03-04-2019, 12:58 AM
Things to consider.
Compressor displacement in cubic feet per minute (cfm) is not the same as FAD - free air delivery (in cfm) which is the air you actually get out of the machine. Typically FAD is about two thirds of the compressor displacement.
Sand blasting usually needs around 12 cfm FAD. Unfortunately a lot of sellers only quote the compressor displacement and not the FAD which is lower.
The storage tank will determine how long you can use the air for before the compressor cuts in again after it has reached the pressure you set it to run to (90ish psi for blasting). The cut-on pressure is lower than the cut-off pressure.
For happy blasting you need to get at least 90ish psi and around 12 cfm FAD. The reservoir tank would be as large as possible. My one is 210 lit.
Then there is the electric motor consideration. My motor is 4HP 3.0KW 18.2 amps 230 volts (asynchronous) This is run off a standard household supply taken out to a 30 amp circuit breaker. (remember a higher current is taken as the motor starts) as used for your cooker outlet. There should be an automatic pressure cut-off and cut-on valve/switch fitted. The motor really aught to have a reset push button (motor overheat cut out).
A good make of air pump is a CHINOOK.
My set up will run sand blasting at 100psi (at the tank) all day with the motor cutting on and off as the tank pressure dictates.....will cut out even while blast gun is blasting.
Consider this.......my one was obtained FREE from a good friend who does professional accident repair work including spraying (with a heated purpose built cooking shop). Since he had taken on an apprentice he had to have the compressor tested and certificated (annually?) and it was cheaper to buy a new compressor than get it certificated!!!!! so would I like to take it away for him!! His is switched on all day.
Take the tank outlet to a filter/pressure control valve so you can vary the output pressure from low (15/30 psi for spraying and small tools) to 100psi for blasting (mine has tank max working 12 BAR (170 psi) (tested to 18 BAR).
So maybe ask around at small garages/spray shops.
It is worth getting one that you can get spares for.....check with the seller. I have had to get one new motor cut out switch (badly mounted contacts in switch allowed loose contacts and sparking so burn out) and have had to renew the seals in the pressure valve that is used to outlet pressure to the pressure on/off switch......cheap parts that allowed easy repair to keep the machine in use (pressure valve opened up for cleaning and spring loaded seal went ping and disappeared never to be seen again in-spite of emptying out the area!! Those thieving pixies again.) If you can't get the bits you may have to ditch the whole machine.
Dennis
Compressor displacement in cubic feet per minute (cfm) is not the same as FAD - free air delivery (in cfm) which is the air you actually get out of the machine. Typically FAD is about two thirds of the compressor displacement.
Sand blasting usually needs around 12 cfm FAD. Unfortunately a lot of sellers only quote the compressor displacement and not the FAD which is lower.
The storage tank will determine how long you can use the air for before the compressor cuts in again after it has reached the pressure you set it to run to (90ish psi for blasting). The cut-on pressure is lower than the cut-off pressure.
For happy blasting you need to get at least 90ish psi and around 12 cfm FAD. The reservoir tank would be as large as possible. My one is 210 lit.
Then there is the electric motor consideration. My motor is 4HP 3.0KW 18.2 amps 230 volts (asynchronous) This is run off a standard household supply taken out to a 30 amp circuit breaker. (remember a higher current is taken as the motor starts) as used for your cooker outlet. There should be an automatic pressure cut-off and cut-on valve/switch fitted. The motor really aught to have a reset push button (motor overheat cut out).
A good make of air pump is a CHINOOK.
My set up will run sand blasting at 100psi (at the tank) all day with the motor cutting on and off as the tank pressure dictates.....will cut out even while blast gun is blasting.
Consider this.......my one was obtained FREE from a good friend who does professional accident repair work including spraying (with a heated purpose built cooking shop). Since he had taken on an apprentice he had to have the compressor tested and certificated (annually?) and it was cheaper to buy a new compressor than get it certificated!!!!! so would I like to take it away for him!! His is switched on all day.
Take the tank outlet to a filter/pressure control valve so you can vary the output pressure from low (15/30 psi for spraying and small tools) to 100psi for blasting (mine has tank max working 12 BAR (170 psi) (tested to 18 BAR).
So maybe ask around at small garages/spray shops.
It is worth getting one that you can get spares for.....check with the seller. I have had to get one new motor cut out switch (badly mounted contacts in switch allowed loose contacts and sparking so burn out) and have had to renew the seals in the pressure valve that is used to outlet pressure to the pressure on/off switch......cheap parts that allowed easy repair to keep the machine in use (pressure valve opened up for cleaning and spring loaded seal went ping and disappeared never to be seen again in-spite of emptying out the area!! Those thieving pixies again.) If you can't get the bits you may have to ditch the whole machine.
Dennis