Archive for November, 2009

How to Select an Air Compressor

November 11, 2009

2 Steps to Select !

1. New Facility

2. Existing Facilities

2a. Compressor always Loading [no off loading]

2b. Compressor can load & off load.

1. New Facility

List all the air operated equipments and devices.

Decide how they are use, all the time or some of the time. Select load or use factor for the devices or equipments.

Example; 15%, 25%, 35%, etc.,  use factor, if use all the time the use factor will be 100%.

Determine the pressure range and volume of air required for each and every devices and equipments.

The Air Compressor should maintain a minimum pressure at least equal to the highest of these pressures ranges.

2. Existing Facilities

2a. Compressor always Loading [no off loading]

Use formulae:

P1V1 = P2V2

2b. Compressor can load & off load.

Use Formulae:

Air Consumption = Vl / u+l

2c. Using Instruments

Compressor always Loading [no off loading]

Compressor can load & off load.

Energy Balancing System

Blowdown Time

November 8, 2009

2. Reduced  Blowdown  Time

ReduceBlowdownTimeUnstable networks  ( systems ) frequently switch between load and idle [no-load]

Sample Calculation:

Energy losses due to blowdown

  • 60 kw Compressor
  • Discharge time approximately 1 minute
  • 15 load – idle cycle per hour
  • Receiver tank volume 2000 l
  • 4000 hours in operation per year
  • Energy cost RM0.25 per kwh

4000 hours per year   X   15 load – idle cycle per hour

60,000 load – idle cycles per year   X   1 minute

60,000 minutes blowdown =1000 hours blowdown time


Energy Loss = 1000 hours blowdown time   X   45/2 kw [ consumption when idling on blowdown]

22,500 kwh   X   25 cents

RM 5, 625.00 per year

Avoid Idling Time

November 8, 2009

1. Avoidance  of  Idling

Reduced IdlingTime


Based on Average capacity utilization [ 70% ] on All Compressors

If a conventional compressor is operated at 70% of its maximum capacity, then it idles for up to 30% of the time. [ Note, these idle time you need to pay ], using a quarter of the energy required for a full load.

This wastes energy.

Sample Calculation:

Average utilization [ 70% ] of a 75 KW Compressor

=> 70% full load

=> 30% idling with approximately 25 – 30% of full load consumption

1. Based on 4000 operating hours per year

4000 hours per year   X   30% idle   X   25% of 75 KW   X   electrical cost [RM0.26/kwh]

1200 hours   X   18.75 KW   X   25 (cent/kwh)

SAVING = RM 5,625.00 per year

2. Based on 8000 operating hours per year

8000 hours per year   X   30% idle   X   25% of 75 KW   X   electrical cost [RM0.26/kwh]

2400 hours   X   18.75 KW   X   25 (cent/kwh)

SAVING = RM 11,250.00 per year

Energy Balancing System

November 8, 2009

EBS —– Energy Balancing System

Energy Balancing System

Planning & Optimising YOUR Compressed Air System

3 Stages

Stage 1 = Measurement

Stage 2 = Analysis

Stage 3 = Simulation


Stage 1

Measuring volume flow with Energy Balancing System

Stage 2

Analysing YOUR compressors provide the following important informations:

  • Leakage
  • Current pressure band
  • Daily & weekly curves of compressed air demand
  • Energy consumed by the Compressor or compressors
  • Utilization of each & every compressors [ Load / Idle / Stand-by Time ]


Now, we have the basic information and we can start


about how to optimize YOUR Compressed Air System.

Stage 3

Simulation by

Change of Pressure Band.

Replacement of one or more old inefficient standard compressor or compressors with modern compressor or compressors.


Measuring Consumption

November 8, 2009

Actual volume flow

4 ways to measure of the actual values

1. Venturi Meter, —- a method using apecture.

2. Method using a pressure head sensor.

3. Calorimeter,

4. Ultrasound flow measurement.

Save Money with Your Compressors

November 6, 2009

Money Saving Potential in Your Compressed Air Systems !EnergyCost

Average Overall Cost of a Compressed Air Station !

Generating or producing Compressed Air Costs a lot of energy, therefore Money !

Energy cost make up the highest proportion ?

Studies show that the maximum Free Air Delivery is only needed at peak time, and most Compressors are only used at 50 – 70% of their capacity.

6 Steps to reduce Cost

1. Idling time

2.  Blowdown time

3. Pressure at Compressor Outlet

4. High Pressure Differential

5. Direct Drive

6. Leaks

Energy Balancing System