KKEK3192 Industrial Training Report

KKEK3192: Industrial Training

Special Semester, 2013/2014

Industrial Training Report T.T.E. Engineering (M) Sdn. Bhd.

Prepared by:

Name : Toh Beng Leong

Matric no. : KEK110060

Course : Chemical Engineering

Company : T.T.E. Engineering (M) Sdn. Bhd.

Industrial supervisor : Mr. Tan Seng Teck

Faculty supervisor : Dr. Brahim Si Ali

Abstract

I have undergone my industrial training in T.T.E. Engineering (M) Sdn Bhd. in Penang, from 30 June

to 5 September 2014 (10 weeks). T.T.E. Engineering (M) Sdn. Bhd. is a company that specialises in

Heating, Ventilation and Air-Conditioning (HVAC). In the company, I was placed in Project B589,

which is the construction of three buildings (B5, B8 and B9) for B.Braun Medical Industries, under an

industrial supervisor, Mr Tan Seng Teck and site supervisor, Mr Choo Beng Wooi.

During the 10-weeks internship, I have learnt the basics of HVAC and also given the chance to do site

inspection as a trainee project engineer. I was also involved in the testing of fan coil units (FCU) in

Project B11. Furthermore, I have learnt about pressure loss calculation for a ducting system and

analysed the feasibility of ductworks in Project B589. I also learnt about analysis of sound and noise

created by HVAC systems. Before the end of my internship, I was given the task to program

Calculators for pressure loss calculations and noise level calculations using Excel and VBA.

One of the most important lesson learnt during my industrial training is that engineers need to know

more than their own field of expertise in order be competent and able to have better cooperation with

engineers of other fields in the industry. Moreover, safety is always stressed for workers regardless of

rank and position at site. Engineers must always check and analyse any data given, in order to detect

any inconsistency or discrepancy, and to determine whether the data obtained is logical and acceptable.

All in all, this industrial training has given me an invaluable insight of being a professional engineer.

i

Table of Content

Acknowledgement ................................................................................................................................ 1

Learning Outcomes of the Training ...................................................................................................... 2

Chapter 1: Company Overview ............................................................................................................ 3

Introduction to the Company............................................................................................................. 3

Company Profile ............................................................................................................................... 4

Company Quality Policy ................................................................................................................... 5

Company Safety Policy ..................................................................................................................... 6

Chapter 2: Project Overview ................................................................................................................. 8

Chapter 3: Project Assignments .......................................................................................................... 10

Understanding the Basics of HVAC ............................................................................................... 10

Site Supervision and Commissioning ............................................................................................. 15

Threaded Hanger Rod Selection ..................................................................................................... 20

Ducting System Analysis ................................................................................................................ 22

Sound and Noise Analysis............................................................................................................... 27

Chapter 4: Conclusion......................................................................................................................... 36

References ........................................................................................................................................... 37

1

Acknowledgement

Firstly, I would like to express my deepest appreciation to my industrial supervisor, Mr. Tan Seng

Teck, and also my site supervisor, Mr. Choo Beng Wooi, for their patience in guiding me throughout

the industrial training with invaluable teachings, advice and constructive suggestions. Even with a

tight schedule, their willingness to sacrifice their time to guide me has been very much appreciated.

Next, I would like to thank the Chemical Engineering department visiting lecturer, Dr. Jegalakshimi,

for taking her time to visit me at my company’s office and construction site in order to evaluate the

progress of my industrial training. I am very grateful for the encouragement and support that she has

given me during the visit.

Furthermore, I am very grateful for the assistance and help given by my friendly colleagues, who

welcomed me as a part of the company and always cheer up the working environment when things

went dull. They have also provided me the precious insight of being a professional engineer.

Moreover, I would like to thank the company supporting staffs, Ms. Jasmine Tan and Ms. Linda Chuah

for helping me during my industrial training application into the company, and for helping me to fit

into the company.

Lastly, I would like to acknowledge the support provided by my family and course mates throughout

the industrial training period. Their unwavering support has kept me motivated and enthusiastic in my

work throughout the period.

2

Learning Outcomes of the Training

The industrial training programme in T.T.E. Engineering (M) Sdn. Bhd., which starts from 30 June

to 5 September 2014, has benefitted me in both theoretical and practical skills. On the completion of

the 10-weeks industrial training, I am able to:

1. Understand the importance and compliance of safety rules when working at site.

2. Explain the basics of HVAC in a building.

3. Describe the important aspects for an engineer to check during site inspection.

4. Use software such as AutoCAD and Excel in designing HVAC system.

5. Analyse the practicability of a ducting system.

6. Analyse the impact of sound and noise from a HVAC system in a room.

3

Chapter 1: Company Overview

Introduction to the Company

T.T.E Engineering stands for Takasago Thermal Engineering. The parent company for T.T.E.

Engineering (M) Sdn. Bhd. is Takasago Thermal Engineering Co., Ltd. in Japan. The Malaysian

branch is one of the earliest oversea branch that has been established, which is in 1982 in Kuala

Lumpur, with only 2 engineers. Now, the company has almost 90 employees, headed by the General

Manager, Mr. Yoshito Ikeda, and had constructed numerous Japanese, European, and American

affiliated factories, such as Komag, Infineon, Ibiden, Seagate, Western Digital and Osram. Currently,

there are two large ongoing projects in the company, namely Project B.Braun B11 and B589.

T.T.E. Engineering (M) Sdn. Bhd. is a company that specialises in Heating, Ventilation and Air-

Conditioning (HVAC). The company also engages in primary-side electrical construction focused on

HVAC systems planning, construction work, and special utility construction.

Figure 1: International Affiliates of Takasago Thermal Engineering Co., Ltd.

Source: http://www.tte-net.co.jp/english/corporate/affiliates.html

4

Company Profile

Date established 11 November 1980

Accounting period 31 December

Capital MYR1 million

Shareholder composition 30% – Takasago Thermal Engineering

70% – TTE Malaysia Holdings Sdn. Bhd.

