Central Pneumatic 47915 User manual

5 HP AIR COMPRESSOR – 20 GALLON
Model 47915
ASSEMBLY AND OPERATING INSTRUCTIONS
3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit our Web site at http://www.harborfreight.com
Copyright 2002 by Harbor Freight Tools®. All rights reserved. No portion of this
manual or any artwork contained herein may be reproduced in any shape or form
without the express written consent of Harbor Freight Tools.
For technical questions, please call 1-800-444-3353.
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SPECIFICATIONS TABLE
SAVE THIS MANUAL
You will need this manual for the safety warnings and precautions, assembly,
operating, inspection, maintenance and cleaning procedures, parts list and
assembly diagram. Keep your invoice with this manual. Write the invoice
number on the inside of the front cover. Keep this manual and invoice in a safe
and dry place for future reference.
GENERAL SAFETY WARNINGS AND PRECAUTIONS
1. KEEP WORK AREA CLEAN AND DRY. Cluttered, damp, or wet work areas
invite injuries.
2. KEEP CHILDREN AWAY FROM WORK AREA. Do not allow children to handle
this product.
3. STORE IDLE EQUIPMENT. When not in use, tools and equipment should be
stored in a dry location to inhibit rust. Always lock up tools and equipment, and
keep out of reach of children.
4. DO NOT USE THIS PRODUCT IF UNDER THE INFLUENCE OF ALCOHOL OR
DRUGS. Read warning labels on prescriptions to determine if your judgement or
reflexes are impaired while taking drugs. If there is any doubt, do not attempt to
use this product.
SKU 47915 PAGE 2 Rev 01/03

5. USE EYE AND HAND PROTECTION. Wear ANSI approved safety impact
eyeglasses and heavy-duty work gloves when using this product. ANSI
approved safety impact eyeglasses and heavy-duty work gloves are available
from Harbor Freight Tools.
6. DRESS SAFELY. Do not wear loose clothing or jewelry, as they can become
caught in moving parts. Wear a protective hair covering to prevent long hair from
becoming caught in moving parts. If wearing a long-sleeve shirt, roll sleeves up
above elbows.
7. DO NOT OVERREACH. Keep proper footing and balance at all times to prevent
tripping, falling, back injury, etcetera.
8. INDUSTRIAL APPLICATIONS MUST FOLLOW OSHA REQUIREMENT.
9. STAY ALERT. Watch what you are doing at all times. Use common sense. Do
not use this product when you are tired or distracted from the job at hand.
10. CHECK FOR DAMAGED PARTS. Before using this product, carefully check that
it will operate properly and perform its intended function. Check for damaged
parts and any other conditions that may affect the operation of this product.
Replace or repair damaged or worn parts immediately.
11. REPLACEMENT PARTS AND ACCESSORIES: When servicing, use only
identical replacement parts. Only use accessories intended for use with this
product. Approved accessories are available from Harbor Freight Tools.
12. MAINTAIN THIS PRODUCT WITH CARE. Keep this product clean and dry for
better and safer performance.
13. MAINTENANCE: For your safety, service and maintenance should be performed
regularly by a qualified technician.
14. USE THE RIGHT TOOL FOR THE JOB. Do not attempt to force a small tool or
attachment to do the work of a larger industrial tool. There are certain applica-
tions for which this tool was designed. It will do the job better and more safely at
the rate for which it was intended. Do not modify this tool, and do not use this
tool for a purpose for which it was not intended.
15. WARNING: The warnings, precautions, and instructions discussed in this manual
cannot cover all possible conditions and situations that may occur. The operator
must understand that common sense and caution are factors, which cannot be
built into this product, but must be supplied by the operator.
SKU 47915 PAGE 3

