If you’re not looking at lowering the psi in your compressed air system, you’re probably throwing away money for no reason.
Every 2 psi increase in pressure over 100 psi increases the electrical cost to run the air compressor by 1%. The average cost of electricity in Florida, as of February 2018, is about 11 cents per kW/hr. If your business runs a 60 hour workweek, and the compressor runs about 60% of that time, on average it costs about $152.55 to run one horsepower for a whole year.
If you’ve got a body shop with a 5hp compressor, that’s no big deal. It costs about $763 per year to run it, so you might save about $191 per year turning down your 5hp piston from 175 psi to 125 psi. That’s actually pretty good, for just changing a $40 pressure switch.
Let’s look a typical rotary screw application. A pretty typical installation would be 20 hp and the machine would cut off at 125 psi. In a rotary screw compressor installations, they tend to run about 80% of the time (that’s why you buy a rotary screw – for the high duty cycle). It costs about $4000 in electricity to run per year. Normally no more than 90 psi is needed, and realistically with a few fixes, we could turn down their pressure to 100 psi. That would save them 12.5%, which is $500 per year. Sometimes no modifications are needed; all it takes is just to adjust the pressure in the controller or the adjustment of a pressure switch.
Our customer is starting up a new grain mill. The manufacturer of the mill equipment specified they wanted a 60 hp compressor that produced 160 psi. In our experience we have never seen a mill that needed over 100 psi – most mill equipment needs 90 psi or less. We emailed the manufacturer and asked them why they wanted 160 psi, and they said the machine only needs 88 psi, but they recommend 160 psi to their customers, because they’re worried about pressure drop!
This particular customer paid 15 cents per kW/hr and ran 5 days per week, 3 full shifts, so at that time it would cost them about $42,120 per year to run a 60hp compressor. Because they only need 88 psi at the equipment, they can run the compressor at 110 psi – that saves $10,530 per year! Not only that we were able to supply a compressor with less hp, because a smaller compressor could put out the same amount of CFM at 125 psi, as the 60hp at 160 psi.
By asking one question we saved them over $10,000 per year. With a properly designed air system, they can probably drop the psi down to 100 and save even more.
Now let me ask you one question: Why aren’t you looking at reducing your system pressure right now?
We can help. We can offer many different ways for you to achieve these energy savings with no effect on your production.