[imc188222]

Here is an old air compressor that I picked up. I have searched the interweb for info on it without any luck so I figured I would throw it up here and see if anyone can help. It is a Worthington made in Holyoke Ma. The tag on it says 4 1/4 x 4 1/4 x 2 3/4 and 46216. I am guessing that the latter is a serial #. On the first number, it would seem that 4 1/4 x 4 1/4 is the bore and stroke but what is the 2 3/4?

My main questions are what rpm should this thing be run at and how many hp is it going to take to do that. My uneducated guess at rpm is 750. I have a new supposed 6hp 3450rpm motor that according to the tag draws 25amps. So, with a motor closer to 5hp turning a 3.5" pulley I am concerned that I don't have enough hp or enough belt wrap to run this compressor. Before I go buy a 3.5" pulley for this motor I would like to get some idea of the hp requirements of this compressor. For all I know it needs 10hp to spin it at 750rpm. I am really shooting in the dark here.

Ignore the motor that is currently hooked up to it, that is just to spin it to check operation. Also, ignore the tank that it is on, I have read the tank explosion threads.

Thanks for the help.

 

[WyoRoy]

Twin cylinders so it would be 4 1/4" bore (times 2) by 2 3/4" stroke.

 

[fredschrom]

try giving these guys a call with you serial number and model number:

http://worthingtoncompressor.com/worthington-parts-products.html

Your guess on rpms is just that, on a twin V like that they can vary from 450 to 950 rpms, and even once you know the rpms there is a range. It looks old so I wouldn't ry to run it at the top range and would sacrifice some cfms for durability ( I did that on my fresh rebuilt head, and ran about 50 rpms under the rated nominal rpms and didn't try to hot rod it.)

If I was guessing I would say 650 rpms, and setting it up at 625 would be a good number. But I would try calling the above and see if you can get a real number not just a scientific wild assed guess before exploring that.

It won't hurt it to run it slow, but there is a minimum rpm speed to produce air. Do you have a photo tack? What is the motor on it right now spinning it at and does it function?

Another clue is the size of the intake and discharge NPT's. If its 3/4 its a 22-28 CFM machine, if its 1" its a probably a 30 + CFM.

And your 6 HP motor might be a tad small, I am thinking by the bore ( which is big BTW ) that your machine is a min 7.5 HP, that nipple again is the clue and if its a 1" its probably a 10 HP.

 

[fredschrom]

A last thought, I have read and fully understand the air compressor tank posts. If you have a bore scope or a means to look into the tank I would, if its rusted out on the inside its junk but it might not be, looking on the inside is the only real way to know, and a snake video or scope is about the only way to see inside check the whole bottom of the tank about 4 inches up where the water sits and rusts out the tank. I would rinse it out good to break up any crude so you can see the metal before looking though.

 

[farmshop]

Most of those older twins run on 1725 rpm motors. 3450 motors don't have enough starting torque. While lower Rome are better for longevity too low will result in decreased lubrication so stay close to the recommendations of the manufacturer.

 

[fredschrom]

" While lower Rome are better for longevity too low will result in decreased lubrication so stay close to the recommendations of the manufacturer. "

True but 50-75 rpms slow won''t effect anything.

 

[farmshop]

True I have seen guys take a newer high rpm compressor and cut the Roma in half thinking it would be better only to burn up the pump for lack of oil

 

[imc188222]

Thanks for the replies.
I do have a photo tach and the motor that is on it now is spinning it at 740rpm and it pumps air. The motor that I have on there is only 1.5hp and is being used out of convenience to check the function of the compressor.

The discharges are 3/4npt.

I tried calling worthington and they referenced specs off a modern compressor (1400rpm) and suggested calling grainger if I needed a compressor. Not a whole lot of help.

I have a pulley coming for the 6hp(?) motor that I have. I guess I will put it on there and keep a close eye on the amp draw. I think I am in the market for a 1ph 7.5hp motor. Big bucks.

 

[fredschrom]

" I have a pulley coming for the 6hp(?) motor that I have. I guess I will put it on there and keep a close eye on the amp draw. I think I am in the market for a 1ph 7.5hp motor. Big bucks. "

Sorry for the bun lead.

You might want to think twice about a 7 1/2 hp single phase...... major amp draw. When your up at that level a phase converter and going three phase is good route. If you look you can find a 7 1/2-10 hp used in a three phase and it will for sure be cheaper.

6 hp is that and old motor or one of the the new special rated motors, as 6 is an odd number?

If its one of the new new special service rated jobs keep a close eye on that motor as thats marketing terms for 3-1/2 to -4 hp but making the customer thinking he is getting something he is not. It will torgue to death, I just fixed a air compressor a couple of months ago in a shop and it was a high end home depot unit that said 5 hp special service on the motor label, it was a maybe 3 hp motor and had torgued to death, taken out the caps and the bearings.
I replaced it with a Leeson 5 HP and it was good to go.

Just because it has 3/4 inch nipples I would say its 7 1/2 hp unit min.

 

[imc188222]

The 6hp motor I have is a tractor supply special. According to the tag it is 6hp, 3450rpm, service factor of 1.0, 25 amp draw. I am sure that at best it is 5hp. That and not having much starting torque I do not expect it to work. I already ordered a pulley so I guess I will at least try it. I will have to look into phase converters, 3ph motors of that size definitely are easier to come by.
thanks for the help

 

[WyoRoy]

Maybe two 3-phase motors and build yourself a rotary convertor to power the compressor and any other tool toy your heart can fall in lust with...

