip>

True, if you make a mistake with the program, you may never find out!
However, about everything that can be sensed with electronic sensors can be fed into a controller and acted upon or at least sound an alarm. So, on a wood stove you could monitor temperatures, carbon monoxide, or any other relevant conditions that you might want to monitor on a wood stove. Controls checking and acting on conditions hundreds of times per second can catch and correct a problem better than a person can.
I used to attempt to fly R/C helicopters before Gyro's were common to assist tail rotor control, probably averaged 1/4 tank of fuel between crashes. After purchase of a cheap mechanical gyro, next crash was around 70 full tanks of fuel later. The crash after 70 tanks of fuel was due to getting it too far away and losing orientation, not a control or gyro related problem.
RogerN
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I share Iggy's concern enough that I don't run the stove when I'm away. In midwinter I came home from work to a 50F house, the setting of the electric backup.
The control I was considering would have closed the air inlet on the door as the stove came up to temperature. I didn't add it because I don't want any possible interference if the fire runs away and I need to shut it down.
After Thanksgiving I let the house cool to measure the rate vs outdoor temperature. At 2AM on Saturday the smoke alarm blasted me out of bed, to the smell of something electrical that had overheated. I rushed around checking all the electronics, found nothing warm, rechecked them twice anyway. Then I noticed that the smell was strongest near the hallway radiator, which hadn't been disassembled and vacuumed out in a long time. I had forgotten about the backup setting. The radiator had turned on, and the alarm and hot plastic smell were from rug fibers in it.
jsw
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On Mon, 9 Dec 2013 10:05:08 -0500, "Jim Wilkins"

What fun!
I woke up to some fun this morning. -=No water=- The pump pressure is up but the lines are frozen. I put a heater in the pump house (the light had burned out, allowing the freeze?) an hour ago but no joy yet. I'll put it in the crawlspace in a few minutes and see if that does it. <sigh>
It has been 10 or 11F here two days in a row. The lowest I've seen here before is 17F, and my outside line burst 8 years ago. I have insulated the exterior pipes and shut them off for the winter now, so this is the first problem I've had, and the first time losing water. There's a shutoff valve for each inside and outside lines.
Crap!
--
I hate being bipolar ....... It's awesome!

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I bought a 200W Lasko personal heater for \$12 in WalMart to see if it can keep my water meter above freezing when I'm away without running up an excessive electric bill. Right now it's defrosting dinner. It could be wired through an electric heat wall thermostat as a backup to the light bulb that distributes heat differently, like downwards or through a conduit.
For the light bulb: http://www.crmagnetics.com/Products/CR2550-P13.aspx
jsw
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On Mon, 9 Dec 2013 17:53:55 -0500, "Jim Wilkins"

Wow, aren't those little cuties? That's much better for ladies' feet under the desk than a 1,500W energy sucker. I wish I'd seen that earlier today when I visited Wally World for my prescription, which just left the \$4/mo list and cost me \$15.68 instead. Big Pharma ended their price deal with Wally and bumped prices a wee bit! The Lasko MyHeats are \$18.62 today.

Dinner, eh? <heh heh heh>

That's a thought.
I've been wanting to replumb in PEX and insulate the crap out of it when done, but the ongoing recession took care of that for me. Red Beacon (thru Home Depot) is bringing more work to me during the wet season than ever before, so I may be able to afford that next year.

Hmm, I may do that some day...
3:30pm update: Shit, still frozen shut. I had warmed the pump house for over an hour, then put the heater aimed at the pipe in the crawlspace for about 4 hours, but it's still frozen. Temps had risen to 31F for awhile, but are back to 28F now and dropping. <sigh> Rain is due Weds, so I hope to have water again by then.
I saw no indication of burst pipes during my quick foray under the house. The visqueen was dry to the end. I'm keeping my fingers crossed.
--
I hate being bipolar ....... It's awesome!

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