General manager Mr. Yoshito Ikeda

Number of employees 89

Description of business Design and construction of HVAC, sanitation, and electrical systems

Company management

T.T.E. Engineering (M) Sdn. Bhd. has 5 offices established throughout Peninsular Malaysia and one

in East Malaysia (Sarawak):

Figure 2: T.T.E. Engineering offices in Malaysia.

Source: http://www.ttemalaysia.com.my/network.html

5

Company Quality Policy

The management and staffs of T.T.E Engineering (M) Sdn. Bhd. are committed to enhance customer

satisfaction and continual quality improvement through:

1. Excellent quality

2. On-time Delivery

3. Customer Satisfaction

T.T.E Engineering (M) Sdn. Bhd. strives to maintain and continually improve its management quality

through MS ISO 9001:2008, which is a standard that provides a tried and tested framework for taking

a systematic approach to managing the organisation's processes so that they consistently turn out

product that satisfies customers' expectations. There are eight principles that are used by the

management to guide their organisation towards an improved performance in the quality management

system standard ISO 9001:2008 [1, 2]:

a) Customer focus

The organisation should understand its current and potential customers’ needs, meet or exceed

customers’ expectations. Customer focus is achieved when every person in the organization

know and understand both its internal and external customers, and their requirements, to ensure

that both the internal and external customers are satisfied.

b) Leadership

Leaders of an organization establish unity of purpose and direction of it. They should go for

creation and maintenance of such an internal environment, in which people can become fully

involved in achieving the organization's quality objective.

c) Involvement of people

People at all levels of an organization are the essence of it. Their complete involvement enables

their abilities to be used for the benefit of the organization.

d) Process approach

The desired result can be achieved when activities and related resources are managed in an

organization as a process.

e) System approach to management

An organization's effectiveness and efficiency in achieving its quality objectives are

contributed by identifying, understanding and managing all interrelated processes as a system.

6

Quality Control involves checking transformed and transforming resources in all stages of

production process.

f) Continual improvement

One of the permanent quality objectives of an organization should be the continual

improvement of its overall performance, leveraging clear and concise PPMs (Process

Performance Measures).

g) Factual approach to decision making

Effective decisions are always based on the data analysis and information.

h) Mutually beneficial supplier relationships

Since an organization and its suppliers are interdependent, therefore a mutually beneficial

relationship between them increases the ability of both to add value.

Company Safety Policy

T.T.E. Engineering (M) Sdn. Bhd. is a company that stresses very much on safety of its employees.

Thus, the company’s motto is “Safety first!” T.T.E. Engineering has its own Safety and Health Policy

for contractors:

a) Complying with the Occupational Safety and Health Act (OSHA) 1994 with other relevant

statutory requirements and codes of practice.

b) Preventing Occupational Safety and Health (OSH) related fatalities, injuries and illnesses

through the effective safety and health management and implementation of safety work

procedures.

c) Maintaining high level of safety awareness through continuous education and training relating

to safety and health. Our ultimate aim is to develop a safety and health culture amongst our

employees.

d) Encouraging employees to report any unsafe acts, unsafe conditions, any accidents or near

misses to management promptly.

e) Conducting regular inspection and taking appropriate corrective action.

f) Providing appropriate Personal Protective Equipment (PPE).

All of the company’s and contractors’ workers and employees are required to be above age 16, have

a valid work permit (for foreign workers), and be in possession of a valid CIDB green card or NIOSH

7

Safety Induction Certificate (SICW). PPE, such as safety helmet, safety shoes, masks and harness, is

to be provided by contractors or employers for their workers. For first-time workers at a construction

site, they must go through a safety induction course, held by the safety division of the main contractor.

There will be a toolbox meeting at 8.30 am before starting work, in order to brief all the workers of

their job scope and the relevant safety precautions. Workers are also regularly reminded of the basic

safety rules at construction site, for example, don’t drink/smoke/sleep at the construction site to

prevent unwanted accidents.

8

Chapter 2: Project Overview

As a trainee, I am assigned to Project B589. Project B589 involves the construction of 3 buildings, i.e.

Block B5, B8 and B9. B8 is an 8-storey office building, while B5 is a 2-storey cafeteria. B9 is a 6-

storey building that consists of a production plant, car park and offices (called the spine area). B5 also

acts as a link bridge between an existing building (B3) and B9. B8 is linked to B3 through a covered

bridge as well. The rough layout of B589 buildings are shown in Figure 3 below.

Figure 3: Rough layout of B589 buildings.

The project can be divided into three phases – first sectional completion phase involves construction,

commissioning and hand-over of buildings B8, B5 and B9 spine (office) area; second sectional

completion phase involves demolition of old B5 building and completion of production area A in B9;

third sectional completion phase is the completion of production area B in B9. The phases of

completion are shown below in Figure 4.

Figure 4: Sectional completion phase 1, 2 and 3 (from left) of Project B589.

In both Project B589 and B11, T.T.E. Engineering (M) Sdn. Bhd. is the mechanical and electrical

(M&E) subcontractor for Daya CMT Sdn. Bhd., who is the main contractor under the consultation of

Phase 1: Phase 2: Phase 3:

9

Synertec Asia (M) Sdn. Bhd. The owner of the project is B.Braun Medical Industries Sdn. Bhd. A

simplified project management pyramid is illustrated in Figure 5 below.

Figure 5: B589 Project management pyramid.

In T.T.E. Engineering, the project is headed by the Penang Branch Manager, Mr. Tan Kok Peng,

followed by the Executive Project Manager, Mr. Tan Seng Teck, who is also the industrial supervisor

assigned by the company. The project hierarchy is shown in Figure 6 below.

Figure 6: B589 Project hierarchy for T.T.E. Engineering.

