air compressor pressure drop

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gstuart

gstuart

D3 Grandad
Full Member
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Location
Kent
hi

finally after a long while have bought a compressor , also handy with the versility of the tools u can get

https://www.sgs-engineering.com/sc50h-50-litre-high-flow-air-compressor-air-kit

Air Displacement: 9.6 CFM
Discharge Pressure: 115 PSI / 8 bar
Air Outlet: 1/4"

have been working out the pressure drop according to the hose length , as i wish to increase the standard hose of 5m that comes with the compressor, mainly so i can tuck it out of the way and save my back not having to move it

will indeed change the most important outlet fitting to 1/2 inch

may i ask what would u consider the permissible amount of pressure drop before it has an adverse effect on the CFM plse

of course zero drop is better , current calc is showing a hose @40 x feet with a 1/2 inch dia hose , pressure drop 0.35 psi

would that effect the Cfm by much plse or is 2-3 psi permissible without noticing

don’t know how much oil i’ve got to buy , assume it will tell me in the instructions when it arrives

would it be worth buying a water filter plse

aplogises once again asking the daft questions and always appreciate the help

many thks in advance

E9EEF965-A380-453E-B8FA-7251131DD88F.png
 
The Free Air Delivery will be around 2/3 of the displacement figure given. They use that to make a compressor look more powerful than it is & AFAIAC is a con.
If you're going to spray paint then a water separator is a must. You'll be surprised how much it will catch & how much builds up in the bottom of the compressor tank which you need to drain periodically.
You may find that that compressor will run a rattle gun at full power for a few seconds before the pressure in the tank falls away & you have to wait for it to refill, it isn't going to deliver the volume of air required AND keep it at 90psi. You'd need a big garage size compressor to do that. For the same reason you're likely to find a random orbit air sander won't work.
I've never bothered with an in-line tool oiler as mine is used mainly for spraying & you don't want oil in the airline! I do use a rattle gun from time to time & it gets a few drops into its airline connector.
Too small an airline bore will restrict the amount of air available at the tool in exactly the same way as turning down the nozzle on a garden hosepipe. The curly wurly ones are OK for tyre inflation. Minimum 8mm bore for a hose.
 
neilly said:
Hi Geezer.

Being nosey, what tools are you planning on using with it?

Cheers
Click to expand...

not nosy at all , would like to get over time

air wrench
air chisel
recip saw
spray gun attachment for underseal, dinotrol

the list goes on, mainly for , wishbone replacement , blowing suspension airlines out from any old silica , getting wheel nuts off, tyre inflater , anti roll bar bushes , re applying underseal , etc,etc

ideally a cordless impact wrench would be ideal for the seriously tight items but they are really expensive so thought a compressor would be more versatile for me and can make life easier
 
Ratae said:
The Free Air Delivery will be around 2/3 of the displacement figure given. They use that to make a compressor look more powerful than it is & AFAIAC is a con.
If you're going to spray paint then a water separator is a must. You'll be surprised how much it will catch & how much builds up in the bottom of the compressor tank which you need to drain periodically.
You may find that that compressor will run a rattle gun at full power for a few seconds before the pressure in the tank falls away & you have to wait for it to refill, it isn't going to deliver the volume of air required AND keep it at 90psi. You'd need a big garage size compressor to do that. For the same reason you're likely to find a random orbit air sander won't work.
I've never bothered with an in-line tool oiler as mine is used mainly for spraying & you don't want oil in the airline! I do use a rattle gun from time to time & it gets a few drops into its airline connector.
Too small an airline bore will restrict the amount of air available at the tool in exactly the same way as turning down the nozzle on a garden hosepipe. The curly wurly ones are OK for tyre inflation. Minimum 8mm bore for a hose.
Click to expand...

many thks for the great advice

seen this ref the hoses

https://www.ebay.co.uk/itm/111416920773?var=410403279022

spraying wise it would only be to apply underseal, ( dinotrol )

ideally i would have liked a cordless impact wrench but alas are expensive , so thought with the compressor would be better in having with more tools available and understand where ur coming from ref air capacity
 
mick the builder said:
Definitely fit an air filter, regulator and lubricator. Drain water from tank regularly .
Click to expand...

