Hi Considerations for Choosing an Industrial Ventilation System!.

Hi Your Choices for Consideration of an industrial ventilation system!!!

Industrial Ventilation Fan Systems can be a necessary component to any commercial or industrial operating company.  These ventilation systems benefit not only the productivity of your employees and machines, but can affect your company’s bottom line as well.  When considering ventilation systems for your building, there are five key factors to consider:

1.  Objectives of the Ventilation Fan System;

These are generally multi-faceted, from personnel comfort and employee health to increased production efficiency and more.  For example, are you looking to provide general ventilation for fume or odor removal, or are you looking for personnel cooling because of heat stress on employees? Ensure your objectives are overcoming the biggest problems and accomplishing the most important benefits.

2.  Budget;

Availability of money to finance the system is a key factor that must be considered early in the planning stage. The funds available will affect the objectives you set and influence the system of ventilation selected. Expenses include equipment, as well as mechanical and electrical installation costs.  In some cases you may set out a ventilation plan that takes two or more years to complete due to limited funding. 

3.  Practical Limitations within the Building;

There are certain limitations in any production environment. The location of heat-generating equipment, partitions such as pallet racks or machinery within the building, or large cross-sectional areas are a few. Other circumstances may be air circulation obstructions such as machinery, raw materials, or finished goods.  We see a lot of what we call “short circuits,” where ventilation fans are placed next to wall openings or loading dock doors.  Thus, air is brought in thru the openings and then discharged by the fan before it's had a chance to provide cooling within the structure.

4.  Common Sense Factors;

In planning a ventilation system, taking advantage of the location of exhaust fans and prevailing wind direction will aid the system’s efficiency.  Economy of “long dimension” is helpful in reducing the cross-sectional area of a building, thus minimizing needed air velocity. Significance of noise production of a ventilation system must be taken into account. Additionally, you will always want to use the cleanest, coolest air source to circulate through the building. Other considerations include other production equipment that depends on airflow to perform its intended purpose such as paint booths, dust and fume extraction systems, make-up air systems, etc.  

5.  Benefits of a Ventilation Fan System;

All companies want to realize economies from good planning.  The greatest benefit that can come from a well-designed ventilation system is that it achieves its basic purpose and design.  A system where all components work together is essential. Replacement of exhaust air with “make-up air” fans may be necessary. Good planning will also recognize the necessity for proper air distribution and circulation through an occupied building, not just exhausting bad air.

These five considerations, when accounted and planned for properly, will ensure a unified industrial ventilation system that accomplishes tangible benefits for a company’s productivity and profitability. There are many industrial ventilation fan system design manufacturers including Hammam Industries & Co. in Egypt who supply, install, maintain & service the fan system design equipment. Visit the web site click link here. Hammam Industries & Co. also specialize in providing all needs for air pollution & climate control projects & solutions.

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Hi Field Testing Brief!.

Hi Field Testing Brief!.

The purpose of a field test is to define, via testing and measurement, the actual aerodynamic performance of a fan when installed in a system. Since installations often include elbows, obstructions, swirl and sudden changes in area, obtaining accurate measurements may be difficult. Additionally, these items may have an impact upon the unit’s performance. This impact is called a system effect.

AMCA Field Test Publications AMCA Publication 203 is a general purpose guide for the measurement of fan performance. This guide is applicable to most air handling equipment installed in any system. It includes the calculation process for loss in performance due to system effects and methods for calculating test results and uncertainties. A wealth of reference material and examples of typical applications pointing out where difficulties may be encountered are included. People involved in field testing should also be familiar with AMCA’s Certified Ratings Program outlined in Publication 211 and the concept of system effect factors (SEF) defined in AMCA Publication 201, Fans and Systems.

You may be interested in viewing an article recently published on Hi Shelf discussing the Topic of Fan Performance with reference to this article & AMCA Standards & Codes which may expand on the knowledge here. Visit Hi Shelf direct publication link post by clicking here. 

Reasons for Field Tests Three main reasons for conducting a field test are:

1. General System Evaluation - A measurement of the fan and system’s performance. This test may be used as a basis for future modifications or adjustment to the system.
2. Acceptance Test - A test specified in a sales agreement to verify that the fan is achieving the specified performance.
3. Proof of Performance Test - A test in response to a complaint to demonstrate that the fan is meeting the specified performance requirement.

