Snap-On HP12 Compressor Operation and Maintenance

[JonnyAlpha]

Hi;

I now the compressor in this thread in my possession to test it and being a Compressor Newbie, I need some help please :-)

I have searched for a manual on the Internet to no avail, I even emailed Snap-On but got no reply. I would like to know how to operate it correctly (i.e. turn it off and on properly and use it, as well as how to service and maintain it.

I have bought some Sealey Compressor Oil (SAE 40), was advised by rtbcomp to get SAE 30 Compressor Oil but it was all that was available, slightly thicker oil I guess?

There are also a few things damaged so advice on these would also be welcomed.
Here are some pics I have taken of the components, with questions / comments under each pic or group of pics, can anyone identify the parts for me and what they do?

Is this the main On / Off Switch, I states that this switch should be turned off before turning of the Mains Power, is that the same in reverse? Or do you switch the Mains on at the wall before switching this switch on.

The mains power lead cover has pulled out, It has a short thread, so I'll screw it back in or super glue it?

What is this brass connection?

What pressure gauge is this under the main switch?

Is this the oil filler plug, if so it looks like its snapped off, what can I replace it with? I have not tried to remove it yet.


There is what looks like an oil level just to the left in this picture, it has a red dot in the middle of the glass, what does the red dot signify correct level or low oil?

What is this pressure guage behind the output?
I guess the red knob is the regulator?
The black knob with ANA visible turns around and clicks what is it and what does it do?

There are two large red screw plug fittings at either end of the tank, the one in this pic also has a smaller screw plug in the centre, would this be 1/2 BSP and is this where I should run a line from into my air line water trap setup (not yet made).

Also as I am testing this before I part with my cash how should I test it? What pressure should it achieve. I have an old Air Flow Meter connected to my welder, should I use this to see what CFM output I get or will the pressure gauge on the output be sufficient to check operation?

One of the wheels is knackered, I guess any old free rotating wheel will do, I may make a frame for it out of Angle Iron and mount the compressor in my shed to reduce the noise in the garage?

Sorry for all the questions and thanks in advance :-)

 

[mfletch]

Hi I will let others tell you about the other pictures but

{What is this brass connection?} this is the safety valve do not touch

{What pressure gauge is this under the main switch?} this is the pressure gauge to show the tank pressure

{What is this pressure guage behind the output?} this is the gauge to show the output pressure altered by the red nob

 

[Wallace]

On/off switch.

Is this the main On / Off Switch, I states that this switch should be turned off before turning of the Mains Power, is that the same in reverse? Or do you switch the Mains on at the wall before switching this switch on.
Yes it is the main on/off switch. Mains on at the wall then that switch to on.

The mains power lead cover has pulled out, It has a short thread, so I'll screw it back in or super glue it?
With the power disconnected, take the cover off and see if the gland back nut has vibrated loose.

What is this brass connection?
The pressure relief valve, spring loaded and will vent tank pressure if the pressure switch fails and tank pressure rises too high.

What pressure gauge is this under the main switch?
Main tank pressure.

Is this the oil filler plug, if so it looks like its snapped off, what can I replace it with? I have not tried to remove it yet.
Yes, it is also the crankcase breather and is snapped off. Don't fit a solid plug in there!

There is what looks like an oil level just to the left in this picture, it has a red dot in the middle of the glass, what does the red dot signify correct level or low oil?
Not certain, but on Clarke compressors it is usually the low level when switched off and should be above it.

What is this pressure gauge behind the output?
Regulated outlet pressure.

I guess the red knob is the regulator?
Regulator control knob on what looks like a filter regulator.

The black knob with ANA visible turns around and clicks what is it and what does it do?
Looks like an on/off valve, the clicking might be the plastic knob spinning on the shaft knurling. Looks like it says DIANA.

There are two large red screw plug fittings at either end of the tank, the one in this pic also has a smaller screw plug in the centre, would this be 1/2 BSP and is this where I should run a line from into my air line water trap setup (not yet made).
Difficult to tell from the photo.

