Air Compressors and Pumps Flashcards
Piece of machinery that draws in ambient air, pressurises this air, and delivers in to a holding tank (receiver) or to its end user
Air compressor
7 basic components of an air compressor system
Lubricating system Driving connections Cooling system Compressor element Driving power Control components Air receiver
Three types of driving power
Electrical motors
Internal combustion engine
Reduction gear
Three types of drive connections
Close-coupled
V-belts and pulleys
Reduction gears
When the compressor and the driving unit are mounted on the same shaft, they are ___
Close-coupled
Close-coupling is usually restricted to ___
Small capacity compressors that are driven by electric motors
Sometimes used to join the driving unit to the compressor when the speed of the compressor and the speed of the driving unit are the same
Flexible couplings
Drive connection commonly used with small, low pressure, and some medium-pressure motor driven compressors
V-belts and pulleys
Three types of compressing elements
Centrifugal
Rotary compressors/blowers
Reciprocating
Continuous flow compressor in which the rotating bladed wheels impart a high velocity to the air; the velocity energy developed raises the static pressure of the air without use of valves as it is passed through a diffuser
Centrifugal
Positive displacement compressor in which the displacing and compressing elements are interacting lobes, screws, or eccentrically oriented vanes rotating within housings fitted with suction and discharge ports
Rotary compressors/blowers
Positive displacement compressor in which the displacing and compressing elements are pistons moving back and forth in a cylinder fitted with suction and discharge valves
Reciprocating
Most widely used compressors
Reciprocating compressors
Low operating pressure
150 psi or less
Medium operating pressure
151 to 1000 psi
High operating pressure
Above 1000 psi
Ship’s Service Air
150 psi or less
Start Air, or Diesel Start Air
151 to 1000 psi
SSA
Ship’s Service Air
SA
Start Air
DSA
Diesel Start Air
Total compression form atmospheric pressure to the final discharge pressure, is accomplished in one stroke of the piston
Single-stage compressor
In a two-stage compressor, in ___ of the crankshaft, a compression cycle is completed
One revolution
Cylinder designs very widely depending upon ___
The number of stages of compression required
Two types of pistons
Trunk pistons
Differential pistons
Modified trunk pistons having two or more diametres
Differential pistons
Arranged so that more than one stage of compression is achieved by one piston
Differential pistons
With a differential piston, compression for one stage takes place over the ___, compression for the other stage takes place in the ___
Piston crown
Annular space
The opening and closing of the valves is caused by the difference between ___
The pressure of the air in the cylinder
The pressure of the external air on the intake valve or the pressure of the discharge air on the discharge valve
Valves are either ___
Strip (feather) or disk type
Used for suction and discharge valves of higher pressure stages. These valves are spring-loaded
Disk-type valve
Commonly referred to as a flask or tank
Air receiver
Acts as a storage tank during intervals when the demand for air exceeds the capacity of the compressor
Air receiver
Enables the compressor to shut down during periods of light load
Air receiver
The volume of existing air receivers for low-pressure and high-pressure compressors may be as low as ___ the combined free air capacity per minute of the compressors located in the respective compartment
1/5
Helps to eliminate pulsations in the discharge line of the compressors, and provide a stable pressure sensing station for compressor control
Air receiver
Two types of cooling devices
Intercoolers
Aftercoolers
Devices that remove the heat of compression from the air or gas between consecutive stages of multistage compressor
Intercoolers
Why have a cooling device?