Owner B.Braun Medical Industries

Consultant Synertec Asia

Subcontractor (Firefighting)

Pentamex

Subcontractor (Mechanical and Electrical)

T.T.E. Engineering

Subcontractor (Civil and Structural)

Daya CMT

Main contractor Daya CMT

Mr. Tan Kok Peng

Penang Branch Manager

Mr. Tan Seng Teck

Executive Project Manager

Mr. Choo Beng Wooi B589 Project Manager

Mr. Yong Sea Peng B589 Assistant Manager

Mr. Remy B589 Safety Officer

Mr. Lim Jin Xin B589 Project Engineer

Mr. Chong Yi Kang B589 Project Engineer

Mr. Ch’ng Chor Ee B589 Project Engineer

Mr. Lee Wai Keat B589 Project Engineer

Toh Beng Leong B589 Trainee

10

Chapter 3: Project Assignments

Understanding the Basics of HVAC

HVAC is the acronym for Heating, Ventilation and Air-Conditioning. It is the technology of indoor

environmental comfort, based on the knowledge of thermodynamics, fluid mechanics and heat

transfer. HVAC is very important in providing a comfortable environment and acceptable indoor air

quality for occupants in a building. This is done by manipulating various parameters of air inside the

building, such as temperature, humidity, flow rate, composition, smell, etc.

Humans are sensitive to humid air because the human body uses evaporative cooling as the primary

mechanism to regulate temperature. Under humid conditions, the rate of perspiration or evaporation

of sweat on the skin is lower than it would be under dry conditions. Since humans perceive the rate of

heat transfer from the body rather than temperature itself, the environment feels warmer when the

relative humidity is high as rate of evaporation is lower. Therefore, it is determined that the human

comfort range is around 40% to 70% relative humidity and 18 to 25°C for people who are adequately

clothed [3], as shown in a psychrometric chart in Figure 7 below.

Figure 7: Human comfort range highlighted in the psychrometric chart

Source: http://www2.ca.uky.edu/poultryprofitability/Production_manual/Chapter7_Ventilation_principles/Psychrometric_Chart.png

11

In a room whereby an air conditioner is used to circulate air, the air that is supplied by the air-

conditioner is called supply air, while the air that returns to the air-conditioner is called Return air.

Sometimes, air returning to the air-conditioner is not enough to cater for the required amount of supply

air due to air leakage from the room, so a certain amount of air is required to make-up for the loss.

This air stream is called the make-up air. Figure 8 illustrates the flow of air in a room fitted with an

air-conditioner.

Figure 8: Diagram of the flow of air in a room fitted with an air-conditioner.

In a centralised air-conditioning system, air flow in the system is regulated and circulated by air

terminals or air handlers. Air handlers are large metal boxes containing a blower, heating and/or

cooling elements, filters, and dampers. There are many types of air terminals or air handlers available,

some common ones are:

a) Fan coil unit (FCU)

b) Make-up air unit (MAU)

c) Air handling unit (AHU)

The make-up air unit (MAU) is a type of air handler that only conditions outside air or fresh air. MAU

supplies make-up air to a room from intake of fresh air, which goes through a heating/cooling coil and

air filter treatment. The heating/cooling coils are used to adjust the temperature and humidity of fresh

air, while filters are used to remove particulate matter such as dust. Sometimes, UV lights are fitted

into the chambers of MAU to kill bacteria and microbes that are present in the fresh air. A typical

MAU is shown in Figure 9.

Mass balance of air:

𝑆𝑢𝑝𝑝𝑙𝑦 𝑎𝑖𝑟 = 𝑟𝑒𝑡𝑢𝑟𝑛 𝑎𝑖𝑟

+ 𝑚𝑎𝑘𝑒 − 𝑢𝑝 𝑎𝑖𝑟

Make-up air

Room

Air conditioner

Return air

Supply air

12

Figure 9: Diagram of a typical make-up air unit (MAU).

Normally in an air-conditioning system, a chiller is used to produce chilled water for the cooling coils

in the air handlers via heat transfer between two fluids, which are usually water and refrigerant. The

cooling of water is occurs via the refrigeration cycle, as shown in Figure 10. In this cycle, a circulating

refrigerant enters a compressor as a vapour and exits as a superheated vapour. This superheated vapour

enters a condenser, whereby it is cooled and condensed into liquid. The heat from the superheated

vapour can be either removed by water (water-cooled chiller) or air (air-cooled chiller). The liquid

then travels through an expansion valve, whereby it undergoes flash evaporation, resulting in a mixture

of liquid and vapour at low temperature and pressure. The mixture enters the evaporator, whereby it

completely vaporises due to heat transferred from the hot water from the cooling coil in the air handler.

Thus, chilled water is produced and the vapour returns to the compressor, completing the

thermodynamic cycle.

Figure 10: Typical refrigeration cycle in a chiller.

UV light

Preheating

coil

Cooling

coil Water

drain

Bag filter

Fresh air

intake

Blower

Make-

up air

Compressor

Expansion valve

Condenser Evaporator

Superheated vapour Saturated vapour

Saturated liquid Liquid-vapour mixture

Water/air in

Water/air out Hot water

Chilled water

13

In an air-cooled chiller, a fan will blow air through the condenser, thus cooling the superheated vapour.

However, this is only feasible for small scale air-conditioning systems. For larger scale systems, water

is used to cool the superheated vapour in the condenser, and the water is, in turn, cooled in a cooling

tower via evaporative cooling process. To better illustrate the entire system, a diagram of air-cooled

water chiller air-conditioning system is shown in Figure 11 below.

Figure 11: Diagram of a typical air-cooled water chiller air-conditioning system.

Clean room is one of the most important features in HVAC for industrial buildings. Some industries,

such as electronics and medical industries, require manufacturing environment that is free from

contamination, such as dust, vapours and microbes. So, a clean room is designed for this purpose.

There are many clean room standards available in the market, due to different requirements of

customers. Generally, there are 6 ISO standards, ranging from ISO 1 to ISO 9 in ISO 14644, with ISO

1 as the standard that permits the least amount of particles in air and ISO 9 for normal room air [4].

Other clean room standards are also available such as the American US FED STD 209E cleanroom

standards (which is now obsolete), the British BS 5295 clean room standards and European GMP EU

classification.

Normally, clean rooms are air-locked chambers that is continuously ventilated with clean air. In a

clean room, air flow rates and direction, pressurization, temperature, humidity and specialized

filtration all need to be tightly controlled. This is to ensure that the cleanroom is maintained and

cleaned to the same standards as it was built. An example of a clean room is shown in Figure 11 below.

Make-up air

Supply air

Return air

AHU

Chiller

Cooling tower

Room Cooling coil

Damper

14

Figure 11: Diagram of a typical clean room.

