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General => The garage => Topic started by: Guy on 14 October 2011, 10:57

Title: air compressors
Post by: Guy on 14 October 2011, 10:57
anyone know anything about them?

after the following

able to fit in a van (mobile) with access to 240v
10bar (pref) 8bar (min)

i don't know anything about these but I have to have one for a new secret weapon I hope to be bringing on board  :wink:
Title: Re: air compressors
Post by: Ant1981 on 14 October 2011, 15:24
10 bar? That will need a massive van. The compressor unit and receiver will be huge.
Title: Re: air compressors
Post by: pid on 14 October 2011, 17:07
I've got a rhyas one

50ltr
14cfm
3hp twin

Does the job. Not that big or heavy but I don't use mine all day so can't say if it would coupe being used all day.
Title: Re: air compressors
Post by: danny_p on 14 October 2011, 23:38
do quite a lot with compressors.

120 psi ( 8 bar ) is about the top end of most diy ones  its not that cant do more pressure its that the tnks arn't specked for it and tha safty valves blow.some  don't even make the 120 psi.   150 psi is the pressure that proper industrial compressors work at.

the big question is how much air you need and do you need a contius or intermittent supply

if your after an intermittent supply a smaller dispalcement pump with a big tank will cope but for a permant supply tank size is irrelivant the pump needs the displacement.

as you mention running off 240v   i juessing you'll be runing it of an extension lead from a customers house  :sad:   if you want any seious airflow your stuffed  you'll be down to a 2.2 kw 3 hp motor in most likelyhood   so about 14 CFM  free air displacement,   what will really upset you is that won't run a tool rated at 14 cmf  continusly  it'll be more like 4  :sad:

if your needing lots of air and theres room under your vans bonnet i've got an Engine driven screw compressor in the corner of the workshop  it's only a littel one but good for about 40 CFM at upto 160 psi
Title: Re: air compressors
Post by: jakirave on 20 October 2011, 17:11
tornador gun?
Title: Re: air compressors
Post by: Guy on 20 October 2011, 19:24
tornador gun?

yep.. hopefully
Title: Re: air compressors
Post by: Guy on 20 October 2011, 20:10
do quite a lot with compressors.

120 psi ( 8 bar ) is about the top end of most diy ones  its not that cant do more pressure its that the tnks arn't specked for it and tha safty valves blow.some  don't even make the 120 psi.   150 psi is the pressure that proper industrial compressors work at.

the big question is how much air you need and do you need a contius or intermittent supply

if your after an intermittent supply a smaller dispalcement pump with a big tank will cope but for a permant supply tank size is irrelivant the pump needs the displacement.

as you mention running off 240v   i juessing you'll be runing it of an extension lead from a customers house  :sad:   if you want any seious airflow your stuffed  you'll be down to a 2.2 kw 3 hp motor in most likelyhood   so about 14 CFM  free air displacement,   what will really upset you is that won't run a tool rated at 14 cmf  continusly  it'll be more like 4  :sad:

if your needing lots of air and theres room under your vans bonnet i've got an Engine driven screw compressor in the corner of the workshop  it's only a littel one but good for about 40 CFM at upto 160 psi

danny... thank you for your post

the specs for the tool that I am using state that it needs 8bar min... but as i understood it that means an 8bar compressor will run down to 6bar before it recharges

the tornador will be used for intermittent periods... of say shorts bursts during a hour or so of work on an interior detail

being able to run this from the van and driven from the engine would be ideal...

this is the tornador http://www.autosmart.co.uk/Tornador.html (http://www.autosmart.co.uk/Tornador.html)

danny... is there a chance that you could write your post for someone who doesn't understand compressor speak please? just got my head around bar (i think) and now we have cfm, psi, kw and hp  :laugh:
Title: Re: air compressors
Post by: danny_p on 22 October 2011, 22:18
buying compressors is a minefield.

and there specifactaions are confuseing and quite offten massivly exagerated


KW and HP  are just the measurements of motor power  2.2 KW motor will give about 3 horsepower to drive the compressor with,  meany cheep compressors are badged as haveing a "powerfull 3 HP motor"  thats about the biggest size of 230v motor commonly used and plugging anything bigger into a 13A socket in a customers house may not go down to well.  the problem comes with the AIR end of the compressor as all singelphase motors are much of a muchness efficency wise.

with the air end is where CFM comes in or  cubic feet per minute it's basicly just a measurement of how much air the compressor can move.  what you have to watch out for is the, FREE AIR DISPLACEMENT or FAD.

