Shared Flashcard Set

Details

cem 472
mech facilites with fratella
135
Engineering
Undergraduate 3
03/17/2013

Additional Engineering Flashcards

 


 

Cards

Term
our teacher is a ________
Definition
larry
Term
What is the purpose of air handling equipment?
Definition
To deliver conditioned air to a space and return it to the heating/cooling equipment as efficiently as possible
Term
Forced Air distribution system (using a fan) include
Definition

* Ductwork (supply and return)

* Registers, diffusers, grills, dampers

* blower (fan)

Term
What are Ducts?
Definition
Hollow pipes that convey air in an HVAC system
Term
What are fittings?
Definition
Section of duct that change the direction or manner of flow (elbows, tees, couplings, etc.)
Term
What happens to pressure in ducts?
Definition
It drops
Term
Ductwork material is composed of ________
Definition
rigid steel or aluminum sheet metal, fiberglass/metal composite, plastic with metal wire coil ("flex" ducts)
Term
Flexible ducts are common for ____ aplications and for connections to _______. they have _____ pressure drop then rigid ducts; problems occur with ________ pressure.
Definition
Common for residential applications and for connections to supply registers (higher pressure drop than rigid ducts; also problems with negative pressure)
Term
circular ductwork is _____ out of all the ductwork.
Definition
most efficient (volume of air per material used)
Term
oval ductwork is efficient but ____ then circular ductwork.
Definition
efficient but shallower
Term
rectangular ductwork allows for ______ but has a _____ cross section.
Definition
allow for more head-room, shallower cross-section
Term
whats the purpose of  accoustical ductwork insulation?
Definition
reduce noise
Term
purpose of thermal ductwork insulation?
Definition
reduce heat transfer
Term
R-5 insulation is minimum for ________ and _______s ______ from exterior
Definition
minimum for unconditioned spaces and to seperate plenum space from exterior
Term
R-8 insulation is minimum for _________
Definition
minimum for exterior ductwork
Term
When is insulation not required?
Definition
when ductwork is in conditioned space, for exhaust ducts, for ducts with ΔTin-out<15°F, for ducts within equipment
Term
what is Duct mastic?
Definition
A thick adhesive that is applied wet to fill gaps, and dries to soft solid. It's a flexible sealant so it can move with the thermal expansion and mechanical vibration of the components
Term
duct tape for long term sealant on metal ducts?
Definition
not an acceptable long-term sealant for metal ducts
Term
ductwork dampers are ________. They are used in _______
Definition
A bladed device used in the ductwork to vary the volume of air through the outlet, inlet, or duct. Used in balancing a system to ensure the proper air flow to the right spaces. Manually adjusted dampers or automatic dampers
Term
how do Fire dampers work?
Definition

automatically close, triggered by a fusible link (similar to sprinkler systems)

*Installed in the plane of the fire wall.

Term

1. purpose of smoke dampers is _______

2. smoke dampers controlled by ________

 

Definition
  • can be part of an engineering smoke control system which uses walls and floors as barriers to create zones of pressure difference
  • controlled by a smoke or heat detector signal that is part of a fire alarm control system
  • so these need electrical sub coordination
Term
ductwork outlets are _____
Definition
An opening by which air is introduced into the space, selected to ensure both occupant comfort and adequate ventilation (diffusers and grilles)
Term

1. diffusers have ________

2.  what do fire rated diffusers do?

Definition
  • Have built-in louvers or defletors that throw and dispense air (supply air)
  • Fire-rated diffusers closes to isolate the space under fire conditions
Term

Grilles are ______

example of grill is ____

Definition
  • Sets of vertical and horizontal vanes that are typically fixed (return air, typically)
  • A register is a grill with a built-in damper (supply air)
Term
2 ways Return air travel ______
Definition
can be ducted to the air-handling unit or can travel through plenum space, commonly above drop-ceilings
Term
Axial Fans airflow is ________ to the axis of rotation of blades.  axial fans are often connected to _______ which avoids losses associated with a ____________.
Definition
  • Airflow is predominantly parallel to the axis of rotation of the blades
  • Often directly connected to their motors, which avoids losses associated with a drive belt
Term

1. Centrifugal Fan example?

2.  airflow is turned ______ to axis of rotation

3. mass of fan is ___ from the axle requires _________ but is generally _________.

