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Cost.
Depending on how you review your application, there are many costs associated with compressor ownership.
Buying trends would indicate that if you're looking for a general purpose industrial air compressor up to 20 HP most folks select a reciprocating unit which, anecdotally, are lower cost units than rotary screw or rotary vane type compressors.
For more demanding industrial applications, and in a wide range of available horsepowers, the rotary screw seems to be the next most popular type of industrial air compressor.
The rotary vane, while still prominent, appears to be selected for specialty applications more than the first two.
Your first cost of compressor ownership is, of course, the purchase of your unit.
What you are doing with that compressor and the discharge flow rate in CFM and the necessary PSI for your applications will determine what size and type of compressor is required.
The rule of thumb in industry is that for compressors over 10HP in size, each motor horsepower can generate about 4 CFM of compressed air at 90 PSI.
After purchasing or leasing the compressor, next on the ownership cost list is the maintenance of your compressor.
After the warranty period, who is going to fix the compressor when it's down? Your staff, the compressor supplier, or a third party maintenance group? What are their labor costs, and what hours are expected to be consumed in both regular maintenance and emergency repair.
Included in the maintenance part of the equation is the cost of the spare parts for regular maintenance, and parts costs for emergency repair.
The major compressor manufacturers will be able to provide a forecast of annual maintenance costs, the sum of which might help you decide to purchase a more expensive yet more reliable compressor, which will provide lower cost over the life of the unit.
One expense that will ultimately overwhelm all other cost considerations for most industrial applications is the cost of operating your compressor.
Since the vast majority of industrial air compressors in plants run on electricity, the details below will help you determine the operating cost of the unit you are considering purchasing.
There are many formulae available to help determine your operating costs. We will offer a simplified version. If you seek greater detail, a couple of sources are noted below for you as well.
Things you'll need to know:
If you don't pay the bills at your company, ask the accounts payable person to check on your last company hydro bill. Make sure that delivery costs, etc. are included in the kWh amount.
The number of hours per day, times number of days per week, times 52 weeks a year, resulting in a number of hours per year
This information should be available from the compressor manufacturer. In the absence of that information, work on the basis of 90% efficiency.
If your compressor runs all the time, and only compresses air part of the time, the time it's actually compressing air is the load factor. When it's running unloaded, the motor will use less energy.
If you are contemplating a compressor that only runs when it's compressing air, the load factor would be 1. If in doubt, use a load factor of 0.8. That should suffice for most applications.
Here's what the simple formula to calculate your compressor operating cost looks like.
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Let's throw a few numbers at it, shall we? Here's a chart with the numbers for our theoretical application, from which you may be able to extrapolate to yours compressor application.
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And last, here's the formula referred to earlier, now with our theoretical application numbers plugged into the formula.
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And when you do the math, you'll see that this relatively small compressor, will cost $4,887.00 per year in energy operating costs!.
We know you've a real interest in reducing operating costs so you'll want to know that it's generally recognized that about 10% of a compressor's total output is wasted ( folks using your air for other than it's desired use) or leaked from your system. So you can save some real money every year by curtailing air waste, and ridding your plant of air leaks.
It is possible to provide a significant amount of heat for your plant from your compressor. Since the process of compressing air creates a huge amount of heat, and you want the air to cool as completely as possible before it gets out into the plant, a heat exchanger / aftercooler might be a way to recapture that heat and turn it into an asset.
The topic of heat reclamation is likely sufficient for a web site unto itself, and we won't delve further into details right here.
For additional information about compressor costs, energy, etc., please visit this URL.
Other sources for information about the cost of running a compressor are the IR/ARO site please click here, and also, some excellent information can be found at the Kaeser Compressor web site.
Need to find a bit more information on compressor costs? Try using the Google search box below.
Compressor costs will escalate as compressed air requirements. Cost info and compressor sizing is here.
Did you know that....
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