SPECIFIC PRODUCT WARNINGS AND PRECAUTIONS
1. MAINTAIN A SAFE WORKING ENVIRONMENT. Keep the work area well lit.
Make sure there is adequate surrounding workspace. Always keep the work
area free of obstructions, grease, oil, trash, and other debris. Do not use the Air
Compressor in areas near flammable chemicals, dusts, and vapors.
2. ALWAYS DISCONNECT THE AIR COMPRESSOR FROM ITS ELECTRICAL
POWER SUPPLY SOURCE, RELEASE ITS AIR PRESSURE, AND
DISCONNECT ALL PNEUMATIC TOOLS FROM THE MACHINE BEFORE
PERFORMING ANY SERVICES OR MAINTENANCE.
3. WHEN CHECKING THE OIL LEVEL: Make sure to unscrew (do not pull) the
Dip Stick out.
4. WARNING: Make sure to fill the Air Compressor with a premium quality,
30-weight, non-detergent, compressor oil before each use. Running the Air
Compressor with no oil or low oil will cause damage to the equipment and
void the warranty.
5. MAKE SURE ALL TOOLS AND EQUIPMENT USED WITH THE AIR
COMPRESSOR ARE RATED TO THE APPROPRIATE PSI CAPACITY. Do not
use any tool or equipment that operates over 145 PSI.
6. DRAIN AIR COMPRESSOR EVERY DAY. Do not allow moisture to build up
inside the Air Compressor. Do not allow the Air Compressor to sit pressurized for
longer than one hour.
7. DO NOT REMOVE THE FACTORY SEALED TOOL PRESSURE VALVE
ADJUSTER (part #59).
8. DO NOT OPEN THE DRAIN VALVE (part #44) SO THAT MORE THAN FOUR
THREADS ARE SHOWING.
9. CAUTION: The Internal Pressure Switch (part #55) should not be adjusted. Any
change to the automatic ON/OFF pressure levels will cause additional stress on
the motor, which may result in shortened motor life.
10. THIS AIR COMPRESSOR DOES NOT COME EQUIPPED WITH AN
ELECTRICAL POWER PLUG. For your safety, only a qualified, certified
electrician should attach the Power Plug onto the Power Cord. Never remove the
grounding prong or modify the Plug in any way. Do not use adapter plugs with the
Power Plug.
SKU 47915 PAGE 4

11. GROUND THIS PRODUCT. To comply with the National Electric Code, and to
provide additional protection from the risk of electrical shock, this product should
only be connected to an electrical outlet that is protected by a Ground Fault Circuit
Interrupter (GFCI).
12. DO NOT ABUSE THE POWER CORD. Do not use the Power Cord (part #72) to
pull the Power Plug from a power outlet. Keep the Power Cord away from heat,
oil, sharp edges, and moving parts. Route the Power Cord safely. Do not route
the Power Cord where it can be walked on or tripped over. Replace a damaged
Power Cord immediately.
13. IF AN EXTENSION CORD (not provided) IS USED, MAKE SURE TO USE
ONLY UL APPROVED CORDS HAVING THE CORRECT GAUGE AND
LENGTH. (See Figure A.)
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EXTENSION CORD LENGTH
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FIGURE A
14. TO EXTEND THE LIFE OF YOUR AIR TOOLS AND EQUIPMENT, it is
recommended to install an oiler and water filter in series with the Air Output Line
of the Air Compressor. (See Figure C, next page.)
15. WARNING: This product contains or produces a chemical known to the State of
California to cause cancer and birth defects (or other reproductive harm).
(California Health & Safety Code 25249.5 et seq.)
SKU 47915 PAGE 5
FIGURE B