Definition
  • AKA Squirrel cage fan
  • Airflow is turned parallel to the axis of rotation
  • Mass of the fan is farther from the axle requires more starting torque, but are generally quieter
Term
Air Handling Unit (AHU) typically consists of ______ (4 things)
Definition
Typically consists of a fan, fan drive, coil, and a filter contained with a cabinet
Term
Fan Filter Unit (FFU) combines _________ and ______ in an _________.
Definition
Combines the filter(s) and fan(s) in an air-handling unit
Term

Types of air in buildings

supply air supplies are to from ____ to ______

return air supplies air to- ____ to _________

recirculated air  supplies air to______ to ______ to ______

exhaust air supplies air from _____ to ________

make up air supplies replaces ________

ventilation air supplies air from ______ to ______

mixed air is ______

 

Definition
  • Supply air -- from AHU to a space
  • Return air -- from a space to AHU
  • Re-circulated air -- space to AHU to space
  • Exhaust air -- from a space to outdoors
  • Make-up air -- replaces exhaust air
  • Ventilation (outdoor, fresh) air -- from outdoors to a space
  • Mixed air -- combination of air types
  • Economizers/heat exchangers
Term

CAV stands for

flow is ______ from _______ to _______

many require _______ at terminal units containing ________

generally_____ energy eficient than VAV

Definition

Constant air volume

  • Flow (cfm) is constant from AHU to space
  • May required re-conditioning at terminal units containing reheat coils
  • Generally less energy eficient that VAV (b/c CAV's cool air then heat it later)
Term

VAV stands for ________

flow controlled by _____ at terminal units

reconditioning required?

generally _____ energy efficient than CAV

more/less common b/c of _________

Definition

variable air volume

  • Variable flow controlled by dampers at terminal units (VAV boxes)
  • No re-conditioning required (usually)
  • Generally more energy efficient than CAV
  • More common b/c of energy efficiency
Term
Zones are___________
Definition
A space controlled by a thermostat, and defined by a terminal unit which controls flow and heat transfer
Term
Single-zone vs. multi-zone buildings
Definition
Multi-zones use either separate equipment or multiple terminal units
Term

Positive pressure building zone = 

where does air from building go?

Definition

blow

  • Air from building exfiltrates to the outdoors
Term

Negative pressure building zone = 

where does air go?

Definition

suck

  • Air from outdoors infiltrates into the building
Term
Energy recovery ventilator (ERV) is the same as ________
Definition
AKA heat recovery ventilator (HRV)
Term

Heat Wheel is a type of ______

also known as _______ or ________

what does heat wheel do between exhaust air and makeup air?

fabric of wheel ________ between two air streams

do air streams mix?

Definition
  • A type of ERV
  • AKA rotary enthalpy
  • AKA heat recovery wheel
  • Transfers heat between exhaust air and make-up air
  • Fabric of wheel exchanges heat between the two air streams
  • Air streams do not mix!
Term
Typical wheel media materials?
Definition
consists of polymer, aluminum, and synthetic fiber
Term

Economizers are 

also known as _____ control airflow

Definition

Mechanical device adjusting the amount of outdoor air allowed into an HVAC system.

dampers control airflow

Term

Hydronic (water) systems

what is delivered to terminal units?

air passes over ____ at terminal units

 

Definition
  • conditioned water delivered to terminal units
  • air passes over conditioned water in coils at terminal units
Term
Air-water system example at school
Definition
Kearney 201 example: mixed air-water system and zoning
Term

Advantages of all-air systems

1.

2.

3.

