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Sunday, 19 November 2017

HVAC Engineer interview 70 question & answers

(Mechanical engineer)

HVAC:-
1)What is the Unit of Heat?(1M)

Ans) Units: BTU (British Thermal

Units)1BTU: It is the amount of energy
required to raise 1 Degree Fahrenheit
temperature of 1 Pound of water(OR)It is
the amount of heat when added to 1 Pound
of water increases the temperature of water
to 1 Degree Fahrenheit1 Lb = 0.45 Kgs
(or) 1kg = 2.2 Lbs. Types of Heat:-Sensible
Heat: It can be sensed or measured by an
ordinary drybulb thermometer.Eg: Human
body temperature can be measured using
thermometerLatent Heat: It can’t be sensed
or measured by an ordinary dry bulb
thermometer. It is a hidden heat.
Latent heat is absorbed or released when
ever there is a change inphase.Eg: When
the water becomes vapor and vice versa

2)What is TON & 1 TON = ?(2M)

ANS) TON or Ton of refrigeration:

It is the amount of energy required
to Freeze 1 pound of water in 24 hours (or)It
is the amount of energy required to Melt 1
Ton of Ice in 24 Hours

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3)Volume Of Air is measured in?(2M)

ANS) Volume of air is measured in terms

of:CFM = Cubic Feet per MinuteCMH =
Cubic Meter per HourM3/Sec = Cubic Meter
per SecondL/Sec = Liters per secondCMH
= 1.7 x CFMCFM = 2118 x m3/secCFM =
2.119 x l/sec

4)What is ASHRAE?
Answer- ASHRAE: American Society of
Heating Refrigeration and Air-conditioning
Engineers

5)What is the Room Temperature that you

maintain in any room?(1M)

Answer- 24 Degree Celsius or 76 Degree

Fahrenheit Ad

6)CFM = Velocity(usually 1500) * Area in sqft

{(d/2)^2*3.1416/144}
7) 1 ton = 12000 BTU/hr = 3.516 KW.
8) Heat Transfer Coefficient (U):
1 (Btu/hr. sqft . *f) = 5.6782 (watt/m^2 . Calvin)
Thermal Conductivity (K):
1 (Btu/hr.ft.*f) = 1.73 (watt/m. calvin)
9) Q-9-What is CFM
Answer - Cubic feet minute, it is the unit of air
flow.
10) Q-10-What is Aspect Ratio?
Ans- it is the ratio between ht n length of the
duct generally we take 1:2 can vary with space
and size up till 1:4.
11) Q-11-What is Collar Length?
Ans-it is the strip left at the joining of duct and
machine. Informantion

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12) Q-12-What are the important things to be SYED MUHAMMAD AFREEN ALI

View my complete profile

considered before selecting devices like AHUs
and Chillers: Blog Archive

▼ 2017 (7)

Ans-For AHU/FCU for chilled water system = ▼ November (5)

HVAC Engineer interview 70 question &
CFM, Static pressure, Ton (capacity), Air Temp, answers (Mec...
What is the duties and Responsibilities of
water flow (gpm). Civil S...
Electrical Engineer job description in
For AHU/FCU for direct system = CFM, Static constructio...
What are the key responsibilities of hvac
Pressure, Ton, Sensible. site eng...
What are the key responsibilities of Fire
For Chiller: Ton, outside air temp, GPM, Fighting...

► October (1)
Note: ► January (1)

(Sensible/3.4 = heating capacity.) ► 2016 (13)

Static pressure to be considered to make fan

selection.
1GPM = 2.4 Ton (we need gpm in finding pipe
dia)
13) Q-13-What is Pumps supply fittings:
Ans- Thermometer, Shutoff valve, pressure
gauge, strainer, test point, drain cock, union
flexible connector, and Eccentric reducer.
14) Q-14-What is Pumps return fittings:
Ans-Eccentric reducer, flexible connector, union
test point, check valve, strainer, gate valve,
check valve, temp sensors,
15) Q-15-CFM distribution wrt the given floor
plan?
Ans-Use ductulator.
16) Q-16-Calculating loads wrt any plan by
using software.
Ans- Use Hap-4.32 or any to find the loads.
17) Q-17-Type of Dampers?
Ans-Fire dampers = Butterfly damper, Non
Return Damper, Motorized Damper, Fire
damper, Smoke damper, Gravity damper.
18) Q-18-Types of motorized damper?

