gwr7800
Part of the e-furniture
Member of Portsmouth mes
Posts: 384
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Post by gwr7800 on Jan 5, 2016 14:47:59 GMT
Hi Iam considering a compressor just for general use really, cleaning, blowing up car and motor bike tyres, light spraying perhaps, from what I've seen in catalogues etc ( machine mart ) Iam in the option I need a 2 hp motor with either a 25/50 Ltr receiver most have a max working pressure of around 8 bar, single phase. I would be grateful if any members can recommend from experience suitable compressors that they have or use thanks in advance Chris
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Post by marshall5 on Jan 5, 2016 16:23:39 GMT
I've had a Machine Mart Airmaster Tiger 8/250 for several years and have been so pleased with it that I bought one for the Club last Summer. 2HP motor, 24l tank and currently 95.85 inc VAT. Cheap as chips and does exactly what it says on the box! If you subscribe to their e-mails every so often you'll get a "VAT free" coupon which makes it even cheaper. No connection other than a satisfied customer. Ray.
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Post by ejparrott on Jan 5, 2016 17:48:09 GMT
Mine is Machine Mart. It's a 50l tank, belt driven, and I think 3Hp. Can't remember the working pressure offhand, but I know it's higher than my direct drive little jobby which is also machine mart, which means I can't run the two together to boost output.
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Post by andyhigham on Jan 5, 2016 20:00:27 GMT
If possible get a belt drive compressor, they are a lot quieter than direct drive
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Post by chris vine on Jan 5, 2016 20:51:18 GMT
If you can get an oil free compressor, you won't have any problem with oil contamination if you want to use it for spray painting!
However if you only want it for general stuff, it makes no odds...
Chris
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SteveW
Elder Statesman
Posts: 1,397
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Post by SteveW on Jan 5, 2016 21:09:04 GMT
GWR, I bought a 1.5HP unit from Machine Mart when they were a load more money and I wished I'd dug really deep to get the 2.5HP unit. The smaller compressor does the usual things even tried it for grit blasting with success. Generally anything sub-2HP is going to run out of air very quickly. To get an idea of useful air volumes check out the Machine Mart air tools for what they need. Maximum pressure output is less important than maximum volume.
A couple of months before this Christmas I bought a 2.5HP unit from Aldi of all sources.
When buying a compressor don't forget you'll also need some air hoses to get the air to where you need it. Also include, perhaps choose, one or other of the snap-on fittings and get enough to fit all your air tools and hoses. A very useful addition is a filter/water trap and remember to regularly blow the air tank down to remove the water. Grit blasting without a water trap gets you drops of water combining with the grit and going solid in the nozzle.
Some air tools need lubricated air, so do our locomotives. The down side of including a lubricator in your system is you can contaminate your hoses with oil and this doesn't work well when you either spray paint or inflate tyres.
Again from Aldi I bought an air hose reel that retracts the hose on a quick flick and at only 20 quid. I would recommend one of these mounted nearest to your car. Again the reel is best fitted with quick release air connectors.
When I first bought my compressor I also bought the cheap beginner's air tools set to include tyre inflator, air gun, paraffin gun and paint sprayer. The cast monkey metal tyre valve connector fell apart very quickly and the better replacement cost more than the whole set. A point here being the tyre inflation gauges all seem to go up to 140psi making them nearly useless for acturate car/bike tyre inflation. You don't usually use the remaining 100psi scale.
The final point being where are you going to store/hide the thing. A 50ltre tank is a whole lot bigger than the 25ltre tank. If your predicted applications are going to use a lot of high pressure air then you'll need to learn to love the bigger 50ltre tank even after having to walk around the bloody thing all the time. I've got a 25ltre tank and it works for me.
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Post by Deleted on Jan 5, 2016 21:41:25 GMT
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steam4ian
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One good turn deserves another
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Post by steam4ian on Jan 5, 2016 22:17:37 GMT
My contribution is to advise spraying some oil inside the tank.
I left my compressor for a week or so after use before draining it down. When I did drain it rusty water came out. WARNING; the tank is corroding internally.
SOLUTION; inject fish oil rust preventative into the tank through the drain valve.
OUTCOME: no more rusty water
Considering that the tank is a pressure vessel that will never get tested in your life time and sits near where I work in the shop I don't want to be around when corrosion finally causes the tank to fail. A spray can of fish oil is good insurance.
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NickM
E-xcellent poster
Posts: 230
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Post by NickM on Jan 6, 2016 0:05:23 GMT
Unless you intend using your compressor to spray paint anything that is! The slightest amount of oil contamination will put so many fish eyes in your paint it will look like you have been trawling 500 yards off Sellafield!
A rusty compressor tank will at worst suffer pinhole perforations resulting in it not holding pressure, it is very unlikely to burst.
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steam4ian
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Post by steam4ian on Jan 6, 2016 8:09:09 GMT
Unless you intend using your compressor to spray paint anything that is! The slightest amount of oil contamination will put so many fish eyes in your paint it will look like you have been trawling 500 yards off Sellafield! A rusty compressor tank will at worst suffer pinhole perforations resulting in it not holding pressure, it is very unlikely to burst. Then why are air receivers routinely and regularly tested and pressure certified? An industrial air receiver can just as easily get a pin hole and leak as you say, so why the fuss unless the experience of others has demonstrated other modes of failure?
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NickM
E-xcellent poster
Posts: 230
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Post by NickM on Jan 6, 2016 8:26:51 GMT
I don't know about Australia, but in the UK, air receivers used for domestic (as opposed to commercial) compressors don't require testing and certification. If they were going pop in peoples sheds on a regular basis, I'm sure the 'elf n safety brigade would be all over it like a rash.
