Forney 550 User manual

ITEM# 550 & ITEM# 555
REV 08.11.2021
OWNER’S MANUAL
ENGLISH
AIR COMPRESSOR
4 GALLON • OIL-FREE • 120 PSI
ITEM# 550 ITEM# 555

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Forney Promise
We are committed to your success regardless of location, size or
needs. We understand it is your goal to get the job done right,
and we are ready to help you do just that.
President's Message
We market the highest quality tools, equipment and accessories
for the do-it-yourselfer and professional. Our passion and
dedication in bringing new products to the industrial and retail
market, combined with our personal service, is unmatched in our
industry. Our ability to listen to our customers’ needs enables us to
create solutions to their problems.
Our dedication to the highest quality customer service within our
corporate headquarters and the service provided in the field is
unequaled. We are committed to creating the best solutions to our
customer’s needs. Above all, our employees will provide the same
respect and caring attitude within the organization as they are
expected to share with every Forney customer. Our goal will be to
exceed our customers’ expectations through empowered people,
guided by shared values and commitments.
We work hard so our customers trust us because of our integrity,
teamwork and innovation in the welding & metalworking industry.
80 years of unmatched product quality and an unwavering
commitment to our customers.
When our customers succeed we succeed.
STEVEN G. ANDERSON, President & CEO
Copyright©2021 Forney Industries,
Inc. All rights reserved. Unauthorized
reproduction and/or distribution is
subject to US copyright laws.
U.S. Facilities:
- Fort Collins, CO
- Tipp City, OH
FIVE WAYS TO ORDER
Web: www.forneyind.com
Phone: [phone]
Fax: [phone]
Mail: Forney Industries
2057 Vermont Drive
Fort Collins, CO 80525
Email: [e-mail]
Steven G. Anderson

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TECHNICAL ISSUES?
FORNEY CAN HELP!
WE MAKE IT EASY!
Please contact Forney Industries Technical
Service at 800-521-6038 x2 or
customerserv[email protected] for inquires,
technical and general questions.
Thank you for choosing Forney! Please note: The store you
purchased this machine from DOES NOT handle product returns.
Forney Industries will repair or replace defective products at no
charge to you!
When you call Forney’s Technical Service department, you will speak
to a trained product and application expert. Forney’s primary goal
is to get your machine up and running in as little time as possible.
In fact, the majority of issues can be fixed over the phone! Please
be near your machine when you call, so the Forney technician can
guide you.
Speaking to a Forney Technician directly helps us gather better data,
and improve our products. It is our highest priority to ensure our
customers are cared for.

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WARRANTY..........................................................................................................................................................................3
TABLE OF CONTENTS............................................................................................................................................................4
SYMBOLS LEGEND................................................................................................................................................................5
SAFETY SUMMARY ...............................................................................................................................................................5
CALIFORNIA PROPOSITION 65 WARNING.....................................................................................................................5
FIRE PREVENTION..........................................................................................................................................................5
ELECTRIC SHOCK...........................................................................................................................................................6
NOISE...........................................................................................................................................................................6
RESPIRATORY.................................................................................................................................................................6
PRESSURE VESSELS ........................................................................................................................................................6
FLYING PARTICLES..........................................................................................................................................................7
COMPRESSOR TEMPERATURE.........................................................................................................................................7
ADDITIONAL SAFETY INFORMATION .............................................................................................................................7
BEFORE YOU BEGIN .............................................................................................................................................................8
AIR COMPRESSOR SPECIFICATIONS...............................................................................................................................8
AIR COMPRESSOR COMPONENTS...............................................................................................................................10
AIR COMPRESSOR COMPONENTS DETAILS......................................................................................................... 10 & 11
OPERATION........................................................................................................................................................................11
MOTOR OVERLOAD PROTECTION ...............................................................................................................................12
DISCONNECTING AIR HOSES......................................................................................................................................12
COMPRESSOR BREAK-IN PROCEDURE .........................................................................................................................12
MAINTENANCE & SERVICING .............................................................................................................................................13
GENERAL MAINTENANCE ...........................................................................................................................................13
ACCESSORIES .............................................................................................................................................................14
PARTS LIST & EXPLODED VIEW .....................................................................................................................................15
Table of Contents