Increase the efficiency of compressing the air, and removing the heat caused by compression
Devices that remove the heat of compression from the air after the last stage of compression prior to its arrival at the air receiver
Aftercoolers
Two types of lubrication systems
Pressurised
Splash
An oil pump is connected to the compressor crankshaft supplying lubrication to the moving parts within the crankcase
Pressurised system
Lubrication system usually found on small, low pressure air compressors
Splash system
Used to provide control of the automatic operation of the air compressor, removal of the compression load, modes of compressor control, and protection capabilities
Components
Designed to remove all but the friction loads on the compressors
Unloading system
Automatically removes the compression load from the compressor while the unit is starting and automatically applies the load again after the unit is up to operating speed
Unloading system
Used on some oil-pressurized compressors in the event of a potentially damaging oil pressure drop
Hydraulic unloaders
Allows the compressor to start in the unloaded state, meaning that the compressor starts, but does not begin to create compressed air until oil pressure is established
Hydraulic unloader
Used in conjunction with unloader towers when the compressor is to be run continuously and an operating pressure range is to be maintained
Pilot valve
Whenever there is a demand for air, the ___ closes, allowing the unloader in the unloader tower to actuate
Pilot valve
As soon as the demand for compressed air is met, the pilot valve ___, allowing air pressure to deactuate in the unloader. The compressor continues to run but does not compress air
Opens
Used to control the method of operation
Manual/Off/Auto switch
Designed to change air pressure without changing air compressors
Pressure-reducing stations
All-in-one unit lubricates the air system, reduces the moisture vapour concentration, and prevents water formation in compressed air lines which, if allowed to accumulate, causes rust in the lines as well as system components
Lubricator/Regulator/Filter
A valve connected to accumulators, separators, filters, receivers, air flasks or other components to remove water, oil and sediment from the component
Blowdown
Usually a small ball valve or petcock which may be attached to a hose and which will vent the sediment away from the operator
Blowdown
Safety precautions for compressors are described in ___
NSTM, Chapter 551
Do not install a ___ between the compressor and receiver unless the compressor is fitted with a relief valve
Stop or check valve
Moisture occurs naturally in air lines as a result of ___
Compression
Recommended companion to filters, aftercoolers, and automatic drains for improving the productivity of compressed air systems
Separators
The area at the compressor intake is constantly under a ___ while the compressor is in operation
Vacuum
Performed on all accumulators, separators, filters, receivers, and air flasks to remove deposits of water, oil, and sediment
Blowdowns
(Blowdown) If double valved, start with ___
Both the upstream and downstream valve closed
(Blowdown) If double valved, open the ___ valve first
Downstream
(Blowdown) Open the upstream valve to the bleed position for ___
10 - 20 seconds
Moisture separators downstream of the compressor shall be blown down ___
Once per hour
Manually drained compressor separators shall be drained ___
Once per watch, or every four hours, whichever comes first
Air filters will be checked ___
Weekly or per PMS schedule
Improper pulley/sheave alignment and belt tension are causes for ___
Motor overloading
Excessive vibration
Premature belt and/or bearing failure
Clean air cleaning element by ___
Blowing LP air from the inside to the outside of the element
Where should you not clean the air cleaning element?
Lazarette
Check belt for:
Cracks
Wear
Alignment
Proper tension
Belt tension shall be ___ drop from middle
7/16”
Test compressor relief valve by ___
Lifting valve by hand and release
Most commonly found displacement type of pumps in the CG
Centrifugal pump
Pump large volumes of flow at low pressure
Centrifugal pump
A centrifugal pump is of what type
Nonpositive displacement type pump which delivers a variable flow rate depending upon system lineup
The discharge flow rate from a nonpositive displacement pump is inversely proportional to ___
The discharge pressure it faces
As discharge pressure rises, flow rate from the pump ___
Drops
The maximum pressure that a pump can produce
Shutoff head
The fluid being pumped also acts as a ___ for the pump internals
Cooling medium
If the discharge pressure of a nonpositive displacement pump approaches shutoff head, the flow approaches ___ and the pump ___
0
Overheats
The force that tends to throw an object outward from a center of rotation
