Industrial Ventilation Utilization Statistics



Using data extracted mostly from the woodworking industry, the following is a summary and explanation of a statistical analysis of workstation activity. The full report is available for PDF download below.


Spoiler alert! Most will be surprised at how low the actual workstation utilization really is.


Ecogate Industrial Ventilation Statistics IETC 2006
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How Data Has Been Captured


The sensor is built-in to all connected workstations (workstations may include table saw,

CNC router, sander, welding station, or others). The sensor reads whether the motor of the cutting tool is active or not. Information from the sensor is transmitted to the greenBOX control unit. The greenBOX saves data in binary form every 10 seconds (24/7) and sends data to the Ecogate clou d server along with the time and date of the recording. Downloaded data is converted by the Ecogate DataMining software to the standard SQL database. The “DataMining” reporting feature along with filters is then used to generate reports. For more information on DataMining, contact Ales Litomisky (ales@ecogate.com).


“Use of workstation” is considered from the point of view of dust collecting: a workstation is usually switched ON the entire shift time, but not all of this time is extraction (ventilation) necessary. For example, on CNC machinery, you need to move material in, program the machine, move material out and clean the machine. During these operations, no extraction is necessary. Extraction should only run during the “cutting time” when the dust (or fumes or mist) is produced.



How to Use This Report


This report can be used to estimate energy savings by installing an on-demand ventilation system because it helps to predict potential savings. Select a system similar to your system according to the type of production, production volume, and system size, and then jump to the proper page for details about the selected system.


Chart A, Trend Report

This chart shows the average activity of all of the workstations per month (the pictured chart is for the first shift). During the first shift, the machinery is used the most; the second shift’s use is usually about one-half of the first shift, and the third shift is about one-half of the second shift. In effect, numbers from the first shift are the most important for designing the proper system capacity and performance. Variations of numbers are caused by “how high orders are”, a factor that is affected in most industries by seasons.


Chart B, Workstation Activity

This chart shows the activity of each workstation separately as a green column and as a percent of the selected time (pictured is the chart for the first shift, which has the highest use of workstations).


Chart C, Percent of Active Workstations per time Selected

On the x axis is the number of workstations active at the same time, and on the y axis is the percent of shift time. This chart can be used to determine for what capacity a specific system should be designed.


Table 1: Average Workstation Use (sorted by production volume)



On the following pages are several detailed examples: the first system is from a furniture manufacturer (high volume production), the second one is from a low-volume furniture manufacturer, and the third example is from a dental lab.


System #1: Furniture Manufacturing, High Volume Production, USA, 200 HP


Chart 1A

Average Workstation Activity, 1st shift March 2003 to April 2005 (7AM- 3PM, Monday to Friday):


The overall average is 14.07% of shift time, the maximum 21% of shift time


Chart 1B

Percent of shift time individual workstations are active (7AM- 3PM, Monday to Friday); a total of 40 workstations:



In typical furniture manufacturing, some workstations are used a high percentage of the time (for example sanders), while the use of most machinery is relatively low.



Chart 1C

x axis = the number of active workstations at the same given time, y = percent of shift time that number of workstations was active.



Used system capacity: maximum 45% (18 workstations out of 40 total)


Note: 18 workstations at a time are running 0.02 % of shift time, i.e. only 6 seconds per 1st shift. For this type of factory, it is not necessary to design the system for full air-volume because the probability that all workstations will be used at the same time is zero.


Chart 1D

Overall average workstation activity (all shifts, all days incl. weekends):



Chart 1E

Average workstation activity (1st shift, Monday to Friday):



Chart 1F

Average workstation activity (2nd shift, Monday to Friday):



Chart 1G

Average workstation activity (3rd shift, Monday to Friday):




System #4: High End Furniture Manufacturing, Low Volume Production, USA, 250 HP


Chart 4A

Average Workstation Activity, 1st shift May 2003 to Oct. 2004 (7AM- 3PM, Monday to Friday):



The overall average is 8.51% of shift time, the maximum 11% of shift time.


Chart 4B

Percent of shift time individual workstations are active (7AM- 3PM, Monday to Friday); a total of 77 workstations:



Chart 4C

x axis = the number of active workstations at the same given time, y = percent of shift time that number of workstations was active.