Performance Rating Parameters As already stated, the specific objective of a field test is to determine the aerodynamic performance of a fan when installed in a system. The operating point will occur at the intersection of the system resistance curve and the fan curve.

Operation at any other point is impossible without altering either the fan or the system. An operating point must be fully defined by obtaining test data that allows you to determine each of the following parameters:

1. Flow Rate - The fan flow rate is the volumetric flow rate corrected to the gas density at the fan inlet. The volumetric flow rate at any location in a system can be obtained by measuring the velocity pressure according to a specified grid in the plane of interest. The number and distribution of points is
stipulated in AMCA 203. The flow in that plane is calculated by converting the average velocity pressure to its equivalent velocity and multiplying by the area of the traverse plane. The flow rate obtained in the measurement plane must be referred back to the fan inlet using the ratio of densities at the measurement plane to that of the fan inlet.

2. Fan Static Pressure - The fan static pressure is the algebraic difference between the static pressure at the fan outlet and the total pressure at the fan inlet. Static pressures using a pitot tube or static pressure taps are obtained near the fan outlet and fan inlet. The total pressure at the fan inlet is a measured value that consists of the sum of the inlet velocity and static pressures.

3. Fan Speed - This is the rotating speed of the fan shaft in revolutions per minute. Typically, measurements of fan speed are obtained at the beginning and end of a test and then averaged providing there is a small difference.

4. Fan Brake Horsepower - This is the power delivered to the fan shaft and does not include any drive losses other than the fan bearings. Nearly all field installations are driven by an electric motor in conjunction with a v-belt drive or variable frequency controller. Portable analyzers are available that read volts, amps, watts and power factor into the motor. Power out of the motor must be calculated using motor efficiency values or the ratio of actual amps and volts to nameplate values when the motor is at least loaded to 90% of full load. Fan brake horsepower values for units with v-belt drives must be calculated using the v-belt drive loss graph in Appendix L of AMCA 203. Units driven by a variable frequency controller must be by-passed to obtain accurate electrical values due to sine wave distortion. These values must then be corrected by the fan laws to the actual operating speed.

5. Fan Gas Density - The fan gas density is the density of the gas being handled at the fan inlet. The inlet density is calculated using the barometric pressure, wet and dry bulb temperature and corrections for suction or pressurized inlet conditions.

Calculation and Analysis of the Results Detailed calculations are contained in AMCA 203 for obtaining test results. To compare test results with the factory-specified fan curve it is necessary to include SEF values, relevant drive losses, and speed and density corrections. The converted operating points can then be plotted on the factory- AMCA certified performance rating curve for analysis An estimate of the individual uncertainties for each test parameter must be made. These can be combined to provide an
overall uncertainty in flow, pressure and power. An error rectangle is then established around the test point using plus and minus absolute values of the combined uncertainties. Assuming the procedures from AMCA 203 are followed, combined uncertainties range as follows:

Volume 2% to 10%
Pressure 2% to 8%
Horsepower 4% to 8%

Hi Summary';

Keep in mind that the factory tests are conducted in ideal conditions. Because fans are rarely installed in ideal conditions, field tests are frequently performed. 

Hi My Mechanic Re-visited!.

Hi My Mechanic Cooling Tower Revisited:

System Calculations

To properly operate and maintain a cooling tower, there needs to be a basic understanding of the system water’s use. Water use of the cooling tower is the relationship between make-up, evapora- tion, and blowdown rates. There are a couple simple mathematical relationships between the blowdown rate, evaporation rate, make-up rate, and cycles of concentration of a cooling tower that are very useful to understand the principal flow rates. 

