Plumbing School Year 3 Module 8

Measured at sea level, air pressure expressed in psig is

0

It takes 7 cubic feet of air to make 1 cubic foot of compressed air at

100 psig

The barometric pressure at standard conditions is

29.92 inches of mercury

In a typical building system, the operating pressure of an air compressor is generally no more than

500 psig

________________________________ is a measure of the air volume at the air-compressor inlet under actual temperature and pressure conditions.

Actual cubic feet per minute

All air receivers and relief valves are required by code to meet the safety standards set by the

American Society of Mechanical Engineers

When air expands, what does it absorb from its surroundings?

Heat

Centrifugal air compressors are also available, but these are large systems used in highly specialized applications.

Plumbers are less likely to encounter these on the job than rotary and reciprocating types.

__________________________ is the set of physical laws governing the motion of air and other gases.

Pneumatics

If the design of a compressed-air system requires supply pipe with a diameter of 2.5 inches or greater, use

Schedule 40 black-iron pipe

_________________________ is the measure of the air volume at the air-compressor inlet under standard conditions.

Standard cubic feet per minute

Use caution during installation of piping form compressed-air systems. Wear appropriate personal protective equipment (gloves) when installing threaded pipe.

The chips made from threading pipe are sharp and could cut you.

Wear proper hearing protection.

The very high pitch of some air-operated tools could cause hearing damage or loss.

True/False: Air dryers are installed to remove all moisture. Refrigeration air dryers and desiccant air dryers are the most common types.

True

True/False: Compressed-air pressure is measured in pounds per square inch gauge (psig). Psig uses local air pressure as the zero point, At sea level, 0 psig is 14.7 pounds per square inch absolute (psia).

True

True/False: When air is compressed, its temperature increases, and it gives off heat. Consequently, compressed-air systems are designed to protect operators against temperature extremes. Compressors have insulation to prevent operators from touching a hot surface. Pneumatic tools are designed to protect operators from the cold.

True

When is it safe to place a compressed-air source in or near your nose, mouth eyes, or skin?

Under no circumstances

To remove excess oil from pipe, always use

a rag

A device that cools air by passing it through a heat exchanger, causing moisture to condense out of the air is called an _______________.

aftercooler

A device that removes all moisture from compressed air is called an

air dryer

If all moisture must be removed from compressed air, it is passed through an

air dryer

A chamber at the end of the rotary screws in a rotary compressor where air is compressed is called an

air end

In a reciprocating compressor,

air is compressed by a piston. The compression stroke pumps the air into the supply line. Reciprocating compressors are most widely used in residential applications and to power smaller tools such as nail guns.

A valve taht keeps air pressure within the control range is called an

air pressure regulator

An _____________________________ is a storage tank for compressed air.

air receiver

An ___________________________ is a spring-loaded valve used to control or shut off airflow in a compressed-air system.

air throttle valve

In addition to removing moisture from compressed air, refrigeration air dryers are

also effective at removing compressor lubrication oil

Before replacing bits or starting any servicing tasks on any pneumatic tools,

always discharge the pressure

Before operating tools that use compressed air,

always refer to the manufacturer's manual

rotary compressors

are widely used in commercial and industrial applications.

When threading or handling pipe, you should always wear gloves

as protection against sharp metal chips

Scfm is the volume of air measured

at standard conditions.

When installing a compressed-air system, locate the takeoffs for branch and feeder lines

at the top of the main line

Always discharge the air pressure for any tool

before you replace parts such as bits, blades, or discs

A type of compressor that plumbers are not likely to encounter on the job is the

centrifugal compressor

To be able to be reduced in volume is to be

compressible

Insulation is used on compressors because

compressors get very hot

As compressed air passes through an after cooler's heat exchanger, the moisture in the air

condenses

A control that vents excess air pressure from ain air compressor is called a

constant speed control

The ____________________________ is the range between the highest-and lowest-allowable air pressures in a compressed-air system.

control range

A _________________________ is a snap-fit plug connecting a tool or machine to a compressed-air system.

coupling

A ______________________ is a type of air dryer in which chemical pellets absorb moisture from compressed air.

dessicant air dryer

The chemical pellets used to remove moisture from compressed air are called

dessicants

To eliminate the transmission of vibrations from the compressor to the rest of the system, install

flexible metal hoses

Plumbers use portable air compressors

for pressure tests on water supply systems.