Centrifugal force
The impeller creates a ___ at its center, and is discharged to ___
The center
Outer rim
The liquid can be slowed down by being led through a ___
Volute or a series of diffusing passages
As the velocity of the liquid decreases, the pressure ___
Increases
The pump casing is sometimes referred to as the ___
Housing
The part of the pump that, by design, directs the flow of liquid
Pump casing
Two basic designs of pump casing
Volute
Diffuser
This type of casing uses a gradually widening spiral channel which changes velocity into pressure
Volute
This type of casing serves the same purpose as the volute, but is more efficient. It directs more fluid to the outlet by the use of stationary vanes
Diffuser
Two classifications of centrifugal pumps
Single-stage
Multi-stage
Transfers the motion from the prime mover to the impeller
Shaft
Protects the shaft from excessive wear and corrosion from the seal or packing
Shaft sleeve
The sleeve is often made of ___ and is ___
Softer metal
Inexpensive to replace
Using a sleeve avoids ___
Shaft replacement and is cost effective
Most important part of the pump
Impeller
Transmits centrifugal force to the fluid by spinning at a high number of RPMs
Impeller
An impeller must be ___ to avoid vibrations and wear
Balanced
Impellers can be classified as ___
Closed
Open
Semi-closed
Collar-type rings that protect the impeller and housing from wear
Wearing rings
When the maximum allowable clearance has been exceeded, wearing rings must be ___
Replaced
Prevent stiffing box water from entering the bearing housing
Water flinger rings
Fitting pumps with ___ eliminates excessive stuffing box leakage
Mechanical seals
Prevent air or fluid from entering or exiting the pump housing, and they are installed on the shaft behind the impeller
Mechanical seals
Mechanical seal consists of two parts
Stationary seal
Rotary seal
Composed of a ceramic face held in the pump housing by a rubber cup or seal seat
Stationary seal
Composed of a carbon face, a rubber grommet or o-ring, a tension spring, and a driving band
Rotary seal
Rides on the shaft sleeve and rotates with the shaft and impeller
Rotary seal
The ___ is held against the stationary ceramic seal by the force applied by the tension spring
Carbon face
The rotary seal head is sealed to the pump shaft or shaft sleeve by the ___
Rubber grommet
The carbon face and the ceramic seal are ___
Lap-mated
When replacing the mechanical seal, you must ___
Replace the whole seal
Care must be taken not to touch the mated faces with your hands, because ___
The acid in the body oils of the fingers will break down the carbon face
Mechanical seals should be ___ whenever the seal is removed for any reason, or if the leakage exceeds ____ for new seals, or ___ for used seals
Replaced
5 drops per minute
60 drops per minute
All stuffing boxes are designed to leak for ___
Shaft cooling
Cylindrical space in the pump casing surrounding the shaft
Stuffing box
___ are placed in the stuffing box to form a seal, controlling the rate of leakage along the shaft
Rings of packing material
The packing rings are held in place by ___
Studs with adjusting nuts
The ___ causes the packing to expand radially
Axial compression
Component used in large stuffing box applications which is a hollow perforated ring located near the center of the packing
Lantern ring
Usually supplied with liquid piped from the discharge side of pump to help lubricate, cool, and/or seal the joint between the shaft and packing to prevent the leakage of air into the pump
Lantern ring
Used to keep the shaft or rotor in correct alignment with the stationary parts under the action of the radial and transverse loads
Bearings
Known a line, radial, or shaft bearings
Bearings that give radial positioning to the rotor
Bearings that locate the rotor axially are called __
Thrust bearings
Maintain position of the rotor and can be of the angled roller or pivoted segmented type
Thrust bearings
Provides rotation to the impeller, it is either an electric motor, diesel engine, or gas engine
Prime mover/driver
Four common types of couplings
Jaw
Flex
Grid
Gear
This coupling requires no lubrication and provides highly reliable service for light, medium, and heavy duty power transmission applications
Jaw coupling
This coupling is usually used with an elastomer or “spider” which decreases hard starts and provides additional flexibility within the coupling
Jaw coupling
This coupling is designed to be simple, reliable, and easy to assemble. Most will tolerate some amount of parallel and angular misalignment. Require no lubrication, and help dampen vibration and control shock
Flex coupling
This coupling reduces vibration and cushions shock loads to safeguard driving and driven equipment. Usually used in high-speed applications.