Also as I am testing this before I part with my cash how should I test it? What pressure should it achieve. I have an old Air Flow Meter connected to my welder, should I use this to see what CFM output I get or will the pressure gauge on the output be sufficient to check operation?
Switch on and watch the tank pressure gauge, it should switch off once it reaches whatever pressure the switch has been set to. Listen for leaks. DON'T USE THE WELDER FLOWMETER AS IT MIGHT BURST!

One of the wheels is knackered, I guess any old free rotating wheel will do, I may make a frame for it out of Angle Iron and mount the compressor in my shed to reduce the noise in the garage?
The wheel are handy for moving it around, should be easy enough to replace.

 

[brightspark]

make sure the pressure switch is turned off then plug in mains then turn on swich to run . when finished turn of pressure switch and unplug

 

[rtbcomp]

On the safety valve, is there a cross-drilling in the bit that sticks out of the end? If so fit a keyring into it and give it a pull once a month just to make sure it doesn't stick.

The switch does 2 things. 1) switches the motor on and off and 2) empties the pipe between the pump and the tank when it switches off. The pipe must be empty before the motor starts otherwise it could stall.

So, make sure the black knob points to "off" before applying power and then move to "on". If you want to stop the compressor before it reaches cut-off pressure turn the knob to "off". You shouldn't really stop it by switching off at the plug, but if you do set the knob to "off" before reconnecting the mains. To be really safe, run the compressor through a no-volts release, this will prevent the compressor from restarting after a power cut, but I don't know anyone who does do this!

 

[Wallace]

Don't forget the tank water drain just visible in the last photo under the tank!

 

[rtbcomp]

If you can't get the proper filler, make one from a blanking plug with a hole drilled in it, solder some copper pipe into the hole and bend it so it faces downwards.

 

[JonnyAlpha]

Don't forget the tank water drain just visible in the last photo under the tank!

That needs to be shut when in operation and open afterwards right? Thanks for taking the time to reply with all the pics as well

 

[JonnyAlpha]

Hi I will let others tell you about the other pictures but

{What is this brass connection?} this is the safety valve do not touch

{What pressure gauge is this under the main switch?} this is the pressure gauge to show the tank pressure

{What is this pressure guage behind the output?} this is the gauge to show the output pressure altered by the red nob

Thanks

 

[JonnyAlpha]

On the safety valve, is there a cross-drilling in the bit that sticks out of the end? If so fit a keyring into it and give it a pull once a month just to make sure it doesn't stick.

The switch does 2 things. 1) switches the motor on and off and 2) empties the pipe between the pump and the tank when it switches off. The pipe must be empty before the motor starts otherwise it could stall.

So, make sure the black knob points to "off" before applying power and then move to "on". If you want to stop the compressor before it reaches cut-off pressure turn the knob to "off". You shouldn't really stop it by switching off at the plug, but if you do set the knob to "off" before reconnecting the mains. To be really safe, run the compressor through a no-volts release, this will prevent the compressor from restarting after a power cut, but I don't know anyone who does do this!

I'll have a look at the safety valve.
Thanks for the info on running.

 

[JonnyAlpha]

If you can't get the proper filler, make one from a blanking plug with a hole drilled in it, solder some copper pipe into the hole and bend it so it faces downwards.

Any idea what other make of compressor would have the same filler plug? Can't find any info on Snap-On? Otherwise do you mean find a bolt of the same thread and drill a hole through the centre some tiny copper piping?

 

[Wallace]

If you can get it out you might be able to make a repair.

 

[JonnyAlpha]

If you can get it out you might be able to make a repair.

It came out easily here it is, the thread is about 16mm diameter?

 

[JonnyAlpha]

Don't forget the tank water drain just visible in the last photo under the tank!

Here's a pic of the tank water drain, which way is open / closed and when should it be open / closed? Closed during operation and open when not being used?

On the safety valve, is there a cross-drilling in the bit that sticks out of the end? If so fit a keyring into it and give it a pull once a month just to make sure it doesn't stick.

The switch does 2 things. 1) switches the motor on and off and 2) empties the pipe between the pump and the tank when it switches off. The pipe must be empty before the motor starts otherwise it could stall.

So, make sure the black knob points to "off" before applying power and then move to "on". If you want to stop the compressor before it reaches cut-off pressure turn the knob to "off". You shouldn't really stop it by switching off at the plug, but if you do set the knob to "off" before reconnecting the mains. To be really safe, run the compressor through a no-volts release, this will prevent the compressor from restarting after a power cut, but I don't know anyone who does do this!