In Figure 11, make-up air enters the plenum through an MAU. The plenum serves as a chamber for

the mixing of make-up air from MAU and return air from the clean room chamber. The mixed air

enters the clean room chamber through Fan Filter Units (FFU). FFU is a fan fitted with filters that

filters away the contaminants and particulates in the air. Continuous blowing of air into the clean room

chamber causes the air-locked room to become pressurised and plenum to become depressurised.

Thus, in order to counter this, air must be returned to plenum. There are several methods of returning

air to the plenum – one of them is through a perforated raised floor. Air escapes the clean room through

tiny perforations on the floor and returns to plenum through the return air chase and Dry Cooling Coil

(DCC). DCC cools the air by removing only sensible heat, so no condensation occurs during cooling,

and hence the name “dry cooling”.

Outside air

MAU

Plenum

Clean

room

Perforated

raised floor

Return air

chase

Dry cooling

coil (DCC)

Fan filter unit (FFU)

15

Site Supervision and Commissioning

As engineers, we are required to ensure that the workers and contractors are doing what that has been

planned to ensure that the building is built according to specification, and systems and equipment are

able to carry out their function as designed. Furthermore, engineers, together with the appointed safety

officers, are required to ensure that the workers and contractors are complying with the safety and

health policies of the company, as well as OSHA 1994.

Safety is the most important aspect when doing site supervision. As mentioned previously in the

Company Safety Policy, all workers at site, regardless of unskilled labourers or engineers, are required

to go through a safety induction talk before they are allowed to work at the site. After the talk, all

workers will be given a tag to show that they are legitimate workers at site and will be given a set of

PPE, which includes a safety helmet, a pair of safety shoes and a vest. There are colour codes for

safety helmet to differentiate responsibilities between site workers – yellow is for general construction

labourers, red is for signalman, white is for supervisors and engineers, and blue is for safety officers.

Figure 12 below shows different colour codes for safety helmets.

Figure 12: Different colour codes for safety helmet.

Source: http://tcgroupuae.com/personal-industrial/head_protection/safety-helmet-hhq4rch/

Special PPE are provided for workers that are undertaking more dangerous tasks. For example,

workers working at a height of 3 metres above finished floor level (FFL) are required to wear a harness

as fall protection. Workers working with power tools are provided with safety gloves and goggles.

Welders are also given welding masks, which is a must in welding works. Dangerous tasks such as

these also the workers to obtain certain permits, called Permit To Work (PTW), before they can

perform such tasks. These PTWs are:

a) Hot-Work – Welding, cutting, etc.

b) Work At Height – Above 3 metres.

c) Hazardous Substance.

d) Confined Spaces.

16

Scaffolds are very common equipment used by workers to work at high places. Scaffolds are

temporary structures used to support people and material in the construction or repair of buildings and

other structures. Only a scaffolder with qualified training and license can erect and dismantle a

scaffold. Scaffolds that are erected are then checked by a safety officer before it can be used. Scaffolds

that are safe for use are given a green tag (as shown in Figure 13 below), while scaffolds with a pending

status are given a yellow tag. Unsafe scaffolds are given a red tag to warn workers not to use the

scaffolds.

Figure 13: Scaffold with a green tag is safe for use.

As required by OSHA 1994, a toolbox meeting will be held every morning before starting work. For

T.T.E. Engineering (M) Sdn. Bhd., the toolbox meeting will be held at 8.30 am, headed by a safety

officer. The purpose of toolbox meetings is to brief both supervisors and labourers of their job scope

of the day’s work and their relevant safety precautions, so all workers know what they will and others

need to do on that particular day. Workers are also regularly reminded of the basic safety rules at

construction site. Engineers, although not compulsory, are encouraged to join the toolbox meeting to

know their workers and give professional advice.

In the B589 Project, I have been entrusted with the task of ensuring that equipment are assembled

according to the correct standards and procedures. Some of the things to note are:

17

a) Insulation for duct should be at least 2 inch thick. Insulation is made up of fibre glass to prevent

heat transfer between air in the duct and the environment (as shown in Figure 14).

Figure 14: Fibre glass lining for ducts.

b) Length of flexible duct must not exceed 2 metres to prevent excessive pressure loss in the

ductwork (shown in Figure 15).

Figure 15: A flexible duct (in red circle) that does not comply with the 2-metres limit.

c) There must be at least one copper link connecting between wire trunking to ground electricity

leakage in the trunking (shown in Figure 16).

18

Figure 16: A copper link connecting between two wire trunkings, highlighted in a red circle.

d) Ensure trunking and piping services are above ceiling (around 3 metres from FFL), so that

these services are not exposed to the occupants of the building.

e) Ceiling equipment, such as diffusers, must be tied to secondary frame to prevent ceiling

collapse due to excessive burden on the ceiling.

As opposed to B589 Project, which is still in its initial construction stages, the B11 Project will be

completed by early September, and so it is currently in the testing and commissioning phase. As a

trainee, I have been involved in the testing of FCUs in building B11. There are three important things

to check for FCUs. Firstly, the rotation direction of the centrifugal fan in the FCU must be in the

correct direction, which is either clockwise or anti-clockwise depending on the location of the outlet.

An example of rotation direction of the centrifugal fan in FCU is shown in Figure 17 below.

Figure 17: Rotation direction of centrifugal fan (highlighted in red) for different outlet location.

Air out

Air out

Air out

19

When a centrifugal fan is found to be rotating at the other direction, the rotation correction can be

made by adjusting the wiring in the isolator box. However, it should be noted that this can only be

done for three phase motors only. Three phase wires are labelled in three colours – red, yellow and

blue. In the case of a three phase motor, any two of the supply leads (normally red and blue wires) in

the isolator can be reversed. This will reverse the direction of the rotating magnetic field in the motor's

windings and thus its direction of rotation. Figure 18 below shows the arrangement of three phase

wiring before and after adjustment to change fan rotation direction.

Figure 18: Adjustment of three phase wires in the isolator box.

Furthermore, the belt alignment between the motor and impeller is also another important point for

engineers to check on. Misalignment may cause ‘skidding’ noises during motor start-up and will

accelerate the wear-and-tear process of the belt in long term use. Normally, lubrication is also required

for the belt to move more smoothly.

