compressor info


Staff member
most shops have or would like to have an air compressor to run air wrenches, fill tires, run die grinders ETC.
the problem, is most reasonably priced air compressors can,t maintain the flow volume at reasonable pressure levels and your constantly waiting for the tank to re-pressurize,
so you can use the air tools for more than a few minutes at a time,
cheap compressors lack the tank size and flow to keep up,
and few guys have the room or want to spend several thousand dollars on a commercial compressor, which can easily cost twice too three times what two home shop,compressors cost,
compressors will have a rated air flow
lets say, your looking at a compressor that
Delivers 11.5 SCFM at 40 psi and 10.2 SCFM at 90 psi

take that as a absolute MAX and figure theres transmission line losses, so you then look at your air tools and look at what they require!
and if its even close the compressor will need to have some time to catch up or the tool cant be used 100% of the time (FEW ARE)
but its nice not needing to wait for pressure to build back up so get a decent sized tank and compressor ... 99698.html
Air consumption: 18 SCFM, 4.5 CFM



look at the two ratings and you see why I need dual compressors.
REMEMBER TO shop carefully ,you might find, that you can buy two compressors that will have a larger total holding tank capacity, more total horsepower and a higher total CFM rating than a single compressor costing two to three times as much can produce

youll tend to get what you pay for and a $600 home depot , or harbor freight compressor is not going to be the same quality , durability or flow volume as a commercial compressor that costs 4 times as much
Id also point out that a bit of careful thought going into the install will allow your compressor to last many years longer than it will if you just bolt it to the floor of your shop and plug it in.....

take the time to think about how and where you'll want to install the compressor,
it will need to be close to a 220 volt source,
ideally mounted on rubber vibration absorbing mounts,
if you want it to last you'll need to drain moisture from the storage tank before and after every use.
Ideally youll take the time and effort to run the compressors pressurized air flow out through a heat and moisture trap, before the hot moist air can reach the holding tank, too significantly reduce the
moisture that reaches the storage tank,
because moisture and steel are not going to play well together long term.
youll also want to check the compressors oil level before every use. ... logId=1005 ... ies/?n=490,8008.html?b=d*8063!r*Brand*Flexzilla

what you need depends on what your doing! I found I needed TWO compressors working in tandem, as I do a good deal of cylinder head PORT work on heads and using air ratchets, and it tends to tick me off if I need to wait for pressure to build up, my brother-in-law has a 2hp/20 gallon compressor and for a single air ratchet he has that just fine.
remember to check the oil in your compressor and drain water from the tank before and after each use, and to carefully OIL air TOOLS before and after each use, !

you really should take the time to read this linked info, posted in the links and sub links, obviously most of us are limited by budget concerns, but check and compare the pressure limits and flow capacity and tank size ... 0002309894

viewtopic.php?f=27&t=3444 ... ifications ... ies/?n=490 ... ed2009.pdf



viewtopic.php?f=59&t=6246&hilit=franzinator ... _200396621 ... ating.aspx ... c-271.html

yeah, the use of TWO of the cheaper 60-80 gallon single stage compressors feeding a single common air pipe with taps around the shop is usually far cheaper than trying to find a decent single compressor that will keep up with most tool demand, keep in mind pressures above about 125 psi are not usually needed or necessary but having the volume of air flow two separate compressors can provide is usually a big plus. BTW I got my current compressors at HOME DEPOT for $450 each, rated at 7hp 80 gallon, 130 psi
IM not debating which compressor is superior, only pointing out the advantages of TWIN compressors, in significantly reduced wait times under multi use conditions