Here's a pic of the safety valve, it has no cross drilling and the brass protruding bar does not seem to move in any direction (did not force it just a little push and pull)?

 

[JonnyAlpha]

Took it apart and gave it a further inspection and clean before testing it.

The mains connector shroud has sheared, it pushed back in but is only temporary.

Any idea what its called and were I could get a new one RS Components? Here's the Pressure Switch:

The Air Filter is a simple sponge affair, it was caked in old paint so I cleaned it up with hot soapy water, rinsed it out dried it and refitted it. Could do with a new one I guess?

This is the regulator pressure gauge, it was reading over 1 bar and the tank was empty, looks like the regulator has been re-fitted on the wonk?

Topped the oil up, I think that's the drain plug directly underneath the site glass.

Couple of other problems with it, not show stopper I hope.

The shroud that sits over the cooling fan on the compressor pump is held on with 4 x push fit clips 2 of which have snapped, I could drill through the plastic and use small bolts.

The compressor pump cooling fan has lots of broken fins will this be OK or does it need renewing if so how and where from? It was caked in paint but cleaned up OK.

This is the red knob that sits behind the PCL Quick Connector, it pulls up and down and says Push to Lock, here is a pic of the top:

Turning the red Knob does not seem to affect the PCL Pressure Gauge?

The problem I am going to have is getting spares unless I can identify the actual make / model and a supplier - any ideas would be helpful.

I ran it up and did a few test, the results are at the end of this post

Oil looked a little discoloured after running it?

And here it is back together and a little cleaner :-)

Here's the test results:

With the pressure On Off switch set to off I plugged it into a live power socket, I the switched on the Compressor using the Compressors On Off Switch.
When I first fired it it seemed to build up working pressure 150 PSI quite quickly but I didn't time it. Once up to 150 the motor cuts out correctly and I then started to use the air with a simple blow gun.

With the trigger pressed it took about 30 seconds to fall back to 100 PSI and then the Compressor Motor kicked back in and I carried on blowing Air out of the gun. The flow rate seems pretty good, seems more powerful than little Magnum Beaver sat next to it.

I then switched the Compressor off using the pressure switch On Off and emptied the tank using the Air Gun.

I then timed how long it took to build up pressure, this time it seemed to take a lot longer?

0 - 50 (1 Min)
50 - 100 (3 Min) (Total time from 0 - 4 Min)
0 - 150 (3 Min) ) (Total time from 0 - 7 Min)

Does this seem OK.

Once up and running it blows air fine and kicks back in once it drops to 100 PSI, if you then keep the gun trigger depressed it did not seem to want to increase pressure but that's because I was using it constantly, not a real spraying situation.

 

[rtbcomp]

When you tested the regulator knob you did have the tank at full pressure didn't you? Sometimes when you adust from high to low pressure you have to let a bit of air out.

Don't worry too much about not being able to move the safety valve plunger, they require quite a bit of force. You might be able to pull it with some pliers.

You should be able to get a cable gland easily enough, maybe take the old one to an electrical wholesalers.

 

[brightspark]

if u realy want to test the blow off safety valve fill the tank up to pressure then give it a pull with pliers it should then pull out easy and blow off

 

[JonnyAlpha]

Thanks guys, from my test results is this good to go?

 

[eil]

7 min to 10 Bar is quite slow for a 50L tank, that would indicate that's is only doing about 2.5 cfm free air delivery. Try and run it without the filter on see how long it takes. judging by the look of the filter and the motor fan the valves might well be covered in paint.

 

[Wallace]

Overall I would say it's had a hard life and might be tired out as it does seem a bit slow, depending on how old it is a new capacitor might liven it up a bit. Have you checked the belt condition, tension and alignment as it could be slipping? The pressure gauge on the regulator has probably had a knock looking at the rest of the machine and jumped a tooth on the rack & pinion, you can take them to bit for recalibration but they are cheap enough to replace. Undo and fit the gauge with a spanner, don't be tempted to turn the plastic body as they break quite easily if tight, there is usually a spanner square on the back adjacent to the mounting thread.