As the building is still in the testing and commissioning stage, the FCU are not allowed to suck in

return air, as the return air, which contains large amount of dust due to some minor construction

processes still going on, will dirty the filter and decreases its operating life. A dirty filter before project

handover will not be acceptable for the project owner, and so precaution must be taken to avoid this

from happening. To prevent this, the source of air intake must be changed temporarily. One method

to do this is by closing the air intake dampers and opening the door to the air intake compartment so

that air intake comes from the door instead of its usual ductwork. However, care must be taken to keep

the door open at more than 90° to prevent the door to be sucked in due to the low pressure region

created in the FCU when the fan starts. This is illustrated in Figure 19 below.

Before: After:

20

Figure 19: Closing of damper and opening of door in FCU (Top view).

Threaded Hanger Rod Selection

A threaded rod, which is also called a stud, is a long metallic rod that may be threaded on both ends

or threaded along the whole rod. The rods are normally used to suspend equipment, piping or ductwork

in the ceiling, so they are designed to be used in tension [5].

In order to select a suitable threaded hanger rod, the weight of the load in which the rod is required to

support and the allowable tensile stress is needed. The allowable tensile stress is usually 60% of the

minimum yield strength of the material of the rod. In many cases, a safety factor is used to multiply

with the load to obtain the apparent load, as the actual load may vary from its given specification. With

the weight of the load and allowable tensile stress known, the tensile stress area can be calculated from

the equation:

𝑇𝑒𝑛𝑠𝑖𝑙𝑒 𝑠𝑡𝑟𝑒𝑠𝑠 𝑎𝑟𝑒𝑎 (𝑚𝑚2) =𝑙𝑜𝑎𝑑 (𝑘𝑔) × 𝑔𝑟𝑎𝑣𝑖𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 (𝑚/𝑠2)

𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 𝑡𝑒𝑛𝑠𝑖𝑙𝑒 𝑠𝑡𝑟𝑒𝑠𝑠 (𝑀𝑃𝑎)

Tensile stress area is the effective cross-sectional area of the threaded rod that resists rod fracture.

When the tensile stress area is obtained, it is then compared with a list of tensile stress area, which is

calculated from a predetermined list of nominal diameters. An example of these predetermined list of

preferred threaded rod sizes is the ISO 261 Standard. From this list, the tensile stress area that is closest

to the calculated value of tensile stress area is selected. From the value of tensile stress area and its

corresponding nominal diameter, the thread pitch can be calculated using the equation:

𝐴 =𝜋

4(𝐷 − 0.938194 𝑃)2

Closed damper

Opened door

Air intake compartment

Filter

From ductwork To fan

Air intake

More than 90° angle

21

where D = nominal diameter (mm)

P = thread pitch (mm)

Furthermore, with the selected value of tensile stress area, the actual stress and maximum load can

also be calculated using previous equation. The actual stress and maximum load can then be compared

to the given values to determine whether the selected rod is able to support the load. If the actual stress

is less than the allowable tensile stress and the maximum load is more than the given load, then the

rod is acceptable. If not, then the rod with a larger tensile stress area will be selected.

With these information and equation, a Threaded Hanger Rod Selector is created in Excel, as requested

by the site supervisor for future use. In Excel, the user is required to input three values, i.e. load (kg),

safety factor and allowable tensile stress (MPa). The tensile area required is then calculated

automatically. Then functions such as INDEX, MATCH and VLOOKUP are used to match the

calculated tensile area with the list of tensile area in the ISO 261 Standard. Then, the actual stress and

maximum load is calculated to compare with the input values. If the values are acceptable, then the

status for both stress and load will display an “OK”, otherwise a “NOT OK” status is displayed. The

user interface in Excel is shown in Figure 20 below.

Figure 20: User interface of Hanger Rod Selector in Excel.

22

Ducting System Analysis

Ducts are used in HVAC to transport air, such as supply air, return air and exhaust air. Ducts are

typically made up of Galvanized Iron (GI), with a lining of fibre glass as insulation layer to prevent

heat transfer. There are various types of ducts – the common ones are straight ducts and flexible ducts.

Straight ducts also have a variety of shapes, such as rectangular, circular and oval. However,

rectangular ducts are often used as its rectangular shape allows the ducts to be used in places where

spaces are limited. Flexible ducts are normally made up of flexible plastic or aluminium foils covering

metal wire coils to form the shape of a tube. Flexible duct is often used for attaching supply air outlets

to the rigid ductwork, as they are able to bend easily to reach confined spaces.

In the design of ducting system, it is important to maintain the required flow rate of air from its source

(air handlers) to its outlets. One crucial parameter that significantly affects the flow rate of air is the

pressure drop in the ducting system. Therefore, the pressure loss in a ducting system must be known

to an engineer in designing a ducting system or even piping system, as both ducting and piping systems

differs only in the type of fluid being transported (normally ducts transport gaseous fluid, while pipes

transport liquid). The procedure for calculating pressure drop in a ducting system is as follows:

1. Collect the required information on the ducting system

a) Duct element: duct, fittings, dampers, etc.

b) Duct dimension: width, height and length

c) Duct characteristics: surface roughness

d) Required air flow rate

e) Physical properties of air: density, viscosity

2. Calculate major pressure loss (pressure loss due to flow in straight ducts)

a) Obtain equivalent diameter of duct (if duct is rectangular):

𝐷𝑒 =1.3(𝑎𝑏)0.625

(𝑎 + 𝑏)0.25

b) Obtain cross-sectional area of duct:

𝐴 =𝜋𝐷2

4

c) Obtain velocity of flow:

𝑣 =𝑄

𝐴

23

d) Calculate Reynolds number:

𝑅𝑒 =𝜌𝑣𝐷

𝜇

e) Solve Colebrook equation for friction factor, 𝑓. This implicit equation can be solved by

using iterative method or using Goal Seek function in Excel.

0 =1

√𝑓+ 2 log (

𝜀

3.7 𝐷+

2.51

𝑅𝑒 √𝑓)

f) Solve Darcy-Weisbach equation for pressure loss, ∆𝑃𝐿.

