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Testing and Balancing > Test Balance Midterm > Flashcards

Test Balance Midterm Flashcards

1
Q

What information is on a motor nameplate?

A

Max I Load, E, Phase, rpm, service factor

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2
Q

What is a General Information Report and what is on it?

A

Describes the type of systems with key information. Lists job location, type of systems, manufacturer, instruments of measure used, building and system completion check

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3
Q

What heating or cooling condition should most systems be put in before balancing?

A

Max flow through cooling coil by setting t-stat to 55 degrees.

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4
Q

What is the range for a High Pressure system?

A

2000 fpm and up, 6 in. WC and up

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5
Q

What does a pitot tube and manometer measure?

A

Total pressure and Static pressure in ducts and plenums. Inner tube senses total pressure, outer tube senses static. Velocity Pressure achieved by reading TP and SP at once

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6
Q

What is the CFM formula?

A

CFM = Duct Size / 144 x fpm

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7
Q

What is a Velometer and what does it measure?

A

Instantaneous direct reading for velocity in fpm and pressures in in. WC. Great for SA at ceiling diffusers. Also reads exhaust velocities at grilles, hoods and duct openings, currents in open spaces, etc.

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8
Q

What is important about thermal overloads in motor starters?

A

Check that they are installed, 3 phase requires 3 by OSHA standards, check for correct size to motor,

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9
Q

What is a Rotating Vane Anemometer and what does it measure?

A

Reads velocities in fpm at grilles, louvers, exhaust hood openings, duct openings, etc. Operates as a windmill with timed counts

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10
Q

What does an Oriface Plate do?

A

Creates a temporary pressure drop across the plate in in. WC and correlated against flow in gpm. Placed straight length of pipe and read with a Dial Type differential pressure gauge.

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11
Q

How does a Photo Tachometer work and what does it measure?

A

Light beam directed a shaft or pulley and reads 120-19,999 rpm. The rotating item must be marked for it to count

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12
Q

What is Standard Air?

A

air at 70 degrees F and 50% RH at 14.7 psi atmosheric pressure

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13
Q

What is on an Outlet Balance Report?

A

Info from blueprints, shop drawings, schematics and grille schedule from manufacturer. Gives models, size, AK, velocity, cfm, and final measurements

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14
Q

What is important about Instrument Calibration?

A

Should be checked regularly about once a year. It can be sent to a factory or checked against calibrated instrument

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15
Q

Which flow rate areas are balanced on a Chiller and for what systems?

A

Design water pressures, temps, and flows on the evaporator and condenser. Report also requires info on compressor, conditions of refrigerant and oil and control settings, motor, and starter

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16
Q

Describe the differential pressure gauge connections?

A

Two connections to dual inlets of gauge. Bourdon, bellows, or diaphram and measures in in. WC, ft. WC, or in. Hg.

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17
Q

How is energy affected by proportional balancing?

A

Most effective and efficient method for balancing, and requires the least amount of input resistance for balance.

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18
Q

How many characteristics are required to measure anything on a psychrometric chart?

A

2

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19
Q

Where do you reread CFM after balancing a low pressure system?

A

Reread total CFM, amps, and static pressure from the fan and compare with the outlet CFM

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20
Q

What is the best way to measure air flow through a grille?

A

Take equally timed and spaced readings at the center of the spaces of the grille

21
Q

What is the operating pressure of a low pressure system?

A

0-2000 fpm, 0-2 in. WC

22
Q

On what type of system is an Air System Recap Report used?

A

On all but the smallest projects. If there are several supply, return, and exhaust systems

23
Q

When balancing an Air Return System without a return fan, what position do you want the OA Dampers in?

A

Minimum position and recirculation damper to max

24
Q

What is meant by Traversing?

A

Taking several air velocity readings in a duct over a cross sectional area of air flow and averaged out

25
Q

What are the pressure ranges for a Medium Pressure System?

A

2000 fpm and up, 2-6 in. WC

26
Q

What type of system would use a Board with a Gang of Magnehelics for balancing?

A

Large system with many zones, can mount in series for simultaneous readings

27
Q

What is meant by Capture Velocity of an exhaust system?

A

Velocity required to pick up contaminants from their source area. It must overcome spillage, air, and heat currents, and contaminants’ weight and velocity

28
Q

What is the most accurate way of measuring a flow on a Hydronic system?

A

Reading the actual flow (oriface plate flow meter, venturi flow meter, pitot flow meter, etc.)

29
Q

What type of instrument is used with a manometer?

A

Pitot Tubes, straight metal tubes, and various static pressure sensors

30
Q

What do Flow Hoods measure?

A

A diffuser or grille and converts air flow directly to CFM

31
Q

Name all of the benefits of balancing.

A

Reduced energy, lower operating costs, safer systems, reduction or elimination of service callbacks, preventions of premature wear, healthier air, customer satisfaction, improved reputation, and profitability

32
Q

What component needs to be set before balancing a High Pressure system?

A

Automatic dampers to 100% OA and no RA

33
Q

Name all of the components of a Grille.

A

Vanes only with no control damper behind it

34
Q

How is a Rotating Anemometer positioned to measure a grille?

A

Swept in an S curve across the grille one or more times

35
Q

Where are zone t-stats set at when measuring a Low Pressure Reheat system?

A

Set on Max Cooling

36
Q

How do you determine CFM output on an Inductive Unit?

A

Take static pressure at nozzles in IDU with magnehelic and metal tube, which are correlated to manu CFM ratings for static pressures

37
Q

Which system is balanced first, Supply or Return?

A

Supply Air

38
Q

What is the rating between the Supply Fan and Return Fan?

A

Return fans usu. Designed to handle around 70-80% of supply air

39
Q

Which direction is a High Pressure Constant Volume system proportionally balanced in?

A

They are not proportionately balanced, but pressure control balanced. System is filled with air and pressurized. Volume of air then metered out at terminal boxes and pressure controlled with constant volume regulators and controllers, which are set.

40
Q

Where are OA Dampers set in a High Pressure System?

A

100% OA with no recirculation of return air

41
Q

Where are the t-stats set in a High Pressure System?

A

Max cooling, typically 55 degrees

42
Q

What should the discharge temp be in a High Pressure Constant Reheat system?

A

55 Degrees

43
Q

Where do you begin balancing in a High Pressure Constant Inductive system?

A

The induction unit nearest the fan. Measure the nozzles in the induction units with magnehelic gauge and metal tube.

44
Q

How much is Return Air versus OA in a High Pressure Constant Inductive System?

A

1/3 air is OA, 2/3 RA

45
Q

How do you connect a pitot tube to a manometer for Static Pressure?

A

From the right side of the manometer to the outer tube connection that is parallel to the end with the holes

46
Q

How do you connect a pitot tube to a manometer for Total Pressure?

A

From the left side of the manometer to the inner tube at the bottom of the pitot tube

47
Q

How do you connect a pitot tube to a manometer for Positive Pressure?

A

Connect to the left hand side of the gauge for above atmospheric static pressure readings

48
Q

How do you connect a pitot tube to a manometer for Negative Pressure?

A

Connect to the right hand side of the gauge for below atmospheric static pressure readings

Testing and Balancing (3 decks)

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