The first relationship illustrates the overall mass balance consideration around a given cooling tower:

(1) Make-up = Blowdown Evaporation
In this case, the blowdown accounts for all system losses including leaks and drift, except for evaporation.
The second principal relationship defines cycles of concentration in terms of make- up flow and blowdown flow:
(2) Cycles of Concentration = Make-up ÷ Blowdown
This equation can be rearranged to either of the following to solve for the make-up rate or blowdown rate:
(3) Blowdown = Make-up ÷ Cycles of Concentration
(4) Make-up = Cycles of Concentration × Blowdown

If the evaporation rate and cycles of concentration are known, the blowdown rate can then be determined by substitut- ing equation 4 into equation 1: 

(5) Cycles of Concentration × Blowdown = Blowdown + Evaporation
Solving for blowdown:
(6) Blowdown = Evaporation ÷
(Cycles of Concentration -1)

Also, if the blowdown rate and cycles of concentration are known, the make-up rate can be determined by solving equation 4, and then the evaporation rate can be determined by solving equation 6 for evaporation:

(7) Evaporation = Blowdown × (Cycles of Concentration – 1) 

System Concerns

Cooling towers are dynamic systems because of the nature of their operation and the environment they function within. Tower systems sit outside, open to the elements, which makes them susceptible to dirt and debris carried by the wind. Their structure is also popular for birds and bugs to live in or around, because of the warm, wet environment. These factors present a wide range of operational concerns that must be understood and managed to ensure optimal thermal performance and asset reliability. Below is a brief discussion on the four primary cooling system treatment concerns encountered in most open-recirculating cooling systems.

Corrosion:

Corrosion is an electrochemical or chemical process that leads to the destruction of the system metal- lurgy. Figure 7 illustrates the nature of a corrosion cell that may be encountered throughout the cooling system metal- lurgy. Metal is lost at the anode(3) and deposited at the cathode.(4) The process is enhanced by elevated dissolved mineral content in the water and the presence of oxygen, both of which are typical of most cooling tower systems. 

Figure 7. Example of a Corrosion Cell.

There are different types of corrosion encountered in cooling tower systems including pitting, galvanic, microbiologically influenced (Figure 8), and erosion corrosion, among others (expanded

discussion is available at www.gewater. com/handbook/cooling_water_systems/ ch_24_corrosion.jsp). Loss of system metallurgy, if pervasive enough, can result in failed heat exchangers, piping, or portions of the cooling tower itself.

Figure 8. Microbiologically Influenced Corrosion (Source: Taprogge GmbH).

Scaling;

Scaling is the precipitation of dissolved minerals components that have become saturated in solution. Figure 9 illustrates calcium carbonate scale collecting on a faucet head. Factors that contribute to scaling tendencies include water quality, pH, and temperature. Scale formation reduces the heat exchange ability of the system because of the insulating properties of scale, making the entire system work harder to meet the cooling demand. An expanded discussion for scaling is available at the following link; click here.

Figure 9. Calcium Carbonate Scale (Source: Hustvedt).

Fouling;

Fouling occurs when suspended particles fall out of solution forming deposits. Common foulants include organic matter, process oils, and silt (fine dirt particles that blow into the tower system, or enter in the make-up water supply). Factors that lead to fouling are low water velocities(5), corrosion, and process leaks. Fouling deposits, similar to scale deposits, impede the heat exchange capabilities of the system by providing an insulating barrier to the system metallurgy. Fouling in the tower fill can plug film fill reducing the evaporative surface area, leading to lower thermal efficiency of the system.

Microbiological Activity;
 

Microbiological activity is micro-organisms that live and grow in the cooling tower and cooling system. Cooling towers present the perfect environment for biological activity due to the warm, moist environment. There are two distinct categories of biological activity in the tower system. The first being planktonic, which is bioactivity suspended, or floating in solution. The other is sessile biogrowth, which is the category given to all biological activity, biofilms, or biofouling that stick to a surface in the cooling system. Biofilms are problematic for multiple reasons. They have strong insulating properties, they contribute to fouling and corrosion, and the bi-products they create that contribute to further micro-biological activity. They can be found in and around the tower structure, or they can be found in chiller bundles, on heat exchangers surfaces, (see Figure 10), and in the system piping. Additionally, biofilms and algae mats are problematic because they are difficult to kill. Careful monitoring of biocide treatments, along with routine measurements of biological activity are important to ensure bio-activity is controlled and limited throughout the cooling system.(6)

Figure 10. Biofouled Heat Exchanger (Source: Taprogge GmbH).

(3) The anode in a corrosion cell is defined as the site where metal is lost from the system structure and goes into solution.

(4) The cathode in a corrosion cell is defined as the site where the metal lost at the anode is deposited.

