|
Volume and pressure are your two separators between single and two stage units. Most single stage units will max out between 100 and 135 psi while most two stage units will not max out until 150 to 200 psi. This really does not mean much unless you require constant pressure above 90 psi such as for filling big truck tires and such. If you require higher volumes of delivered air, you'll want to go with a two stage unit. Most common single stage units are limited to around 2 to 5 cfm of devilery at 90 psi while most two stage units of like Hp are double this amount. Every unit differs as they are all built differently. Thus, you may have one 3 Hp unit that will deliver only 1.5 cfm at 90 psi while you may have another one of the same size that will deliver 2.5 cfm. This is why you need to shop carefully and understand what it is you are comparing and buying. You need to look specifically at the delivered cfm rating, not the cfm which is taken on the intake side and means nothing toward running tools, sometimes this requires a call to the mfg since most companies choose to mislead you on ratings to make their product look better than it really is. Two stage units will cost you more since there are more parts to them but there are no disadvantages to them. In general, you will get more delivered air at higher pressures with a 2 stage unit than you will with 1 stage unit. If all you're doing is running an impact gun for a short time once every three months, then spending a good deal of money on a big two stage compressor is foolish. If you're looking at getting a lot of air tools or supplying ones that require a lot of air, then you should look at buying the biggest 2 stage unit you can. Rule of thumb is to look at the biggest draw tools you will be using, then select a compressor that will deliver at least double that amount. No doubt, you will outgrow a small compressor and end up spending more in the long run. If you buy a compressor that is twice what you need, you have room to grow into it without wasting money.
|
