So you want to do a compressed air audit. Congratulations, you are taking a big, important step! Measuring your compressed air system is a very good way to start understanding the costs associated with your system — and what challenges you are facing with efficiency, pressure, air quality and reliability. If you are calling in someone to do the work, here are some important pre-audit steps:
- Gather nameplate information
The auditor will want to know what kind of compressed air equipment you have installed. Take pictures and record the data of the equipment, equipment nameplates, and controls of all compressors, dryers, filters, and flow controllers. If you have flow meters and power meters, identify these. Make a diagram of how the equipment is connected in your compressor room. Find piping diagrams for the plant.
- Estimate your operating hours
The operating hours work into calculating the annual energy costs. The auditor will need to know how long your compressed air system runs per week — and if there are any changes to this schedule through the year based on seasons, product demand, holidays, plant shutdowns and the like.
- Identify your critical demands
There will be some critical demands in the plant that require the highest pressure, and a pressure level below which production machinery starts having problems. Be sure to find out what and where these are, to help the auditor measure your system correctly. Also critical are compressed air demands that consume large flows of compressed air, perhaps every once in a while … these are important to measure.
- Make a list of your problems
The auditor needs to know what problems are plaguing your system … this is likely the reason you called them in in the first place. A list like this gives the auditor important clues in finding the root cause of the situation.
- Communicate your future plans
If you are planning on adding future compressed air-consuming equipment, it is best to tell the auditor up front — to ensure they make the correct recommendations. S/he will then determine if your system has enough capacity for higher flows and if not what to do about it. Systems can be designed to accommodate the addition of new compressor capacity, if desired.
- Gather your maintenance costs
Energy is only part of the cost of operating a compressor. Other costs like rental, maintenance, consumables, maintenance contracts and other items can be a significant part of the real cost. Be sure to put together a complete list of all your costs to help make the business case for change.
- Choose your auditor
Carefully choose your auditor. Be sure you understand that some free audits may be worth their price, and may be designed to simply sell you a new compressor. It is best to employ a company that does not make a profit in selling compressors, or if they do, a firm who always conducts their audits on a product neutral basis while looking at the complete compressed air system (check their references). It is important they not only to measure things in the compressor room, but also go out into the plant and find potential reduction of wasteful compressed air uses and leaks. It is in reducing the end uses of compressed air where most of the savings lie.