And forgot the obvious: Do Not Overfill your crankcase.
-
Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
Compressor Question
- Thread starter YYCHM
- Start date
Chicken lights
Forum Pony Express Driver
First time I’ve ever had to thaw oil to drain it.
Thanks! I think
I always wondered why the bottom couple inches of compressor tanks weren't coated with urethane or similar. But when you see pics of them after years or service (or after they go bang catastrophically) there seems to be an almost even rust coating in the whole can.... with just a little bit more around the drain.
So you'd either have to line the whole vessel like with a rubberized coating or just get in there to clean & inspect if possible. Seeing the insides sure gives one perspective about supposedly clean air going into pneumatic tools or your spray gun.
So you'd either have to line the whole vessel like with a rubberized coating or just get in there to clean & inspect if possible. Seeing the insides sure gives one perspective about supposedly clean air going into pneumatic tools or your spray gun.
Attachments
That sure seems like it would be a desirable feature. I don't think there is a big enough opening on most home compressor tanks to get in there with a roller or brush, just welded pipe fittings. I've heard of fabricated metal gas tanks where they pour in a volume of specialized goop & constantly rotate the tank about until it sets up & cures.
Yet another application for the amazing Flex Seal. Repair your gutters! Coat your back yard pool! Make a fishing boat from a screen door!
https://www.flexsealproducts.com/product/flex-seal-liquid-rubberized-coating/
Yet another application for the amazing Flex Seal. Repair your gutters! Coat your back yard pool! Make a fishing boat from a screen door!
https://www.flexsealproducts.com/product/flex-seal-liquid-rubberized-coating/
Brent H
Ultra Member
On one ship, the larger air tanks will be two part epoxy coated - a serious sized man hole you can get into and literally paint the tank - BUT - These tanks are limited to about 100 psi and are vintage 1960's.
On our ship the tanks are long (10 feet) and about 2 feet in diameter. They hold air at 27 Bar (roughly 400 psi) for starting air (main engines) and service air (dropped to 100 psi). The tanks have a hand hole for inspection purpose and are not coated inside. Part of the routine is to blow off the drain before each watch (2 x a day) to prevent any build up of moisture.
Other pressure cylinders I have worked on - scuba tanks and smaller compressor tanks are not coated. This helps when doing visual inspections for cracking, flaws, deep rust pitting etc. and you do not need flakes of coating plugging up downstream gear. Provided you are blowing off the water (you can install an auto drain as well) you should be a-ok. You are always going to have some moisture build up given you are going through the compression cycle and then allowing the gas to cool and water will then condense out.
The biggest trouble with the water in your tank is not necessarily the rust of the tank factor but if you build up enough that you are carrying over the moisture into your supply hoses to your tools. You can wreck air tools, wreck air cylinders or other pneumatic machinery. Paint sprayers have to have very dry and clean air and plasma cutters work best with dry air as well. Dryers and oil/water collectors are typical-
Blowing off your tools or chips etc - not such a big deal - but getting a fuel valve actuator stuck open during fueling because the actuator is partly full of water and rusted out is not fun...
On our ship the tanks are long (10 feet) and about 2 feet in diameter. They hold air at 27 Bar (roughly 400 psi) for starting air (main engines) and service air (dropped to 100 psi). The tanks have a hand hole for inspection purpose and are not coated inside. Part of the routine is to blow off the drain before each watch (2 x a day) to prevent any build up of moisture.
Other pressure cylinders I have worked on - scuba tanks and smaller compressor tanks are not coated. This helps when doing visual inspections for cracking, flaws, deep rust pitting etc. and you do not need flakes of coating plugging up downstream gear. Provided you are blowing off the water (you can install an auto drain as well) you should be a-ok. You are always going to have some moisture build up given you are going through the compression cycle and then allowing the gas to cool and water will then condense out.
The biggest trouble with the water in your tank is not necessarily the rust of the tank factor but if you build up enough that you are carrying over the moisture into your supply hoses to your tools. You can wreck air tools, wreck air cylinders or other pneumatic machinery. Paint sprayers have to have very dry and clean air and plasma cutters work best with dry air as well. Dryers and oil/water collectors are typical-
Blowing off your tools or chips etc - not such a big deal - but getting a fuel valve actuator stuck open during fueling because the actuator is partly full of water and rusted out is not fun...
Which is why they don't recommend galvanized pipe for plasma setups. It flakes off inside the lines and travels to your torch.
Years ago The City of Calgary did a study—similar to other municipalities—and discovered that letting metal light standards and traffic poles form a layer of rust was just as effective as painting them in certain situations. Once evenly oxidized (and I think cathodic protection is a factor), the pole self-protects with its own rust. That's why you see a lot of unpainted poles. The same applies to compressor tanks in some situations. I think pressure is a factor and for certain usage scenarios lining the tank makes sense.
I knew a guy once that got the great idea to spray the inside of his tank with CLR in a effort to remove the rust. Biggest mess I've ever seen, and for some reason nothing ever worked the same again. Probably one of those ideas that seems logical on first thought, but in reality is just a practice run for a Darwin award.
BAAAA HAAA HAAAA. Best laugh of the day.
So..... another question for you guys.
I originally purchased the compressor to boost vehicle tires (truck, car, travel trailer etc.) and discovered 1/3HP 2gal really isn't sufficient to say add 10lbs of pressure to a truck tire without letting the tank recharge at least once or sometimes twice. Kind of annoying when it's -25C outside with a howling wind. The tank is rated for 100PSI and the pressure switch kicks in at 70PSI and out at 100PSI. If I was to change the pressure switch to one that kicks in at 90PSI and out at 120PSI would that help the situation?