In an after cooler, air is cooled by passing it through a

heat-exchanger

The set of physical laws governing the motion of water and other liquids is called

hydraulics

An _________________________ is a heat exchanger that removes heat from air as it moves through a multistage air-compressor system.

intercooler

Multistage compressors are usually equipped with an

intercooler

The unit scfm

is a measure of air volume under conditions that are standard

One of the most common problems in compressed-air systems is

low pressure

A device that injects a fine oil mist into the air supply line, lubricating tools and machines, is called a _________________________.

lubricator

Aftercoolers must use pipe

made from materials that will not corrode

When using any air-operated tool or machine,

make sure that all hoses and couplings are secured. Otherwise, the pressure may be too low for the tool or machine to operate properly.

A device that controls multiple compressors by linking them together into a single network controlled by a computer is called a

network control

A ________________________________ is a device that allows an air compressor to operate at a given percentage of its normal output.

part-load control

Water cooling systems requires the use of

pipe materials that will not corrode when exposed to water.

Systems that involve the use of compressed air are governed by principles of

pneumatics

The pressures of compressed air are measured in

pounds per square inch guage

When air is compressed,

pressure increases

Plumbers use portable air compressors to

pressure-test water supply lines

Water vapor is removed from compressed air

prevent rusting of the system's components

Avoid pressure loss at connections between tools and the compressed-air source by using

properly sized couplings

At the end of the compressed air systems, main line and each branch line,

provide drainage by installing a water drip leg

A ___________________________ is a type of air compressor in which air is compressed by a piston.

reciprocating compressor

The type of compressor most commonly used to power small pneumatic tools such as nail guns is the

reciprocating compressor

An air dryer in which air is cooled as it passes through a heat exchanger cooled by a liquid refrigerant is called a

refrigerant air dryer

The two common types of air dryers are

refrigeration and dessicant

Refrigeration air dryers are also effective at

removing compressor lubrication oil from the air.

Marking 1 cubic foot of compressed air

requires 7 cubic feet of air at 100 psi

The most widely used type of compressors on commercial applications is the

rotary compressor

A helical device in a rotary compressor that compress air by passing it down a screw-shaped path is called a

rotary screw

Flexible hoses used to connect compressed-air sources to tools are reinforced to prevent them from

rupturing

A commonly used desiccant material in desiccant air dryers is

silica

An air pressure of 14.7 psi, temperature of 68 degrees F, and barometric pressure of 29.92 inches of mercury are considered

standard conditions

A device that turns an air compressor off when the control range is exceeded is called a

stop/start control

Compressed air is dangerous because of its high air pressure and its high

temperature

From the compressor,

the air flows into an air receiver, which acts as a storage tank and also smoothes out the airflow from a reciprocating compressor.

After being compressed,

the air is stored in an air receiver

If a compressed air tool functions poorly because of low air pressure,

the cause is most likely an improperly secured hose or coupling

Water vapor in the air can cause rust inside

the compressed-air system and inside the machines that use the air.

Hearing protection should be worn when working with many types of compressed tools because

the very high-pitched sound can cause hearing damage

A ___________________ is a device that controls airflow into an air compressor by adjusting the compressor's intake valve.

throttle

The process of relieving excess air pressure from an air compressor is called

unloading

The process of removing excess air pressure from a compressor when the control range is exceeded is called

unloading

The _____________________, expressed as a percentage of an average hour of use, is the amount of time that a tool or machine will be operated.

use factor

A vertical pipe on an air supply line that acts as a drain for condensed water in the line is called a

water drip leg

Wear appropriate personal protective equipment

when using any air-powered tool

A __________________________ is a cable attached to the ends of an air supply hose and a tool, or to the ends of two hoses tat are connected to each other, to prevent the hose from whipping uncontrollably when charged with compressed air.

whip check

To prevent injury from loose air hoses, OSHA requires hoses to be secured by cables called

whip checks

Before operating a compressed air tool for the first time,

you should refer to the manufacturer's manual