What is a compressed air system audit?


General industrial compressed air systems are often viewed as the fourth utility (behind electricity, gas, and water) in most organizations. Consequently, they are relegated to afterthought when allocating capital improvement dollars. A compressed air system audit can clearly identify the process improvement opportunities available in the compressed air system, point a way toward their solution and provide baseline information to measure future performance against.  It may also provide sound, proven solutions to commonly misinterpreted compressed air system problems.


 Why does my facility need a compressed air systems audit?


Compressed air systems have been identified by the US DOE as the single largest opportunity for savings in the industrial electric motor driven sector of the economy.  Most user organizations are not focused on the true costs of compressed air.  Most organizations keep their eyes on the capital budgets and maintenance budgets and consider utility costs, such as compressed air electric energy as just a per production unit cost. Indeed, when life cycle costs are evaluated it can readily be seen that most of the cost of compressed air is “energy in”:


*US DOE Compressed Air Challenge


General industrial compressed air systems are typically made up of multiple supply side compressors, filters, and dryers.  Often times, these are from multiple manufacturers and are of varying ages and types. As a rule, their controls are not integrated with one another and consequently they often operate inefficiently.  Often, a coherent “system level” control system can eliminate waste and reduce costs by 10-20%.


 The demand side of these systems can include a bewildering array of users.  Some uses are efficient and appropriate. Others are employed because they are easy.  These uses are referred to as "potentially inappropriate uses of compressed air". Some of these uses can be retrofitted to use other forms of energy with a attractive return on investment.  Cost reductions can range from 5-30%.


 How does a compressed air audit improve my facility?


An audit can get a handle on the true cost of compressed air and can help management make the correct decisions regarding allocation of capital to improve operational efficiency.


 Where can I expect to find savings in the cost of compressed air?


In the course of auditing compressed air systems some common savings streams have been identified. Listed in their general order of importance they are:


  • Sequencing or load sharing multiple compressors. Eliminating part load capacity controls on  rotary screw compressors and avoiding blow-off on centrifugals.
  • Lower discharge pressures.
  • Lower Header pressures.
  • Applying load shaping technology to significant demand events.
  • Measuring and trending data to augment maintenance planning and control.
  • Leak management.
  • Retrofit inappropriate users.
  • More closely match supply with demand.
  • Apply no loss drainage technology.
  • Heat recovery.
  • Dryer energy modifications.
  • Deferred running maintenance.
  • Deferred overhaul maintenance.
  • Reduce excessive DP across cleanup equipment.
  • Reduce production spoilage.
  • Increase production throughput.
  • Reduce production downtime.
  • Use outside air intake.
  • Deferred replacement expense (capital).
  • Reduced compressor rental expense.
  • Reduced cooling water ops costs.
  • Opportunity cost on redirected maintenance staff.


 What problems will a compressed air audit likely identify in my facility? 


 Commonly found and potentially costly issues include:


  • Moisture
  • Oil contamination
  • Pressure too low
  • Pressure instability
  • Reliability
  • Remote monitoring
  • Storage
  • Leakage
  • Drainage


In addition to these issues the audit can identify inappropriate uses of compressed air. (Potentially) Inappropriate uses of compressed air may include:


  • Any open blowing application
  • Dewatering applications
  • Drying applications
  • Air operated mixing motors
  • Air operated bin vibrators
  • Air operated diaphragm pumps
  • Eductors
  • Vacuum generators
  • Mass Transport mechanisms
  • Sparging


 How will an audit of my facility improve my compressed air system?


Identifying issues with your compressed air system allows the auditor quantify your savings potential and to provide sound, proven reccomendations by utilizing existing technologies to retro fit the application effectively.


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