similar to this, but I don,t currently see the exact one listed
I used several hundred feet of 3/4" schedule 80 PVC pipe rated at 660 PSI to pipe the air around the shop and used brass fittings screwed and glued into the pick-up access points , both compressors feed a 3/4" pipe that then dips to a drain valve then shoots over the rafters to a (T) where its routed along the walls to every place I might EVER use air flow to clean or operate tools in the shop,and its worked flawlessly at about 1/8 the price of copper pipe and sweated joints I used in the previous shop., and its worked fine for 5 years now at the 130 psi max I use.
yes IM WELL AWARE your not suppose to use PVC but after looking into most PVC failures they were related to SCHEDULE 40 pipe, pipe in direct sun light or pipe that got mechanically damaged
keep in mind moisture tends to run down hill so route your pipes so that the pipes drain to drain valve locations and all access points to draw air are higher than the drain points IE don,t run the pipe level with the floor,pick-up points should be higher than drains and there should be several drain valve points, one near the compressors and at least one more before any access to the air for tools my compressors are feeding the pipe at 5 feet from the floor,it slants to a drain at 4.9 ft from the floor,then shoots directly up the wall,over the rafters in a sweeping curve and drops to the opposite side of the shop at a drain at 5 ft from the floor, all access points are tees 6 ft from the floor

yes IM fully aware that PVC pipe is not generally suggested for pressurized air....and sweated copper or galvanized steel is suggested... yes 3/4" copper pipe with soldered fittings is the best choice, and iron pipe works fine if you have an air drier,I used several hundred feet of 3/4" schedule 80 PVC pipe rated at 660 PSI

Oh IM only too aware of the minimal risks, but Im also aware of the huge cost difference, like 800% higher for copper and steel pipe rusts,, the copper pipe I used in the last shop would have cost me hundreds of dollars in this shop,the better moisture tolerance and several hundred psi safety margin (pipes rated at 660 psi and it will never see 140 psi) and almost negligible risk of injury, the worst case is it fails too hold air pressure and my air tools don,t work
I probably would never have tried it if a buddy's shop had not used it without any problems for over 12 years now , and hes located less than 5 miles from here so he gets similar shop temps and pressures on the pipe,any compressors a huge improvement over having none it the shop, I could not believe how helpful having access to air ratchets and die grinders was when I got my first compressor and a few air tools.
when I go over to the BROTHER IN LAWS garage his compressors a huge help over nothing at all, but its a P.I.T.A. to use if your doing serious repairs because its only something similar to this ... umber=5637

a HUGE improvement over not having any compressor but you constantly wait for the pressure to build to use tools
I got asked what compressor I use, well heres a picture, I use twin 7hp/60 gallon compressors feeding a single garage wide run of schedule 80 3/4" PVC piping with brass fittings rated at 660 PSI, yeah! IM well aware you should NEVER USE PVC for air, I used it for 10 PLUS years ,in my old shop, my buddies used it for over 12 years in his shop,and its what Ive installed in the new garage, schedule 80 3/4" PVC piping with brass fittings rated at 660 PSI, if and when I have problems it will be replaced, I fully agree, if you used larger diam,or schedule 40 your just asking for problems

At $375 each ID by two of these


duplicating my current set-up, which allows me to port heads and run air tools etc. having the twin compressors reduced down time significantly so I don,t need to wait on the pressure to build back up, most guys don,t realize the volume of air thats required to run air tools continuously, almost anything works if your just using a single air ratchet, but porting heads or having several air tools in use makes the required flow necessary skyrocket


what happens is that both compressors are set up to max out and stop at 130 psi on separate pressure switches and both are set up to come on once the pressure hits 100 psi,that's the theory, in reality the control switches are not precise,
now if your only using a little air volume only one compressor generally kicks in, and yes its usually the same one kicking in first, BUT if your using a good deal of flow volume,the pressure drops fast enough for both compressors to kick in!, both compressors kick in as the second compressor generally kicks in seconds after the first if the pressure drops below about 100 psi,and both keep running until the pressure reaches about 127 psi, and yes one tends to kick out early,but the net effect is that both compressors do run and while one probably does 70% of the work, the pair do work to stabilize and keep the tanks fully pressurized, and yes you can easily adjust the pressure switch settings to reverse the order the compressors kick in, which I have done every few months, to basically keep the rate of stress or wear fairly consistent between the two compressors.