(5) Low water velocities may occur in poorly designed or improperly operated heat exchangers, in the cooling system piping, or in locations across the tower fill where uniform distribution is not maintained.

(6) Beyond the operational and mechanical problems bioactivity causes in cooling tower systems, there is a human health issue if the system develops a specific bacterium known as Legionella. For more information regarding Legionella and Legionnaires’ disease go to www.cdc.gov/legionella/patient_facts.htm.



DECSA INSTALLATIONS REVIEW:

Closed circuit coolers

RIKSHOSPITALET HOSPITAL VERONA GENERAL WAREHOUSE ENI OIL COMPANY BANCO DE ESPANA ABB POWER SYSTEM Centrifugal cooling towers PRINCIPESSA SOFIA INTESABCI BANK NOYFIL TEXTILE FIBERS TAMPEY SUBWAY FERRARI AGIP OIL CO. Axial Decsaplast MOPLEFAN ELEOURGIKI OIL CO. ZAMBELLETTI PHARMACEUTICAL CO. FORD MOTOR CO. BOEHRINGER PHARMACEUTICAL CO. CROW CORK CO. Metal axial towers INTESABCI BANK LEONARDO DA VINCI AIRPORT SSAB STEEL MILL UNDERGROUND SHOPPING CENTER ST MICROELECTRONICS FERRERO CHOCOLATES

 Hi MiMechanic Fans Revisted:

Fan Efficiency, An Increasingly Important Selection Criteria:

The Importance of Fan Efficiency:

Why is fan efficiency so important? As a general rule, successive generations of electronic enclosures such as personal computers, telecommunications cabinets, as well as system routers, pack increasing functionality into smaller and smaller spaces. Accompanying this trend is the need to remove ever higher levels of heat energy from within those enclosures. Thermal engineers will often force air through a system using fans to regulate the internal temperatures; however as the aerodynamic performance increases so will input power.

In modern day equipment racks it's not uncommon for the total fan load to be a significant factor in the system's power budget. Coupled with the advent of equipment efficiency legislation and a growing awareness of cost of ownership, fan efficiency is becoming a critical selection parameter. Engineers now need to gain an understanding of fan efficiency, balancing it against more familiar metrics such as airflow and noise.

Understanding Fan Static Efficiency:

Fan manufacturers typically provide static efficiency as the value of efficiency, while total efficiency includes the outlet velocity term. Fan total efficiency is calculated using total pressure. Static efficiency is calculated using only static pressure.

Positive static pressure is created as a fan moves air through a system. Negative static pressure is what all other components in the airflow path create as they resist air movement. Different fan types will generate different airflow values while creating a positive static pressure to balance the negative static pressure caused by system obstructions. The fan performance curve (see Fig 1) is a representation of the airflow (X axis) that a particular fan type produces to overcome given static pressure values (Y axis).

Total pressure is the summation of static pressure and outlet velocity pressure. Outlet velocity pressure does not contribute to a fans ability to remove system heat energy; therefore it's not normally included in fan efficiency calculations.

Calculating Fan Efficiency:

As with any energy converter, efficiency is the ratio of input and output power:-

Fan efficiency = Pout / Pin
Fan input power (Pin) is:-
Pin (Watts) = V <Volts> x I <Amps>

Fan output power (Pout) or airpower using Metric units is:-
Pout (Watts) = Air pressure <m3/sec> x Air flow <Pascal's>

Using standard units the formula becomes:-
Pout (Watts) = (Air pressure <inch H2O> x Air flow <cfm>) / 8.5

Example:-
A 48V fan drawing 1A working at an operating point of 200 cfm and 0.5 inch H2O
Pin = 48 x 1 = 48 W
Pout = (200 x 0.5) / 8.5 = 11.76 W
Fan efficiency = 11.76 / 48 = 0.245 or 24.5 %

The Fan Efficiency Curve:

Fan efficiency varies dramatically as a function of aerodynamic loading. Because airpower is the product of flow and pressure, a fan working in the free air condition (no backflow pressure) has zero pressure and thus is producing no airpower and by definition has zero efficiency. Similarly, a fan in the fully shut off condition (no flow) has zero flow and is also producing no airpower and zero efficiency. The peak efficiency of an axial fan typically occurs at a pressure point of 1/3rd the maximum pressure.