∆𝑃𝐿 = 𝑓𝐿

𝐷

𝜌𝑣2

2

3. Calculate fitting/minor pressure loss (pressure loss due to fittings)

a) Obtain fitting loss coefficient, 𝐶𝐿, from suitable references.

∆𝑃𝐿 = 𝐶𝐿

𝜌𝑣2

2

4. Calculate total pressure loss in the system

a) Add major and fitting pressure loss to obtain total pressure loss, ∆𝑃𝐿,𝑇.

∆𝑃𝐿,𝑇 = (𝑓𝐿

𝐷+ ∑ 𝐶𝐿)

𝜌𝑣2

2

It is important to correctly identify the number and types of fitting in a ducting system. Some useful

references that provide a comprehensive list of fitting loss coefficient for various fittings of different

types and dimensions are the ASHRAE Handbook [6] and the book on duct design by SMACNA [7].

Figure 21 below shows an example of determining fitting loss from a ducting system.

24

Figure 21: Determining fitting loss from a ducting system.

Another parameter that is related to pressure loss is the external static pressure (ESP) of a fan. ESP is

the pressure that the fan has to overcome due to ducts and fitting losses to give the required space

ventilation and cooling requirements at least equal to the designed flow. It is a function of the length,

equivalent diameter, velocity, frictional losses and density of the fluid flowing, which is commonly

air in HVAC systems. Fan manufacturers also rate the fan's static pressure minimum requirements so

that the fan will operate optimally. Therefore, it is important to ensure that the pressure loss in the

ducting system is less than the ESP in order for the fan to operate optimally.

FCU

Swirl diffuser

ΔP = 3 mmH2O

(Provided by manufacturer)

Return air

Fresh air

Flexible duct (max. 2 m)

ΔP/L = 3 Pam/m

Damper

CL = 0.19

Elbow

CL = 0.21

Straight duct

(ΔP calculated using

Darcy-Weisbach

equation)

Wye

CL = 0.53

Diverging transition

CL = 0.23

Reducer

CL = 0.24

Dovetail

CL = 0.30

Supply air

25

A Duct Pressure Loss Calculator is created in Excel as requested by the site supervisor. In this

calculator, several user inputs are required, for example, the fluid (normally air) physical properties,

air flow rate, duct dimensions and types of fitting used. The entire ducting system to be analysed is

also required to be divided into sections, with the tags R1 to a maximum of R12 for return air duct,

and S1 to S12 for supply air duct. Each duct section can have its own specifications such as dimension,

air flow rate and roughness. The calculations are based on the equations given above. Since Colebrook

equation is an implicit equation, the Goal Seek function is required to obtain the value of friction

factor. However, Didier Clamond has presented an efficient resolution of Colebrook equation, which

is a simplified albeit highly accurate explicit form of the Colebrook equation and is efficient for the

whole range of parameters involved in the equation [8]. Visual Basic for Applications (VBA) in Excel

is used to help achieve this as directly using Clamond’s resolution of Colebrook equation in Excel is

complicated and tedious. Using VBA, a custom function, which is used to calculate for friction factor

using Clamond’s equation, can be programmed. The source code in VBA for this custom function,

named ‘Colebrook’, is shown below.

With this custom function defined in VBA, the friction factor can be calculated in the Excel worksheet

without the need of using Goal Seek. Figure 22 below shows the user interface of a few spreadsheets

in the Duct Pressure Loss Calculator.

26

Figure 22: User interfaces (top and bottom) of Duct Pressure Loss Calculator in Excel.

27

Sound and Noise Analysis

Sound is a form of energy that is transmitted by pressure variations which the human ear can detect.

Noise is unwanted sound, which is usually unpleasant to the human ear. Noise perception is subjective.

Factors such as the magnitude, characteristics, duration and frequency of exposure to the noise may

affect one's subjective impression of the noise. For example, a hum from a fan may be a reassuring

sound for the facilities manager but could be an intrusive noise to the office worker [9].

A pure tone sound will travel through air in a sinusoidal wave, as shown in Figure 23 below. The

distance between two successive peaks of the wave is called the wavelength, λ (m). The number of

waves that pass a fixed point in one second is called frequency, f (Hz). The pressure wave will travel

through air at speed, c (m/s), at around 343 m/s in room temperature. Wavelength is related to

frequency and the speed of sound by the equation:

𝜆 =𝑐

𝑓

Figure 23: Representation of a simple pure tone travelling through air.

The actual strength of a particular sound felt by the ear is related to the fluctuations of sound

pressure (Pa) reaching the ear. The strength of the source itself is determined by the sound energy

output, known as sound power (W). Therefore, sound pressure is defined as the acoustic pressure at

a point in space where the receiver (microphone or listener) is situated while sound power is defined

as the rate at which acoustical energy is radiated from a sound source. However, sound power and

sound pressure are not usually used in sound and noise analysis. Instead, sound levels are used,

whereby the unit for sound level is decibel (dB).

Sound power level:

𝐿𝑤 = 10 𝑙𝑜𝑔10 (𝑊

𝑊0)

Distance

Wavelength

28

where W = sound power

W0 = reference sound power = 10-12 W

Sound pressure level:

𝐿𝑝 = 10 𝑙𝑜𝑔10 (𝑝2

𝑝02)

where p = sound pressure

p0 = reference sound pressure = 2 × 10-5 Pa

As shown in the equations above, sound levels are logarithmic in nature, so they cannot be added

algebraically. Therefore, if there are more than one sound emitted in an area, the total sound level

can be determined as follows:

𝐿𝑡 = 10 𝑙𝑜𝑔10 (∑ 10𝐿𝑖/10

𝑛

𝑖=1

)

where Lt = total sound level

Li = i-th sound level

The typical human hearing frequency range is from 20 to 20,000 Hz. In order to ease sound analysis

in this frequency range, the range is divided into sets of frequencies, called octave bands. There are

several other types of octave bands, such as 1/3 octave band. However, the commonly used octave

band has a frequency band with an upper band limit that is twice the frequency of the lower band limit.

The mid frequency of an octave band is the geometric mean of its upper and lower band limits [10].

