UTILITIES | Mechanical Systems | 13 Questions (EASY)

MECHANICAL SYSTEMS

(13 Questions, Difficulty Level: EASY)

by Raison John J. Bassig

Q#1: The typical floor-to-floor height of the mall you designed measures 4.75m. Among the choices below, what is the smallest horizontal length of an escalator can you specify to conform with the National Building Code?

a. 27 feet
b. 15,833mm
c. 513.8"
d. 795cm

According to the 2004 Implementing Rules and Regulations (IRR) of the National Building Code of the Philippines (PD 1096) under Mechanical Regulation,

"The angle of inclination of an escalator shall NOT exceed 30° from the horizontal."
(Rule XIII, Sec. 1302.6.a of the 2004 IRR of PD 1096)

Now, let's first convert my above given choices (the horizontal length or "run") to similar units (in meters) for ease of comparison,

Choice a.) 27 feet * (1m / 3.28084 feet) = 8.2296m
Choice b.) 15,833mm * (1m / 1,000mm) = 15.833m
Choice c.) 513.8" * (0.0254m / 1") = 13.05052m
Choice d.) 795cm * (1m / 100cm) = 7.95m

Since the given Rise is [4.75m], we can determine the resultant slope and angle for each of the "Run" choices by simple trigonometric function. Recall that,

Tan(Angle) = Opposite (or Rise) / Adjacent (or Run)

So,

Choice a.) Angle = Arctan (4.75m / 8.2296m) = 29.99°
Choice b.) Angle = Arctan (4.75m / 15.833m) = 16.70°
Choice c.) Angle = Arctan (4.75m / 13.05052m) = 20.00°
Choice d.) Angle = Arctan (4.75m / 7.95m) = 30.86°

Among the choices given, choice a.) 29.99°, choice b.) 16.70°, and choice c.) 20.00° all CONFORMS with provisions of the Code; while choice d.) 30.86° does NOT as it exceeds the minimum prescribed by the Code at 30° maximum inclination.

But, based on the question, we are looking for the SMALLEST HORIZONTAL LENGTH (or shortest run) that will conform with the Code.  So, choice a.) 27 feet would be the smallest run/length that will achieve an angle of inclination conforming to the Code, at almost the 30° limit.

Therefore, the correct answer is a. 27 feet (or 8.2296m).

Q#2: The transfer of heat from the warmer to the cooler particles of a medium, occurring without perceptible displacement of the particles themselves.
a. Conduction
b. Transmission
c. Radiation
d. Convection

Convection:
"The transfer of heat by the circulatory motion of the heated parts of a liquid or gas owning to a variation in density and the action of gravity."

Radiation:
"The process in which energy in the form of waves or particles is emitted by one body, passed through an intervening medium or space, and absorbed by another body."

Conduction:
"The transfer of heat from the warmer to the cooler particles of a medium, occurring without perceptible displacement of the particles themselves."

(Page 118, A Visual Dictionary of Architecture by Francis D.K. Ching)

Therefore, the correct answer is a. Conduction.

Q#3: If an exhaust ducting of a window-type air-conditioning unit is to be located on the side of an arcade or sidewalk where people will pass-by, what would be the minimum clearance of such duct above the floor level?
a. 2.40m
b. 2.50m
c. 2.70m
d. 2.10m
e. 2.00m

According to the 2004 Implementing Rules and Regulations (IRR) of the National Building Code of the Philippines (PD 1096) under Mechanical Regulation,

"Window type air conditioners shall be provided with exhaust ducts if the exhaust is discharged into corridors / hallways / arcades / sidewalks, etc., and shall be installed at not less than 2.10 METERS above the floor level."
(Rule XIII, Sec. 1302.8.n of the 2004 IRR of PD 1096)

Therefore, the correct answer is d. 2.10m.

Q#4: A sprinkler system having sprinkler heads open at all times, through which water flow is controlled by a valve operated by a heat-, smoke-, or flame-sensing device.
a. Wet-pipe system
b. Deluge system
c. Preaction system
d. Dry-pipe system

Wet-pipe system:
"A sprinkler systems containing water at sufficient pressure to provide an immediate, continuous discharge through sprinkler heads that open automatically in the event of fire."

Dry-pipe system:
"A sprinkler system containing pressurized air that is released when a sprinkler head opens in the event of fire, allowing water to flow through the piping and out the opened nozzle. Dry-pipe systems are used where the piping is subject to freezing."

Preaction system:
"A dry-pipe sprinkler system through which water flow is controlled by a valve operated by fire-detection devices more sensitive than those in the sprinkler heads. Preaction systems are used when an accidental discharge would damage valuable materials."

Deluge system:
"A sprinkler system having sprinkler heads open at all times, through which water flow is controlled by a valve operated by a heat-, smoke-, or flame-sensing device."

(Page 90, A Visual Dictionary of Architecture by Francis D.K. Ching)

Therefore, the correct answer is b. Deluge system.

Q#5: The tendency of air or gas in a shaft or other vertical space to rise when heated, creating a draft that draws in cooler air or gas from below.
a. Venturi effect
b. Chimney effect
c. Cross-Ventilation effect
d. Greenhouse effect
e. Special effects

(Page 127, A Visual Dictionary of Architecture by Francis D.K. Ching)

Therefore, the correct answer is b. Chimney effect (or Stack effect).