As far as your compressor goes, it appears to be a single stage. You may want to check on that as a single stage compressor head may be well served with the motor you have now. The piping appears single stage as does the tip-off that both compressor pistons are the same size and stroke...high pressure side is usually a smaller piston.

EDIT: Give these folks a call. In the past I've always had great luck with them being able to give me concise answers to my inane questions and provide fine customer support.

http://www.stewartandstevenson.com/equipment/category/air-compressors/stationary-air-compressors

 

[fredschrom]

" As far as your compressor goes, it appears to be a single stage. You may want to check on that as a single stage compressor head may be well served with the motor you have now. The piping appears single stage as does the tip-off that both compressor pistons are the same size and stroke...high pressure side is usually a smaller piston."

I think your right on the single stage, basically like the EL Smith compressors. I would let that upset the cookie cart though as there were some good old single stages that put out a ton of air. Yeah its not high pressure but both of my two stages have a regulator on them and I don't go over 100 psi for my applications ( nails guns, sanders, DA, impact, air rachet, I know there is more out there but off the top of my head I can't remember), my regs are usuall set to 90-95 psi.
What your going to loose on pressure you will more than make up in CFM. Single stage with that bore and stroke its probably a 35-45 CFM head. Here is a lnk from a old post of mine on EL Smith single stage compressors: http://www.stellar-industries.com/pages/pumps.htm

Assuming your head turns slower ( ???? ) its a little shorter stroke, I would guess that 35 ish or slightly better is your cfm.

Your motor although 3400 rpms will work, just make sure you get a unloader installed. It might croak eventually but the unloader with extend that time.

 

[WyoRoy]

Sorry Fred, I corrected your post and added "n't" on the "would" in your post's quote above. Gotta agree with you one the high volume single stage being a worthwhile compressor head to fix/rebuild/slap back on a tank...especially if was going cheap to start off with. Wouldn't mind having a similar head on mine for sand blasting duties!

 

[fredschrom]

Wyoroy,

Nothing to be sorry about it needed correcting.

I did some more looking at that head this am, and I can't find anything. I am convinced that is a 35 + cfm machine though, because of the nipple and the bore. I am not sure that the rpms guesses are even close though, my gut tells me that that head has a range and I am thinking high 5's to 600 on the low end and about 900 on the high. Look at the stellar spec sheets closely. I think 7 1/2 ( 10 ) hp run at 800-850 rpm is the number but I can't substantiate that.

Here is a number to someone who probably knows:

Advanced Air Compressor
Post Falls, Idaho
ask for Curtis *****
(208) 665-7878

While I had him on the line I would ask about parts availability also, I am guessing he even knows where to get parts for that beast. Have the model and serial number ready though.

 

[fredschrom]

I did some number crunching on your bore/stroke to determine volume The stellar v480 listed is 86.35 volume and your unit is 73.39. Which brings the cfm volume back to rpms, I am still thinking that that is a faster pump than 650 rpms by a couple of hundred rpms ( which will cut your cfm considerably).

Try calling Curtis he is the owner of Advanced and knows his stuff on Air Compressors.

 

[dumb as a stump]

contact the manufacterer for the recomended speed and go from there.I had a similar discussion last year? about pully speed formulas. You should always do searches. Here is the link for calculating speed some one gave me then.
http://weldingweb.com/showthread.php?t=59854&highlight=pully
good luck

 

[imc188222]

contact the manufacterer for the recomended speed and go from there.I had a similar discussion last year? about pully speed formulas. You should always do searches. Here is the link for calculating speed some one gave me then.
http://weldingweb.com/showthread.php?t=59854&highlight=pully
good luck

I had a whole reply typed up and decided to delete it. Thanks for the help.

 

[imc188222]

Thanks for all the help guys. When the pulley gets here I will give that motor a try and let you know what happens. Thanks for the contact fredschrom, I will definitely give him a call.

This is a single stage, two cylinder. I had just put the heads back on when I took the pics, that is why the discharge manifold is not on there.

This compressor has been a good reminder for me that not everything is on the internet. I have not been able to scrounge up anything on this, not even a pic. Also interesting that I have been having to search so far and wide when this thing was made 30 miles from me. From what I have gathered from relatives of people that worked there, none of the old stuff (or old people for that matter) made it through the companies acquisition by Atlas Copco.

 

[fredschrom]

" This compressor has been a good reminder for me that not everything is on the internet. I have not been able to scrounge up anything on this, not even a pic. Also interesting that I have been having to search so far and wide when this thing was made 30 miles from me. From what I have gathered from relatives of people that worked there, none of the old stuff (or old people for that matter) made it through the companies acquisition by Atlas Copco. "

I actually did a fair amount of searching for you and found zip just the one link that said call grainger.

I am usually pretty good a digging up something but this was zero, when did they get purchased by Atlas?

 

[dumb as a stump]

Here is an old air compressor that I picked up. I have searched the interweb for info on it without any luck so I figured I would throw it up here and see if anyone can help. It is a Worthington made in Holyoke Ma. The tag on it says 4 1/4 x 4 1/4 x 2 3/4 and 46216. I am guessing that the latter is a serial #. On the first number, it would seem that 4 1/4 x 4 1/4 is the bore and stroke but what is the 2 3/4?

My main questions are what rpm should this thing be run at and how many hp is it going to take to do that. My uneducated guess at rpm is 750. EDITED.

I have found that When compressers get larger in capacity they Usually require slower speeds than smaller compressers.So I would shoot for about 500 rpm if I were you.