Central Pneumatic 42321 User manual

SKU 42321 For technical questions, please call 1-800-444-3353. Page 3
WORK AREA
1. Keep your work area clean and well lit. Cluttered benches and dark areas invite
accidents.
2. Do not operate compressors in explosive atmospheres, such as in the presence
of flammable liquids, gases, or dust. Compressors create sparks which may ignite
the dust or fumes.
3. Keep bystanders, children, and visitors away while operating a compressor.
Provide barriers or shields as needed.
ELECTRICAL SAFETY
1. Grounded compressors must be plugged into an outlet properly installed and
grounded in accordance with all codes and ordinances. Never remove the
grounding prong or modify the plug in any way. Do not use any adapter plugs.
Check with a qualified electrician if you are in doubt as to whether the outlet is
properly grounded. If the compressors should electrically malfunction or break down,
grounding provides a low resistance path to carry electricity away from the user.
2. Do not expose compressors to rain or wet conditions. Water entering an electric
motor will increase the risk of electric shock.
3. Do not abuse the Power Cord. Never use the Power Cord to pull the Plug from an
outlet. Keep the Power Cord away from heat, oil, sharp edges, or moving parts.
Replace damaged Power Cords immediately. Damaged Power Cords increase the
risk of electric shock.
4. AN EXTENSION CORD MUST NEVER BE USED WITH THIS ITEM. Connecting
this item to an outlet through an extension cord MAY CAUSE ELECTRICAL
DAMAGE TO THE MOTOR and could present a FIRE HAZARD.
PERSONAL SAFETY
1. Stay alert. Watch what you are doing, and use common sense during use. Do not
use while tired or under the influence of drugs, alcohol, or medication. A moment
of inattention while operating may result in serious personal injury.
2. Dress properly. Do not wear loose clothing or jewelry. Contain long hair. Keep
your hair, clothing, and gloves away from moving parts. Loose clothes, jewelry, or
long hair can be caught in moving parts.
3. Avoid accidental starting. Be sure the Power Switch is turned off before plugging
in. Plugging in compressors with the Power Switch on, invites accidents.
4. Remove adjusting keys or wrenches before turning the compressor on. A wrench
or a key that is left attached to a rotating part of the compressor may result in personal
injury.
5. Do not overreach. Keep proper footing and balance at all times.

SKU 42321 For technical questions, please call 1-800-444-3353. Page 4
6. Use safety equipment. Always wear eye protection. Make sure you are wearing
your protective clothing, safety glasses with side shields and dust mask or air respirator,
if appropriate.
TOOL USE AND CARE
1. Do not force the compressor. Use the correct compressor for your application.
The correct compressor will do the job better and safer at the rate for which it is designed.
Never attempt to force the compressor to provide more pressure than it was designed
for.
2. Do not use the compressor if the Power Switch does not turn it on or turn it off.
Any compressor that cannot be controlled with the Power Switch is dangerous and
must be repaired or replaced.
3. Disconnect the Power Cord Plug from the power source before making any
adjustments, changing accessories, or storing the compressor. Such preventive
safety measures reduce the risk of starting the compressor accidentally.
4. Keep idle compressors out of reach of children and other untrained persons.
Compressors are dangerous in the hands of untrained users.
5. Maintain compressors with care. Keep all components of this product clean and
dry. Do not use a damaged compressor. Tag damaged compressors “Do not use” until
repaired.
6. Check for misalignment or binding of moving parts, breakage of parts, and any
other condition that may affect the compressor’s operation. If damaged,have the
compressor serviced before using. Many accidents are caused by poorly maintained
compressors.
7. Use only accessories that are recommended by the manufacturer for your model.
Accessories that may be suitable for one compressor may become hazardous when
used on another compressor.
SERVICE
1. Compressor service must be performed only by qualified repair personnel. Service
or maintenance performed by unqualified personnel could result in a risk of injury.
2. When servicing a compressor, use only identical replacement parts. Follow
instructions in the
“Inspection,Maintenance, And Cleaning” section of this manual.
Use of unauthorized parts or failure to follow maintenance instructions may create a
risk of electric shock or injury.
SPECIFIC SAFETY RULES
1. CAUTION! Prior to its first use, and thereafter prior to each subsequent use, make
sure to fill the Air Compressor with a premium quality, 30 weight, non-detergent
oil to the specified level. Running the Air Compressor with no oil or with low oil will