Q#6: In a 2-storey restaurant provided with a dumbwaiter to serve the kitchen and serving area of both floors, what is the maximum capacity of the car/enclosure of such dumbwaiter that will conform with the National Building Code?
a. 250 kilograms
b. 215 kilograms
c. 277 kilograms
d. 278 kilograms
e. 225 kilograms

According to the 2004 Implementing Rules and Regulations (IRR) of the National Building Code of the Philippines (PD 1096) under Glossary,

"DUMBWAITER - A hoisting mechanism design to materials and other loads such as food, laundry, etc., equipped with a car, which moves in fixed guides and serves two or more fixed landings through a hoistway. This equipment shall be designed to carry small materials in a car, or partitioned or shelved enclosure measuring NO more than 0.86 sq. meters of net platform area; with a maximum height of 1.20 meters and a MAXIMUM RATED CAPACITY of 225 KILOGRAMS."
(Glossary of the 2004 IRR of PD 1096)

Therefore, the correct answer is e. 225 kilograms.

Q#7: A heating device consisting of a series or coil of pipes through which hot water or steam passes.
a. Radiator
b. Bleeder
c. Convector
d. Boiler
e. Bucket Trap

Bleeder:
"A valve for draining a pipe, radiator, or tank. Also called bleeder valve."

Convector:
"A heating unit in which air heated by contact with a radiator or fin tube circulates by convection."

Boiler:
"A closed vessel or arrangement of vessels and tubes in which water is heated or steam is generated to supply heat or power."

Bucket Trap:
"A valve for eliminating air and condensed moisture from a radiator without allowing steam to escape. Also called steam trap."

Radiator:
"A heating device consisting of a series or coil of pipes through which hot water or steam passes."

(Page 123, A Visual Dictionary of Architecture by Francis D.K. Ching)

Therefore, the correct answer is a. Radiator.

Q#8: Which among the following violates the provisions for Fuel, Gas, and Steam Piping provisions in the IRR of the National Building Code of the Philippines?

1. Galvanized piping shall not be used for steam.
2. Piping smaller than 100mm in diameter may be screwed.
3. Steam and hot water pipes may be embedded in concrete walls or floors as long as they are properly insulated.
4. Piping for propane, butane and other gas which are heavier than air, shall be provided with automatic shut-off devices.

According to the 2004 Implementing Rules and Regulations (IRR) of the National Building Code of the Philippines (PD 1096) under Mechanical Regulation,

1. "Piping shall, as much as possible, run parallel to building walls.
2. Grouped piping shall be supported on racks, on either horizontal or vertical planes.
3. Piping on racks shall have sufficient space for pipe or chain wrenches so that any single line can be altered/repaired/replaced without disturbing the rest.
4. Piping 100 millimeters in diameter and above shall be flanged. Smaller sized pipes may be screwed.
5. Piping subjected to varying temperatures shall be provided with expansion joints.
6. Galvanized piping shall not be used for steam.
7. Piping carrying steam, hot water or hot liquids shall NOT be embedded in concrete walls or floors and shall be properly insulated.
8. Piping carrying propane, butane and other gas which are heavier than air, shall be provided with automatic shut-off devices. The automatic shut-off device is most effective if provided to each burner before the flexible connection."

(Rule XIII, Sec. 1302.10 of the 2004 IRR of PD 1096)

Therefore, the correct answer is c. Steam and hot water pipes may be embedded in concrete walls or floors as long as they are properly insulated (VIOLATES the Code -- it should NOT be embedded in concrete walls or floors).

Q#9: These detectors do not detect fires producing heavy smoke such as alcohol and plastic fires, until they are about to enter active flaming stage. They are generally classified as early-warning devices.
a. Smoke detectors
b. Photoelectric detectors
c. Flame detectors
d. Ionization detectors

Smoke detectors = detect smoke
Photoelectric detectors = detect smoke/fire optically
Flame detectors = detect flame/fire

Therefore, the correct answer is d. Ionization detectors.

Q#10: The mechanical equipment that is installed on the top of the main doors of air-conditioned commercial, office or public buildings, used to retain cold air at interiors.
a. Air Diffuser
b. Dehumidifier
c. Condenser
d. Air Curtain

An air curtain is a fan-powered device that creates an invisible air barrier over the doorway to separate efficiently two different environments, without limiting the access of the people or vehicles. (https://www.airtecnics.com/technology/what-is-an-air-curtain)

(Image courtesy of airtecnics.com)

Therefore, the correct answer is d. Air Curtain (or Air Door)

Q#11: A row of elevators in a high-rise building, controlled by a common operating system and responding to a single call button.
a. Strip
b. Bank
c. Row
d. Battery

(Page 80, A Visual Dictionary of Architecture by Francis D.K. Ching)

Therefore, the correct answer is b. Bank.

Q#12: Hoistway pits shall be of such depth that when the car rests on the fully compressed buffers, a clearance of not less than ________ remains between the underside of the car and the bottom of the pit.
a. 30cm
b. 1000mm
c. 500mm
d. 600mm
e. 2.4m

According to the 2004 Implementing Rules and Regulations (IRR) of the National Building Code of the Philippines (PD 1096) under Mechanical Regulation,

(Rule XIII, Sec. 1302.5.c of the 2004 IRR of PD 1096)

Therefore, the correct answer is d. 600mm.

Q#13: Which among the following laws is also known as the Mechanical Engineering Act of 1998?
a. RA 9292
b. RA 8495
c. RA 7920
d. RA 8560
e. RA 8749

In my given choices,

Choice a.) RA 9292 ==> Electronics Engineering Law of 2004
Choice b.) RA 8495 ==> Mechanical Engineering Act of 1998
Choice c.) RA 7920 ==> New Electrical Engineering Law of 1995
Choice d.) RA 8560 ==> Geodetic Engineering Act of 1998
Choice e.) RA 8749 ==> Clean Air Act of 1999

Therefore, the correct answer is b. RA 8495 (Republic Act No. 8495).