the free air displacement is basicly the volume of the compressors cylinder/s multiplyed by how meany cycels it dose per minute, this will give a volume of air the compressor would supply in theory if it was 100% volumetricly efficent,  sadly a compressors real world performance is rather a lot diffrent how diffrent is a case of how well made the pump itself is,  cheep chinesse direct drive compressors have quite large free air displacement figures quoted but provide very littel air at pressure  and as the pressure rises they get more and more inefficent.  they also make a lot of noise

they look something like this

(http://www.alltoolsdirect.co.uk/ekmps/shops/alltoolsdirect/images/sealey-50ltr-direct-drive-compressor-2.0hp-sa2250-2-11736-p.jpg)

belt driven compressors cost more but are rather a lot better there pumps have a larger dispalcemet but operate at a lower speed they are much less noisey than direct drive and more efficent  and in the real world provide more air than a direct drive would do given the same size of motor, they also last rather a lot longer.

they'll look somethign like this
(http://www.p-wholesale.com/upimg/19/740a1/3hp-belt-drive-industrial-air-compressor-dp-2065-806.jpg)

i think for you the only real option you have is a 3hp belt driven compressor unless your funds can strech a bit more.  there bloody expensive and not very common on 230v singel phase but a hydrovane is probaly the ideal solution in all ares bar cost.

there more efficent than piston compressors, quieter, very heavy duity will give more air for give size of motor than any piston compressor and the manufactures don't tend to bullsh!t the specs. they are also much more compact

they look a bit like this (http://www.rheological.co.uk/wp-content/uploads/2010/08/HV01-RM-Hypac.jpg)



Title: Re: air compressors
Post by: Guy on 07 November 2011, 14:25
thanks for your responses Danny and apologies for my late response to this thread

do you think then that there is a way/opportunity to realistically power an air compressor from my van?
Title: Re: air compressors
Post by: Guy on 07 November 2011, 15:07
thanks for your responses Danny and apologies for my late response to this thread

do you think then that there is a way/opportunity to realistically power an air compressor from my van?


also - found this...

http://www.diy-compressors.com/catalog/product_info.php?cPath=28_23_57&products_id=52 (http://www.diy-compressors.com/catalog/product_info.php?cPath=28_23_57&products_id=52)
Title: Re: air compressors
Post by: danny_p on 08 November 2011, 00:42
what i think you really need to do, as i think it's just the one tool you want to run is get hold of the tool and borrow a compressor and see just how much air it actualy needs to work. 

there are ways of fitting up a van mounted compressor ( van dependant ) that would supply more air than you need without a problem  but they do cost espectaly as your after clean air. 

if a 3hp electric one won't do the job  a petrol compressor may be the anser but they are expensive to run and make your van smell :(
Title: Re: air compressors
Post by: Guy on 08 November 2011, 11:28
thanks again Danny :afro:

yeah... you might be right on trying some different compressors... even though the tool costs £80 it would be worth getting hold of it just to try some different solutions and seeing what works effectively

can you link me up to any suppliers of 'in-van' air compressors please?
Title: Re: air compressors
Post by: Guy on 30 November 2011, 17:22
right... I have the specs needed for the Tornador

8bar min (8.5bar max) - will need a regulator
min tank 25ltr
7.8CFM / 200L/min

does all that make sense?

so can anyone link me up to something that I can have in the back of the van (electric off an extension cable, petrol or diesel or vw caddy powered). It won't be used continuously but on and off as and when needed. Say for doing a dashboard, then a door card, then maybe a footwell etc

I don't mind buying a cheapy that does the job... I just want to test if it is any good and if I use it often... if I need to upgrade in the future then I can do.

thanks in advance

Guy

Title: Re: air compressors
Post by: Bellend on 30 November 2011, 18:35
What sort of wattage will the compressor draw at 230v?

I have no idea what wattage it would need but you can get very beefy power invertors, would have to have the van running though as it would kill batteries quick!
Title: Re: air compressors
Post by: Guy on 30 November 2011, 20:26
Are power inverters easy to fit and could I run other kit off one?
Title: Re: air compressors
Post by: danny_p on 01 December 2011, 00:08
so it's got to fit in a caddy van.

somewhere in the depth of the workshop is an engine mount compressor off a 1.9 TDi that was in aa T4 van that ,ay possobly fit.  provides loads of air but need van engine running.

you won't need a regulator tho they just restrict air flow your working right at the top end of most compressors outpu anyway.

from the figures you provided i can guess some duity cycels

60 ish CFM  free air displacement for 100% duity
30 ish CFM FAD for 50%  duity
15 ish CFM FAD for 25% duity

a 3 ish  hp pump will let you use it for 1 minute in 4 or 25 % of the time.  the bigger the tank the longer you can use it for in one hit but the longer it'll take to pump back up.   


if you were closer id say pop down and have a play with one of our airlines