Comments for Industrial Air Compressors | What You Need to Know http://aircompressorswa.com.au/blog What You Need To Know About Air Compressors! Thu, 26 Nov 2009 16:39:59 -0500 http://wordpress.org/?v=2.8.2 hourly 1 Comment on How can I convert 120 Volts DC into 120 Volts AC??? by tj3f3rsn http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/comment-page-1/#comment-210 tj3f3rsn Thu, 26 Nov 2009 16:39:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/#comment-210 No offense, but I'm reading between the lines of your question and I'm guessing that you don't have a lot of expertise in this. (One of those "if you have to ask how, you probably shouldn't be doing it" things...) A quick search and I found two 2000 watt 12VDC inverters (linked below) for $300 and $159, respectively. Why try and re-invent the wheel when you can buy the wheel for that cheap? Plus, you have a lot less hazard working with your batteries when connected for 12VDC than you do for 120VDC. Have you ever dropped a wrench across 12VDC? Pretty impressive sparks. You drop it across 120VDC and it won't be so much sparks as it will a plasma ball! (And that's no exaggeration. Electrician's Mates in the Navy working on submarine batteries at 200+VDC have had their tools disappear in a flash and bang after touching across terminals.) <br><b>References : </b><br>http://www.amazon.com/Coleman-2000-Watt-Power-Inverter/dp/B00020BOKS http://www.topsalesdepot.com/bwadctoacpoi.html No offense, but I’m reading between the lines of your question and I’m guessing that you don’t have a lot of expertise in this. (One of those "if you have to ask how, you probably shouldn’t be doing it" things…)

A quick search and I found two 2000 watt 12VDC inverters (linked below) for $300 and $159, respectively. Why try and re-invent the wheel when you can buy the wheel for that cheap?

Plus, you have a lot less hazard working with your batteries when connected for 12VDC than you do for 120VDC. Have you ever dropped a wrench across 12VDC? Pretty impressive sparks. You drop it across 120VDC and it won’t be so much sparks as it will a plasma ball! (And that’s no exaggeration. Electrician’s Mates in the Navy working on submarine batteries at 200+VDC have had their tools disappear in a flash and bang after touching across terminals.)
References :
http://www.amazon.com/Coleman-2000-Watt-Power-Inverter/dp/B00020BOKS

http://www.topsalesdepot.com/bwadctoacpoi.html

]]> Comment on How can I convert 120 Volts DC into 120 Volts AC??? by Sigmacaptor http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/comment-page-1/#comment-209 Sigmacaptor Thu, 26 Nov 2009 16:30:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/#comment-209 If you really want to run this compressor converting DC to AC you are going to run into electronics and effifiency problems in the way. However, the best way in my opinion, is to replace the 2.5 HP AC motor for a 96 VDC, 18 amps motor.You can rearrange your battery bank to get 96VDC output. I hope this helps.<br><b>References : </b><br> If you really want to run this compressor converting DC to AC you are going to run into electronics and effifiency problems in the way. However, the best way in my opinion, is to replace the 2.5 HP AC motor for a 96 VDC, 18 amps motor.You can rearrange your battery bank to get 96VDC output. I hope this helps.
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]]> Comment on How can I convert 120 Volts DC into 120 Volts AC??? by Galen B http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/comment-page-1/#comment-208 Galen B Thu, 26 Nov 2009 15:58:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/#comment-208 The first question is does your device require AC? Can it be changed to a DC motor easily? Then you need no converter. An inverter uses a chopper circuit to convert dc to a square wave, Then some shaping if needed. <br><b>References : </b><br> The first question is does your device require AC?

Can it be changed to a DC motor easily? Then you need no converter.