Used system capacity: maximum 23.37% (18 workstations out of 77 total).


Note: 18 workstations at a time are running 0.07 % of shift time, i.e. only 20 seconds per 1st shift


Chart 4D

Overall average workstation activity (all shifts, all days incl. weekends):



Chart 4E

Average workstation activity (1st shift, Monday to Friday):



Chart 4F

Average workstation activity (2nd shift, Monday to Friday):



Chart 4G

Average workstation activity (3rd shift, Monday to Friday):




System #27: Dental Lab, Medium Size (71 workstations), USA, 40 HP


Chart 27A

Average Workstation Activity, December 2005 2003 to February 2006:



The overall average is 3.5% to 4.2% of shift time.


Chart 27B

Percent of shift time individual workstations are active; a total of 71 workstations:



The average use of ventilation in the dental lab is low.


Chart 27C

x axis = the number of active workstations at the same given time, y = percent of shift time that the number of workstations were active.



Used system capacity: maximum 25% (18 workstations out of 71 total)


Note: 18 workstations at a time are running 0.01 % of shift time, i.e. only 3 seconds per 1st shift.


For this type of lab, it is not necessary to design the system for full air volume because the probability that all workstations will be used at the same time is zero.


Chart 27D

Overall average workstation activity (all shifts, all days incl. weekends):



Chart 27E

Average workstation activity (1st shift, Monday to Friday):



Chart 27F

Average workstation activity (2nd shift, Monday to Friday):




Appendix A: Air Velocity Statistics


Measurements were made in woodworking factories in the USA. Type of air velocity meter: Kurtz Instruments, Series 2440 Anemometer.


Chart 29

“Air Velocities in the Main Duct”



Tab. 5: The percentage of the measured air velocities out of recommended range

27%

37

out of

138

in proper range 4000-4500 FPM

25%

34

out of

138

below 4000 FPM

49%

67

out of

138

higher than 4500 FPM

73%

out of correct range


138 main duct velocity measurements in existing ventilation systems revealed that only 27% of air velocities are in the recommended 4,000-4,500 FPM (Feet per Minute) range. That means that 73% of main duct velocities are outside of the recommended range. When air velocity is higher than recommended, systems are wasting energy; when air velocity is lower, sawdust will drop in the duct system and expensive and time-consuming cleaning is necessary.



Conclusions


The summary of the results are in Table 1 (sorted by production volume) and Table 2 (sorted by percentage of use).



Quick Facts

The total average use of machinery (as a percent of shift time when the cutting tool is active) is 30% of shift time during the first shift, 14% during the second shift, and 6% of shift time during the third shift.


The highest recorded use of a single workstation (as a percent of shift time when the cutting tool is active) is 75% of the shift time in the mill.


Air velocity measurements in over one thousand drops within existing ventilation systems revealed that only 12% of air velocities are in the recommended 4,500-5,000 FPM range.


One hundred and thirty-eight main duct velocity measurements in existing ventilation systems revealed that only 27% of air velocities are in the recommended 4,500 - 5,000 FPM range; 73% of measured air velocities were out of the proper range.


The low use of machinery is a major argument for implementing on-demand industrial ventilation systems. According to the Fan Law [4], if a system is designed for 100% capacity and the real demand is, as this statistic shows, 27% of air volume capacity, then savings can theoretically be higher than 80% of the original fan power. In reality, savings are reduced to a lower number because the minimum air transport velocity in the duct system has to be maintained. Real savings depend on the duct system and are generally in the range of 50 to 70 percent of the original power.


The traditional industrial ventilation design consumes 50-70% more energy than necessary. Total potential electricity savings achieved by using on-demand systems, instead of classically designed industrial ventilation systems, in the U.S. could be up to 26 billion kWh annually with a pollution offset of 66 billion lbs. CO2 gasses. [1]



For more information:


  1. New saving opportunity: on-demand industrial ventilation, 28th World Energy Engineering Congress, Austin, Texas 2006.

  2. The United States 2002 review, International Energy Agency, 9 rue de la Federation, 75739 Paris, France.

  3. Industrial Ventilation, A Manual of Recommended Practice, 24th Edition, published by American Conference of Governmental Industrial Hygienists.


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