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Ans- Motorized volume damper, Motorized fire

and smoke damper.
19) Q-19-Types of grills and diffusers?
Ans = 2-way, 3-way, 4-way, 1-way, jet diffusers
with fan.
20) Q-20-What is VFD?
Ans-Variable frequency drive-it is use to control
the speed of motor by controlling the frequency
applied to it. It is used with Chillers; AHU etc.
(use to control the RPM of pumps)
21) Q-21-How do you control or balance the
chilled water
Ans - Double regulating valve in main line return
(usually controlled from return using drv)
22) Q-22-How do you control the noise or
vibration in the duct
Ans- lining (nc-35) and Rainforcement.
23) Q-23-Temperature of water at outlet of
chiller and inlet of AHU ?
@ outlet of chiller - 6-7^c & @ inlet of AHU – 7
– 8^c
@ outlet of AHU – 10 - 11^c & @ inlet of Chiller
- 13-15^c.
24) Q-24-What are primary pumps and
secondary pumps
Ans - the pumps from chiller to building is
Primary and in building transfer is Secondary.
25) Q-25- AHU & FCU Valve connection
details ?
Ans- check my AHU installation details video .
26) Q-26- What is CFM value?
Ans-CFM = 0.417 L/s.
27) Q-27-What are the refrigerants used in
split unit?
Ans - R22, R12, R34 (Depends).

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28) Q-28-What are duct heaters and why do

we use them if we already have heating option
in AHU.?
- Just to provide heating in some specific
areas .
-
29) Q-29-What is VAV and its working?
= Ans- Pressure dependent & Pressure
independent:
- To control the flow of air and temp.
(variable air volume).
- Pressure dependent:- The volume of air
supplied by the terminal unit varies
depending upon the static pressure
(SP) in the primary air duct.
- Pressure independent terminal units:-
have flow-sensing devices that limit the
flow rate through the box. They can
control the maximum and minimum cfm
that can be supplied and are therefore
independent of the SP in the primary air
duct.
- Almost all HVAC systems installed or
retrofitted at present have pressure
independent VAV terminals. Pressure
independent systems can be balanced
and will allow the correct airflow from
each terminal.
-
30) Q-30-What is 3 way valve and 2 way
valve. Where we will use them and why?
Ans-2 way valve = it will regulate the flow as per
demand and it will be fitted in the return line.
3 way valve = if the AHU is closed and is
running on min load then it will by-pass
(Connected to BMS).
31) Q-31-What is duct guage normally we use
in buildings for cooling and for exhaust ducts?
Ans-For supply we use 22 guage and for
exhaust we use 18 guage.
32) Q-32-Types of Duct joints ?
Ans- Slip joint, flange joints etc.. see ‘internet.’
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33) Q-33-Standard books for HVAC?

Ans- we follow in duct designing are Ashrae
and Smacna, .
34) Q-34-What is smoke and light test?
Ans-Check ‘HVAC smoke test and light test in
internet’.
35) Q-35-What are the different method used
for duct sizing?
Ans-Equal Friction, Velocity,Static Regain.
36) -Q-36-How do you measure & control the
noise level in A/C system?
Ans-Noise level can be measured by dB
meter.It can be controlled by providing acoustic
to the unit panels, if the sound crosses the set
noise criteria we have to go for sound
attenuatos.
37) Q-37-What are the recommended
pressure drop in Chilled water pipes?
Ans- 210 PASCAL'S per meter (0.84 inches).
38) Q-38-Where do you use Fire
Damper,Spliter Damper & Non Return Damper?
Ans-Fire dampers (FD) are used to stop the fire
wherever duct passes thro fire wall.
Spliter dampers(SD) are used to split the main
duct for propotional air balancing
Non Return Dampers(NRD) are used to stop
the back flow of air in the duct. NRD's used in
exhaust and ventilation system only.
39) Q-39-What are the different types of
exhaust fans used to extract the air?
Ans-Axial type propeller fan, forward curved,
twin fan, direct driven centrifugal fan.
40) Q-40-What are different duct shapes
normally used?
Ans-Rectangular, Round, Spiral, Oval.

