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Compressor

Posted: Tue Jun 09, 2009 8:28 am
by Stig
I've just been given a small compressor but have no idea what CFM it can deliver. It's Japanese, i.e. it's labelled in Japanese only and though I do know some Japanese it'll take me a while with a dictionary to translate.

Any rule-of-thumb I can use from the motor spec to guesstimate the CFM?

I suppose I could time how long it takes to get the reservoir up to pressure and work it out from that (once I've found out the reservoir capacity which looks 10-15litres). There'll be various conversion factors for the odd mixture of metric/imperial units too.

It's only 5kgf/cm2 (which I understand is near enough 5 bar) so I'm not about to buy shed-loads of big air tools for it.

Posted: Tue Jun 09, 2009 1:09 pm
by alainmoran
I believe that you are right in thinking that you can calculate the CFM from the amount of time it takes to get up to pressure.

http://www.truetex.com/aircompressors.htm

Posted: Tue Jun 09, 2009 1:29 pm
by Stig
Excellent. That's a really useful link. Thanks for that.

Posted: Wed Jun 10, 2009 9:47 am
by bmcecosse
At that pressure - it's only going to be good for blowing up tyres and spraying. To get enough air to comfortably spray a complete panel - just add another reservoir *Apologies, Mr Ecosse - I really do try to leave your posts alone, but this has been edited (just as Roger did last time it was posted) on the grounds of being potentially lethal advice*

Posted: Wed Jun 10, 2009 11:08 am
by tortron
i think the general rule of thumb is 4.5 cfm per motor HP

Posted: Wed Jun 10, 2009 3:32 pm
by bmcecosse
Not lethal advice - to add a reservoir where it will be protected by the main safety valve - perfectly safe and well worth doing. No doubt this too will be edited out! I will pm the poster instead.
Shame the 'editor' isn't willing to identify themself - or to send me a polite PM which I thought was the acceptable way of doing these things ?

Posted: Wed Jun 10, 2009 8:27 pm
by bigginger
Fair enough re forgetting my name - as you'll have guessed, it was me, As for "polite PM first" - nope, not that I know of. Generally a PM afterwards if it's something (like this) that NEEDS to be removed, but I chose to leave the explanation in situ. Why wouuld your second post be edited? No dangerous 'advice', no breaking of the rules? Odd comment.
Not getting into this, I'm afraid. I've already resigned my commision as a mod largely because I'm sick to the teeth of reading this kind of nonsense, and as soon as I'm removed from the mod list you can carry on ot your hearts content repeating the gospel according to BMC, at least until somebody else sees red and actually comments on it. Have fun.

Posted: Wed Jun 10, 2009 10:51 pm
by bmcecosse
Thanks Andrew - that's all I needed to know. Sorry you are 'resigning' - don't see the need for that!! Roy

Posted: Wed Jun 10, 2009 11:47 pm
by rayofleamington
pressure vessels should be appropriately certified - otherwise you may be certified (dead / insane).
However presuming the additional reservoir is ok, it will help with spraying small panels. Spraying things that needs more than the tank of air won't be possible unl;ess your compressor CFM is above that of the gun - and a decent spray gun will take plenty.

Posted: Thu Jun 11, 2009 12:24 am
by alainmoran
bigginger wrote:Fair enough re forgetting my name - as you'll have guessed, it was me, As for "polite PM first" - nope, not that I know of. Generally a PM afterwards if it's something (like this) that NEEDS to be removed, but I chose to leave the explanation in situ. Why wouuld your second post be edited? No dangerous 'advice', no breaking of the rules? Odd comment.
Not getting into this, I'm afraid. I've already resigned my commision as a mod largely because I'm sick to the teeth of reading this kind of nonsense, and as soon as I'm removed from the mod list you can carry on ot your hearts content repeating the gospel according to BMC, at least until somebody else sees red and actually comments on it. Have fun.
Hmm .. if you are so bothered then why do you continue to edit posts? Let alone whinge about the fact that people take issue to the fact you have edited their posts without telling them why.

Sorry, but common courtesy costs nothing, and if you have a problem with that then you need to take a long hard look at yourself.

IMO, the role of a moderator should be light-touch ... you should be sending PM's advising people that their post might lead people into causing harm to themsleves ... ONLY if someone refuses to mod their post should you be considering editing their contribution .. better still would be a post of your own explaining exactly why their post is a bad idea ... if you want respect then EARN IT by showing that you know better.

Simply editing someone else's post is just a power trip ... get over yourself.
rayofleamington wrote:pressure vessels should be appropriately certified - otherwise you may be certified (dead / insane).
ABSOULTELY ... while I may consider myself competent to adjust my gas fittings, there is NO WAY I would actually do it ... there are some things in this world where I know that I do not know enough.

Posted: Thu Jun 11, 2009 7:01 am
by LouiseM
IMO, the role of a moderator should be light-touch ... you should be sending PM's advising people that their post might lead people into causing harm to themsleves ... ONLY if someone refuses to mod their post should you be considering editing their contribution .. better still would be a post of your own explaining exactly why their post is a bad idea ... if you want respect then EARN IT by showing that you know better.

Alain,

One of the roles of a moderator is to ensure that posts are regularly reviewed and that the contents do not breach the board Terms & Conditions. All those registering on the site agree to follow these T&C's.

If a post needs to be moderated the poster will be sent a PM to explain the reason for the moderation or, as has happened here, the reason will be contained within the body of the post.

The T&C's are there for a reason, to protect both the MMOC and contributors to the board. If a post clearly breaches the T&C's it would be wholly inappropriate, even negligent, to follow your suggestion and wait for the poster to consider moderating the post themselves first, particularly in the case of advice that may be potentially dangerous. Think of the possible consequences should someone follow that advice and harm themselves, or others.

Whilst you may not agree with the role of moderator they are there for a reason.

Lou

Posted: Thu Jun 11, 2009 9:29 am
by bmcecosse
Actually - for personal use - pressure vessels don't have to be certified or tested. That is only required for Industrial use - where there are employees. I'm very familiar with the Pressure System regs - having been a Safety Officer for many years!
The cylinders I suggested are made and tested to WAY over the operating range of the compressor in question - and since it would be charged from that compressor, which I assume has a pressure switch and safety valve fitted - will only be filled to that limit, and will be perfectly safe. I used such a system for many years - when i had a very low cfm compressor, although I have since graduated to a better compressor which is fine with it's own reservoir tank.
My only query was to 'who' had modified the post (with no PM) - Andrew has apologised and all is now well - I hope!

Posted: Thu Jun 11, 2009 10:32 pm
by rayofleamington
having been a Safety Officer for many years!
safety doesn't just apply to the workplace. Having worked as a design engineer for pressurised equipment I'm glad to have left the sector now that engineers are responsible to guess how people will missuse equipment and be liable for it :(
Sadly in the current silly "sue anyone" culture, the MMOC has to be protected from litigation via forum activities - It's happened already so i'm sure it'll happen again.