Grid coupling
This couplings are typically used in heavy duty applications where is is desirable to align shafts as accurately as possible. These couplings are designed to absorb angular, parallel, and axial misalignment without damage to the driver or driven machinery. Internally lubricated
Gear coupling
Gear couplings have large sizing up to ___
44 inches
Gear couplings have a capacity of ___
7,600 inch-lbs to 50,000,000 inch-lbs
Do not use what on an elastomer seal
Petroleum jelly
Tetrafluorethylene (TFE)
Silicon grease
Ethylene-propylene rubber (EPR) must not be libricated with any ___
Petroleum-based substance
When handling a mechanical seal, make sure you wear ___
Latex gloves
Ensure the ___ is facing out when you install it, or you will destroy the mechanical seal
Raised ring
Inspect the following items when inspecting a shaft bearings
- Freedom of rotation
- Excessive heating of the bearings
- Excessive bearing noise
- Loose or broken bolts or parts
- Distorted bearing supports, cracked or bent bearing caps, and loose balance rings
- Loose or inaccurate coupling alignment
- Coast-down time
Short coast down times indicate ___
High torque
Methods for removing a bearing are outlined in ___
NSTM, Chapter 244
Two most frequently used methods to remove a bearing
Arbor press
Bearing puller
The wear ring should be concentric to within ___
.002 inches
The process of adjusting two or more machines coupled together so their shaft centerlines form one continuous straight line
Alignment
The goal is to align shaft centerlines, not ___
Couplings
The process of measuring offset and angularity of one shaft centerline in relation to the other shaft centerline
Alignment check
Describes the maximum shaft alignment tolerances
NSTM, Chapter 503
The misalignment of suction and discharge piping connections can cause ___
Pump and driver misalignment
Piping flanges must be aligned so that no __ is required to attach flanges
External force
___ shall not be used to position piping
Chain falls
Pry bars
Jacks
Wedges
Headless, cylindrical pin that is sunk into corresponding holes in adjoining parts to locate pars relative to each other or to join them together
Dowel pin
Approved material of dowel pins
304 stainless steel
The machine chosen to be shimmed in relation to the other
Machine to be shimmed
Machine that is not moved during the alignment process
Stationary machine
Process of adjusting a piece of machinery so the centerline of its shaft is accurately positioned
Alignment
When the MTBS must be shimmed to adjust machinery position in a vertical plane
Vertical misalignment
When the MTBS must be moved to adjust machinery position in a horizontal plane
Horizontal misalignment
Angle formed between the MTBS shaft centerline and the SM shaft centerline
Angularity
Slope on angle in thousandths of an inch per inch
Angle
Distance between two shafts when measured at the centerline of the coupling
Offset
Offset is expressed in ___
Thousandths of an inch
Feet closest to coupling of the MTBS
Inboard feet
Feet farthest from coupling of the MTBS
Back/Outboard feed
Process of setting dial indicator to 0
Zero
Bending of dial-indicator mounting hardware
Indicator sag
Bending is referred to as ___
Sag
Condition caused when bottom of all four feet of the MTBS are not sitting square on machine base
Soft foot
MTBS
Machine to be Shimmed
SM
Stationary Machine
Bolts and nuts used to secure each foot of movable machine-to-machine base
Hold-down bolts and nuts
Horizontally positioned bolts on machine base which are located at each foot of machine. These bolts are used to adjust the horizontal position of machine
Jacking bolts
Amount of change in relative shaft position that occurs when horizontally mounted machinery changes frim room temperature to operating temperatures
Thermal growth
Alignment of a unit at operating temperature
Hot alignment
Hot alignment readings must be taken within ___ of shutting down machinery
30 minutes
Motor-driven units must run a minimum of __ to achieve operating temperature (Shaft alignment)
Four hours
Alignment condition at room temperature
Cold alignment
Preferred method of pump shaft alignment
Indicator reverse method
Radial dial indicator readings are taken on both driver and driven shafts for the purpose of calculating relative position of shafts
Indicator reverse method
Must have final shaft alignment checks accomplished with the unit at normal operating temperatures to compensate for thermal growth
Horizontally mounted, flexibly coupled, pumps
Do not require a final hot alignment check
Vertically mounted, flexibly coupled pumps
How long should you operate a shaft driven by steam turbine drives before checking hot alignment?
2 hours
What kind of shims for alignment should not be used
Laminated or brass
The P6 is primarily designed for __
Dewatering
The P6 is a ___
Centrifugal pump driven by a Honda GX series gasoline engine
CG owned equipment that is operated by civilians in distress
P6
CG Rescue and Survival Systems Manual
COMDTINST M10470.10 (series)
P6 is capable of delivering ___
Over 250 gpm at a 12-foot suction lift
The complete dewatering kit with fuel weighs ___
Less than 120 lbs
The P6 by itself with gas weighs ___
55 lbs
The P6 is run by a ___
6 1/2 HP, 4-cycle Honda engine, fueled by 86 octane unleaded fuel
Dewatering pump kit includes what 8 items
P6 pump 2.5 gallon fuel tank 15-ft, 3-in suction hose 20-ft, 3-in discharge hose Spare pull rope Flashlight Laminated instruction card in four languages Operation and maintenance manual
How long will the P6 operate on one tank of gas?