Definition
  • mechanical equipment can be isolated
  • no drain pipes, electrical wiring, and filters at the conditioned space
  • seasonal changeover very simple and easy to automate
  • good flexibility because heating and cooling can occur in different zones simultaneously 
Term

Disadvantages of all-air systems

1

2

 

Definition
  • additional duct clearance required, which can reduce usable floor space and increase building height
  • air balancing is complicated and requires periodic care
Term
Advantages of all-water systems (4)
Definition
  • central air-handling units and ductwork are not required
  • unused zones can be shut down from central control
  • individual room control with little or no chance of cross-contamination of recirculated air from one space to another
  • easier to retrofit to existing buildings
Term

Disadvantages of all-water systems

(4)

Definition
  • more maintenance required. often the maintenance is done in occupied areas
  • units that have condensate and drip pans must be flushed and cleared
  • filters are small, low in efficiency, and require frequent replacement
  • ventilation is unsophisticated--usually accomplished by opening windows or by installing outside wall vents
Term

Advantages of air-water systems

(2)

Definition
  • rooms can be individually controlled at relatively low cost
  • size of the central air-handling unit can be reduced
Term

Disadvantages of air-water systems

(4)

Definition
  • controls tend to be complex
  • secondary air can cause induction coils to foul
  • filtering can be done at the terminal unit; however this requires frequent in-room maintenance
  • a low chilled-water temp is needed to accurately control humidity levels
Term

Chilled Beams

use _____ in pipes and _____ to distribute ____ from _____ to space

requires seperate_____ called passibe beams

major concern of chilled beams?

Definition
  • Emerging sustainable technology (in the US, already used more frequently in Europe and elsewhere)
  • Uses chilled water in pipes and natural convection (hot air rises, cool air sinks - induction) to distribute "coldness" from water to the space
  • requires separate ventilation system (passive beams), though "active beams" may combine ventilation and cooling in one unit
  • Must be at a temp to prevent condensation - moisture is a major concern!
Term

Floor space for M/E systems

typically range from ___ to ____ %

Definition
typically 5-10%
Term

Use of roof space for M/E equipment when designed for building

must be accounted for by a _____ engineer

Definition
must be accounted for by structural engineer
Term

Total pressure

always _____ in the direction of flow

total pressure = _____ + _______

Definition

always decreases in the direction of flow

 

Total Pressure = Static Pressure + Velocity Pressure

Term

Static pressure and Velocity pressure

are mutually convertible and __________ in direction of flow

Definition
Are mutually convertible and can either increase or decrease in the direction of flow
Term
noise an issue for air velocity at ______ fpm or greater
Definition
at 1250 ft/min (fpm) or greater
Term

What should the duct aspect ratio be? 

 

_____ : ________

Definition
2:1 or less
Term

round duct cost multiplier roughly

 

.34?

.22?

.66? 

.87?

Definition
.66
Term

square duct cost multiplier

 

ratio = 

 

1.0?

.87?

.48?

.67?

Definition

1.0

 

1:1 ratio

Term

rectangular duct cost multiplier 

1.0?

.84?

1.4?

1.1?

Definition

1.1

 

2:1 ratio

Term

higher aspect ratio cost multiplier

>___

Definition
>1.1
Term

What is a building code?

(2)

Definition
A set of rules and guidelines to ensure the safety of a building or component of a building; a code becomes a law when adopted by a particular jurisdiction
Term
2 different codes
Definition
  • 2010 Oregon Mechanical Specialty Code
  • 2009 International Mechanical Code (IMC)
Term

Purpose of mechanical drawings and specs

to _______ 

has 4 things

Definition

To convey design and layout info to a contractor

  • heating/cooling equipment (capacities, controls, layout, switches, design temps)
  • air flows and quantities (ventilation and exhaust air quantities, vent and fan locations, duct layout and sizing, duct material, diffuser and grill sizing)
  • water heating and piping - size and layout
  • construction details
Term

Labor costs for subcontractor

hourly wage = ______

employer tax - __________

fringe benefits - ________

insurance - ________

small tools ____________

total  60 $/hr

Definition
  • Hourly wage-----$23-25/hr
  • Employer tax, etc.------$4/hr (approx. 15-16%)
  • Fringe benefits------$20/hr (fixed amount)
  • Insurance-------$10/hr (approx. 22%)
  • Small tools-------$1/hr (approx. 4%)
  • Total = $60 / hr
Term

fees that are a % of the base hourly rate

(3)

Definition
fringe benefits (most of them), insurance premiums, small tools
Term

Employer taxes

are a percentage of _______

 

Definition
a % of the actual hourly rate (1.5x or 2x base rate if overtime is worked)
Term