FIGURE C
16. WARNING: People with pacemakers should consult their physician(s) before
using this product. Operation of electrical equipment in close proximity to a heart
pacemaker could cause interference or failure of the pacemaker.
UNPACKING
When unpacking, check to make sure all the parts shown on the Parts List on page 14
are included. If any parts are missing or broken, please call Harbor Freight Tools at the
number shown on the cover of this manual as soon as possible.
ASSEMBLY INSTRUCTIONS
NOTE: For additional references to the parts listed below, refer to the Assembly
Diagram on page 15.
1. Prior to using, the Air Compressor requires the attachment of a 1/4” NPT Female
Quick Coupler (not provided) to the Tool Pressure Adjuster Valve (part #59). To
do so, wrap approximately 4” of thread seal tape around the male threads of the
Tool Pressure Valve Adjuster. Then, wrench tighten the Quick Coupler onto the
Tool Pressure Valve Adjuster. (See Figure D, next page.)
2. To attach the Handle (part #50) to the Air Tank (part #41), insert each end of the
Handle into the mounting brackets on the Air Tank. Then, secure the Handle to
the Air Tank with two Plate Washers (part #65) and two Hex Head Bolts
(part #68). (See Figure E, next page.)
SKU 47915 PAGE 6

TOOL PRESSURE
ADJUSTER VALVE
(#59)
1/4” NPT
FEMALE QUICK COUPLER
(NOT PROVIDED)
TOOL PRESSURE GAUGE
(#60)
HEX HEAD BOLT (#68)
PLATE WASHER (#65)
HANDLE (#50)
AIR TANK
(#41)
FIGURE F
FIGURE D
TANK WHEEL
BOLT (#42)
AIR TANK (#41)
3. To attach the two Tank Wheels (part #43) to the Air Tank (part #41), insert a Tank
Wheel Bolt (part #42) through the hub of a Tank Wheel. Then, wrench tighten the
Tank Wheel Bolt onto the wheel bracket located at the back of the Air Tank.
Repeat this procedure for the remaining Tank Wheel. (See Figure F.)
4. To wire the Motor to accept 220 Volt electrical power supply, remove the cover
from the electrical junction box on the Motor. Next, connect each of the four
wires within the Wire Cable (part #71) to its proper electrical terminal in the junc-
tion box. Then, reattach the cover to its junction box. CAUTION: For your safety,
only a qualified, certified electrician should attach the Wire Cable to the
Motor’s junction box. (See Figure G, next page.)
FIGURE E
SKU 47915 PAGE 7
TANK WHEEL
(#43)
Rev 01/03

FIGURE G
OPERATING INSTRUCTIONS
To Check And Fill The Oil Level:
1. CAUTION: ALWAYS make sure the Air Compressor is filled to the proper
level with a premium quality, 30-weight, non-detergent compressor oil prior
to turning on the machine. Failure to do so will result in damage to the Air
Compressor and void its warranty.
2. To check the level of oil in the Air Compressor, observe the Oil Sight Gauge
(part #26) located on the Crankcase (part #31). Proper oil level is
indicated when the oil appears in the middle of the circle in the Oil Sight Gauge.
(See Figure H, next page.)
3. If the oil level is below the middle of the circle in the Oil Sight Gauge (part #26),
UNSCREW (do not pull) the Dip Stick (part #29) out of the Oil Fill Hole. Next,
add oil into the Oil Fill Hole until the level of oil reaches the middle of the circle as
indicated on the Oil Sight Gauge. Do not overfill. Then screw the Dip Stick back
into the Oil Fill Hole, being careful not to strip the plastic threads.
(See Figure H.)
SKU 47915 PAGE 8
JUNCTION BOX
5. To wire the Motor to accept 120 Volt electrical power supply, remove the cover
from the electrical junction box on the Motor. Next, connect each of the four wires
within the wire Cable (part #71) to its proper electrical terminal in the junction
box. Then, reattach the cover to its junction box. CAUTION: For your safety,
only a qualified, certified electrician should attach the Wire Cable to the
Motor’s junction box. (See Figure G)
WIRE CABLE (#72)
MOTOR
PRESSURE
SWITCH (#55)
Rev 01/03

DIP STICK
(#29)
CRANKCASE (#31)
OIL SIGHT GAUGE (#26)
(PROPER OIL LEVEL)
FIGURE H
To Turn The Air Compressor On:
1. Check to make sure the Drain Valve (part #44) is fully closed. (See Figure I)
V-BELT (#66)
MOTOR PULLEY
(#62)
SAFETY NET (#69)
PULLEY (#38)
HEX HEAD
BOLT (#68)
PLATE WASHER
(#65)
AIR TANK (#41)
DRAIN VALVE
(#44) FIGURE I
SKU 47915 PAGE 9