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Fire Prevention
California Proposition 65 Warning
CAUTION!
BEFORE INSTALLING, OPERATING OR CARRYING OUT MAINTENANCE ON THE MACHINE, READ THE CONTENTS
OF THIS MANUAL CAREFULLY, PAYING PARTICULAR ATTENTION TO THE SAFETY RULES AND HAZARDS.
If these instructions are not clear, please contact your
Forney Authorized Dealer or Forney Customer Service 1-800-521-6038.
WARNING: Cancer and Reproductive Harm – www.P65Warnings.ca.gov
• Some dust contains chemicals known to the state of California to cause cancer, birth defects, or other reproductive
harm such as asbestos, lead, and lead-based paint.
• SAVE THESE INSTRUCTIONS. Read and understand all instructions, precautions, and safety warnings before
operating this equipment to avoid injury or property damage
RISK OF FIRE OR EXPLOSION! During normal operation and use of this air compressor, sparks can be produced
by the electrical contacts within the motor housing. If sparks come into contact with flammable liquids, vapors, gases, or
other combustible materials, a fire or explosion could erupt causing serious injury, death, or property damage. ALWAYS
store flammable liquids or other combustible materials in a safe location away from the air compressor. ALWAYS operate
the compressor in well ventilated areas that are free of flammable liquids, vapors, gases, or other combustible materials.
If spraying flammable materials using compressed air, ALWAYS locate the air compressor at least 25 feet (7,62m) away
from the spray area.
This compressor is air cooled and has numerous ventilation ports. Covering any of these ventilation ports could cause
excessive heat to build up within the compressor. This could cause a fire which may result in serious injury, death, or
property damage. NEVER cover any of the ventilation ports on the compressor. NEVER place any object on top of, or
leaning against, the compressor during use. ALWAYS ensure the compressor has at least 12 inches of open space on all
Symbols Legend
SYMBOL MEANING
WARNING / CAUTION / DANGER / NOTICE
LOUD NOISES
HEALTH HAZARD
FIRE / EXPLOSION
PROTECT AGAINST HEAT/FLAME
ELECTRIC SHOCK
HIGH TEMPERATURE
PRESSURIZED CYLINDER
General Safety
Safety Summary