SKU 42321 For technical questions, please call 1-800-444-3353. Page 5
cause damage to the equipment and void its warranty. Refer to the “Operating
Instructions”
section for details on filling the Air Compressor with oil.
2. When filling the Air Compressor with oil, make sure to unscrew (do not pull) the
Oil Fill Cap to remove.
3. Use eye and ear protection. Always wear ANSI-approved safety impact eye goggles,
and ear plugs when using the Air Compressor.
4. Make sure all tools and equipment used with the Air Compressor are rated to the
appropriate air pressure capacity of the Air Compressor. Do not use any tool or
equipment that does not operate from 0-115 PSI. If necessary, check the owner’s manual
of the tool or equipment for its air pressure rating.
5. Always disconnect the Air Compressor from its electrical outlet, release any
remaining air pressure from the unit, and disconnect all pneumatic tools and
equipment from the unit, before performing any services or maintenance.
6. Avoid injury. Never direct the air jet at people or animals.
7. Inspect safety valve daily.If the safety valve is not working properly, tank pressure can
build up to dangerous levels. The tank could explode. For this reason, pull the ring on
the safety valve before each use and verify that it operates freely. Replace safety valve
if it does not operate freely.
Never remove or alter the factory sealed Safety Release Valve.
8. Do not attempt to readjust the automatic start and shutoff valves. Any change to
the automatic ON/OFF pressure levels will cause additional stress on the motor, which
may result in shortened motor life.
9. Drain the Air Compressor’s air tank every day. Do not allow moisture to build up
inside the Air Tank.
10. Do not unscrew the tank drain valve so that
more than four threads are showing.
11. Avoid risk of tank explosion.
a) Avoid weakening of tank by draining condensation after each use.
b) Never modify tank by drilling holes, welding to it, or modifying it’s parts.
c) The tank is designed, and factory set, to operate within a specific pressure range.
For that reason, never make adjustments to, or substitute parts, to the compressor.
12. Avoid bodily injury from moving parts. The compressor cycles on automatically,
without notice. For this reason, always keep hands and arms away from compressor
parts when the unit is connected to electrical power. Always have compressor safety
guards in place before turning compressor on.
13. Use approved air hose. Never use plastic or PVC pipe (unless specified for Air
Compressors) to carry air under pressure. Regardless of its pressure rating, it can burst
under pressure. Use only metal pipe.
14. Never plug the power cord of this product into an electrical outlet while standing
on a wet or damp surface.

SKU 42321 For technical questions, please call 1-800-444-3353. Page 6
15. THIS AIR COMPRESSOR MAY REQUIRE A DEDICATED ELECTRICAL CIRCUIT
AS THE AMPERAGE DRAW UNDER FULL LOAD, COMBINED WITH USE OF ANY
OTHER ITEM, MAY OVERLOADYOUR CIRCUIT.
16. Always turn off the Air Compressor in the event of a power failure.
17. Performance of this Air Compressor may vary depending on variations in local
line voltage.
18. Maintain labels and nameplates on the Air Compressor. These carry important
information. If unreadable or missing, contact Harbor Freight Tools for a replacement.
19. WARNING! People with pacemakers should consult their physician(s) before using
this product. Electromagnetic fields in close proximity to a heart pacemaker could cause
interference to or failure of the pacemaker.
20. WARNING! The brass components of this product contain lead, a chemical known
to the State of California to cause birth defects (or other reproductive harm). (California
Health & Safety code § 25249.5,
et seq. )
21. WARNING! The warnings, precautions, and instructions discussed in this instruction
manual cannot cover all possible conditions and situations that may occur. It must be
understood by the operator that common sense and caution are factors which cannot
be built into this product, but must be supplied by the operator.
SAVE THESE INSTRUCTIONS

SKU 42321 For technical questions, please call 1-800-444-3353. Page 7
Setup
Dipstick
Warning: Fill compressor with oil before using; running with NO OIL or with LOW OIL
will void the warranty. The optimal capacity of the oil reservoir is 7.8 ounces of oil.
The Dipstick is used to determine if oil is needed. Never operate the compressor without
sufficient oil. Use a 30 weight, non-detergent compressor oil. To check the oil:
1. Unscrew the Dipstick.
2. Check the level of the oil. There are two lines on the bottom of the Dipstick. The oil
level should be somewhere between the two lines, as high as possible.
3. Add oil through the Gauge’s hole as necessary, but do not overfill. Always use a high
grade oil specially designed for air compressors. Never mix oils of different types.
Never use a low quality oil which may not afford adequate lubrication.
4. Replace the Dipstick.
Install an Air Intake Filter and Hose (not included)
The filter and oiler (not supplied) are recommended but not mandatory for operation.
1. Remove and discard the plastic cap which covers the threaded hole at the top of the
Cylinder Case (B-6).
2. Screw the threaded part of the air filter assembly into the Cylinder Case until it is
firmly seated.
3. Connect the air tool, air hoses, filter, and oiler to the Compressor Air Output as
illustrated on the next page.
If the filter and oiler are not used, connect the air hose directly to the 1/4 inch NPT
barbed connector located at the Air Flow Valve (A-8). For easy connection or removal,
a quick coupler should be installed on the end of the air output.
Note: Use pipe thread seal tape on all threaded connections.
REV 08/01; 02/04