An inverter uses a chopper circuit to convert dc to a square wave, Then some shaping if needed.
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]]> Comment on How can I convert 120 Volts DC into 120 Volts AC??? by wingstwo http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/comment-page-1/#comment-207 wingstwo Thu, 26 Nov 2009 15:32:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/#comment-207 A VFD is a variable frequency drive. It uses electronics to rectify AC into DC, generate a frequency, then use output electronics to synthesize an AC waveform. With a battery bank, you need to do only the last part of this. I don't know if anyone makes just this module. AC motors are generally pretty forgiving of waveform, it doesn't need to be a perfect sine wave. They generally are made using a pulse width modulated output. 120VAC has 170V peak to peak. I expect your batteries need to be this, or half this, to work directly. Google to find circuits used for VFD's. You can leave yours at 60Hz, don't need to change speed, though this may not make much difference. PIC microprocessor site and others have example VFD circuits. Their application note nicely explain the PWM schemes and tradeoffs. Yours could be fairly simple. Some VFD's may also run on DC. Check their specs. A 3HP unit is about $300 USD, so probably not too much cheaper than the inverter. Why not start by checking pricing on a 2000 watt inverter powered by 12V or 24V? Should be able to find for about $200 new. Plus, if you get an inverter, it could be used to drive other loads if needed. Maybe you can get a used inverter to use or VFD to experiment with on ebay, if you are comfortable working with transistors. I would use 96V, use a MOSFET bridge to allow positive and negative going waveforms, then set up a controller and output transistor to PWM the output. It's actually a fairly complex project, and the time required may be big compared to the money saved. Maybe your friend can help... The voltages involved make it a little bit dangerous. Be safe, use caution.<br><b>References : </b><br> A VFD is a variable frequency drive. It uses electronics to rectify AC into DC, generate a frequency, then use output electronics to synthesize an AC waveform. With a battery bank, you need to do only the last part of this. I don’t know if anyone makes just this module. AC motors are generally pretty forgiving of waveform, it doesn’t need to be a perfect sine wave. They generally are made using a pulse width modulated output.

120VAC has 170V peak to peak. I expect your batteries need to be this, or half this, to work directly.

Google to find circuits used for VFD’s. You can leave yours at 60Hz, don’t need to change speed, though this may not make much difference. PIC microprocessor site and others have example VFD circuits. Their application note nicely explain the PWM schemes and tradeoffs. Yours could be fairly simple.

Some VFD’s may also run on DC. Check their specs. A 3HP unit is about $300 USD, so probably not too much cheaper than the inverter. Why not start by checking pricing on a 2000 watt inverter powered by 12V or 24V? Should be able to find for about $200 new. Plus, if you get an inverter, it could be used to drive other loads if needed.

Maybe you can get a used inverter to use or VFD to experiment with on ebay, if you are comfortable working with transistors. I would use 96V, use a MOSFET bridge to allow positive and negative going waveforms, then set up a controller and output transistor to PWM the output. It’s actually a fairly complex project, and the time required may be big compared to the money saved. Maybe your friend can help…