This octave band is shown in Table 1 below:

Table 1: Commonly used octave band

Octave band Mid frequency, Hz

1 63

2 125

3 250

4 500

5 1000

6 2000

7 4000

8 8000

29

In sound and noise analysis, it is presumed that sound travels from a source, through a path, to a

receiver. Sound sources can be air terminals such as FCU or AHU, and outlets such as diffusers. Sound

path is the route where sound travels and attenuation of sound occurs. Receiver is the person or object

(such as microphones) in the occupied space that receives the sound at the end of its path. This concept

can be illustrated in a diagram, as shown in Figure 24 below. An example scenario of the various

sources and paths of sound from an air terminal to the receiver at the middle of the room is shown in

Figure 25 below.

Figure 24: Concept of sound source, path and receiver.

Adapated from AHRI Standard 885-2008 with Addendum 1

Figure 25: Example scenario of sound sources and paths in a room.

Source: AHRI Standard 885-2008 with Addendum 1

Source Path

Receiver

Legend:

Sound source:

• C : Unit casing radiated

• D : Unit discharge

• O : Outlet generated

Sound attenuation elements:

• I : Duct insertion loss

• B : Duct breakout loss

• T : Duct elbow/tee loss

• F : Flow division loss

• R : Duct end reflection loss

• P : Ceiling/space effect

• S : Space effect

30

From Figure 25 above, it can be observed that there are six different paths for sound to travel from an

air terminal unit. The first path originates from the air terminal, and travels through the ceiling directly

to the receiver. The next four paths originates from the point of connection between the air terminal

unit and the ductwork. The sound in paths 2, 3 and 4 travels in the ductwork before ‘breaking out’ of

the duct, goes through the ceiling, and reaching the receiver’s location. The sound in the 5th path travels

through the whole ductwork and exits through the outlet and reaches the receiver. The last path is

taken by the sound generated at the outlet, whereby it goes directly to the receiver. Each path has its

own sound attenuation elements. Sound that travels in the duct has duct insertion loss and duct

breakout loss, while sound that goes through an elbow or tee fitting will have duct elbow/tee loss.

Flow division loss is only present for paths that has tee fittings, whereby the flow of air is split. Duct

end reflection loss is only present when the sound has to go through an outlet, whereby some of it is

reflected back into the duct by the outlet. When sound travels through a ceiling, it will have

ceiling/space effect, and if there is no ceiling in its path, there will be space effect instead. These

attenuation losses are measured by AHRI and tabulated for various specifications and dimensions of

duct and fittings [10], while the sound power level emitted by air terminals and outlets must be

provided by their manufacturers.

The value of sound pressure level may be weighted in terms of the human ear’s ability to hear them.

There are four types of weightings:

a) A-scale weighting: simulates response of human ear to low pressure level

b) B-scale weighting: simulates response of human ear to medium pressure level

c) C-scale weighting: simulates response of human ear to high pressure level

d) D-scale weighting: simulates response of human ear to aircraft noise

Of all the weightings that are available, A-scale weighting is the most commonly used weighting in

the industry. The A-scale weighting is advantageous as it simulates low level sounds, which is around

40 phon, by attenuating lower frequencies and clipping higher frequencies. However, this may

underestimate the apparent loudness for cases with predominantly low frequency noise. The equations

for A-weighting sound pressure levels is shown below [11]:

31

Weighting function:

𝑅𝐴(𝑓) =122002𝑓4

(𝑓2 + 20.62)√(𝑓2 + 107.72)(𝑓2 + 737.92)(𝑓2 + 122002)

Offset:

𝐴(𝑓) = 2.0 + 20 log10(𝑅𝐴(𝑓))

Weighting sound pressure level:

𝐴 − 𝑤𝑒𝑖𝑔ℎ𝑡𝑒𝑑 𝑠𝑜𝑢𝑛𝑑 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑙𝑒𝑣𝑒𝑙 = 𝑆𝑜𝑢𝑛𝑑 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑙𝑒𝑣𝑒𝑙 + 𝑜𝑓𝑓𝑠𝑒𝑡

With these, there is a predetermined offset values for different frequencies. These offset values are

shown for octave band mid frequencies in Table 2 below:

Table 2: A-weighting offset values for octave band mid frequencies

Octave band frequency 63 125 250 500 1000 2000 4000 8000

A-weighting offset -26 -16 -9 -3 0 1 1 -1

There are several design guidelines and standards when for sound and noise analysis in various rooms

and spaces. Some common ones are Noise Criteria (NC) and Room Criteria (RC). NC measures indoor

noise, noise from air-conditioning equipment, while RC measures background noise in a building.

However, it can be generalised that both NC and RC are measures of mechanical system noise in a

room. Noise Criteria curves were defined by Leo Beranek of the Boston based Acoustical Consulting

firm of Bolt, Beranek and Newman (BBN) in 1957. On the other hand, Room Criteria curves were

first proposed by Warren Blazier for the American Society of Heating Refrigeration and Air-

Conditioning Engineers (ASHRAE) in 1981 [12].

For Noise Criteria, the sound pressure levels are plotted in the octave bands. The highest point of the

sound level curve is the Noise Criteria. The Noise Criteria curve very closely resembles equal loudness

curves that correspond to human's sensitivity to higher frequency tones and lack of sensitivity to lower

frequency tones. Similarly, the sound pressure levels are plotted in the same octave bands for Room

Criteria, but a subjective decision is required to report a suitable level that corresponds to the

environment of interest. The RC 'curve' is actually a straight line with a slope of 5 decibels per octave.

In other words, the RC curve does not correspond to how humans hear. NC and RC are useful as they

are used to define the limits of octave band spectra that must not be exceeded to meet occupant

32

acceptance in certain spaces. For example, typical residential buildings have an NC or RC of 25 to 35,

so the noise level of a designed residential house must not be lower than 25 or exceed 35. Furthermore,

NC and RC are able to identify frequency bands that may cause potential noise problems. With this,

designers can pinpoint the problematic frequency band and find solutions to it. Figure 26 below shows

both NC and RC curves.

Figure 26: NC (top) and RC (bottom) Curves.