look closely youll see the compressors are mounted on two layers of 3/4" marine ply wood 2' x 2' and two layers of rubber waffle mat, this reduces noise in the shop, theres three 8" long expansion set 4" into the concrete slab, the bolts holding the compressors mounted firmly to the concrete have rubber washers further insulating vibration
BTW if you purchase a couple 3 ft x 5 ft rubber waffle mat it can be cut to produce required matching sections of rubber pads that can be screwed and glued to the compressor base support stack lower surface this prevents the pads from sliding on wet floors and reduces the damage potential damage to the vibration support over time,if the stack of wood were subjected to water on the shop floor

two compressors, feeding my air lines in the shop solved most of my pressurized air needs, allowing me to run tools without down time about 90%v of the time vs about 60% with a single compressor (I still need a decent air drier)
keep in mind if your just running a single air ratchet its a non-issue, but if your running several tools its far more important
down here in Florida you need to drain the tanks before and after every use, that's several times a day if you don,t want rusted air tools
most days the moisture in the airs fairly high
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First off, the manual usually gives the manufacture's recommendations for a breaker size for safe operation of this equipment:

3/4" copper pipe is almost ideal for running air lines but it can get expensive in a larger shop, at $18 per 10 feet ... UHYklfko8c ... ble3c.html

its usually a good idea to verify replacement parts are available ... c-271.html ... ing+Layout ... penElement
removing moisture from compressor high pressure air requires TIME , for the moisture in that air to condense,
DISTANCE, a long cool surface , like dozens if not hundreds of feet of metal pipe,will improve the odds of moisture collecting ,condensing and draining as the air cools, for the moisture to form on and drain, into, AND a pronounce reduction in air temperature or COOLING,obviously a condenser or radiator with its increased effective surface area and a fan to allow fast heat absorption will have benefits, keep in mind water or condensed moisture tends to run down hill , so giving it several places to collect that you can easily drain and pulling air you want to remove the moisture from, only from higher points placed after the air flow has had a chance to cool and condense is far smarter, design features, in planing your shop.



This particular compressor pulls 16 full load amps at 230V single phase line to line. The manufacturer requires a 30A 2 pole breaker to feed this equipment. The 80 gal. model in the column to the right pulls 23A and requires a 40A 2 pole breaker. The wiring as described below, will work for either model (wire size included).

Always start wiring at the end of the circuit and work your way back to the panel. Start by wiring up the pigtail (or cord) to the compressor.

You can use flat blade type receptacle & cord cap, (NEMA 5-30) but I don't recommend it. Use a twist lock so it won't accidentally come out of the wall if it's kicked or bumped.


most locals REQUIRE a power cut off switch, youll need a DUAL POLE 30 amp ... item=93469

one factor many guys over look when planing a shop is locating several quick connect chucks in convenient locations for connecting air lines
you don,t want to be draping air hose all over the shop floor or over your car. running a main feed thru the shop rafters with vertical drops with quick connect chuck about every 10 feet at about as high as you can easily reach along the walls or down the center of the room makes using air tools far easier ... -2363.html

3/4" galvanized pipe is almost ideal for air compressor piping in a shop if its laid out correctly, with drains
I recently helped a friend plumb his shop with 3/4" galvanized pipe for the air system
we covered all the threads , both female and male with the sealant pictured here and tightened the fittings then let it set up 24 hours before applying air , that was last week and he used s soapy paint brush to check for leaks at 125 psi and so far hes has none, he has at least 140 ft of 3/4" pipe so its not like theres no joints to leak

this works also
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btw this may help, most garages need a welder or a lift, sooner or later so youll more than likely need a 220 volt outlet (30-100amp)

this wiring stuffs not hard to do, but use the correct gauge wire and the correct plugs and sockets for the application and ID strongly suggest useing a MINIMUM of 10ga wire for 110volt and 3/4" metalic conduit (use the correct single breaker rating for the application on the 110 volt)
110 v outlet end
black/power to the gold screw
white/neutral to the silver screw
green/ground to the green screw