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41) Q-41-How do you control vibration of AHU

& Chillers?
Ans-Spring vibration isolators, Rubbers pads,
Kinetic Chain, flexible bellows.
42) Q-42-What is the difference between VAV
& CAV?
Ans-Variable Air Volume & Constant Air Volume.
43) Q-43-Mention typical valve arrangement
for chiller connection?
Ans Check internet for ‘HVAC’.
44) Q-44-What do you consider while making
plant room layout explain briefly?
Ans-Space, site orientation, plant room location,
A/C unit (ready made or tailor made).
45) Q-45-What are the different type of
Louvers used?
Fresh air louvers, sand trap louvers, door
louvers, acoustic louvers, supply air and return
air louvers.back draft louvers.
46) Q-46-Classify the different types of
chillers?
Ans-Air Cooled & Water Cooled. With
Compressors -
Reciprocating,screw,centrifugal & scroll
chillers.
47) Q-47-What are the standard test pressure
for chilled water piping for Industrial application?
Ans- Test pressure 1.5 times of working
pressure.
48) Q-48-What are the Securities checking in
chillers?
Ans-Flow switch, Chiller and Pump interlocking,
High Pressure cut-out, Oil Pressure switch,
High Suction superheat, Anti Freeze.
49) Q-49-What are the temperature & RH
required for human comfort?

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Ans- 22 ±2 degree celcius & 50%RH.

50) Q-50-At what temperature degree
Ferhenite & degree Celcius are same?
Ans- -40°C.
51) Q-51-Which gas is used to purge the
refrigerant line during the brazing?
Ans-Nitrogen gas.
52) 1 TR= 365 to 400 CFM, 3.516KW.
53) Q-53-How much design velocity required
in the main duct of an office building?
Ans-900-1100 FPM

54) How we install internal insulation in

Ducts?
And What is the insulation thickness of inside
and outside ducts?
Ans- 25mm inside and 50mm outside and
ducts passing thru unconditioned spaces.

55) Q-55-Difference between nominal

capacity and Actual capacity?
Ans-Ceckk on internet.

56) Q-56-Is this nominal capacity equal in

every country?
Ans- Yes.
57) Q-57-How to find Weight of Duct?
Wt in Kg = 8.0318 x Thickness x Perimeter
= ____Kg.
Where Perimeter of Duct = (W x D)²/1000

58) Q-58-What are the different materials used

for underground chilled water supply?
Ans-Pre-insulated Black steel pipe sch-40 with
rubber cladding.
59) Q-59-How to find velocity (FPM)?
Ans-We need to know GPM and Friction. Then
coincide them in a graph and you will get
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velocity. And for chilled water we need to know

no. of cycles per year (in
ksa=6months*30days*24hrs = 4320) search for
this value in the annexure of ashrae to find the
FPM. The fpm you get will be for the roof , to
get the fpm in risers take 20% of roof and to get
in runners take 20% of risers.
60) What Is The Fcu?
A Fan Coil Unit (FCU) is a simple device
consisting of a heating and/or cooling heat
exchanger or 'coil' and fan. It is part of an HVAC
system found in residential, commercial, and
industrial buildings
61) What Is The Function Of Ahu?
An Air Handling Unit (AHU) is used to re-
condition and circulate air as part of a heating,
ventilating and air- conditioning system. The
basic function of the AHU is take in outside air,
re-condition it and supply it as fresh air to a
building.
62) What Are The Types Of Air Conditioning
Systems?
Types of Air Conditioning Systems The choice
of which air conditioner system to use depends
upon a number of factors including how large
the area is to be cooled, the total heat
generated inside the enclosed area, etc. •
Window Air Conditioner. • Split Air Conditioner. •
Packaged Air Conditioner. • Central Air
Conditioning System.
63) What Does A Hvac Engineer Do?
An HVAC engineer's job duties can include the
design, installation, maintenance, and repair of
heating, ventilation, air conditioning, cooling,
and refrigeration systems.

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64) What Is The Hvac System?

While the Energy Center usually tries to avoid
the use of acronyms, HVAC is in common use in
the heating and cooling industry. It stands for
"heating, ventilation and air conditioning," three
functions often combined into one system in
today's modern homes and buildings
65) What Is The Meaning Of Btu In Air
Conditioners?
Btu – British Thermal Unit (Btu) is the
international measure of energy. A Btu is the
amount of heat needed to raise 1 (one) pound
of water by 1(one) degree Fahrenheit. In HVAC
industry, Btu's measure the quantity of heat a
conditioning unit can remove from a room per
hours. One BTU per hour is equal to 0293 watts
66) What Is Variable Air Volume System &
Dual Duct System?
Variable Air Volume (VAV) is a type of heating,
ventilating, and/or air- conditioning (HVAC)
system. Unlike constant air volume (CAV)
systems, which supply a constant airflow at a
variable temperature, VAV systems vary the
airflow at a constant temperature.
67) What Is Constant Volume System?
Constant Air Volume (CAV) is a type of heating,
ventilating, and air- conditioning (HVAC)
system. In a simple CAV system, the supply air
flow rate is constant, but the supply air
temperature is varied to meet the thermal loads
of a space. Most CAV systems are small, and
serve a single thermal zone.
68) What Is Centralised Air System?
The most common central cooling system is a
split system, which includes an outdoor cabinet
containing a condenser coil and compressor,
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and an indoor evaporator coil, usually installed