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sides during operation to ensure adequate air flow. This compressor has two cooling fans within the compressor body.
ALWAYS verify the fans are mounted on their respective shafts, and free of damage or obstruction before use. If the fan
blades are damaged, or if the fan has come free of the shaft, DO NOT use the air compressor.
WARNING: ELECTRIC SHOCK CAN KILL! This air compressor is powered by electricity. Like all other electronic
devices, if not used properly it may cause electric shock. Electric shocks can vary in severity from minor pain or tingling to
unconsciousness, arc burns, cardiac arrest, and death. To avoid the possibility of electric shock, NEVER attempt to use the
air compressor in a damp environment or outside while it is raining. NEVER attempt to use the air compressor if any of the
protective covers are not properly in place.
NEVER attempt to repair any electronic device without the proper training or guidance from a licensed professional. Any
repairs to your air compressor should be performed by a Forney Warranty Service Center. To find Warranty Service
Centers in your area, please visit www.forneyind.com.
ALWAYS turn off and unplug your air compressor before performing any maintenance procedures.
LOUD NOISE CAN CAUSE HEARING DAMAGE! Though this air compressor features quiet technology, in some
situations the noise can become amplified to potentially dangerous levels. Hearing loss is permanent! ALWAYS use
certified hearing protection equipment in accordance with: ANSI S12.6 (S3.19).
RISK TO RESPIRATORY SYSTEM! The air produced by this compressor may contain harmful vapors, gases, or solid
particulates that are not safe for consumption. Breathing any of these toxins can cause serious injury or death. DO NOT
use the air from this compressor for consumption without additional in-line safety equipment that is in accordance with all
local and federal codes, laws, regulations, and guidelines.
Sprayed vapors or liquids such as cleaning products, paint, solvents, paint removers, insecticides, weed killers, etc. could
be harmful when inhaled and can lead to serious injury or death. ALWAYS operate this compressor in a well-ventilated
area. ALWAYS use appropriate safety equipment that is in accordance with: OSHA 29 CFR 1910.134.
PRESSURE VESSELS MAY BURST! PRESSURE VESSELS MAY BURST! The air tank on your air compressor may be
UM coded according to ASME Section VIII, Div. 1 rules. Pressure vessels fail suddenly with an explosion that could cause
serious injury, death, or property damage. All pressure vessels including compressed air tanks should be inspected by a
state certified vessel inspector once every two years. To find your state pressure vessels inspector, search for the Division of
Labor and Industries on the internet or in the government section of your local phone book.
NEVER attempt to use an air compressor with visible cracks or bulges in the air tank. NEVER attempt to repair and re-use
a ruptured pressure vessel or air tank.
DRAIN THE AIR TANK AFTER EACH USE. During normal use and operation of your air compressor, water will condense
in the air tank. If this water is not drained from the tank after each use, rust may build up inside of the tank, weakening
its structural integrity and increasing the likelihood of a catastrophic burst or tank explosion. Proper maintenance is the
easiest way to avoid catastrophic tank failure.
FLYING PARTICULATES ARE DANGEROUS! The compressed air stream can damage exposed skin and clothing
and may contain particulates that are propelled at extremely high speeds. NEVER point any nozzle or sprayer at any
part of the body, other people, or animals.
ALWAYS wear certified eye safety equipment that is in accordance with: ANSI Z87.1.
ALWAYS turn the compressor off, drain the tank, and remove any air hoses before performing any maintenance
procedures to avoid accidental exposure to the compressed air stream.
FLYING PARTICULATES ARE DANGEROUS! The compressed air stream can damage exposed skin and clothing
and may contain particulates that are propelled at extremely high speeds. NEVER point any nozzle or sprayer at any part
of the body, other people, or animals.
ALWAYS wear certified eye safety equipment that is in accordance with ANSI Z87.1.
ALWAYS turn the compressor off, drain the tank, and remove any air hoses before performing any maintenance procedure.
Pressurized Cylinder
Electric Shock
Loud Noises
Respiratory System Health Hazard
Flying Particles
Compressor Temperature

