Determining the actual demand in your compressed air system can be difficult but is a critical first step. Air demand often fluctuates significantly; however, if real flow demand at any given time is known, storage and distribution systems can be designed to meet demand without installing additional compressors.
The most accurate method of establishing demand over time in an existing system is to monitor the airflow using a flow meter. Flow meters can be installed at various points in the system but are typically installed in the main headers. Recorded data, such as airflow and pressure, can be evaluated to determine the flow pattern. It is essential to note the peaks and valleys in demand and their duration.
Electronic data loggers offer an effective means to track compressor activity over time. While they don’t directly measure as many system parameters as flow meters, they provide substantial information to assess system dynamics accurately.
For smaller, less complex systems, the ratio between loaded and unloaded compressor running time (online/offline or start/stop times) can indicate average demand over a long period.
When establishing compressed air demand for a new system, you must consider operating pressure requirements and the duty cycle of individual equipment.
The manufacturer rates equipment using compressed air for optimum performance at a certain pressure and airflow. Ensure all tools and equipment work efficiently within a narrow pressure range to deliver uniform pressure. If this cannot be done, you can operate the entire system at the higher pressure and regulate pressure down as required, add a booster compressor to increase pressure for a particular application, or install two independent air systems working at different pressures.
Leakage and artificial demand often represent a significant portion of your overall demand. All systems have leaks. Leakage can be measured in several ways while no pneumatic equipment is running:
Your existing compressed air demand will also include artificial demand caused by excess system pressure that does not increase productivity. Artificial demand can be reduced significantly by installing a regulator at the point of use or a flow controller at the beginning of the distribution network.
If your supply, storage, and distribution are not in tune, excessive pressure fluctuation will occur, resulting inn increased operating costs and reduced productivity. In part two we will discuss supply requirements.