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Free Air Delivery(FAD) Metering : Week 1/15/2012

In the last article, we discussed about some basics of FAD (the Free Air Delivery) of a compressor. We also observed that Compressed Air - in any plant, can be a very costly affair if not controlled properly. Firstly, the compressed air is costlier to produce than steam & secondly, it gets wasted very silently through various leakage points.

Major Problem Areas:

Let’s see what are the major problems that most of the plants face in this regard:

  • The pressure fluctuations: Many air operated systems or equipment are being used in a very inconsistent manner or are faulty. This results in wastage of compressed air
  • Higher compressor capacity: If the compressors are sized to excessive capacity than is needed, it results in higher operating and maintenance costs. Many plants buy compressors taking into account peak performance + possible leakages + some additional capacity. This sounds fine, but in the background, they are already preparing for inefficiency due to leakages.
  • Excess load conditions: At times, the load is increased beyond the actual capacity of the plant. This undoubtedly results in increased maintenance costs as well a reduced life of equipment
  • Wet air: When the compressed air is being distributed, the moisture seeps in through leakages.

Does someone notice these problems?

Many of these problems can go un-noticed, thus wasting a lot of money in terms of energy lost, if there is no effective method of measuring the FAD.

Is there any benefit in measuring the FAD accurately?

An accurate measurement of FAD at the delivery end of the compressor would reveal these losses in a very accurate manner, thus saving the electricity cost by 8- 10 %. This would happen, because you will run the compressor at optimum efficiency always & any deterioration will be seen up front .

Also, one can plan predictive Maintenance based on the FAD reading on a very factual inputs.

However, it is difficult to measure the FAD, as it is important to have on-line pressure & temperature compensation and calculations based on RPM & Humidity.

Is there any method to do this? Let’s see in the next article.

In our next article, we will discuss on how can we measure the accurate FAD at the discharge point of the compressor with on-line pressure & temperature compensation and calculations based on RPM & Humidity.