|
Hi Chris, I suggest you do NOT compare compressors based on HP. Many of the current HP ratings are extremely deceiving. I have an old (27 yr) Sears single stage machine that is rated at 7.8 cfm @40 and 6.3 cfm @90. It has a true 2 HP motor. That was when it didn't take a 5HP motor to do the job of a 2 :o). Seriously though, some of these ratings are really out-to-lunch, IMO. They seem to be coming up with very short term HP ratings on some of these machines just to "make 'em sound bigger". They are definitely not continuous ratings. Inflated ratings like that have no real bearing on actual performance. It's the cfm that really counts. The only way to increase the capacity of the same air pump is to increase the speed. The required HP will increase proportionally for the same discharge pressure. A true 5 HP machine will draw about 22 amps at 230 volts and fully run a compressor delivering around 17 cfm @175 in two stage and a little more in single stage @90. Check the amperage on the motor nameplate. If it is not over 20 amps at 220/230 volts, it is NOT a true 5 HP motor. It may even have a telltale "spl" associated with the HP rating. This would indicate a "special" rating that is short term and not continuous. You want continuous. My recommendation would be to buy all the cfm @90 that you can afford. Forget the HP rating altogether, but check the required motor amperage at full load to be sure your existing electrical wiring is satisfactory. And stay away from the 110 volt stuff. If you want to run any serious air tools, you want the 220/230 in order to keep the amperage draw within reason. For example, a true 5 HP requires a 30 amp circuit at 220 volts...or an unrealistic 50 or 60 amp one if at 110! I don't have an opinion on "extreme duty". I have never heard that one before. Sounds like marketing hype to me. Just like the 5 HP that produces less air than my old 2 HP. Rod
| 