in conjunction with your furnace. or air handler .
The compressor pumps a chemical called
refrigerant through the system
69) What Is The Meaning Of Fahu?
FAHU is the abbreviation used for FRESH AIR
HANDLING UNIT. These are usually centralized
units employed to induce fresh air quantities to
the confines spaces. They come into picture
wherever there are limitations to fresh air intake
either directly or through AHUs.
70) What Is Cfm & Infiltration?
The infiltration rate is the volumetric flow rate of
outside air into a building, typically in cubic feet
per minute (CFM) or liters per second (LPS).
The air exchange rate, (I), is the number of
interior volume air changes that occur per hour,
and has units of 1/h. 4

Posted by SYED MUHAMMAD AFREEN ALI at 07:43 1 comment:

Saturday, 11 November 2017

What is the duties and Responsibilities of Civil Site

Engineer?

What is the duties and Responsibilities of Civil Site Engineer?

There are two types of site civil engineer ,

Work activities vary depending on the type of employers and
nature of the project but typically involve:
1. First job is a supervisory one if he works with the consultant,
2. In this case he needs to make sure that the document in hand is
the correct designed and issued for construction ,
3. Then he will supervise the construction contractor to make sure
that work is being carried out as designed and in accordance to
standards.

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4. The second type , is the execution part where he works with the
construction contractor,
5. In this case he has more responsibilities,
6. Where he has to adhere to the design document,
7. Quality of work, the schedule, safety of the people,
8. Costs and more over to satisfy the consultant at a personal
level
9. Work activities vary depending on the type of employers and
nature of the project but typically involve:
10. Acting as the main technical adviser on a construction site
for subcontractors, crafts people and operatives;
11. Setting out, leveling and surveying the site;
12. Checking plans, drawings and quantities for accuracy of
calculations;
13. Ensuring that all materials used and work performed are as
per specifications;
14. Overseeing the selection and requisition of materials and
plant;
15. Agreeing a price for materials, and making cost-effective
solutions and proposals for the intended project;
16. Managing, monitoring and interpreting the contract design
documents supplied by the client or architect;
17. Liaising with any consultants, subcontractors, supervisors,
planners, quantity surveyors and the general workforce
involved in the project;
18. Liaising with the local authority (where appropriate to the
project) to ensure compliance with local construction
regulations and by-laws;
19. Liaising with clients and their representatives (architects,
engineers and surveyors), including attending regular
meetings to keep them informed of progress;
20. Day-to-day management of the site, including supervising
and monitoring the site labour force and the work of any
subcontractors;
21. Planning the work and efficiently organizing the plant and
site facilities in order to meet agreed deadlines;
22. Overseeing quality control and health and safety matters on
site;
23. Preparing reports as required;
24. Resolving any unexpected technical difficulties and other
problems that may arise.

Posted by SYED MUHAMMAD AFREEN ALI at 23:11 No comments:

Monday, 6 November 2017

Electrical Engineer job description in construction DUTIES

AND RESPONSIBILITIES.
HI Viewers I am Afreen Ali .I bring this video for Electrical Engineer job description in
construction. Kindly Subscribe my channel. AfreenAli

Electrical Engineer job description in construction

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DUTIES AND RESPONSIBILITIES.

Generally responsible for implementations and monitoring of all
electrical related works at site.

1. Estimates, prepares and assigns the resources such as manpower,

materials, consumables, equipment, tools, etc., required for all
electrical and related works prior to execution.
2. Plans and analyses all possible construction methodologies and
recommends the best options to the Asst. Project Manager for approval
prior to execution at site.
3. Interprets construction drawings and studies the contract documents
and applicable standards or specifications prior to execution of any
jobs.

4. Manages directly and provide engineering and technical supports to

all the electrical work groups at site.

5. Plans the execution of all electrical related works and coordinates

the works to mechanical and civil groups.

6. Coordinates with Client / Consultant’s representatives for any site

instructions and inspection of works.

7. Assign targets for accomplishments and ensure targets are met on

daily basis for all electrical groups at site.