2. Turn the Tool Pressure Adjuster Valve (part #59) clockwise all the way to allow
compressed air to build up in the Air Tank (part #41). (See Figures D, and J.)
3. Connect the air hose (not provided) to the previously installed 1/4” NPT Female
Quick Coupler on the Tool Pressure Adjuster Valve (part #59). Then, connect the
other end of the air hose to the pneumatic tool (not provided) that is to be used.
(See Figures C and D)
4. Plug the Power Cord (part #72) into a grounded, three-hole electrical outlet. (See
Assy. Diagram.)
5. Pull up on the Tool Pressure Adjuster Valve (part #59) to turn the Air Compressor
on. (Push down on the Tool Pressure Adjuster Valve to turn the Air Compressor
off.) (See Figures C and J)
6. Allow sufficient time for the Tank Pressure Gauge (part #56) to indicate 80 PSI
before using the Air Compressor. (See Figure I)
RESET BUTTON
TOOL
PRESSURE
GAUGE
(#60)
SAFETY
RELIEF
VALVE (#57)
TANK
PRESSURE
GAUGE
(#56)
AIR TANK (#41)
FIGURE J
SKU 47915 PAGE 10
TOOL
PRESSURE
ADJUSTER
VALVE (#59)

7. Turn the Tool Pressure Adjuster Valve (part #59) counterclockwise to allow air to
the pneumatic tool. (See Figures C and J)
8. NOTE: With the Air Compressor turned on, the operation is automatic and under
the control of the internal Pressure Switch (part #55). (See Figure G)
9. When finished using the Air Compressor, press down on the Tool Pressure Ad-
juster Valve (part #59) to turn the Air Compressor off. (See Figures C, and J)
To Adjust The Air Output To The Pneumatic Tool:
1. NOTE: When adjusting the air pressure being forwarded to the pneumatic tool,
you will need to compare the pressure readings of both the Tank Pressure Gauge
(part #56) and the Tool Pressure Gauge (part #60). The reading on the Tank
Pressure Gauge dictates the maximum air pressure at which the Tool Pressure
Gauge may also be set. (See Figure J)
2. With the Air Compressor running, and the air hose and pneumatic tool hooked up
to the Air Compressor, turn the Tool Pressure Adjuster Valve (part #59)
counterclockwise to increase the air output to the tool, up to the maximum
rated pressure (125 PSI) as indicated on the Tank Pressure Gauge (part #56).
(See Figure J)
3. Turn the Tool Pressure Valve Adjuster clockwise to decrease the air output to
the tool, down to the minimum rated pressure (0 PSI) as indicated on the Tank
Pressure Gauge (part #56). (See Figure J)
To Use The Safety Relief Valve:
1. The Safety Relief Valve (part #57) is used when decompression is needed
quickly and efficiently. (See Figure J)
2. Press down on the Tool Pressure Adjuster Valve (part #59) to turn off the Air
Compressor. (See Figures C, and J)
3. Pull out on the Safety Relief Valve (part #57) to immediately release air pressure
in the Air Tank (part #41). (See Figure J)
To Use The Reset Button:
1. The Reset Button is used in the event of an electrical power failure or an unex-
pected, automatic, shut down of the Air Compressor. (See Figure J)
SKU 47915 PAGE 11

