Air Compressor Help,,
Thinking of getting an air compressor for the garage. Would be handy to have, and mainly wanting it to blow out sprinkler system at end of season. I have 5 zones that I intend to blow out each zone individually. Looking on line the recommended delivery of air should be 50 CFM at 50 PSI.
Found a 20 gallon portable Craftsman vertical compressor that looks nice. Specs says can do up to 175 PSI. Good, covered there. But the volume is in SCFM and states 5 SCFM at 45 PSI. Huh, can you translate that for me?? Is that only a tenth of what I need?
Specifications
- Product Type: Air Compressor
- Air Compressor Pump Type: Oil-Free
- Corded or Cordless: Corded
- Handle Included: Yes
- Horsepower: 1.8 HP (horsepower)
- Maximum Pressure: 175 pound per square inch
- Portable: Yes
- Tank Material: Steel
- Tank Pressure Gauge: Yes
- Tank Size: 20 gallon (US)
- Tank Style: Vertical
- Volts: 120 volt
- Warranty: 1 Year
- Weight: 89.29 pound
- Wheeled: Yes
- Air Delivery SCFM at 40PSI: 5 standard cubic foot per minute
- Air Delivery SCFM at 90PSI: 4 standard cubic foot per minute
- Phases: Single-Phase
- Stages: Single Stage
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SCFM vs CFM, https://trident.on.ca/what-is-the-difference-between-scfm-and-cfm-in-air-compressors/
50 CFM @ 50 PSI takes a pretty good sized compressor. I'd stay away from the 'oilless' types as they usually use a diaphragm to pump the air and tend to be quite noisy. A pump that uses pistons will be much quieter and will generally give you higher CFM.
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Agree with what Neo said on all points. 50 CFM @ 50 PSI is a healthy machine. This could be compensated for by adding extra air receivers in the system.
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20 gallons is just over 2.5 cubic feet.
Your tank at 175 PSI will translate to 8.75 cubis feet at 50 psi.
This will give you 11 seconds of 50 psi at 50 cfm.
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In my shop I bought a Lowes 5 hp 2 stage compressor on an 80 gallon vertical tank.
You will never need more than 100 PSI pressure, so the 175 pressure Just shows that the compressor is 2 stage. You will not want to put more than 40 psi through your pvc water pipes/zone valves for blowout.
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Thanks all
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B
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Agree with NEO & HPD. Would be perfect for blowing out your sprinkler system and running impact wrenches & drills.
I have a similar setup to what Alpine has and its ideal for whole paint jobs on vehicles, high speed buffers, sanders, & grinders.
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A friend told me decades ago that timing is everything. I boils down to how long do you need the 50CFM@40psi. As others have said you can get a very large and expensive compressor or have a large tank capacity which is less money. You probably have done this before so you should have some idea how long it takes per zone. Years ago I could tell you how large a tank you need with the Craftsman compressor you mentioned. I'll leave that to the younger engineer types for now.
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"50 CFM @ 50 psi"
50 CFM is a HUGE output. Not something a 'homeowner' would otherwise need.
As an interim until I can afford a replacement for the 220V two cylinder 8 CFM 80 gallon tank commercial compressor that burned in my old shop building, I bought a 110V 4CFM 30 gallon oil less compressor @ Harbor Freight. It's done a decent job for a year but definitely not up to heavy air impact tool use or inflating large ag tires. I sort of like the adjustable line pressure vs tank pressure when using certain air drive tools.
The 175PSI standby pressure does offset the smaller tank and low output compressor but only for the first couple of minutes of air use. As mentioned, adding another tank will extend the capability of a smaller output compressor.
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The great, or not, thing with search engines is getting different answer to come up each time. Recent search now shows anywhere from 10 CFM up to the 50 previous mentioned. Answers are all over the place. To get a compressor I want and know will do the job I'd be paying $1300 or more. Really about the only thing it'd be used for is the blow out. I pay $100 a year to have the system blown out. It would take me 12+ yrs to pay for the compressor. Not worth it, just going to pay a guy end of each season and be done. Thanks for the replies.
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When I do a sprinkler blow out ( I have 2 acres that are irrigated) I only run each zone for less than 2 minutes. My observation is that all the water is blown out in that time. 20 years and no problems.
If you have patience any CFM/ tank size compressor will the job.
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Real-world experience tells me that a small compressor will do the job . 1 hp to 1&1/2 hp 8 to10 gallon will do the trick ,about $175.00
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Tell us Joe, how long do you need that 50CFM & 50 PSI available for each leg?
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There's gotta be a way to move a bunch of air using a long pipe, some hose, and a half pound of black powder…
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^^^The problem with that solution is: there's a limited outlet for the residual water so trying to send ALL of this water out the exit in a single 'blast' won't work.
In a remote barn with limited AC service, I've been running a small 'pancake' compressor for years by simply adding an 80 gallon pressure tank from an old compressor to the line. Sure, it takes 15 minutes to charge this tank but the volume of compressed air allows the little 3CFM compressor to run big impact wrenches for much longer before pressure drops.
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