thks, never had a compressor before and has been a long time coming

along with the disco having considerably heavier suspension parts i thought it would be a useful tool to have

but if i do ever get stuck , i never have to struggle as i can always call on some really good LZ mates
 
also thinking about it

would it also effect the outlet pressure if u go too big with the air hose , ie , seeing u have the factors of volume and pressure to consider or am i just overthinking it plse

so would u say getting 10 mm would be suffice instead of using 1/2 inch

many thks
 
Hose I use is 8mm id & not had any problems with any tool that the compressor is capable of running subject to the caveat in my earlier post that some will only work for short periods as they are very air hungry. Ideally I'd go to a 3hp compressor like a friend has but you're getting to the top end of what you can use on normal domestic single phase electrics without installing a cooker type circuit & he has occasionally tripped a customer's electrics!
There will be some drop in an airline & to solve that I have the tank one fully open & a small pressure regulator/gauge on each gun so I set the pressure at the gun. This type:
https://www.ebay.co.uk/itm/MINI-AIR...INLINE-PRESSURE-PSI-METER-GAUGE-/253308657648
For your uses I'd suggest not necessary.

ETA. I'd say 10mm would be fine.
 
Last edited:
Ratae said:
Hose I use is 8mm id & not had any problems with any tool that the compressor is capable of running subject to the caveat in my earlier post that some will only work for short periods as they are very air hungry. Ideally I'd go to a 3hp compressor like a friend has but you're getting to the top end of what you can use on normal domestic single phase electrics without installing a cooker type circuit & he has occasionally tripped a customer's electrics!
There will be some drop in an airline & to solve that I have the tank one fully open & a small pressure regulator/gauge on each gun so I set the pressure at the gun. This type:
https://www.ebay.co.uk/itm/MINI-AIR...INLINE-PRESSURE-PSI-METER-GAUGE-/253308657648
For your uses I'd suggest not necessary.

ETA. I'd say 10mm would be fine.
Click to expand...

many thks , alas couldnt go to a higher HP , mainly down to cost and storage ,plus didn’t realise that ref the electric supply so ideal not having to mess around

this is the spec of the one i bought , know u mustn’t use them with an extension lead

Engine Size: 2.5 HP
Power Consumption: 1.5 kW
Voltage: 230 V @ 50 Hz
Rated Speed: 2850 rpm
Current: 7.5 A
Air Displacement: 9.6 CFM
Sound Level: 97dB
Discharge Pressure: 115 PSI / 8 bar
Restart Pressure: 70 PSI / 4.8 bar
Tank Capacity: 50 litres
Air Outlet: 1/4

did see it had pressure regulators and indeed would replace the 1/4 outlet fitting for a larger 3/8 , assuming that would otherwise restrict the supply straight away

great. ref the 10 mm as it would also save trying to wield 1/2 pipe around, lol

will also have to read up ref the oil that i need to put in

daft question , is it PTFE that u make the fittings up with plse , thks

thks again

F6864DF5-B64B-426D-AFEF-950C362F45FF.jpeg
 
Mine had one outlet & the bore of the regulator it came with was tiny so took it off & replaced with adapters to fit an inline lever ballvalve as a cut off & then into a combined regulator/moisture separator with a pressure gauge fitted. Airline plugs into a pcl fitting on the reg oulet.
I did try connecting directly into where the plug is you can see on the front of the tank, but just stuck out too far.

Have a play with it first as is then you can consider alterations if necessary.

Several wraps of ptfe tape round any male threads to seal them. Cheap at B&Q etc in the plumbing aisle.
 
Last edited:
Ratae said:
Mine had one outlet & the bore of the regulator it came with was tiny so took it off & replaced with adapters to fit an inline lever ballvalve as a cut off & then into a combined regulator/moisture separator with a pressure gauge fitted. Airline plugs into a pcl fitting on the reg oulet.