Billing costs

hourly cost ______

overhead __ to ___ % roughly _____ $/hr

profit ___ to _____%  roughly _____ $/hr

total costs billed to general contractor - _____ $/hr

Definition
  • Hourly cost-----$60 / hr
  • Overhead----(10-12%)---$6.6 / hr
  • Profit (5-7% of hourly + OH)---$4 / hr
  • Total cost billed to GC = $70.6 / hr
Term

Leed project costs

are typically __ to ____ % of the total building cost depending on level of certification

Definition
typically add 5-50% to the total building cost, depending on the level of certification
Term

BIM

_____ onsite productivity

additional design/overhead ___ and ______

up to ____% reductions in cost and schedule have been reported

_____ typically takes the lead

Definition
  • Mechanical contractor typically takes the lead
  • Additional design/overhead time and costs 
  • Improved productivity on-site
  • Up to 25% reductions in cost and schedule have been reported
Term

Mechanical Estimating

part of ____

(4 steps)

Definition

part of the "Acquisition Process"

 

1st step: document review (bid form, alternates, assemblies, labor feedback

2nd step: Quantity Take-Off (QTO, quantity survey)

3rd step: Pricing: Labor rates, material, equipment costs

4th step: Compiling - adjustements - overhead and profit ("fee")

Term
MCAA Web-based Labor Estimating Manual is widely regarded as ________ database for mechanical construction
Definition
Widely-regarded as the most reliable labor units database for mechanical construction
Term
what does Building Envelope do?
Definition
Separates the controlled inside air from the uncontrolled outside air
Term
Worst interior conditions for condensation

(3)
Definition
High RH, cold surfaces, stagnent air flow
Term
Potable water is ______ for human drinkin, typically specified for _____
Definition
clean, suitable for human drinking; typically specified for mixing concrete
Term
Nonpotable water
Definition
OK for flushing toilets, irrigation, etc. but not for human consumption
Term
Blackwater
Definition
sewage; contains human waste from toilets
Term
Greywater
Definition
wastewater from domestic uses except toilets; may be recycled for irrigation
Term
Water supply systems (pressurized)
Definition
Brings clean water to a building and to individual fixtures
Term
Sanitary drainage system (drain, waste, vent (DWV))(gravity-fed)
Definition
Removes wastewater (WW) from individual fixtures out of the building to a treatment plant then to the environment
Term
Storm sewer system (gravity-fed)
Definition
Brings storm-water (SW) away from a developed area to a natural water source; defferent from wastewater system!
Term
Highest % of household per capita water use
Definition
water closet (toilets) followed by washing machines
Term
3 types of wastewater treatement
Definition
  • Water drained from buildings, treated, and released into the environment
  • Community sewage treatment - preliminary, primary, secondary, and tertiary (final) treatment
  • On-site sewage treatment - septic tanks, typically allowed only when building is +200 ft from sewer
Term
Storm-water treatment
Definition
Returning rainwater runoff to the environment; impervious cover; detention ponds
Term
Pipes
Definition
Used to transport water, wastewater, stormwater, etc
Term
Supply pipes
Definition
pressurized, smaller diameter
Term
Drain pipes
Definition
Gravity driven, larger diameter
Term
Pipe materials
Definition
  • Copper
  • Steel
  • Cast Iron
  • Thermoplastic
Term
Copper pipe
Definition
  • Common for supply pipes
  • Types K, L, M (K has the thickest walls)
  • Soldered fittings
  • Can be rigid (hard temper) or flexible (soft temper)
  • Can corrode with acidic fluids (pH < 6.8)
  • Good water flow (low friction)
  • Easier workability than steel
Term
Black steel pipe
Definition
Common in natural gas supply lines and fire sprinkler systems
Term
Galvanized steel pipe
Definition
Coated with zinc to reduce corrosion; not commonly used anymore b/c minerals in water react with zinc and cause scale build-up
Term
Cast iron pipe
Definition
Common for drainage systems; not suitable for pressurized pipes
Term
Thermoplastic pipe
Definition
  • Joined with cement-solvent welding, insert couplings, clamps
  • Can be cut with a saw
  • PVC can deteriorate under UV light
Term
HDPE (high density polythylene) pipe
Definition

thermoplastic pipe

  • various uses - natural gas supply, water supply, Tyvek "house wrap", waterproofing liners, etc
  • Increasingly popular material
Term

Fittings

elbows?