110v at the box
black/power to breaker
white/ neutral to neutral bar
green/ ground to ground bar

and 4 GA on the high amp 230 volt applications,like WELDERS, little 230volt stuff like compressors and lifts get along fine with (4) 10 ga wires (use the correct dual breaker rating for the application on the 220 volt)

220v at the outlet
red feed to one hot
black feed to one hot
green to ground on plug
(optional but HIGHLY RECOMENDED)
second green to the conduit ground screw

220v at the box
red to one side of DUAL breaker
black to one side of DUAL breaker
green/ ground to ground bar
optional green/ ground to ground bar ... l/apb.html

having two compressors has advantages.
now my HD compressors .....
"This compressor offers a solid cast iron, twin cylinder compressor pump for extreme durability. It also offers 135 PSI maximum pressure and air delivery 11.5/10.2 SCFM @ 40/90 PSI. "

so a single compressor should easily run a single tool easily, the problem comes in when several guys are using air tools at the same time which happens in my shop enough that I got tired of having to delay doing work while the pressure rebuilt.
now obviously the cheap answer is not letting my friends,working on their cars, use air tools ,in my shop at the same time I am , but I chose to just get the second compressor. BTW Ive done all my own electrical work and FAR exceeded building code in all my wiring work as its all larger gauge and in conduit with breakers and switches of better quality than required by code and Ive passed electrical inspections several times, when you do your own electrical work you cut cost by easily 70% as even with higher quality components its labor not parts that generally boost the costs
It cost me about $7K for wire and components to wire my shop, estimates for having the work done to my specs , and all in conduit ranged from $25K-$28K when I bid it out, before deciding on doing the work with my sons following my detailed instructions and certified plans submitted to the local building dept., all the inspector could say was he had never seen anyone take the time to do as nice of work or run every last run with home run 10ga or 4 ga copper wires, and run as many individual breakers IGF outlets and redundant grounds

100%chevy posted this bit of info
"if an electric motor blows the breaker check the capacitor,(s)
do you have a multi-meter?
If so,unplug the compressor.
Un-cover the capacitors.
Take a good insulated screwdriver and carefully short the capacitor terminals to ground.All of them!
Once you do this,the charge is gone.
Now,set the meter on resistance(pick one,you may have to try other settings)and put one probe on each of the capacitor terminals.Do one capacitor at a time.If you get nothing,reverse the leads.
If the meter is set on the right range and you have the polarity right,the scale should jump up to almost full scale and slowly go back down.
If not,the capacitor is bad.
Some motors have 1 cap and some have 2.Some motors also may have a centrifical switch on the end of the motor.This switch switches the windings from start to run.
Sometimes,inside the connection cover on the end of the motor,you may find the terminals burned.On either side of the little board.
Might be the un-loader or check valve is stuck,not letting off the head pressure or allowing air to go in the tank.
Plug it in as close as possible to the breaker and you may need to try a different breaker."


these work for most tests, but not ideal for a capacitor ... 98674.html

this type is far easier to test capacitors with
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BTW the pipes and hose you use to supply your air tools and the fittings have a large effect on the flow rates and tool performance.
yes the 1/2" ID hose is better ,than the 3/8" or worse yet the crappy 1/4" some tools are supplied with. but remember the compressor and tank volume will effect your results a great deal, hose flow rates and ID become almost of no concern if the pressure and volume source feeding the hose won,t supply the demand.
IDEALLY youll want to keep the flexable hose at the 25 ft -30 ft length and have multiple quick connection points around your work area, so the access to the pressurize air is easily accessed.
I ran my pipe , keeping in mind that moisture needs to drain, and locating drain valves at several low points in the runs to easily drain condensation.