2. If this situation occurs, make sure to press down on the Tool Pressure Adjuster
Valve (part #59) to turn the Air Compressor off. Then, turn the Tool Pressure
Adjuster Valve clockwise all the way to shut off the release of compressed air to
the pneumatic tool. (See Figures C, and J)
3. Wait until electrical power is restored to the Air Compressor, and allow sufficient
time for the Air Compressor to cool. Next, press and let up on the Reset Button.
The Air Compressor should now be ready to operate. (See Figure J)
To Empty Condensation From The Tank:
1. The Drain Valve (part #44) is located underneath the Air Tank (part #41), and
should be used daily to release all trapped moisture through this valve. The
Drain Valve will also eliminate condensation that may cause Air Tank corrosion.
(See Figure I)
2. WARNING: Do not open the Drain Valve (part #44) so that more than four
threads are showing.
3. Push down on the Tool Pressure Adjuster Valve (part #59) to turn off the Air
Compressor. Then, unplug the Power Cord (part #72) from the electrical outlet.
(See Figures C, J, and Assy. Diagram.)
4. Slowly and carefully unscrew (no more than four threads) the Drain Valve (part
#44) until the compressed air and condensation begins to be released from the
Air Tank (part #41). Allow sufficient time for all of the air and condensation to
escape from the Air Tank. Then, firmly re-tighten the Drain Valve.
(See Figure I)
INSPECTION, MAINTENANCE, AND CLEANING
1. CAUTION: Always disconnect the Air Compressor from its electrical supply
source, and release all compressed air from the Air Tank, before performing any
inspection, maintenance, or cleaning.
2. BEFORE EACH USE, inspect the general condition of the Air Compressor.
Check all air fittings for leaks. Check for loose screws, misalignment or binding
of moving parts, cracked or broken parts, damaged power cord and plug, and
any other condition that may affect the safe operation of this tool. If abnormal
noise or vibration occurs, immediately disconnect the Air Compressor from its
electrical supply source, release all compressed air from the Air Tank, and have
the problem corrected before further use. Do not use damaged equipment.
SKU 47915 PAGE 12

3. DAILY: Check the Air Compressor oil level. If necessary, fill with a premium
quality, 30-weight, non-detergent, compressor oil. NOTE: When checking the oil
level, make sure to unscrew (do not pull) the Dip Stick.
4. DAILY: Purge the Air Tank (part #41) of all moisture to prevent corrosion.
5. EVERY 100 HOURS OF USE: Clean the Air Filter Sleeve (part #4) with a mild
solvent. Then, dry and re-attach the Air Filter Sleeve. (Replace the Air Filter
Sleeve if it is too dirty to properly clean.) To clean or replace the Air Filter Sleeve,
remove the two Hex Socket Set Bolts (part #5). Remove the Air Filter Cover
(part #3). Remove the Air Filter Sleeve and clean. Then, replace the Air Filter
Sleeve and two Hex Socket Set Bolts. (See Figure K and Parts Diagram)
HEX SOCKET
SET BOLT (#5) FILTER AIR SLEEVE (#4)
AIR FILTER COVER
(#3)
FIGURE K
6. EVERY 500 HOURS OR 12 MONTHS: Replace the old oil with new, premium
quality, 30-weight, non-detergent, compressor oil.
7. TO REPLACE THE V-BELT (part #66), remove the five Hex Head Bolts (part
#68) and five Plate Washers (part #65) which secure the Safety Net (part #69) to
the frame of the Air Compressor. Remove the Safety Net, and remove the old
V-Belt. Next, place the new V-Belt completely around the large Pulley (part #38).
Then, slowly turn the Motor Pulley (part #62) by hand while feeding the V-Belt
onto and completely around the Motor Pulley. (See Figure I)
8. TO CLEAN, wipe with a damp cloth, using a mild detergent or mild solvent.
9. WHEN STORING, Keep the Air Compressor in a clean, dry location.
SKU 47915 PAGE 13

PARTS LIST/PARTS DIAGRAM
SKU 47915 PAGE 14
PLEASE READ THE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS LIST AND ASSEMBLY DIAGRAM IN THIS MANUAL AS A
REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER OR DISTRIBUTOR 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 MANUFACTUER AND/OR DISTRIBUTOR EXPRESSLY STATES THAT 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.
NOTE: Some parts are listed and shown for illustration purposes only, and are not
available individually as replacement parts.