Motivair Compressor

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FourBanger
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Motivair Compressor

Postby FourBanger » Tue Jun 13, 2017 11:29 am

Hi guys, a bit off topic but I thought I’d share my journey restoring, fixing, and converting this old Motivair 150 PSI compressor.
I’m a big fan of old tools and although I’m unsure of the age of this beast it certainly has some age to it.
Like many of my ‘stupid’ purchases this was the result of too much homebrew mild and ebay one night, in retrospect it was quite a good deal, local collection and the price was unreal, £20 an take it away!
IMG_1723.JPG
IMG_1723.JPG (173.93 KiB) Viewed 1991 times
The good points:

• It looks complete
• It was cheap

The bad points:

• Its 100% untested
• I can find next to no information online
• It weighs a ton and I nearly killed myself getting it in and out of the car (not my Morris)
• And the kicker, its 3 phase and I don’t have 3 phase!

Many challenges ahead but I think this will turn out to be a fun little project.
Step 1 is to try and find some more information.
Step 2 full inspection to see if there’s anything obviously broke.
Step 3 ( I think ) find a similar power/age none 3 phase motor to power it.
Step 4 bolt it all together and see if it creates/holds pressure!

Wish me luck!
IMG_1718.JPG
IMG_1718.JPG (160.72 KiB) Viewed 1991 times

firedrake1942
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Re: Motivair Compressor

Postby firedrake1942 » Tue Jun 13, 2017 11:45 am

Looks like they were still around until at least 1966

http://www.gracesguide.co.uk/Small_Electric_Motors

firedrake1942
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Re: Motivair Compressor

Postby firedrake1942 » Tue Jun 13, 2017 11:46 am


firedrake1942
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Re: Motivair Compressor

Postby firedrake1942 » Tue Jun 13, 2017 11:47 am


firedrake1942
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Re: Motivair Compressor

Postby firedrake1942 » Tue Jun 13, 2017 12:05 pm

Motivair also seems to be still around.

http://www.motivair.co.uk/products/opus ... pare-parts

FourBanger
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Re: Motivair Compressor

Postby FourBanger » Tue Jun 13, 2017 12:27 pm

Thank you for the links!

FourBanger
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Re: Motivair Compressor

Postby FourBanger » Tue Jun 13, 2017 1:07 pm

Ive also rethought step 1 in my list...... build a trolley so I can ruddy move the thing without putting my back out!

SageGreenPete
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Re: Motivair Compressor

Postby SageGreenPete » Tue Jun 13, 2017 4:36 pm

It might be possible to alter the wiring in the existing motor to single phase depending what terminals you have.

philthehill
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Re: Motivair Compressor

Postby philthehill » Tue Jun 13, 2017 7:01 pm

Before you do anything remove the receiver tank bungs/plugs, wash out the inside of the receiver tank. let the inside dry and then examine for corrosion.

If there is any doubt as to the condition / thickness of metal of the receiver tank have the receiver tank professionally hydraulically tested.

If the tank failed it can do a lot of damage not only to the workshop but to your self and anyone standing close.

Draining the tank regularly will help with longevity.

With my own compressor I only install the drain plug for use and when finished and no pressure in the receiver tank I remove the drain plug and run the compressor for a short while to clear the receiver of moisture.


olderisbetter
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Re: Motivair Compressor

Postby olderisbetter » Tue Jun 13, 2017 9:23 pm

I used to work on these type of compressors when they have been looked after they just go on and on, For the price you paid it is a great bargain, The old Motivair CompAir or Broomwade has a good following from collectors, As Phil has said check out the tank, They tend to be way thicker than modern tanks but can still rust if they have never been drained, But the ones that have passed a bit of oil over the years get a nice tar like coating in the botton of the tank which acted as a rust proof coating, If you have a look on google you may find a way to run small 3 phase on single phase using a few parts or you might find a cheap inverter on Ebay, A simple test i do is turn the big pulley and hear the valves croaking it normally means it will make air, and cleaned up with a nice blue hammer finish paint they make a nice period looking bit of kit.


biomed32uk
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Re: Motivair Compressor

Postby biomed32uk » Wed Jun 14, 2017 8:44 am

SEM is only the make of the motor, over the years it would have been supplied with motors of varying make probably.