when you put in the compressor in most shops youll want to install pipe to allow easy access to the pressurized air. ... ing+Layout

sweated copper 3/4" pipe & fittings and pipe connections are almost ideal but the cost is significantly higher than 3/4" iron pipe
now theres also the low cost option of SCHEDULE 80 PVC pipe,is less than ideal because its easy to break and if exposed to heat or direct sun-light it degrades over time and its unsafe, the more COMMON SCHEDULE 40, is NEVER A GOOD IDEA but if you do choose to use schedule 80 pvc , make sure the runs set up so its mounted high enough on the wall that is not subject to impact damage or exposed to heat, and is set up on an incline so it drains to a drain valve
water must be drained from compressor tanks daily, in most cases, in humid areas several times a day is preferable, so having a drain valve extended from under the storage tank to an easily accessed location sure helps.
the water drains frequently get clogged with crud inside the storage tanks on older compressors and at times you'll need to use some method of pushing an opening thru that crud in the drain, to allow water to drain.
you can add a desiccant air drier to the pressure lines and routing the air line supply lines along walls , at a slight upward angle or slope as distance increases from the compressor in the shop,so any water that condenses, drains to a second easily accessed location with a ball valve ,or second drain
there's cartridges with desiccant, that will work short term, but they tend to get saturated in short order if the tank on the compressors not drained almost hourly
airguard.jpg ... 2-npt.html ... DEV+130500 ... mber=94346

one or more of these moisture trap/drains along the wall helps, mounted along the wall, between the compressor and the tool hose connectors .
oiling tools frequently helps

yes there are lots of air driers available, but for most of us that don,t paint cars the cost is a bit prohibitive. ... mber=40211
40211.gif ... ryer.shtml


heres a well thought thru idea, placing a double run of air pipes in the rafters that are designed to condense any air in the lines and allow the lines to drain, yet not restrict air flow
So what would you recommend for a typical at home DIY'er? It's only that 1 hour of time I'd like to save, and being without any kind of air tools/compressor and only being able to loosen a bolt 1/8 of a turn at a time gets tiresome, I would just need something that could reduce the time a bit. No major engine work, just simple stuff like loosening suspension bolts, etc. I browsed at Lowe's today, but since i don't know much of anything about compressors or what would be sufficient for typical use, I thought I'd drop a note here and seek your opinion. ... =lowToHigh

It all depends on what your willing to put up with, tools are rated at a certain pressure and flow rate, yes IM fully aware you probably don,t want to hear the truth, but better hear it now before you waste money on a toy compressor,


heres a picture of a guys shop where he obviously went to a good deal of work and expense to get the compressor to supply dry air, the heat radiating copper pipe used to condense the moisture in the hot compressed air must be connected to the compressor before it enters the holding tank NOT after the holding tank, to work correctly

heres the best you linked to (it costs $300
028877366869md.jpg ... lpage=none
notice its rated at
3.2 CFM delivered @100 PSI pump

a common air ratchet might require a MINIMUM of 5.5 cfm and 95 psi

obviously that won,t keep up for more than a minute or so of use

this air ratchet below requires
90 PSI; Average air consumption: 6 CFM; ... mber=47214 ... =100063473

look at this compressor rating

solid CAST IRON, twin cylinder compressor pump for extreme durability. Offers 135 PSI maximum pressure and air delivery 6.5/5.5 SCFM @ 40/90 PSI

my brother in law has this compressor (ABOVE) in his garage, it works ok on an air ratchet provided its not in constant use, but it won,t allow more than about 4-5 minutes of air ratchet use before you need to allow the pressure to build back up to usable levels

Ive got TWO compressors roughly equal to these below
, it allows constant use of the tools, but a single compressor of this size still required some time to catch up under constant use
look at the compressor rating, if its lower it will only run the tool briefly while the tank drains and pressure drops off fast, the larger the tank ,and the higher the compressor rating,naturally the longer it takes for the pressure to drop off with use ... =100083906

these put out

135 PSI maximum pressure and air delivery 11.5/10.2 SCFM @ 40/90 PSI EACH

obviously you need to compare the tool requirements with the compressor out put, and remember theres flow losses, so a compressor rated at 5 cfm and 125psi WON,T CONSTANTLY supply a tool that's in use 100% of the time that's rated at 4.5CFM at 100PSI, and the larger the reserve tank is the better the compressor will maintain intermittent use pressure in most cases, anything less than 30 gallons is basically used to fill tires, and run small paint guns not run ratchets and die grinders, if you expect to use them without waiting for the pressure to build between uses

adding a oil cooler type radiator , or even several to the hot air lines leaving the compressor output , will allow you to cool and separate a great deal of the moisture from the compressed air