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LIFTING HEAVY OBJECTS CAN CAUSE SERIOUS INJURY! Improper heavy lifting techniques can lead to
extreme long-term injury. Your air compressor (4.5CFM compressor only) is too heavy to be safely lifted by one person.
ALWAYS get help when lifting your air compressor. ALWAYS observe proper heavy lifting techniques.
MOVING PARTS CAN CAUSE SERIOUS INJURY! Moving or rotating parts (like the fans in your air compressor)
can cause serious injury and soft tissue damage. NEVER operate your air compressor if any of the guards or covers are
removed. ALWAYS keep hair, jewelry, and loose clothing away from the compressor.
UNSAFE OPERATION OF THE COMPRESSOR CAN LEAD TO SERIOUS INJURY, DEATH, OR PROPERTY
DAMAGE! Read, understand, and follow all of the instructions, precautions, and safety warnings in this manual. KEEP
THIS MANUAL AND ALL WARNINGS FOR FUTURE REFERENCE. KEEP CHILDREN AWAY FROM THE AIR COMPRESSOR
AT ALL TIMES. DO NOT OPERATE THIS COMPRESSOR WHILE FATIGUED OR UNDER THE INFLUENCE OF DRUGS OR
ALCOHOL. NEVER DEFEAT THE SAFETY FEATURES OF THIS AIR COMPRESSOR. EQUIP THE AREA OF OPERATION WITH
A FIRE EXTINGUISHER. DO NOT OPERATE THIS COMPRESSOR WITH MISSING, BROKEN, OR UNAUTHORIZED PARTS.
FALLING OBJECTS CAN CAUSE SERIOUS INJUIRY OR PROPERTY DAMAGE! This air compressor can fall
from a table, workbench, or roof and cause serious injury, death, or property damage. ALWAYS locate the compressor
on a flat secure surface at ground level. NEVER position the compressor on a roof or other elevated surface.
SAVE THESE INSTRUCTIONS FOR FUTURE REFERENCE!
WARNING! SOME DUST CREATED BY POWER SANDING, SAWING, GRINDING, DRILLING, AND
OTHER CONSTRUCTION ACTIVITIES CONTAINS CHEMICALS KNOWN TO THE STATE OF CALIFORNIA
TO CAUSE CANCER, BIRTH DEFECTS, OR OTHER REPRODUCTIVE HARM.
Some examples of these chemicals are:
• Lead from lead-based paints.
• Crystalline silica from bricks, cement, and other masonry products.
• Arsenic and Chromium from chemically treated lumber.
Risk from these exposures varies depending on how often you do this type of work. To reduce your exposure to these
chemicals, ALWAYS work in a well-ventilated area with certified safety equipment such as masks specifically designed to
meet OSHA 29 CFR 1910.134.
• Avoid prolonged contact with dust from power sanding, sawing, grinding, drilling, and other construction activities.
Wear protective clothing and wash exposed areas with soap and water. Allowing dust to get into your mouth, eyes,
or lay on the skin may promote absorption of harmful chemicals.
WARNING! USE OF THIS TOOL CAN GENERATE AND/OR DISPERSE DUST WHICH MAY CAUSE
SERIOUS AND PERMANENT RESPIRATORY ILLNESS OR OTHER INJURY. ALWAYS USE NIOSH/OSHA
APPROVED RESPIRATORY PROTECTION APPROPRIATE FOR DUST EXPOSURE. DIRECT PARTICLES
AWAY FROM YOUR FACE AND BODY.
WARNING! NEVER MODIFY OR ATTEMPT TO REPAIR THE AIR COMPRESSOR OR ANY OF ITS
COMPONENTS. DAMAGE OR PERSONAL INJURY COULD RESULT.
Additional Safety Information

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Model 2.5 CFM Air Compressor 4.5 CFM Air Compressor
Tank Size 4 Gallons 4 Gallons
Horsepower 1.0 HP 2.0 HP
Maximum Tank Pressure 120 PSI 120 PSI
Running Wattage 900 W MAX 1700 W MAX
Tank Style Cylinder Cylinder
Tank Material Steel Steel
Decible Rating 61 dB 69 dB
Pump Type Oil-free Oil-free
Fitting Size 1/4” 1/4”
Power Source Electric Electric
Power Type Corded-electric Corded-electric
Start Type Electric / Auto Electric / Auto
Stage Count Single Stage Single Stage
Voltage 120V 120V
Air Delivery @ 40 PSI 3.1 CFM 5.5 CFM
Air Delivery @ 90 PSI 2.5 CFM 4.5 CFM
Pump-up Time 140 seconds (0-Max PSI) 60 seconds (0-Max PSI)
Recovery Time 25 seconds (85-115 PSI) 15 seconds (85-115 PSI)
AMPS 6A 12.5A
Maximum AMPS 7.1A 13.7A
Certifications ETL Certified ETL Certified
Weight 48.5 lbs 70.5 lbs
Length 25” 25”
Width 15” 15”
Height 15” 15”
Air Compressor Specifications
2.5 CFM Air Compressor
SC012-015 (Forney 550)
120Vac, 60Hz, 7.1A, 4Gal
90-120PSI
4.5 CFM Air Compressor
SC020-015 (Forney 555)
120Vac, 60Hz, 12.5A, 4Gal
90-120PSI

