Google Drive MEP(HVAC , Plumbing, Fire Fighting and Electrical) complete Design Data and Drawings
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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
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
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.
12)
Q-12-What
are the important things to be considered before selecting devices like AHUs
and Chillers:
Ans-For
AHU/FCU for chilled water system = CFM, Static pressure, Ton (capacity), Air
Temp, water flow (gpm).
For AHU/FCU
for direct system = CFM, Static Pressure, Ton, Sensible.
For Chiller:
Ton, outside air temp, GPM,
Note:
(Sensible/3.4
= heating capacity.)
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?
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).
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.’
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.
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?
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 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.
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, 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