I originally purchased the compressor to boost vehicle tires (truck, car, travel trailer etc.) and discovered 1/3HP 2gal really isn't sufficient to say add 10lbs of pressure to a truck tire without letting the tank recharge at least once or sometimes twice. Kind of annoying when it's -25C outside with a howling wind. The tank is rated for 100PSI and the pressure switch kicks in at 70PSI and out at 100PSI. If I was to change the pressure switch to one that kicks in at 90PSI and out at 120PSI would that help the situation?
Last edited:
DPittman
Ultra Member
Robert Boyle, a famous English chemist, discovered in 1662 that if you pushed on a gas, its volume would decrease proportionately. For example, if you doubled the pressure on a gas (increase the pressure two times), its volume would decrease by half (decrease the volume two times). The opposite is also true. If you reduced the pressure on a gas by 3.5 times, then its volume would increase by 3.5 times. This law is an example of an inverse relationship - if one factor increases, the other factor decreases.
Now will the increase in pressure in the tank be enough to fill your tire without the tank needing to recharge? That would involve math above my pay grade. (Or just some experimenting).
I think your bigger issue here is tank volume, not pressure Craig. Your tank—albeit small—already has sufficient pressure to inflate the tire. Unless the compressor can generate enough SCFM on a 100% duty cycle to match the tire pressure, you'll always be cycling. That's why guys often carry a portable air tank that can store 10 Gals or so, such as: https://www.princessauto.com/en/10-gallon-portable-air-tank/product/PA0008474942
Sadly this plus the cost of your small compressor probably puts you in the range of a 26 gallon compressor that would do the job as you wish (careful though—many of these require a 20 Amp 110V circuit). I don't know the calculations offhand, but am sure there are online calculators to answer the question definitively for you. The clue is that those tiny 12V compressors will do the job, but because there is no tank with it they take forever. A small 1/3 HP (nominal measurement) compressor with a 2 gal tank is really not that different than a 12V portable compressor guys carry in their trucks: they just have some tank storage and higher pressures. Now of course the high pressure converts to higher volume at lower PSI (as @DPittman correctly points out), but your issue is really one of volume. You'd have to crunch the numbers to see if the extra PSI will solve it, but I'm always scared to fool around with margins of error in pressure vessels.
For what it is worth those PA tanks go on sale often at PA. You can daisy chain them with a small compressor. Lots of floor guys and roofing guys do this.
Suggest a min size compressor for inflating tires efficiently.... please.... thank you.
All the calculators I found on-line deal with pressure not volume?
I have a 20amp circuit wired out to the back of the house for my welder.
Size is a concern for me due limited storage constraints.
If I went with a portable tank I could only fill it to 100PSI with the current compressor.
Last edited:
Tom O
Ultra Member
I have one of those air tanks also it is a handy thing to have because the 12 volt compressor will pump up a tire but will never reseat the bead on the rim if your lucky you can jack up the vehicle and seal it enough otherwise you need a tank. It is also good to have some screws to plug a hole in a emergency to get to a shop.
if your looking for a spare compressor tank I have one for good home.
if your looking for a spare compressor tank I have one for good home.
PM sent
Assume 35 PSI for the tire. A engineer type crunched the numbers (see link below) and got about 26 gallons @35 PSI (what I originally guessed—likely because I used to own a 26 gallon compressor and filled lots of tires with it). But your compressor will be much higher PSI, so you will need a smaller tank. He calculates if your compressor taps out at 175 PSI (kind of high for a non-industrial unit) you'll only need a 5.2 gallon tank. The way he calculates this is just a ratio estimate, so actual value may vary.
Remember there is a difference between the compressor cycling and being able to fill the entire tire from the tank (called a desert tank...like the PA tank above). I'm assuming your goal is to be able to fill the tire entirely from the tank, without waiting for it to refill. The compresor will still kick in when the pressure switch trips the low setting, but there will be sufficient air to fill the tire from completely empty to completely full @35 PSI.
Also, he based his calculations on a 31" inner diameter tire, so maybe he is thinking those desert race cars. His comment at the end sums it up: it is more efficient to carry a small CO2/N cylinder like those racers guys do @ 2800 PSI in this scenario (which is what they do).
https://ck5.com/forums/threads/how-many-gallons-of-air-does-a-tire-hold.248089/
Please don't take my word or calculations for gospel Craig. I'm just passing on his numbers without validation. In addition to my 60 gallon tank I also have a smaller Makita portable that is about 4.2 gallons I think. It does 4.2 SCFM @ 90 PSI. You are welcome to bring over a tire and try it on this machine to see if it suits your needs. It will fill just fine I bet, but it will also cycle for a full tire fill. Don't know about resetting the bead in cold weather; I've only ever used my 60 gallon compressor for that task.
https://www.homedepot.ca/product/makita-2-5-hp-4-2-gal-air-compressor/1000478084
@YYCHM — Just saw this in the PA Flyer until Aug 15th, although it is out of stock. Looks like a tank with a larger 1/4 turn ball valve. But the key is the exhaust port appears to be 1" or so, which would be crucial to seating beads. Tough to adapt a 3/8" port to do the same thing.
https://www.princessauto.com/en/product/PA0008784738
https://www.princessauto.com/en/product/PA0008784738
Thanks..... but I think I'll get this one and give it a go.
https://www.princessauto.com/en/10-gallon-portable-air-tank/product/PA0008474942