NC 15

NC 20

NC 25

NC 30

NC 35

NC 40

NC 45

NC 50

NC 55

NC 60

NC 65

10

20

30

40

50

60

70

80

90

63 125 250 500 1000 2000 4000 8000

Sou

nd

leve

l, d

B

Octave band centre frequency, Hz

NC Curves

RC 25

RC 30

RC 35

RC 40

RC 45

RC 50

10

20

30

40

50

60

70

80

90

63 125 250 500 1000 2000 4000 8000

Sou

nd

leve

l, d

B

Octave band centre frequency, Hz

RC Curves

33

A Noise Calculator is created in Excel, as requested by the site supervisor in order to calculate for the

noise level of HVAC systems in Project B589. In this Calculator, users are required to input many

parameters, such as sound levels of air handlers and diffusers, and relevant room and duct

specifications. Normally, the sound level of air handlers and diffusers are provided by the

manufacturers in their catalogues. Users are also required to select path attenuation factors or elements

for different paths travelled by sound. Path attenuation factors are elements in a path that cause sound

attenuation. For example, in sound level of unit casing radiated source, there may be either

ceiling/space effect if sound travels from the air handler through a ceiling to the receiver or space

effect if there is no ceiling as a sound barrier. Other path attenuation factor that is available for selection

in the Calculator are:

a) Duct insertion loss

b) Duct breakout loss

c) Duct elbow loss

d) Duct tee loss

e) Branch power division loss

f) End reflection loss

g) Environmental adjustment factor

Therefore, users are able to choose the path attenuation factor that may be present in a path. Users are

also given the option to input custom attenuations for special cases, such as presence of a silencer or

damper in the ductwork. The calculated sound level at receiver location is then plotted on the NC and

RC curves to enable users to decide whether the noise level caused by the HVAC system is still

acceptable and within design standards. Certain special features in this Calculator, such as hiding

certain options when certain path attenuation factors were not selected, were programmed in VBA.

Figure 27 (A and B) below shows the user interface of a few spreadsheets in the Noise Calculator.

34

Figure 27 (A): User interface of Noise Calculator in Excel.

35

Figure 27 (B): User interface of Noise Calculator in Excel.

36

Chapter 4: Conclusion

Throughout the 10-weeks internship, I have grasped the basics of HVAC, including the psychrometrics

of HVAC, the air flow in an air-conditioned room, the various types of air handlers, typical operation

of an air-conditioning system and fundamentals of a clean room design. Moreover, I was exposed to

the various important aspects to check during site inspection for a project engineer. I was also given a

chance to help in the testing of FCUs in Project B11. In addition, I was given the chance to learn about

pressure loss calculation for a ducting system and analyse the feasibility of ductworks in Project B589.

I also learnt about analysis of sound and noise created by HVAC systems. Before the end of my

internship, I was given the task to program Calculators for pressure loss calculations and noise level

calculations using Excel and VBA.

In conclusion, this internship in T.T.E. Engineering (M) Sdn. Bhd. has been very beneficial to me in

various ways. Even though T.T.E. Engineering is a company that focuses mainly on mechanical and

electrical engineering works, I am able to relate many of the work here with what I have learnt in

chemical engineer. A few courses that I have taken in University of Malaya have aided greatly in my

internship – fluid mechanics, heat transfer and thermodynamics. Therefore, the most important lesson

I have learnt here is that engineers need to know more than their own field of expertise in order be

competent and able to have better cooperation with engineers of other fields in the industry.

Furthermore, I have learnt that safety is the topmost priority for anyone working at a site as stressed

by the company. Accidents can happen anytime and anywhere. Thus, everyone, from an unskilled

labourer to a project manager, must understand and obey the safety rules and laws that are set by the

company, contractor and Department of Occupational Safety and Health (DOSH).

Last but not least, it is imperative that engineers must always check and analyse any data given, in

order to detect any inconsistency or discrepancy, and to determine whether the data obtained is logical

and acceptable. This is because small mistakes such as unit conversion or wrongly typed datum may

lead to disastrous results, which may include loss of assets or lives. Therefore, it is the engineers’ duty

to ensure that their designs are feasible, practical and safe.

37

References

[1]: Cianfrani, C.A., & West, J.E. (2009). Cracking the Case of ISO 9001:2008 for Service: A Simple

Guide to Implementing Quality Management to Service Organizations (2nd ed.). Milwaukee:

American Society for Quality.

[2]: Westcott, R.T. (2003). Stepping Up To ISO 9004:2000: A Practical Guide For Creating A

World-class Organization. Chico: Paton Press.

[3]: Takasago Thermal Engineering. (1990). Takasago Handbook. Tokyo: Takasago Thermal

Engineering Overseas Business Division.

[4]: Whyte, W. (2010). Cleanroom Technology: Fundamentals of Design, Testing and Operation

(2nd ed.). New York: John Wiley & Sons.

[5]: Soled, J. (2012). Fasteners Handbooks... Charleston: Nabu Press.

[6]: ASHRAE. (2013). ASHRAE Handbook - Fundamentals. Atlanta: American Society of Heating,

Refrigerating and Air-Conditioning Engineers

[7]: SMACNA. (2006). HVAC Systems - Duct Design (4th ed.). Chantilly: Sheet Metal and Air

Conditioning Contractors' National Association

[8]: Clamond, D. (2008). Efficient resolution of the Colebrook equation. Industrial & Engineering

Chemistry Research, 48(7), 3665 - 3671.

[9]: Cervi, B. (2012). Basic acoustic terminology for building services. CIBSE Journal, 65 - 67.

[10]: AHRI. (2011). Procedure for Estimated Occupied Space Sound Levels in the Application of

Air Terminals and Air Outlets. AHRI Standard 885-2008 with Addendum 1.

[11]: A-weighting. (2014). Wikipedia. Retrieved from http://en.wikipedia.org/wiki/A-weighting

[12]: TA Inc. (2004). Noise Criteria (NC) vs. Room Criteria (RC). In Thorburn Associates: Acoustic

and Technology Consultants. http://www.ta-

inc.com/newshtml/Noise%20Criteria%20vs%20Room%20Criteria.html