4 - 6 hours
The P6 can is made of ___
Aluminium
The P6 takes how much oil?
.63 quarts
Fill P6 gas can to ___
Two inches below the top
Attach the flashlight to the laminated instruction card with ___
A two foot length of cord
Tie what knot in the bitter end of the spare starter rope?
A figure eight
Secure the spare starter rope to ___
The lifting frame of the pump
What is stenciled on the lid of the P6 can?
NO SMOKING. GAS IN CAN
Open the throttle on the P6 how far when starting?
About 1/3 open
Do not operate a P6 for more than __ without water
2 minutes
How long do you have to switch fuel tanks on the P6?
About 30 seconds
After operating the P6, flush with fresh water for how long?
About five minutes
How long for the pump to run out of fuel after disconnected?
30 to 90 seconds
When stowing the P6, fold the discharge hose into a tight, flat coil approximately ____ long, the coupling should hang off the end approximately ___
10 inches
8 inches
Coil the suction hose ___
Clockwise
Use what wire to secure the P6 can lid
.020 diametre copper breakaway wire
The starter rope should exit the P6 recoil shroud at approximately the ___ position
9 o’clock
The P6 should be tuned to start in a maximum of ___ pulls
6
During monthly maintenance, run the pump for how long?
15 minutes
Do not run the P6 dry for more than ___
2 minutes
P6 idle speed should be ___
1400 rpm
P6 full throttle speed should be ___
3900 rpm
After how many hours of operation of the P6 is it required that maintenance be performed?
20
What is the torque value on the P6 oil drain plug?
There is none, do not overtighten
How much oil does the P6 take?
.63 quarts
How many screws hold the P6 recoil starter?
3
Wind the starter rope around the P6 starter reel in the direction of the ___. Leave approximately ___ of the starter rope outside of the starter reel
Arrow
30 cm
Torque P6 recoil starter assembly cap screws to ___
Between 25.3 to 32.5 ft/lbs
After the P6 20 hour maintenance, run the engine for how long?
Less than 1 minute
Use ___ to clean the P6 air filter
LP air (less than 30 psi)
P6 spark plug gap
30 thousandths
The P100 is ___
A Yanmar diesel engine-driven portable pump unit designed for firefighting and limited dewatering
The Yanmar engine is ___
An air-cooled, single cylinder, 4-cycle diesel engine rated at 10 HP
P100 ignition is achieved by ___
Direct injection of fuel
P100 initial compression is initially aided by __
Compression release lever to help overcome its high compression ratio
The P100 is started by ___
Recoil type starter
The P100 fuel injection pump is ___
Bosch type timed at 13 +/- 1 degree TDC
The P100 uses __ lubrication via ___ and ___ lubrication for the valve rocker arm chamber
Forced
Trochoid pump
Splash
The P100 L/O filter is a ___ type
60 mesh
P100 oil capacity
1.65 litres (.44 gallons)
(P100) Recommended oil for Navy/CG use is ___, equivalent to ___
MIL-L-2104
SAE 15W40
P100 air cleaner element is a ___ type
Dry paper element
The P100 is cooled by ___
Forced air generated by a flywheel fan
P100 speed control is accomplished by __
An all speed type mechanical governor
P100 fuel tank is what size?