P1000311.JPG ... Qs6Dmf6k1A

I bought two of these compressors, one was not enough to keep up with the flow required in my shop,I found that was the least expensive route to get a 120 gallon storage capacity and two compressors, be aware that one compressor will always tend to kick in a bit before the other one and the second compressor will kick in a couple psi lower no mater how you adjust the two.each compressor supports about 8cfm at 120 psi, keep in mind you'll want to instal and AIR drier or any painting or sand blasting will quickly have moisture in the lines, you'll need to run a moisture separator, I fabricated mine for 4 air conditioning condensers so each compressor feeds a manifold that feeds all four condensers then returns to a manifold that feeds both 60 gallon storage tanks, the condensers have a electric fan to remove heat, read the link I supplied
the twin 60 gallon tanks act as a cushion, and having twin compressors helps also. but you'll obviously need two 220 volt circuits that each handle 15-20 amps MINIMUM.
remember the flow out of each compressor will be several hundred degrees (F) so you feed that into a shared manifold and that manifold feeds the condenser radiators, the fan, cools and condenses the moisture, the common manifold feeds the franzinator drain pipe assembly the franzinator acts as a moisture trap, which then allows dry air to be routed to the distribution pipe where you can use flex hose to the tools but even the air pipe should be arranged so any moisture will tend to run to a few multiple moisture drain points. as any moisture in the compressed air flow,will quickly cause problems with tools, or painting, or sand blasting jobs.
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Thanks for the info. I'll probably hold off on getting a compressor. I'd rather spend $200-300 more for a good compressor rather than buying a cheap one that won't hold up to constant use. You're right, i didn't want to hear the truth, and I do want to save time, but not at the expense of cussing out the compressor every time I have to wait for it to repressurize. :lol:
hey grumpy would a 4 gallon compressor be good enough for a gravity feed gun paint job. i am planning to start a primer job on my car
fast84vette said:
hey grumpy would a 4 gallon compressor be good enough for a gravity feed gun paint job. i am planning to start a primer job on my car

your paint gun will have a listed minimum air flow pressure rate , so will the compressor, the compressor rating doesn,t take into account factors like hose restrictions etc, Id want the compressor, to be rated at about 150% of the air guns needs,MINIMUM, Id bet a good amount of cash a 4 gallon compressors not going to prove to be nearly ideal in that application, but it may function for short periods if you frequently have stops in work flow to allow the compressor to rebuild pressure and volume between use, but painting usually requires dry air and moisture will be a problem if the compressor has no air drier which will reduce the compressor flow even more, having moist air in the fogged paint frequently results in a bad paint too surface adhesion
example ... 97855.html
Description of Central Pneumatic 97855

Ideal for painting new work or covering up damage repairs, you can get that professional look with this top quality air paint spray gun.

* Ergonomic pistol grip and trigger for comfortable operation
* Heavy duty construction for lasting durability
* Top hook for easy hanging
* One quart aluminum dripless, vented cup
* Spray patterns: 2" H x 8" W horizontal, vertical, and diagonal
* 2-1/8" diameter round

Required pressure: 60 PSI
Maximum pressure: 115 PSI
Average air consumption: 10 CFM @ 60 PSI

Cup size: 1 quart
Nozzle size: 1.8mm
Air inlet: 1/4"-18 NPT
Requires 3/8" diameter hose
Overall dimensions: 7-1/8" L x 4-1/4" OD x 10-7/8" H ... 90234.html

Description of Central Pneumatic 90234

This 10-gallon compressor is rated at 3 HP, with 4 HP peak, and is powered by a heavy-duty motor with thermal overload protection. A clear-view window lets you see when it's time to refill oil. Easy-to-read pressure/regulator gauges indicate CFM and PSI. High-impact ABS shroud.