Several wraps of ptfe round any male threads to seal them. Cheap at B&Q etc.
Click to expand...

thks, thats what i was thinking , it says 1/4 outlet so no point me putting a bigger hose on if i don’t make that bigger, lol

so looking in the pic at the quick release fittings there called pcl fititngs then

still got plenty of PTFE left from my plumbing /heating days so handy to know it will come in handy

good idea ref the dryer , so basically screwing it directly into the outlet after taking the quick connectors off then putting the quick release back in on the other side of the dryer

assume , i would need to ensure what the flow rate is of them so they don’t restrict the outlet

would u say there req if u only sprayed or always best to have one fitted regardless

thks so much once again for being so helpful and really do appreciate it :D:D
 
gstuart said:
not nosy at all , would like to get over time

air wrench
air chisel
recip saw
spray gun attachment for underseal, dinotrol

the list goes on, mainly for , wishbone replacement , blowing suspension airlines out from any old silica , getting wheel nuts off, tyre inflater , anti roll bar bushes , re applying underseal , etc,etc

ideally a cordless impact wrench would be ideal for the seriously tight items but they are really expensive so thought a compressor would be more versatile for me and can make life easier
Click to expand...
I use an extra 200 litre tank fed directly from the compressor then to the drier,this gives me a good volume of air for tool use,the comp keeps it topped up for maybe 20 mins if hard use,say with a da or chisel then have to wait a few minutes for it to catch up.Its brilliant for spraying because you always have plenty of air
 
Unfortunately I don't have a camera on my stone age phone (paint & touchscreens aren't compatible) or I'd post mine.
I was able to do mine without affecting the pressure switch - the big black box thing which shuts the motor off when up to pressure & controls the stop/start of the motor - but I can't make out if the tubing under yours where the regulator knob sits connects into it.
If it didn't then I'd be inclined to consider removing the reg & both gauges & connecting as mine with a 90deg elbow into the black tube.
BUT as I said, try yours as is before doing any mods.

Your airline & tool fittings look like PCL XF ones (Machine Mart etc) but I changed all mine to PCL 'Standard' 3/8 bore fittings as I do occasionally use other garages compressors & airlines so need compatibility. https://www.pclairtechnology.com/pr...tors/genuine-pcl-couplings/standard-adaptors/

My separator looks similar to this, so needs to overhang the front of the compressor: https://www.machinemart.co.uk/p/clarke-cat161-air-filter-regulator/
 
Joemac434 said:
I use an extra 200 litre tank fed directly from the compressor then to the drier,this gives me a good volume of air for tool use,the comp keeps it topped up for maybe 20 mins if hard use,say with a da or chisel then have to wait a few minutes for it to catch up.Its brilliant for spraying because you always have plenty of air
Click to expand...
If you have the space that's a very good way of doing it.
 
Ratae said:
Unfortunately I don't have a camera on my stone age phone (paint & touchscreens aren't compatible) or I'd post mine.
I was able to do mine without affecting the pressure switch - the big black box thing which shuts the motor off when up to pressure & controls the stop/start of the motor - but I can't make out if the tubing under yours where the regulator knob sits connects into it.
If it didn't then I'd be inclined to consider removing the reg & both gauges & connecting as mine with a 90deg elbow into the black tube.
BUT as I said, try yours as is before doing any mods.

Your airline & tool fittings look like PCL XF ones (Machine Mart etc) but I changed all mine to PCL 'Standard' 3/8 bore fittings as I do occasionally use other garages compressors so need compatibility. https://www.pclairtechnology.com/pr...tors/genuine-pcl-couplings/standard-adaptors/

My separator looks similar to this, so needs to overhang the front of the compressor: https://www.machinemart.co.uk/p/clarke-cat161-air-filter-regulator/
Click to expand...

cheers , will have a look

don’t know if this is any use , it’s supposed to be delivered today so can take pics

https://www.sgs-engineering.com/media/manuals/SC50H-K1.pdf
 
Joemac434 said:
I use an extra 200 litre tank fed directly from the compressor then to the drier,this gives me a good volume of air for tool use,the comp keeps it topped up for maybe 20 mins if hard use,say with a da or chisel then have to wait a few minutes for it to catch up.Its brilliant for spraying because you always have plenty of air
Click to expand...

was just reading that with the way you’ve done it, sounds an ideal solution for what you’ve done
 
.I'd missed 'you can't use them with an extension'. You can - mine's in the back of the van so all the time - BUT you need a good quality heavy duty one & fully unroll it.
The chap with the 3 hp I mentioned hasn't had any problems with his extension either.
 
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