Figure 1 below represents a performance plot of a 120mm size axial fan with curves for both airflow and efficiency.

Figure 1: Pressure vs. Flow Curve - 120mm Axial Fan

As a general rule, fan efficiency increases with blade diameter and speed. Fan manufacturers are now focusing on higher efficiency fans, resulting in new designs with significantly increased peak efficiency compared to older designs. Table 1 provides an indication of peak efficiency values for different standard axial fan sizes and the comparative improvement with newer generation designs.

Table 1: Axial Fans Typical Peak Efficiency;

Form Factor	Old	New
40 x 40	10%	25%
60 x 60	14%	30%
80 x 80	16%	33%
92 x 92	18%	35%
120 x 120	24%	40%
172 round	35%	45%

Fan Selection Taking Account of Efficiency:

Historically, fans were chosen by finding a standard form factor to occupy the available space and then matching airflow performance against system requirement; typically using free flow as a figure of merit. This approach has the potential for missing significant power savings which could be realized by carefully matching fan efficiency to the system operating point.

In the example shown below, (Fig. 2), selecting the fan based upon free air performance would favor the high flow fan option. Overlaying the system resistance line on the performance curve shows the high flow fan would achieve the required performance of 110cfm at 0.48 inch H2O.

However, comparing this fan efficiency at the operating point against an alternative lower free air flow fan design, it can be seen the second design would actually provide higher efficiency while still meeting the duty point.

Figure 2: Pressure Vs. Flow Curve with Fan Efficiency and System impedance

Benefits of Selecting High Efficiency Fans:

Higher levels of power are required to cool the large amount of heat generated by today's high end servers. As a result, more electrical power will be needed to be allocated to the system's cooling components. In some instances, 25% or more of the total power budget for a high end rack system is allocated to the cooling fans.

Using high efficiency fans has a cascade effect on system design. Power supplies can be down sized saving weight and space and the fans power distribution network can be minimized.

The long term benefit of specifying high efficiency fans is a reduction of ownership costs. Large data centers can contain tens of thousands of servers with anywhere between 10 and 50 fans in each.

A few percentage points improvement in the efficiency of every fan installed can quickly represent many thousands of dollars in annual energy savings.

High efficiency fans can be more costly than older fan types, and this can be seen as a deterrent. Engineers and purchasing managers should understand the wider implications of using these newer fan designs.

System level savings can result from the lower power requirements and substantial energy savings can be realized by the end user.

(Hi) Worker Benefits of Maintaining Exhaust Fan: Food Industry Case Study.

Hi Case Study:

Application Overview:

A Snack Food Facility in needed to clean vegetable oil residues from its production line exhaust fan systems. The fans were so encrusted that they were out of balance and not adequately drawing the cooking oil vapors off the production line. With an average build-up of six inches of oil, the fan systems also were vibrating severely.

There are three fan systems, each approximately 350 square feet. Each system is comprised of a 6-foot diameter fan and motor in a fully enclosed shroud with hinged outflow louvers designed to open when the exhaust system is functional. However, the louvers were inoperable and propped up with broom handles.

Substrates:

Galvanized steel

Previous Methods:

A chemical solution was sprayed on all surfaces to soften the oils. This was followed with hand scraping and a hot water rinse. Unfortunately, the chemical solution eventually was unable to remove the continued build-up.

Special Concerns:

First, the cleaning materials needed to be approved for use in a food production facility. Second, the fan system needed to be protected from damage. Third, dust had to be minimized to avoid migration throughout the plant.

Project Schedule:

Each fan system had to be cleaned between 5:00 a.m. and 5:00 p.m. on the one scheduled "down day" per week. Cleaning the rooftop mounted exhaust fans in temperature averaging 100 degrees posed a special challenge to the workers.

Containment:

Dust suppression was the only containment required. All material was flushed down the inside of the ventilation chamber to the production room floor below for clean up by the facility sanitation personnel.

Results/Benefits Summary:

The production personnel reaped immediate and measurable benefits. After cleaning, the fans and exhaust systems functioned as designed. The hinged shrouds opened easily, and fans operated with zero vibration. Production personnel reported that there was a "world of difference" on the production floor due to proper exhaust operation. As a result, the maintenance personnel are establishing an ongoing cleaning schedule.