* 4-HP Peak/3-HP Rated
* Air delivery: 5.6 CFM @ 90 PSI, 7.2 CFM @ 40 PSI
* Auto shutoff (115 PSI) and restart (85 PSI)

* 10-gallon air tank

120 volts, 15 amps, 60 Hz, 3400 RPM
115 PSI max. working pressure
Air outlet: 1/4"-18 NPT
Cord length 6 ft.
Overall dimensions: 24-5/8" L x 13-1/4" W x 28-1/4" H
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i saw the 60 gallon husky compressor at homedepot online and i am thinking of getting that one. seems like a good deal for the price. I think good enough for working on cars and painting them right?
for painting one should work ok!

I bought two because I run die grinders and air ratchets
and don,t like waiting for the pressure to build back up

a paint gun uses a good deal less air, flow but remember to drain the compressor every day and before painting and use an air drier ... esnew.html ... 40211.html ... t=0&page=1 ... ryers.aspx

most compressor tanks have a lower drain plug or fitting threaded either 1/4" or 3/8" NPT (national pipe thread) the petcock that threads into that plug or fitting so youll want to replace the main fitting and use a decent sealant on the threads

134-72025.jpg ... tId=744291


read thru this ... valve-mod/

* One 1/4 NPT ball valve.
* One 1/4 NPT elbow. I chose male to female.
* A couple assorted 1/4 NPT extension tubes. Male to male. I bought a 3″ and a 2″.
* One 1/4 NPT to 1/4 ID barbed hose adapter.
* PIPE SEALING COMPOUND! – Forgetting this caused me to go back to the hardware store.
* A short length of 1/4 ID rubber hose.
* And if your tank doesn’t have a 1/4 NPT drain, you’ll need an adapter. Or to buy all this stuff in 3/8 or 1/2.
you need to drain moisture that rapidly collects as compressed outside air cools in the holding tank, from your compressor daily or in some cases almost hourly to prevent problems with rust and moisture in tools or in spray guns ... 68244.html

1294.jpg ... 66857.html


harbor freight sells a automatic compressor drain kit that may or may not fit your compressor
but most hydraulic supply's or larger auto parts stores or hard ware stores can supply most if not all the parts to install at least an easily accessed manual drain
sooner or later all compressors need replacement parts or you decide that upgrading the compressor itself is a good idea, the holding tanks tend to last for years if drained regularly (daily), and most guys won,t do that if they need to almost stand on their heads and fiddle with the stock finger wheel valve thats about the size of a 1/4" wing nut thats very difficult to access and turn

most compressor tanks have a lower drain plug or fitting threaded either 1/4" or 3/8" NPT (national pipe thread) the petcock that threads into that plug or fitting so youll want to replace the main fitting and use a decent sealant on the threads

jegs has a common replacement part as will most really large well stocked hardware stores
134-72025.jpg ... tId=744291


but the compressor pumps and electric motors generally crap out every few years if used constantly, so do yourself a favor and don,t drop a ton of cash on a new compressor just swap to a better pump or motor if your current components fail and save yourself easily more than half the cost, its hardly rocket science to unbolt a defective component and replace it with a different component, yes you may need a drill or a welder to make a new mount in some cases if the new parts radically different in size but even then its hardly difficult for anyone with minimal mechanical skill
when you select a compressor remember tools will have a CFM and REQUIRED PRESSURE listed, if your tool requires lets say 7cfm @ 90 psi, a compressor that supply's just that minimum of 7cfm @ 90 psi,WILL NOT KEEP UP UNDER A CONSTANT DEMAND, because theres flow losses


theres an advantage in twin units

I installed the ball valve drain valves on the two compressor tanks yesterday on both compressors, Ill install the rest of the drain pipe tubing to route the moisture drained outside thru the shop wall this weekend, this mod make draining the tanks far easier,



btw youll need a male/female 1/4" pipe thread 90,

a 10" section of 1/4" pipe threaded on both ends,

the 1/4" ball valve

and a 1/4" barb fitting

and some 3/8" clear tubing to do the job.,

plus some hardening sealant for the threads

the result looks similar to this, but I used a longer pipe section so the ball valve is located close to the outside diameter of the compressor tank, for much easier access