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steam4ian
Elder Statesman
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Post by steam4ian on Jan 6, 2016 9:03:24 GMT
Nick
Why is the failure mode for a domestic air receiver different to that of an industrial air receiver?
Ian
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Tony K
Elder Statesman
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Post by Tony K on Jan 6, 2016 9:20:33 GMT
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NickM
E-xcellent poster
Posts: 230
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Post by NickM on Jan 6, 2016 10:50:51 GMT
Ian
I didn't say there was a difference between how domestic and industrial receivers might fail. Size of bang and damage done might be different though. The low perceived risk level in domestic use is probably what avoids compulsory testing. There are so many differences between domestic and commercial rules I won't bother listing any. I would suggest the design life of the receiver on a domestic compressor is far longer than the compressor itself - I bet that most knackered, low end compressors that have found their way to the tip still have perfectly serviceable receivers attached.
Nick
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Post by johnas on Jan 6, 2016 15:34:27 GMT
Unless you intend using your compressor to spray paint anything that is! The slightest amount of oil contamination will put so many fish eyes in your paint it will look like you have been trawling 500 yards off Sellafield! A rusty compressor tank will at worst suffer pinhole perforations resulting in it not holding pressure, it is very unlikely to burst. (new username, but old user here) From the almost local news a year or two ago: "A Quebec man was forced to have his leg amputated after an air compressor exploded in Chelsea, Que. A 44-year-old man was working on an antique car at this Chelsea, Que., home with two others when an air compressor exploded. Police in the province’s Outaouais region were called to a home on Chemin Maxwell for an explosion at about 12:30 p.m. ET. When officers arrived, they said they found three men injured after an air compressor had exploded. The men had been trying to restore an antique car, police added. A 44-year-old man suffered extensive damage to his lower leg, forcing doctors to amputate the leg at the knee in hospital. Another man, who is 50, suffered head and back injuries, while a 58-year-old man was treated as a precaution but did not suffer any major injuries. Police believe the compressor was old and had been damaged by rust, partially causing the explosion.
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jan 6, 2016 22:40:11 GMT
May be I have had too much contact with high pressure gas mains and pressure vessels and the reasons they have ruptured.
Corrosion induced pits in any vessel act as stress raising points which only increases the corrosion leading to ultimate failure.
The corrosion is more likely to occur at a weld.
The saving grace for the hardware store variety air compressors is that the cylinder will outlast the compressor.
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Post by runner42 on Jan 7, 2016 1:29:36 GMT
Unless you intend using your compressor to spray paint anything that is! The slightest amount of oil contamination will put so many fish eyes in your paint it will look like you have been trawling 500 yards off Sellafield! A rusty compressor tank will at worst suffer pinhole perforations resulting in it not holding pressure, it is very unlikely to burst. Then why are air receivers routinely and regularly tested and pressure certified? An industrial air receiver can just as easily get a pin hole and leak as you say, so why the fuss unless the experience of others has demonstrated other modes of failure? Ian,
as we know the AMBSC code Part 1 treats air vessels the same as small boilers, requiring periodic testing and certification. However the air reservoir in an air compressors doesn't appear to require this testing and certification, if it did then I assume that there would be a stamped date of last certification on the vessel and a known date for retesting similar to the marking on your LPG gas cylinder. My air compressor has no markings on the air reservoir and the owners manual is silent on the issue of retesting. From that I assume that the application is different from say air vessels in so much that the general public is not exposed to a catastrophic failure if it occurred. It's only the operator that is likely to cop it. The max pressure obtainable is a factory setting which is generally 90 psi.
Brian
PS Rust appears to cause failure of the air vessel so those that are safety conscious could do an internal inspection of the reservoir using a borescope camera through the drain plug.
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gwr7800
Part of the e-furniture
Member of Portsmouth mes
Posts: 384
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Post by gwr7800 on Jan 7, 2016 16:44:49 GMT
Thank you for the advice chaps, what I plan to do next is see just how big a 50 Ltr one actual is! Noise isn't to much of an issue as most of the time it will be used for cleaning then pumping tyres, so mostly short periods. my workshop built behind the double garage next to it, so is pretty good for spare space. Oil less and belt drive seem to be a good solution. I've taken Marshall 5s advice and signed up email wise as well thank you. As far as Iam aware most compressors/receives come with a certificate from the manufacturer, the club compressor has I believe a pressure check every 5 years, again with a domestic/ hobby compressors no other checks are required thanks once again very much appreciated, will let you know what I settle for! Cheers Chris
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Post by Deleted on Jan 7, 2016 18:18:22 GMT
Regarding how big a 50L reservoir is, you may find the photo of my workshop (which contains a 50L compressor) on page 22 in the 'What I've done today' thread of use...there are a number of other items in the image that should help you judge the size...
cheers
Pete
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SteveW
Elder Statesman
Posts: 1,397
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Post by SteveW on Jan 7, 2016 20:03:03 GMT
GWR, If you just want a quick squirt of compressed air every now and again you'll find a 50ltr tank will take twice as long to get to a pressure necessary to pump tyres compared to a 25ltr tank.
I've noticed my new 2.5HP compressor gets its 25ltr tank up to pressure a whole lot faster than my old 1.5HP/25ltr compressor. Its a bit louder but for less time.
So if you do the math... if you want a 50ltr tank you'll need a minimum 2.5HP compressor to fill it before you forget why you turned the thing on.
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