It's only a 1HP motor so shouldn't be too tricky to find a single phase one, you need a capacitor start / capacitor run 4 pole motor to get a high starting torque and run speed of 1500RPM (2 pole motors give 3000RPM), from what I can see it looks like it will have to start 'on load' - the compressor has to spin up against the air pressure in the receiver.

Larger and industrial compressors have some form of decompressing arrangment so it can spin up off load, and kick in compressing once running.

An inverter will probably cost as much as another motor, great for machine tools as I have one on my mill, it offers variable speed while maintaining torque, if I rememeber it was well over £100.

I bought a single phase 3HP motor for my old Broomwade compressor from ebay and it has performed really well. They are decent pumps and way beat the tat that the usual tool vendors sell, and are normally much much quieter.

FourBanger
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Re: Motivair Compressor

Postby FourBanger » Wed Jun 14, 2017 8:57 am

philthehill wrote:Before you do anything remove the receiver tank bungs/plugs, wash out the inside of the receiver tank. let the inside dry and then examine for corrosion.

If there is any doubt as to the condition / thickness of metal of the receiver tank have the receiver tank professionally hydraulically tested.

If the tank failed it can do a lot of damage not only to the workshop but to your self and anyone standing close.

Draining the tank regularly will help with longevity.

With my own compressor I only install the drain plug for use and when finished and no pressure in the receiver tank I remove the drain plug and run the compressor for a short while to clear the receiver of moisture.
Thanks for the advice gents, Ill definetly inspect the tank before I proceed.

FourBanger
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Re: Motivair Compressor

Postby FourBanger » Fri Jun 16, 2017 7:20 am

After much WD40 an under the breath swearing I finally got the tank cracked open and she looks like a surgeons table inside, amazingly clean :)
Last edited by FourBanger on Fri Jun 16, 2017 11:05 am, edited 1 time in total.

philthehill
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Re: Motivair Compressor

Postby philthehill » Fri Jun 16, 2017 9:53 am

Well done. :D


olderisbetter
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Re: Motivair Compressor

Postby olderisbetter » Sat Jun 17, 2017 3:51 pm

I have a Broomwade AC10 and AC25 pump bodies in storage that i intend to make into compressors, The AC25 is a bit big on single phase but i want to use a 4HP motor and gear it to run around 450 rpm it should make decent CfM and be quiet, The modern compair i have use of now is 2.2KW and it is deafening, All the cheaper modern compressors seem to use the same pump body and are unrepairable once they have a problem.


FourBanger
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Re: Motivair Compressor

Postby FourBanger » Mon Jun 19, 2017 1:53 pm


olderisbetter
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Re: Motivair Compressor

Postby olderisbetter » Mon Jun 19, 2017 6:18 pm

Well it is making all the right noises and compared to my small compressor it is very quiet, For what you have spent it is a very usefull set up.


FourBanger
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Re: Motivair Compressor

Postby FourBanger » Mon Jun 26, 2017 3:21 pm

olderisbetter wrote:Well it is making all the right noises and compared to my small compressor it is very quiet, For what you have spent it is a very usefull set up.

I just need to hunt down some vintage air tools now!

olderisbetter
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Re: Motivair Compressor

Postby olderisbetter » Sun Jul 09, 2017 8:45 pm

Forgot i had this at the back of my garage, It used to be for a dentist, It runs very quiet but not that powerful, I needed a big compressor so i got this 3hp 14 cfm modern one for £280 it works fine but looks and feels flimsy..
Image
Image


biomed32uk
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Re: Motivair Compressor

Postby biomed32uk » Thu Jul 13, 2017 10:46 pm

A good old B.E.N dental compressor by the look sof it, I have one of them lurking around the workshop somewhere as well, re homed from one of the local dental clinics during an update.


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