Tees:

couplings

adapters

Definition
  • Elbows: 45°, 90°, sanitary bend (gradual)
  • Tees: branch off a straight run of pipe; reducing T, sanitary T, sanitary Y
  • Couplingsa: join straight runs of pipe; union, reducer, increaser
  • Adapters: for supply pipes where threaded pipe connects to non-threaded pipe
Term
Valves
Definition
Gate, globe, angle, check, ball, metered, flow control, thermostatic, T/P (temperature-pressure relief), pressure-reducing, hose bibb, flushometer, sensor-operated
Term
Pressure drop in pipes
Definition
Pressure drop (head loss) increases across valves, fittings, bends in pipe, rough pipe surfaces due to increased friction
Term
Plumbing Fixtures
Definition
  • A device that uses supply water and discharges wastewater
  • Water closets (toilets), urinals, faucets, showers, dishwashers drinking fountains, hose taps, sinks, bathtubs, laundry washing machines, etc
  • Typically the only part of a plumbing system visible to building users
Term
Water closets (toilets)
Definition

Floor-set or wall-mounted

-- Need structural support ("carriers") in either case -- floor joists or wall studs

Term
Gravity fed toilet
Definition

(requires a tank) flushing mechanism

 

Standard WC uses 1.6 gals/flush (GPF)

 

High efficiency WC uses 1.1 gal/flush (GPF)

Term
Siphon-jet (toilets)
Definition
Uses supply water pressure to create siphon
Term
Blowout (toilets)
Definition
(3.5 gal/flush) - for large volumes of waste
Term
Urinals
Definition

Standard urinal uses 1.0 gal/flush

 

high efficiency = .125 gals/flush

Term
what is a Carriers?
Definition
Device to support wall hung fixture (i.e. water closet)
Term
Waterless urinals
Definition
  • Use a less-dense-than-water sealant to trap odors
  • No supply pipes required
  • Require regular replacement of cartridge
  • Popular for water conservation
  • Some problems reported...
Term
Lavatory
Definition

Standard uses 2.5 GPM

 

High efficiency uses down to 0.5 GPM

Term
Showers
Definition

Standard uses 2.5 GPM

 

High efficiency uses 1.8 GPM

Term
Americans with Disabilities Act (ADA) (1991)
Definition
Include requirements for entry route, clear spaces, door width, grab bars, fixture heights and clearances, etc
Term
6 components of water supply layout
Definition
  1. Building supply -- brings potable water from city to the building's meter via a service lateral (undergound pipe suppling building)
  2. Water meter -- measures consumption
  3. Building main -- (rigid pipe distribution) ; Large pipe that serves as the principle artery of the supply system ; Typically run in a basement, ceiling, crawlspace, or beneath the slab ; Carries water from the building supply to the furthest riser in the building
  4. Riser -- (rigid-pipe distribution) ; Vertical supply pipe that extends at least one floor ; Runs in the wall, or within a pipe chase, to supply water to the fixture branches
  5. Fixture branch -- (rigid pipe distribution) ; Runs from the riser to the fixture group, usually in the floor or wall ; Term used for anything other than a main or a riser
  6. Fixture connection -- Runs from the fixture branch to the connection at the fixture ; Typically involve shutoff valves
Term
Rigid-pipe distribution
Definition
  • Traditional system
  • Copper pipe (rigid), hot and cold pipe run parallel
  • Branches supply zones and groups of fixtures
  • Similar to dual-duct HVAC air distribution
Term
Homerun (manifold) distribution
Definition
  • Pipes run from manifold to each individual fixture
  • Plastic pipe (flexible), from 2 chambers in manifold
  • More pipe required, but less labor and less cost
  • Similar to electrical panel distribution
Term
Upfeed distribution
Definition

water pressure (30 to 80 psi) in supply main drives water through the system

Pumps required for buildings above 5 stories

Term
Downfeed distribution
Definition

water pumped to an elevated tank for storage then gravity-distribution

Approx. 10 stories per tank to control pressure

Term
Required min pressure for fixtures
Definition

5 to 15 psi

 