The voltages involved make it a little bit dangerous. Be safe, use caution.
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]]> Comment on What kind of air compressor should I buy for spraying automobiles? by steven s http://aircompressorswa.com.au/blog/2009/11/26/what-kind-of-air-compressor-should-i-buy-for-spraying-automobiles/comment-page-1/#comment-203 steven s Thu, 26 Nov 2009 15:18:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/what-kind-of-air-compressor-should-i-buy-for-spraying-automobiles/#comment-203 you need at least a 5.5 hp compressor. I've painted a car with a pancake compressor. I know you've seen the compressors that stand upright, like they're on a dollie. One of these will be fine, don't go buy some 10hp big ass compressor. Use your money to buy a quility paint gun. Look up bink online. They are reasonable.<br><b>References : </b><br> you need at least a 5.5 hp compressor. I’ve painted a car with a pancake compressor. I know you’ve seen the compressors that stand upright, like they’re on a dollie. One of these will be fine, don’t go buy some 10hp big ass compressor. Use your money to buy a quility paint gun. Look up bink online. They are reasonable.
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]]> Comment on A question about the muzzle energy of a pumpkin…? by Irv S http://aircompressorswa.com.au/blog/2009/11/26/a-question-about-the-muzzle-energy-of-a-pumpkin/comment-page-1/#comment-214 Irv S Thu, 26 Nov 2009 15:08:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/a-question-about-the-muzzle-energy-of-a-pumpkin/#comment-214 Try 200 FPS, ... (300'/1.5Sec.). You're right. It still works out to one big number! I think you're under-estimating the time, and overestimating the 'punkin' though. There's a lot of air in them.<br><b>References : </b><br> Try 200 FPS, … (300′/1.5Sec.).
You’re right. It still works out to one big number!
I think you’re under-estimating the time, and overestimating
the ‘punkin’ though. There’s a lot of air in them.
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]]> Comment on How can I convert 120 Volts DC into 120 Volts AC??? by Mary B http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/comment-page-1/#comment-206 Mary B Thu, 26 Nov 2009 15:07:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/how-can-i-convert-120-volts-dc-into-120-volts-ac/#comment-206 be very careful that you do not accidentally cross +/-, you could blow up the air compressor, or just fry it out totally...ask an electritian, or your local hardware store for help with this one...<br><b>References : </b><br> be very careful that you do not accidentally cross +/-, you could blow up the air compressor, or just fry it out totally…ask an electritian, or your local hardware store for help with this one…
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]]> Comment on What kind of air compressor should I buy for spraying automobiles? by j_airgood http://aircompressorswa.com.au/blog/2009/11/26/what-kind-of-air-compressor-should-i-buy-for-spraying-automobiles/comment-page-1/#comment-202 j_airgood Thu, 26 Nov 2009 14:52:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/what-kind-of-air-compressor-should-i-buy-for-spraying-automobiles/#comment-202 its got to be up there in gallons your best bet is to get 250 or bigger tractor supply has some good ones around 300 dollars and up<br><b>References : </b><br> its got to be up there in gallons your best bet is to get 250 or bigger tractor supply has some good ones around 300 dollars and up
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]]> Comment on A question about the muzzle energy of a pumpkin…? by akluis http://aircompressorswa.com.au/blog/2009/11/26/a-question-about-the-muzzle-energy-of-a-pumpkin/comment-page-1/#comment-213 akluis Thu, 26 Nov 2009 14:44:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/a-question-about-the-muzzle-energy-of-a-pumpkin/#comment-213 I have seen these and I can tell you your time estimate seems VERY low to me. Try calculating with 100 feet per second, and even that is just a 3 second flight for a 100 yard target. Of course, this is why people need to measure things with rulers and stopwatches and scales<br><b>References : </b><br> I have seen these and I can tell you your time estimate seems VERY low to me. Try calculating with 100 feet per second, and even that is just a 3 second flight for a 100 yard target.

Of course, this is why people need to measure things with rulers and stopwatches and scales
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]]> Comment on A question about the muzzle energy of a pumpkin…? by CIH(Ret) http://aircompressorswa.com.au/blog/2009/11/26/a-question-about-the-muzzle-energy-of-a-pumpkin/comment-page-1/#comment-212 CIH(Ret) Thu, 26 Nov 2009 14:22:59 +0000 http://aircompressorswa.com.au/blog/2009/11/26/a-question-about-the-muzzle-energy-of-a-pumpkin/#comment-212 I don't have the formula for figuring the kinetic energy of a pumpkin whose weight is figured in pounds rather than in grains. However, you can convert pounds to grains by multiplying by 7,000. nce you have the weight in grains, you can calculate the foot pounds of kinetic energy by multiplying the weight of the pumpkin in grains times the square of the velocity in ft./sec. and dividing by 450,400. If we assume that your figures are correct, a 5 pound pumpkin will weigh 35,000 grains. If that mass is moving at a velocity of 300 fps, we can multiply 35,000 by 300 squared and divide by 450,400. Doing this we get 6993.7 ft.pounds of kinetic energy. This confirms you calculation of "nearly 7,000 ft. pounds". The reason for this amount of kinetic energy is the tremendous mass of the pumpkin as compared to the mass of a bullet.<br><b>References : </b><br> I don’t have the formula for figuring the kinetic energy of a pumpkin whose weight is figured in pounds rather than in grains. However, you can convert pounds to grains by multiplying by 7,000. nce you have the weight in grains, you can calculate the foot pounds of kinetic energy by multiplying the weight of the pumpkin in grains times the square of the velocity in ft./sec. and dividing by 450,400. If we assume that your figures are correct, a 5 pound pumpkin will weigh 35,000 grains. If that mass is moving at a velocity of 300 fps, we can multiply 35,000 by 300 squared and divide by 450,400. Doing this we get 6993.7 ft.pounds of kinetic energy. This confirms you calculation of "nearly 7,000 ft. pounds". The reason for this amount of kinetic energy is the tremendous mass of the pumpkin as compared to the mass of a bullet.
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