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4.5 CFM Model
2.5 CFM Model
A) On/Off Switch
B) Safety Valve
C) Check Valve
D) Air Filter / Moisture Separator
E) Tank Pressure Gauge
F) Output Pressure Regulator
G) Telescoping Luggage Handle (4.5CFM)
H) Output Pressure Gauge
I) Air Output Quick Connect Ports
J) Compressor
K) 4 Gallon Air Tank
L) Plasma Cutter Rack (4.5CFM)
M) Compressor Cart Interface Pegs
N) Power Cable Wrap
O) Rubber Feet
P) Air Tank Drain Valve
Q) Front Carry Handle (2.5CFM)
R) Rear Carry Handle (2.5CFM)
S) Wheels (4.5CFM)
Air Compressor Components

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Air Compressor Components Details
A) On/Off Switch – Rotate the On/Off Switch lever from “Off” to “Auto” to send automatic power to the compressor
motor. As long as this switch is in the “Auto” position, the air compressor will automatically refill when the tank
pressure drops below a certain limit. Rotate the On/Off Switch lever from “Auto” to “Off” after each use.
B) Safety Valve –The safety valve must be checked for functionality before each use. Simply pull on the ring with your
finger to ensure the valve moves freely. The safety valve will automatically let air out of the tank if the tank pressure
exceeds cut-off pressure (120PSI).
C) Check Valve – The check will automatically close if the compressor continues to run after cut-off pressure is reached.
The check valve functions to prevent dangerous over-pressurization of the tank that could lead to equipment failure,
serious injury, death, or property damage.
D) Air Filter / Moisture Separator – Because this compressor is optimized for use with plasma cutting equipment, an
in-line air filter / moisture separator is present on the front of the unit. Plasma cutters require clean, dry air that is oil
free.
E) Tank Pressure Gauge – This gauge displays the pressure [PSI] inside of the air tank.
F) Output Pressure Regulator – The output regulator allows the user to adjust the pressure of the air flowing out of the
tank. This pressure can be less than or equal to the tank pressure.
G) Telescoping Luggage Handle (4.5CFM Unit Only) – The 4.5CFM air compressor model includes a telescoping
luggage handle for easy transportation. This handle can be used in the extended or collapsed positions.
H) Output Pressure Gauge – This gauge displays the pressure [PSI] of the air flowing out of the air tank.
I) Air Output Quick Connect Ports – This compressor is equipped with two ¼” quick connect air hose ports.
J) Compressor – This is the electrically driven mechanical component that pressurizes the air tank.
K) 4-Gallon Air Tank – This compressor is equipped with a 4-gallon air tank that was designed and may be UM coded
according to ASME Section VIII, Div. 1 rules. All pressure vessels including compressed air tanks should be inspected
once every two years. To find your state pressure vessels inspector, search for the Division of Labor and Industries on
the internet or in the government section of your local phone book.
L) Plasma Cutter Rack (4.5CFM Unit Only) – The 4.5CFM air compressor is equipped with a plasma cutter rack.
Mounting brackets for your Forney Plasma Cutter are sold separately. To determine which mounting brackets you
need based on your plasma cutter model, please visit www.forneyind.com.
M) Compressor Cart Interface Pegs – This air compressor was specifically designed to be mounted on a cart for
customer convenience. The Compressor Cart Interface Pegs (M) and the Rubber Feet (O) are interchangeable based
on the configuration that matches your needs. For normal use, the Rubber Feet should be installed. For use with the
Forney Compressor Cart, remove the Rubber Feet and replace them with the Cart Interface Pegs (SEE IMAGES ON
NEXT PAGE). For more information on the Forney Compressor Cart, please visit www.forneyind.com.
N) Power Cable Wrap – This air compressor has a built-in cable wrap located beneath the control panel for your
convenience.
O) Rubber Feet – 4 rubber feet are supplied with your air compressor. These should be installed on the bottom
of the compressor and act to prevent the frame of the compressor from contacting the ground. These also act
as vibration dampers during compressor operation. Locate the following bolt pattern on the bottom of the
compressor frame to install the rubber feet: