REVIEW

Measuring tools are much needed in Refrigeration and Airconditioning. Can you use some of the measuring tool in welding?

Numbers are part of mensuration it is also important not just to use the different measuring tool but also to know about the system of measurement and how to convert them,which are part in doing Refrigeration and Airconditioning jobs .

Measuring Instruments

Steel ruler- A tool used to rule straight lines and measure legth, width and height. The ruler is marked in cm (centimeters) or mm (millimeters) along the top and inches along the bottom.

Comparison of English and Metric Measurement

Vernier Caliper -

a measuring instrument consisting of an L-shaped frame with a linear scale along its longer arm and an L-shaped sliding attachment with a vernier, used to read directly the dimension of an object represented by the separation between the inner or outer edges of the two shorter arms.It measures the inside, outside diameter of an object and the depth

Micrometer Caliper

an instrument used to check sizes and make accurate measurements to a few thousandths of an inch or hundredths of a millime

THERMOMETER

a device used for measuring temperature . Temperature measures the heat intensity or heat level of a substance. Temperature alone does not give the amount of heat in a substance. It indicates the degree of warmth, or how hot or cold the substance or body is.It can be a regular thermometer with a reading in degrees celcius or degrees farenheit or in degrees kelvin or in degrees Rankine . The thermometer in a regular one is filled with alcohol or mercury inside. Thea digital thermometer such as a pyrometer or a lazer thermometer has a reading in degrees celcius or degrees farenheit with a reading from 0 degrees up to as high as 600 degrees fahrenhiet.

Temperature Conversion

It is often necessary to convert a temperafure from one scale to another. Formulas have been developed for this purpose. li is not necessary to memo ze these formulas,only to refer to them when needed.

ᴼC means temperature in degrees Ceisius

ᴼF means temperature in degrees Fahrenheit

ᴼK means temperature in degrees Kelvin

ᴼR means temperatue in degrees Rankin

To convert from one of these scales to another, follow the procedures outlined in the following

Meter scale is used to identify the amount of voltage current and resistance of the circuit

being measured.

Test Prod Panel is the case of the Positive and Negative Test Prod.

Resistance block is the block that used when measuring the resistance, continuity of an

object.

Direct Current mille Ampere Block – is the block used to measure the small voltage of

direct Current.

Zero Ohms Ω Adjuster Knob – is the control to set into zero position the needle pointer

before and after using multi-tester to attain the correctness of value.

Name Plate- is the location of the brand of the multi tester.

Positive Test Prod- is the color red terminal of the prod

Needle Corrector- is design for calibrating the needle of the test if it is not located in the

infinity sign and not ranging the zero value.

Negative Test Prod- is the color black terminal of the test prod.

Range Selector- is the selector or indicator of the function of multi tester.

Alternating Current Voltage Block- is the block used when measuring the power, voltage

of an object

Direct Current Voltage Block- is the block where used if there is polarity will be check and

commonly used in the battery.

Needle Pointer is a movable part of the multi-tester which reflects or indicates the reading.

Testing the Voltage AC

1. Move the range selector to the proper AC votage range. It must be higher than the voltage value of the voltage to be tested.

SAFETY:If you do not know the value of the tested component set the range to the highest value.

2. Conect the

test prode parallel with the circu

t to be measured

Read the deflection of the pointer or where the value in which the pointer stop

Testing the Voltage DC

1.

Move the range selector to the proper DC votage range. It must be higher than the voltage value of the voltage to be tested.

SAFETY: If you do not know the value of the tested component set the range to the highest value.

2. Connect the test prode red test prode to the positive terminal and the black test prode to the negative terminal.

3. Read the deflection of the pointer or where the value in which the pointer stop.

Amper measurements using Clamp meter

1. Select the highest value of amperage on the selector if you do not know the amperage you are measuring.

2. Clamp the jaw of the clamp meter on one of the wires. Do not clamp more than a single wire or it will cancel out the measurement or get a zero reading.

3. View the reading, being sure to note the unit of measurement.

Voltage measurements using Clamp meter

1.Select Volts AC or Volts DC , as desired.

2.Plug the black test probe into the COM input jack. Plug the red test probe into the V input jack.

3.Touch the probe tips to the circuit across a load or power source (in parallel to the circuit).

4.View the reading, being sure to note the unit of measurement.

By taking a voltage measurement at the circuit breaker and then at the input of the load on that breaker, you can determine the voltage drop that occurs across the wires connecting them. A significant drop in voltage at the load might affect how well the load functions.

Resistance Measurements using Clamp meter

1.Turn off power to the circuit.

2.Select resistance (Ω).

3.Plug the black test probe into the COM input jack. Plug the red test probe into the VΩ input jack.

4.Connect the probe tips across the component or portion of the circuit for which you want to determine resistance.

5.View the reading in the meter’s LCD display.

Cauge Manifolds

A gauge maniJold includes both a high-side gauge and a low-side (vacuum) gauge. It allows the senice technician to check operating pressures, add or recover refrigerant, add oil, and perfom other necessary operations.

SYSTEM OF MEASUREMENTS ENGLISH AND METRIC

The Metric System is known as the most common measurement system used in most

places of the world. There are common prefixes used to represent as multipliers. For example, in

a distance of 2,000 meters can also be expressed as 2 Kilometers.

The English System on the other hand is also known as the British (US) System likewise

commonly used anywhere in the world. This system uses the Inch, Foot and Pound as the basic

units of measurement. Decimal inch based on tenths and hundredths to simplify measurements.

It is commonly used by Engineers, Architects, Surveyors, Draftsmen etc. For better

understanding of the systems one must be familiar with the conversion of the English units of

measurement to the metric system and vice versa by applying the appropriate conversion factors

and procedures.

Measurement Systems

The basic measurement in the English system is the Yard divided into Feet and Inches

abbreviated as follows: Yard – Yd. , Feet – Ft. , and Inches as In. The Metric System or the

Systems International (SI) use Meter as the basic unit of measure divided into Decimeters,

Centimeters, and Millimeters with the following abbreviations when used.

Meter - m Centimeter - cm

Decimeter - dm Millimeter –mm

Measuring accurately is skill that should be developed. Inaccurate measurements would mean waste of time, effort, materials and the quality of the finish product. The skill in measuring starts with the ability to read and interpret the systems of measurement.

The measuring tool available in the workshop contains English System in one side and Metric System on the other. In the English System, the inch is divided into 16 graduations. The first graduation reads 1/16, the second 2/16 or 1/8, the third as 3/16 and so on.

Square measure – a unit used to measure area

Volume Measurement

ALTERNATIVE MEASURING TOOLS

1. Ruler for pull-push rule

2. Vernier for a Micro meter

3. Protractor for compass

4. Pull-push rule for tape measure

5. Digital Weighing Scale for arm balance

6. Clamp Ammeter for multi-tester

Check Point:

Direction: Choose the letter of the correct answer.

1. It is an electrical instrument used to measure the flow of current

A.voltmeter C. ammeter

B. ohmmeter D. wattmeter

2. It is an electrical instrument used to measure electrical resistance

A. voltmeter C. ammeter

B. ohmmeter D. wattmeter

3. It is an instrument used to measure fractions of units.

A. voltmeter C. caliper

B. try square D. ohmmeter

4. It is an electrical instrument used to measure potential difference

A. voltmeter C.ammeter

B. wattmeter D. micrometer

5. It is an device to measure temperature.

A. Anemometer C. manometer

B. Thermometer D. mega-ohmmeter

6. It refers to the part of multi-tester appears the exact amount of voltage and resistance of an object.

A. Meter Scale. C. Zero Ohm Corrector

B. Test Prod D. Resistance Block

7. It refers to the block of the multi-tester when measuring the resistance and

continuity of an object.

A. Direct Current Voltage Block C. Direct Current mille Ampere Block

B. Resistance Block D. Alternating Current Voltage Block

8. It is one of the part of multi-tester and clamp meter that need to adjust when

setting the needle pointer

A. Zero Corrector C. Zero Ohm Adjuster

B. Test Prod D. Ohms Block

9. A part of a multi tester and clamp meter need to select first to indicate what is range

wants to be measured.

A. Range Selector C Zero Ohm Adjuster

B. Zero Corrector D Needle Pointer

10. It is movable parts of the multi-tester and clamp meter which reflect or indicate

the reading of an object

A. Zero Ohm Adjuster C. Range Selector

B. Zero Corrector D. Needle Pointer

Things to Do:

· Performance test -Carry out measurements using the different RAC measuring tools.

· One must understand the concepts, principles of mensurement and other math operations to be able to perform measurements and calculations in Refrigeration and Airconditioning.