1.45 gallon
The P100 tank assembly consists of ___
Tank Fuel filter Isolation valve Injection valve Level sight tube Fuel tank cap
The P100 pump assembly is __
Single-suction, single-stage, centrifugal pump
The P100 impeller is __ design
Closed
The P100 has a ___ for the suction
3 inch male threaded connection
The P100 has a ___ for the discharge
2 1/2 inch male threaded connection
The P100 measures ___
21 x 23.5 x 24.38
The P100 weighs ___
164 lbs
The P100 is designed to provide ___
100 gpm at 83 psi while lifting 20 ft
In high lift operations, the P100 will provide ___
68 gpm at 45 psi while lifting 39 ft
Blocks exhaust port forcing exhaust flow through the eductor priming jet creating a vacuum in the pump housing to overcome suction lift to aid initial pump suction
Exhaust primer valve
Connects exhaust primer jet to the suction side of the pump
Primer hose assembly
2 1/2 inch National Hose connection; diametre discharge hose connection with cutout valve
Discharge valve and head assembly
Located on the pump side of the primer hose assembly. Used to isolate the primer suction from the exhaust
Primer (power) shutoff valve and suction connection
Located at the bottom of pump housing to drain water after use
Pump drain valve (petcock)
Adjusts the packing gland for pump impeller shaft cooling
Packing adjustment plunger
P100 packing drip rate should be ___
Between 5 and 60 drops per minute
Used to check oil level in the sump
Oil dipstick
Adjusts engine speed which increases pump pressure and output
Throttle
Recoil spring pull start
Starter assembly
Used to release compression during initial start-up and make it easier to start
Compression release lever/decompression lever
The P100 block heater is ___
A 200 watt, 120 VAC heater that is mounted between the frame and the engine
- 1 1/2 inches or 2 1/2 inches in diametre
- Connects two male couplings
- Used for jumper line assemblies
- Connects a male coupling to a fireplug
- Has identical ends with swivels and gaskets
Double female coupling
- 1 1/2 inches or 2 1/2 inches in diametre
- Connects two female couplings
- Makes nozzle connections on female outlets
Double male coupling
- Reduces a 2 1/2 inch fireplug or hose to a 1 1/2 inch size
- Has 2 1/2 inch female threads and 1 1/2 inch male threads
Straight reducer coupling
- Increases a 1 1/2 inch fireplug or hose line to a 2 1/2 inch size
- Has 1 1/2 inch female threads and 2 1/2 inch male threads
Straight increaser coupling
- Reduces a 2 1/2 inch line to two 1 1/2 inch lines
- Equipped with two stop valves
- Lines can be controlled independently of the other
Wye-gate
Same as wye-gate, except it is equipped with three stop valves, and an additional 2 1/2 inch outlet with valve in the center
Tri-gate
Facilitates the disconnection of hoses and fittings
Spanner wrench
How many spanner wrenches are provided at each fire station?
2
Standard firehose is coloured ___
Orange
Standard firehose has a maximum operating pressure of ___
250 psi
Standard firehose comes in lengths of ___
50’
Adjustable spray-pattern nozzle
Vari-nozzle
Two styles of vari-nozzles used in the CG
Elkhart
Akron
The 1 1/2 inch vari nozzles come in ___
95 gpm and 125 gpm
Vari-nozzle spray patterns
Straight stream
Narrow angle (30 degrees)
Wide/fog angle (90 degrees)
Wide fog can range from ___
90 to 110 degrees
Used to clear debris from the vari-nozzle tip
Flush setting
The vari-nozzle can produce an acceptable fog pattern down to ___ psi
60
The __ nozzle has a spring-loaded thumb latch that holds the selected water flow pattern shroud in place
Elkhart
Jet-type pumps that contain no moving parts
Eductors
Contains jets, through which water flows under pressure. The velocity of the water increases while flowing through the nozzle and creates a vacuum in the suction area
Eductor
Used to pump liquids that cannot be pumped by other portable pumps (such as heavy oils and flammable liquids)
Eductor
About ___ of the water being discharged from the eductor is the water being removed from the compartment
50%
Two types of eductors
Navy S type
Peri-jet
A maximum suction lift of __ is recommended for best performance of the P100
10 ft
When checking the oil level of the P100 the dipstick should ___
Not be screwed in
Open the P100 pump discharge valve until __ is attained while fireplug is open
83 psi
When stopping the P100 allow it to idle for __
2 minutes
Simplifies the process of flushing the P100
Darley’s flushing adapter
P100 must be flushed for how long?
10 minutes
A hose faked on a fire station should be at least ___ above the deck
6 inches
To make the P100 packing adjustment, raise the discharge pressure to ___
50 psi
Tighten the packing screw using a ___
6 inch long, 9/16” end wrench
Torque of P100 packing screw
24 in/lbs
When adjusting the P100 packing, operate the pump at ___ for ___
50 psi
5 minutes
After having made the packing adjustment on the P100, operate the pump for ___ at ___
10 minutes
83 psi
The P100 uses ___ for fuel
F-76 or JP-5