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Operation
Caution: Prior to use, inspect the compressor or any damaged parts or unsafe condi-
tions. Make any necessary repairs before using again.
Turning Compressor On
1. Verify Tank Drain Valve (A-7) is closed.
2. Verify oil level is correct.
3. Verify that the Safety Valve (A-4) is operational.
4. Turn the Air Flow Valve (A-8) to the OFF position.
5. Plug the power cord into a electrical outlet with a grounding prong.
6. Turn the ON/OFF Switch Lever(A-5) down to turn on. Turn the Switch Lever up
to shut off.Allow the pressure to build up to at least 80 PSI before using air.
7. Open the Air Flow Valve (A-8) and check for air leaks.
The operation of the compressor is automatic, as controlled by the an internal pressure
switch. When the pressure drops below its operating range the compressor turns on.
When the pressure is above 115 PSI, the compressor shuts off.
Warning; The compressor may become very hot during operation. Do not touch the
cylinder area of the compressor, or allow flammable materials to come in contact with
the cylinder area.
Adjusting Pressure Gauge and Pressure Adjustment Screw
Caution:The Pressure Switch is adjustable but changes to the pressure levels are not
recommended; any change to the automatic ON/OFF pressure levels will cause addi-
tional stress on the motor which may shorten motor life.
Adjusting Air Output
1. When the Lever of the Air Flow Valve (A-8) is to the up or down position, the valve is closed.
When it is in the middle, it is open.
2. Turn the Air Flow Valve to the appropriate pressure.
Maintenance
Warning: Do not make any repairs, adjustments, or maintenance on the air compressor
unless it is disconnected from the electrical power and the tank pressure is released.
Maintenance should always be performed by a qualified technician.
1. Check the oil level before each use. If the oil is low, add some. If it is high, drain some
by removing the Drain Plug. Replace the oil once a year.
2. Check and clean the Air Filter (B-5) every 50 hours, or sooner if used in a dusty
environment. REV 02/04

SKU 42321 For technical questions, please call 1-800-444-3353. Page 9
3. Drain the air tanks after each use by opening the drain petcock or the Tank Drain Valve
(A-7). Leave open until the next use.
4. Clean compressor with a damp rag containing mild detergent and water. Do not use
flammable liquids or solvents.
Parts List “A”
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4-AevlaVytefaS1
5-AhctiwSFFO/NO1
6-AknaTriA2
7
-AevlaVniarDknaT1
8-AevlaVwolFriA1
9-AevlaVyaWenO1
01-AebuT1
11-AesaB1
21-AtooFrebbuR4
31-AtuNdnatloB.ae1
NOTE: Some parts are listed and shown for
illustration purposes only and are not available
individually as replacement parts.
PLEASE READ THE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS DIAGRAM INTHIS
MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER NOR DISTRIBU-
TOR MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND TO THE BUYER THAT HE
OR SHE IS QUALIFIED TO MAKE ANY REPAIRS TO THE PRODUCT OR THAT HE OR SHE IS
QUALIFIED TO REPLACE ANY PARTS OF THE PRODUCT. IN FACT, THE MANUFACTURER
AND/OR DISTRIBUTOR EXPRESSLY STATESTHAT ALL REPAIRS AND PARTS REPLACEMENTS
SHOULD BE UNDERTAKEN BY CERTIFIED AND LICENSED TECHNICIANS AND NOT BY THE
BUYER. THE BUYER ASSUMES ALL RISK AND LIABILITY ARISING OUT OF HIS OR HER
REPAIRS TO THE ORIGINAL PRODUCT OR REPLACEMENT PARTS THERETO, OR ARISING
OUT OF HIS OR HER INSTALLATION OF REPLACEMENT PARTS THERETO.