Matching a Compressor To Your Wetblaster
In order to get the most from the Dana-Ridge wetblast system, it is a good idea to have a compressor that allows the full capabilities of the wetblast unit to be realised.
When using these machines, there’s no need to exceed 6.2bar (90psi) of pressure during processing. Doing so will cause increased media usage and reduce the processing advantages. By adjusting the air pressure at the regulator, you can be more gentle or aggressive with your blasting to suit the application you are using it for.
The air-jet in the process gun is large enough to allow atomisation of the slurry and the volume of air available is important. Air volume is a consideration for all types of blasting (even more-so for many dry blasters that may require very large amounts to perform several roles).
The Mercury machine is single phase (240V) and has a process gun fitted with a Ø4.76mm air-jet and a Ø10mm process nozzle. The specs call for 15-26CFM (425-736 LPM) of free air delivery depending on the air pressure setting required for processing.
The next size up is the Comet machine. It has the same pump-set as the Mercury but a larger cabinet interior and a larger gun as standard. It is available in either single phase 240V or three-phase 415V.
The process gun is fitted with a Ø6.75mm air-jet and a Ø12.7mm process nozzle. This larger air-jet means an air requirement of 510 – 849 LPM (18-30 cfm) is required to run the machine efficiently. The higher end of this air delivery is best or you might find your compressor working hard when operating at the higher atomization pressures of 5.5 – 6.2 Bar (80-90 psi).
Note: We can change the gun and hoses to the same as the mercury if requested.
The Mars is a 3-phase machine with its 4 kW motor on the back. The process gun is fitted with a Ø6.75 mm air-jet and a Ø12.7mm process nozzle. The Mars machine has a higher slurry flow so this machine needs an air supply in the range of 510-963 LPM (18-34 cfm).
Multi Process Guns
These machines can use multiple guns and it is commonly supplied with one manually operated process gun and four or five process guns for the semi-automated processing. This model machine needs a free air delivery of around 1,132 – 1,699 LPM (40-60 cfm per process gun) of free-air delivery.
There are many things to consider when choosing a compressor, like available power sources, such as single or three-phase electricity, diesel or petrol for example. Each has their pros and cons.
There are also different configurations including piston, rotary vane or screw types for example; again, with their own pros and cons.
Litres Per Minute (LPM)/Cubic Feet per Minute (CFM)
There are several things to look at when checking out the specifications of an air compressor. The following information is useful when sizing one for your application.
- Displacement (particularly piston compressors) – This is quoted in LPM/CFM and calculates how much air is displaced by the piston(s) in the bore and you might see a compressor quoted as having 18CFM for example.
- FAD (Free Air Delivery) – Free Air delivery is the amount of compressed air delivered at the outlet of a compressor, converted back to the actual inlet (free air) conditions before it was compressed. This is also measured in LPM/CFM but can be much lower than the displacement measurement. In our example above, the 18CFM displacement unit may only have a FAD of 12CFM for instance.
FAD is the number that is most useful to you and the one you need to enquire about with your supplier.
We have actually seen large wetblast machines run off small compressors before and you can get some useful work done to a degree, but you will not get the full range of power from the blasting unit. Efficiencies and capabilities of the machine will not be at the optimum which is a shame.
If you don’t respect the cycling limitations of certain compressors and let them rest every so often, then you will also be replacing air-compressors more often than you should. This is especially true for piston compressors which are not designed to operate at a 100% duty cycle.
You must also look at the total work that your compressor will be doing in your workshop. If you have several air powered machines being used at once, then you will need to size accordingly. Avoid using nitto type fittings where possible.