8. Submits site daily reports, inspection requests, estimates and all

applicable monitoring reports on regular basis or as required.
9. Supports the Asst. Project Manager in accomplishing all the goals
and targets for the electrical groups at site.
10. Ensures that all the works done are in accordance with the
approved construction drawings, contract documents, project
specifications, and all applicable standards whether local, national or
international standards.
11. Ensures that all site works are done according to all applicable
quality standards.

12. Directly responsible for the safety of all electrical groups’ personnel
of the project by ensuring that the project execution will be done
according to all applicable health, safety, sanitary and environmental
standards.

13. Evaluates electrical systems, products, components, and

applications by designing and conducting research programs; applying
knowledge of electricity and materials.

14. Confirms system's and components' capabilities by designing

testing methods; testing properties.

15. Develops electrical products by studying customer requirements;

researching and testing manufacturing and assembly methods and
materials.
16. Develops manufacturing processes by designing and modifying
equipment for building and assembling electrical components; soliciting
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observations from operators.

17. Assures product quality by designing electrical testing methods;
testing finished products and system capabilities.
18. Prepares product reports by collecting, analyzing, and
summarizing information and trends.
19. Provides engineering information by answering questions and
requests.
20. Maintains product and company reputation by complying with
federal and state regulations.
21. Keeps equipment operational by following manufacturer's
instructions and established procedures; requesting repair service.

22. Maintains product data base by writing computer programs;

entering data.

23. Completes projects by training and guiding technicians.

24. Maintains professional and technical knowledge by attending
educational workshops; reviewing professional publications;
establishing personal networks; participating in professional societies.
25. Contributes to team effort by accomplishing related results as
needed.
26. Performs other related duties as may be required by the Asst.
Project Manager.

Posted by SYED MUHAMMAD AFREEN ALI at 08:31 No comments:

Thursday, 2 November 2017

What are the key responsibilities of hvac site engineer?

HI Viewers I am Afreen Ali . I brought this video for basic

What are the key responsibilities of hvac site
engineer?
Kindly Subscribe my channel
AfreenAli

1. Get approved HVAC Shop Drawings, MEP- Coordination Drawings,

Work method statement and Project Specification from Project
Engineer.

2. Ensure the HVAC Ducts, Fittings, accessories and Child water pipes,
fittings, accessories are available and approved by Inspection
department prior to installation

3. Ensure sufficient hand tools, power tools, ladder and scaffolding are
available for installation

4. Coordinate with other discipline and ensure site clearance is

available to start the HVAC Activities

5. Arrange the sufficient manpower such as Supervisor, Foreman, Duct

fitter, pipe fitter, Assistant duct and pipe fitter etc.., and ensure all of
them attended safety orientation and having proper PPE’s prior start
installation activities at site

6. Provide approved HVAC Shop drawing, MEP Co-ordination Drawing

to site supervisor (or) Foreman and inform them to shift the required

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ducting and piping approved material from warehouse to site and
arrange required material to avoid progress delay.

7. Prior to start HVAC activities notify to QC Personal for surveillance to

ensure the quality work

8. To maintain safe all construction HVAC and Chilled water piping

activities are carried out in accordance with the Company’s safety
policies and procedures; ensure that appropriate safety and
protective equipment is used by Company & Contractor staff.

9. Closely monitor site activities to ensure quality of work is in

compliance with approved shop drawing and Specificationand get
daily progress report from site supervisor (or) foreman and update to
project Engineer (or) Manager

10. Preparing relevant documents to conduct inspection for completed

installation activities and raise RFI to QC-Inspector (To ensure that
any activity offered for inspection has an attachment of IFC drawing,
method statement (if required), Inspection & Test Plan (ITP) followed
by check list)

11. Carry out all planned site inspections as per the intervention points
marked in the relevant drawing and standard

12. Preparing the relevant documents to Conduct Testing inspection

such as Duct light testing for Ducts and Hydro test for Above ground
and Underground chilled water piping’s, systems.

13. Active involvement in weekly meetings with the Project management

& QC Supervisor and manager to resolve the site related issues.

14. Assist the Commissioning Team in Pre-commissioning &

Commissioning stages of all HVAC Equipment’s.

15. Assist the Commissioning Team on Testing, Adjusting & Balancing

(TAB) stages of the Air and Hydronic Piping’s.

16. Assist the Project Engineer during Preparation of final Test Reports,
as built drawings, Operation & Maintenance manual and handing
over the project to client

Posted by SYED MUHAMMAD AFREEN ALI at 10:17 No comments:

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