(30 psi for garden hoses)

Term

Water supply pressure

 

typpically supply water at ____ to ____ psi

 

max for plastic pipes = ____ psi

Definition

provided at 30 to 80 psi

 

max of approx 40 psi for plastic pipe

Term

Water velocity (water supply issue)

 

 code allowable ranges for plastic pipe? (fps) ___ to ______

up to ___ fps for equipment in mechanical rooms

Definition

allowable range set by code

  • Typically 5 to 10 fps (5 fps max. for plastic pipe)
  • Up to 15 fps for equipment feed in mechanical rooms
Term
Cavitation (water supply issues)
Definition

drastic drop in liquid pressure creating small vapor bubbles, which implode when pressure is restored

  • deteriorates pipes, valves, equipment; sounds like gravel in pipe
Term
Backflow (water supply issues)
Definition

a type of cross-connection, in which water flows in the opposite direction than intended; can contaminate potable water supply

  • Can be caused by back siphoning, esp. in irrigation systems
  • Prevented by air gaps or backflow prevention devices
Term
Water hammer (water supply issues)
Definition

caused by large pressure that develops when fluid in a pipe suddenly stops, like when an appliance shuts off water supply

  • Noisy; can damage pipes or burst fittings
  • Air chambers, which absorb the hydraulic shock, can become waterlogged or blocked
  • Water hammer arrestors are devices that absorb hydraulic shock
Term
Thermal expansion (water supply issues)
Definition

any pipe expands somewhat due to temp; more for plastic less for copper

  • Expansion bends and loops minimize damage due to thermal expansion
Term
Pipe insulation (water supply issues) what is it used for?
Definition
to prevent heat transfer from pipes (hot water pipes) and to prevent condensation (cold water pipes)
Term
Sanitary drainage systems
Definition
  • Drain, waste, vent (DWV) systems
  • Wastewater flows by gravity
  • Vents introduce air into the system to ensure proper water flow and to prevent suction which breaks trap seals
Term
Traps what is?
Definition
  • U-shaped bend in a pipe that forms a water seal, preventing sewer gas from entering a building ("P-traps" most common)
  • Useful for retrieving dropped items...
Term
Integral traps what is?
Definition
built into fixtures such as toilets
Term
Fixture branches what is?
Definition
horizontal drainage pipes from fixtures to stacks or building drains
Term
Stacks (drainage system component)
Definition
vertical drainage pipe joining branches to building drain; pipe chase -- open vertical space to accomodate stacks
Term
Building drain (drainage system components)
Definition
main horizontal drainage pipe
Term
Building sewer (drainage system components)
Definition
connects from building to city sewer (sanitary sewer main); called building connection or sanitary sewer lateral
Term
Cleanouts (drainage system components)
Definition
capped fittings allowing access to drainage pipes; required in certain locations of the drainage system
Term
Vents (drainage system components)
Definition

empty pipes allowing air at atmospheric pressure into a drainage system

  • purpose: to maintain water seals in traps, keeping sewer gas out of buildings
  • Stack vent - vertical vent pipe extended through roof as high as necessary
  • Individual (one vent per fixture); common, wet, and circuit (one vent for multiple fixtures) vents
  • All fixtures must have a trap, all traps must have a vent
Term
Air admittance valve (AAV) what is?
Definition
One-way valve admitting air into drainage system; same function as vent stack without roof penetration
Term
Supply pipes installation?
Definition
some flexibility in installation
Term
Drainage pipes characteristics?
Definition
  • Very little flexibility in installation
  • Need proper slope for drainage

 

Term
Underground inspection when?
Definition
when all pipes outside (or under) the building are complete and exposed (before backfill or concrete pour); verifies city connections, materials used, pipe depths
Term
Rough-in inspection when?
Definition
when all pipes in a building are complete and exposed; verifies materials, fitting connections, pressures
Term
Final inspection when?
Definition

when all fixtures have been installed; verifies settings, caulking, valves, etc.

AHJ (Authority Having Jurisdiction) must be satisfied

Term

what type of copper pipe has the thickest walls?

 

type l?

Type m?

Type k?

Definition
type k
Supporting users have an ad free experience!