- Thread starter Gas mark 5
- Start date
Gas mark 5
Member
- Messages
- 225
- Location
- Leeds / Harwell, UK
aha! Hello again,
I have managed to test the compressor now, I bunged a pressure gauge into the output of the pump and it whizzed up to 150 psi, I stopped there because that is all I need, and then left it. It took about 2 minutes for it to reach 0 psi, I don't know whether this isa good time or not, but I rushed the plumbing of it so I think that there may have been a small leak in it somewhere. When It got to 100 psi i ran the compressor again just to see if it would start under pressure and it managed that no problem. Is that all right or should I try again with better plumbing?
Thanks everyone for all the help!
I have managed to test the compressor now, I bunged a pressure gauge into the output of the pump and it whizzed up to 150 psi, I stopped there because that is all I need, and then left it. It took about 2 minutes for it to reach 0 psi, I don't know whether this isa good time or not, but I rushed the plumbing of it so I think that there may have been a small leak in it somewhere. When It got to 100 psi i ran the compressor again just to see if it would start under pressure and it managed that no problem. Is that all right or should I try again with better plumbing?
Thanks everyone for all the help!
Gas mark 5
Member
- Messages
- 225
- Location
- Leeds / Harwell, UK
rtbcomp
Moderator
- Messages
- 18,574
- Location
- Sheffield UK
..........I like to make things needlessly complicated...
It's the only way!
I have a selection of copper fittings from 8mm to 22mm (Screwfix) as not all the pipe sizes coming out of the various compressors are the same. They are usually fixed with silver solder, although I've seen brazing. I use soft solder.
I try to get everything ending up in 15mm and BSP threads for compatibility.
You could try the thin nylon pipe with push-fit fittings, I've seen one setup where the guy threaded the output pipe and screwed (by brute force) the nylon pipe onto it. Watch the temperature of the nylon pipe though.
Gas mark 5
Member
- Messages
- 225
- Location
- Leeds / Harwell, UK
Thank you, I have some nylon pipe and push fit fittings from my disposable gas bottle saga (I won't go there...) I might try that. So you tink that the pressure and all that are all right?
thanks
thanks
- Messages
- 22,235
- Location
- Birmingham
You can put a thread onto nylon pipe as we use it to supply cooling water to spot weld tips inside the toolholder, so I suppose it would take an internal thread as well but don't know how much pressure it would take.
rtbcomp
Moderator
- Messages
- 18,574
- Location
- Sheffield UK
Yes, he threaded the outside of the steel pipe and use that to cut the thread on the inside of the nylon pipe.
Holds 10 bar OK.
gasmark I would suggest runing your comp up to heat first then check how your pressure holds oh by the way nobody here would take a comp off a fridge that hasent been de gased by a competant refrig person and the gas disposed of in the correct manner but a lot of the newer domestic refrigs use R600 which is flamable
but a lot of the newer domestic refrigs use R600 which is flamable
Gas mark 5
Member
- Messages
- 225
- Location
- Leeds / Harwell, UK
rtbcomp
Moderator
- Messages
- 18,574
- Location
- Sheffield UK
Depends how hot upto heat is
I took some measurements when I first started playing and I guess in the order of 30 mins filling a 20 litre receiver would be about right.
They may never reach full temp if you discharge into free air as the very act of compressing air produces quite a rise in temperature. I run mine at about 80 degC, although I have had oil temperatures of over 100 degC
If you can read Lotus 1-2-3 or Excel spreadsheets I can Email you the results of my tests.
Last edited:
tested an old one that was sitting on a shelf for a long time today let it run against a head of 150 to heat/warm up. closed discharge valae and it pumped up towards the 500 psi on gauge chickend out and swiched it off,
ive normaly tested by the vacume it pulls and swiching off to see if it holds it.
ive normaly tested by the vacume it pulls and swiching off to see if it holds it.
A very interesting thread.
I am looking for a quiet, low volume (1 cfm would be fine) compressor capable of generating at least 200 psi, and a fridge/freezer compressor seemed ideal. The loss of oil through the outlet pipe would, however, be a problem. The oil content in the air is OK, but having the compressor run short of oil and seize isn’t!
