Which parts

[stewart.d.campbell]

Hi guys i have just bought a sip airmate 5.5hp with 200l receiver and it needs a couple of parts but the thing is originally it was 3 phase with a 5.5hp motor but it is now running a single phase 2.2kw motor which i think equates to 3hp.I need a new pressure switch assembly but dont know whether to get the one for a 5.5hp 3 phase or the one for a 3hp single phase, i was leaning towards the 3hp single phase one as they are electricaly connected to the motor, does it make any difference ie will the switch for the 5.5hp be designed to run 3 phase or does it make no difference, thanks for any help with this.

 

[the snooper]

i think i would get the single phase switch if thats the only way you are ever going to run it the three phase one would still work though

 

[piman]

Hello Stuart,

I don't expect there is any difference between the pressure switches.
But how can you run with a 3 h.p. motor when the original was 5.5 h.p.. It surely won't develop the pressure or you will be plauged with the small motor tripping?

Alec

 

[stewart.d.campbell]

Hello Stuart,

I don't expect there is any difference between the pressure switches.
But how can you run with a 3 h.p. motor when the original was 5.5 h.p.. It surely won't develop the pressure or you will be plauged with the small motor tripping?

Alec

You do get a 3hp version of this compressor but i am aware that the pump will be different on that model, do you think using the 3hp motor on this pump will give problems.

 

[piman]

Hello Stewart.

Yes I would. You can slow down the pump but I don't know how much you will lose doing that. If you drive it at the same speed it will almost certainly overload the smaller motor.

Alec

 

[stewart.d.campbell]

Suppose i will just have to wait and see once the pressure switch is fitted, i also have the 3 phase motor but i am assuming that it would be very costly to get 3 phase in my garage?

 

[piman]

Hello Stewart,

yes it would. You can get single to three phase converters, have a look at e-Bay?

Alec

 

[stewart.d.campbell]

If i do have problems do you expect a 4hp motor would be sufficent to power this pump as this is the highest power motor i can find single phase.

 

[piman]

Hello Stewart,

it's still quite a bit smaller than 5.5h.p. As I say you need to run it slower to drop the power requirement, and how that works, I couldn't say? The other possibility is to run a lower set pressure as most compressors are set to cut out much higher than the normal operating pressure of the air tools. You will lose some capacity though.

Alec

 

[eil]

I would go with a 4hp personally but wire it through a contactor and overload,and using the same pulley but set it to cut off at a lower pressure. what is the present cut out pressure set at with the 5hp.

 

[stewart.d.campbell]

I would go with a 4hp personally but wire it through a contactor and overload,and using the same pulley but set it to cut off at a lower pressure. what is the present cut out pressure set at with the 5hp.

Is the cutout pressure the maximum pressure if not iv no idea as i cant run it at the moment.

 

[the snooper]

i think that the start up amperage draw of a 4hp motor would be too much for a standard 13 amp socket and would constantly blow fuses not to mention what sort of wiring does he have in his garage

 

[eil]

I cant see where Stuart says he wants to run it off a 13 amp socket in his post, he asked if it would be better to have a 4 hp instead of a 3 hp, 4 is closer to what originally ran the pump. I have two compressors that have 3 hp motors and none will run off a 13 amp socket.

 

[stewart.d.campbell]

Have been looking into this today as i dont want to spend too much more or i might as well have bought a new one in the first place so was thinking the cheapest solution might be to fit a petrol motor but i noticed when looking in the machine mart catalogue that petrol motor compressors seem to displace considerably less air than an equivalant hp electric motor eg 4hp petrol displaces 10cfm 4hp electric displaces 18cfm.Why is this and what hp petrol motor would i need to be equivelant to a 5.5hp electric motor, also how does this work for connecting up a pressure switch, help with this appreciated.

 

[shenion]

Has engines are over-rated, the HP is momentary. You typically only get 2/3 the rated HP.

Gas compressors use a bleed valve that limits the pressure and the compressor runs continuously.

 

[eil]

Going the petrol route wont be cheaper, you would need around a 8 hp engine and a genie/ unloader valve. You have not said what kind of electric supply you have to your garage, and which model sip comp you have.

 

[stewart.d.campbell]

Its a 200l airmate 5.5hp, i have the 3hp single phase motor that is fitted at the moment and have another 5.5hp motor that is three phase but the supply in my garage is just single phase.Its just 13 amp but i know a couple of sparkys so could prob get 30 or 40 amp outlets instaled.

 

[eil]

Right getting a better picture now, 40 amp to the garage and electric motor would be my choice, the trouble with the petrol ones is dearer to run and noisy. I suspect your sip on 3 ph would be at a working pressure of 150 psi, running it with the 3 hp motor you would have to set the working pressure lower,and with a 200L receiver you should have a decent set up.

 

[stewart.d.campbell]

Out of interest to get the full potential out of the pump would this be any use http://cgi.ebay.co.uk/ws/eBayISAPI....See-All-Categories&_fvi=1&_rdc=1#ht_500wt_975
or this
http://cgi.ebay.co.uk/Honda-GX240-8...s_ET?hash=item3a5239faf0&_trksid=p3286.c0.m14
and how much is a unloader valve and how do you go about installing one?Just want to investigate all avenues.

 

[shenion]

That is an engine for a generator. So, it has a tapered shaft. Will probably hard to find a pulley for it.