BTW if you do this mod to your compressor, once its installed please take and post some CLEAR PICTURES
btw don,t be surprised to find the current tanks base full of slime, most of the OEM drains don,t work worth $%^&...youll be amazed at how much crud drains and how much easier it is to drain the compressor with the mods done

BTW WEAR SAFETY GLASSES WHEN pulling the old valve, Ive seen supposedly drained tanks suddenly squirt clumps of debris and slime under pressure when you THOUGHT you had drained all the pressure and started to unscrew the current drain because crud in the tank blocked the OEM drain
fast84vette said:
hey grumpy would a 4 gallon compressor be good enough for a gravity feed gun paint job. i am planning to start a primer job on my car

its VERY UNLIKELY but knowing the pressure and cubic feet per minute output of the compressor and the paint gun, would sure help
sooner or later all compressors need replacement parts or you decide that upgrading the compressor itself is a good idea, the holding tanks tend to last for years if drained regularly but the compressor pumps and electric motors generally crap out every few years if used constantly, so do yourself a favor and don,t drop a ton of cash on a new compressor just swap to a better pump or motor if your current components fail and save yourself easily more than half the cost, its hardly rocket science to unbolt a defective component and replace it with a different component, yes you may need a drill or a welder to make a new mount in some cases if the new parts radically different in size but even then its hardly difficult for anyone with minimal mechanical skill

read the links
viewtopic.php?f=27&t=24 ... pumps.aspx ... 3rqn7p12i4 ... r%20motors ... ogId=10053 ... 93274.html
I,m reading thru this thread and it reminded me to point out that theres a great many air compressor hoses sold by various auto parts stores and other vendors that are not worth the cost.
I purchased three 50 foot air hoses from HF ,when I bought my small compressor.
Two were loose rolls and one was on a retractable reel.
In my opinion I should have spent a bit more and got better quality hose, both the loose coil air hoses developed splits or blow outs and the end fittings leaked within months.

heres a few links ... 69580.html ... 69265.html

The retractable hose reel lasted about 8 month then the fittings stated leaking.
I repair those leaks by cutting the ends off and installing new fittings but within months the hose split.
So within a year they all went in a dumpster.
I went to the local hydraulic supply and had a couple 75 ft, long 1/2" inside diam. black, air hoses rated at 300 psi fabricated.
Those hoses are about 7/8" in diameter while the other HF hose was about 5/8" in diam. and noticeably lighter in weight.
Ive been using those newer , and larger hoses, for several years and although they cost me about $76 each at the time I purchased them, its proven to be a great deal better in my opinion, to spend a bit more up front and not have the hoses fail and have to stop and make repairs or a trip to buy a replacement, and the 1/2" inside diam, hose seems to allow the air tools to run a bit better.
Keep in mind I don,t have near the compressors or shop grumpy has my compressor rated at 2hp but its on a smaller 30 gallon holding tank, and it has a hard time exceeding about 125 psi , which is fine for running my air ratchet but not much else.
the subject of compressor tank internal corrosion due to constant moisture in the compressed air contained in the tank came up, and thats a valid concern as it will eventually weaken the holding tank strength.
obviously the first line of defense is to drain the tank at the start and end of each time the compressor,s used.
the earlier posts that show how heat is removed from the compressed air and water trapped before it enters the holding tanks goes a long way towards reducing the corrosion, but theres a spray corrosion reducer product that can be used to coat the inside of the tank, and a 2 lb Magnesium ANODE with a connecting electrical cable that can be used to provide some additional electrical protection, if the anode gets buried a couple feet down in damp soil ,outside the shop, the cable run thru the wall to the compressor and the cable clamped firmly to the compressor tank it will provide some galvanic protection