If I use a fridge/freezer compressor how do I top up the oil? I have an old compressor which I can experiment with. This has an inlet pipe, an outlet pipe and one other pipe which is sealed off (presumably used to fill the system with gas?). Would this be where oil can be added, or would I need to drill into the casing (whilst trying to avoid any metal pieces falling into the casing!)?
Alternatively, I am thinking that a more elegant solution would be to use a Clarke Shhh compressor (or an equivalent product from another manufacturer). I understand that these compressors use freezer compressors, but they presumably have a different lubrication arrangement – perhaps no more than an external inlet pipe and oil that can be topped up and changed? If so how often does the oil need to be checked and/or changed?
I will set out what I intend and perhaps someone could comment on whether it is feasible;
I have no need for an onboard receiver tank as I will be using my own tank, plumbed direct to the compressor's outlet pipe.
The problem is that the Clarke compressors generate relatively low pressure (8 bar) out of the box. However, would I be correct in thinking that this is a limitation imposed by Clarke, and that the freezer compressors that Clarke uses should be capable of at least 200 psi?
Assuming the compressor is mechanically capable of 200 psi, could I increase the pressure at which the compressor’s cut-out operates? If not, is there an aftermarket pressure switch available to replace the standard Clarke item that would allow 200 psi? (Incidentally I would want a switch on which there is no dump valve, or where the dump valve can be turned off, as with Clarke’s standard pressure switch.)
Any comments will be welcome.
Thanks
I am looking for a quiet, low volume (1 cfm would be fine) compressor capable of generating at least 200 psi, and a fridge/freezer compressor seemed ideal. The loss of oil through the outlet pipe would, however, be a problem. The oil content in the air is OK, but having the compressor run short of oil and seize isn’t!
If I use a fridge/freezer compressor how do I top up the oil? I have an old compressor which I can experiment with. This has an inlet pipe, an outlet pipe and one other pipe which is sealed off (presumably used to fill the system with gas?). Would this be where oil can be added, or would I need to drill into the casing (whilst trying to avoid any metal pieces falling into the casing!)?
Alternatively, I am thinking that a more elegant solution would be to use a Clarke Shhh compressor (or an equivalent product from another manufacturer). I understand that these compressors use freezer compressors, but they presumably have a different lubrication arrangement – perhaps no more than an external inlet pipe and oil that can be topped up and changed? If so how often does the oil need to be checked and/or changed?
I will set out what I intend and perhaps someone could comment on whether it is feasible;
I have no need for an onboard receiver tank as I will be using my own tank, plumbed direct to the compressor's outlet pipe.
The problem is that the Clarke compressors generate relatively low pressure (8 bar) out of the box. However, would I be correct in thinking that this is a limitation imposed by Clarke, and that the freezer compressors that Clarke uses should be capable of at least 200 psi?
Assuming the compressor is mechanically capable of 200 psi, could I increase the pressure at which the compressor’s cut-out operates? If not, is there an aftermarket pressure switch available to replace the standard Clarke item that would allow 200 psi? (Incidentally I would want a switch on which there is no dump valve, or where the dump valve can be turned off, as with Clarke’s standard pressure switch.)
Any comments will be welcome.
Thanks
rtbcomp
Moderator
- Messages
- 18,574
- Location
- Sheffield UK
The sealed pipe and the inlet are the same. The easiest way to get oil in is to suck it in the inlet. If the inlet or service stub is an inch or so from the bottom, bend it upwards and attach some clear plastic pipe to use as a sightglass.
I reckon Clarke set their machines at 8 bar is so that they start up OK. They don't use the dump valve in the pressure switch so it has to start under pressure.
You should get 200 psi, the safety valve will probably blow before that and you'll have to make sure the pressure switch and tank would be safe at that pressure.
You can't turn the dump valve off as such, just don't connect it.
I reckon Clarke set their machines at 8 bar is so that they start up OK. They don't use the dump valve in the pressure switch so it has to start under pressure.
You should get 200 psi, the safety valve will probably blow before that and you'll have to make sure the pressure switch and tank would be safe at that pressure.
You can't turn the dump valve off as such, just don't connect it.
