Central Pneumatic 93271 Installation manual

21 GALLON, 230 V~,
CAST IRON VERTICAL
AIR COMPRESSOR
93271
SET UP AND OPERATING INSTRUCTIONS
Distributed exclusively by Harbor Freight Tools®.
3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit our website at: http://www.harborfreight.com
Read this material before using this product.
Failure to do so can result in serious injury.
SAVE THIS MANUAL.
Copyright©2005 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. Diagrams within this manual may not be drawn proportionally. Due to continuing
improvements, actual product may differ slightly from the product described herein. Tools required for
assembly and service may not be included.
For technical questions or replacement parts, please call 1-800-444-3353.
Manual revised 08j

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 2
SPECIFICATIONS
Maximum Air Pressure 115 PSI with Auto Shut-Off
Air Tank Capacity 21 Gallons
Air Flow Capacity 3.5 CFM at 90 PSI
8.8 CFM at 40 PSI
Electrical Requirements 230 V~ / 60 Hz / 7 A / 1 Phase
3 HP rated
Pump Stage Single
Air Outlet Size 1/4” - 18 NPT
Shipping Weight 152 Pounds
Power Cord 10’ - Electrical Plug Sold Separately
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 refer-
ence.
GENERAL SAFETY WARNINGS AND PRECAUTIONS
KEEP WORK AREA CLEAN AND DRY.1. Cluttered, damp, or wet work areas invite
injuries.
KEEP CHILDREN AWAY FROM WORK AREA.2. Do not allow children to handle
this product.
STORE IDLE EQUIPMENT.3. 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.
DO NOT USE THIS PRODUCT IF UNDER THE INFLUENCE OF ALCOHOL OR4. DRUGS. Read warning labels on prescriptions to determine if your judgement or
reexes are impaired while taking drugs. If there is any doubt, do not attempt to
use this product.
USE EYE, HAND, AND HEARING PROTECTION.5. Wear ANSI approved safety
impact goggles, hearing protection, and heavy-duty work gloves when using this
product.
DRESS SAFELY.6. 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.
DO NOT OVERREACH.7. Keep proper footing and balance at all times to prevent
tripping, falling, back injury, etcetera.
REV 05j; 07f; 09a

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 3
INDUSTRIAL APPLICATIONS MUST FOLLOW OSHA REQUIREMENTS.8.
STAY ALERT.9. 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.
CHECK FOR DAMAGED PARTS.10. 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.
REPLACEMENT PARTS AND ACCESSORIES:11. When servicing, use only identi-
cal replacement parts. Only use accessories intended for use with this product.
Approved accessories are available from Harbor Freight Tools.
MAINTAIN THIS PRODUCT WITH CARE.12. Keep this product clean and dry for
better and safer performance.
MAINTENANCE:13. For your safety, service and maintenance should be performed
regularly by a qualied technician.
USE THE RIGHT TOOL FOR THE JOB.14. Do not attempt to force a small tool or
attachment to do the work of a larger industrial tool. There are certain applications
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.
The warnings, precautions, and instructions discussed in this manual cannot cover15. all possible conditions and situations that may occur. The operator must under-
stand that common sense and caution are factors, which cannot be built into this
product, but must be supplied by the operator.
SPECIFIC PRODUCT WARNINGS AND PRECAUTIONS
CAUTION:1. Fill the Air Compressor with a premium quality, 30-weight, non-deter-
gent oil before each use. Running the Air Compressor with no oil or low oil will
cause damage to the equipment.
Note: The oil reservoir has an optimal capacity of 30 ounces of oil.
MAKE SURE ALL TOOLS AND EQUIPMENT USED WITH THE AIR COMPRES-2. SOR ARE RATED TO THE APPROPRIATE CAPACITY. Do not use any tool or
equipment that does not operate at or above the PSI that the compressor’s regula-
tor is set to.
DRAIN AIR COMPRESSOR EVERY DAY.3. Do not allow moisture to build up inside
the Air Compressor. (See “INSPECTION, MAINTENANCE, AND CLEANING”
section of this manual.)
MAINTAIN A SAFE WORKING ENVIRONMENT.4. Keep the work area well lit.
Make sure there is adequate surrounding workspace. Always keep the work area

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 4
free of obstructions, grease, oil, trash, and other debris. Do not use the Air Com-
pressor in areas near ammable chemicals, dusts, and vapors.
AVOID INJURY:5. Never direct the pressurized air stream at people or animals.
DO NOT ALTER OR REMOVE THE FACTORY SEALED PRESSURE RELEASE6. VALVE (5A). (See Assy. Diagram A.)
DO NOT OPEN THE WATER DRAIN VALVE (10A) SO THAT7. MORE THAN
FOUR THREADS ARE SHOWING. (See Assy. Diagram A.)
AN EXTENSION CORD MUST8. 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. Longer air
hoses are typically safer and more effective than extension cords.
THIS UNIT REQUIRES A 230 V~, UL LISTED, TWISTLOCK PLUG (SOLD SEPA-9. RATELY) TO BE INSTALLED BY A QUALIFIED ELECTRICIAN BEFORE SETUP
OR USE.
THIS COMPRESSOR MAY REQUIRE A DEDICATED ELECTRICAL CIRCUIT AS10. THE AMPERAGE DRAW UNDER FULL LOAD COMBINED WITH USE OF ANY
OTHER ITEM MAY OVERLOAD YOUR CIRCUIT.
WARNING:11. 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.)
People with pacemakers should consult their physician(s) before use. Electromag-12.
netic elds in close proximity to heart pacemaker could cause pacemaker interfer-
ence or pacemaker failure.
REV 07f

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 5
UNPACKING
When unpacking, make sure the item is intact and undamaged. 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.
Find the bag/box that contains all hardware for mounting the parts that are shipped
detached.
ASSEMBLY
Before use, thread the Mufer/Air Filter (7A) assembly into the Cylinder Case (2B).
OPERATION
Note: For additional references to the parts listed below, refer to the Assembly Dia-
grams on pages 10, and 11.
To Check The Oil Level:
FIGURE A
Oil Breather (14B)
Oil Window (20B)
Front Cover (18B)
1. The Oil Window (20B) is used to determine if oil is needed. The oil level should
always be at the maximum level (red line on the Oil Window). (See Figure A, and
Assy. Diagram B.)
Unscrew2. (do not pull) the Oil Breather (14B) out. (See Figure A.)
If necessary, add a3. premium quality, 30-weight, non-detergent oil into the Oil Fill
Hole until the level of oil reaches the maximum level as indicated on the Oil Win-
dow (20B). The optimal capacity of the oil reservoir is 30 ounces. Do not overll.
Then thread the Oil Breather back into the Oil Fill Hole, being careful not to strip
the plastic threads.
REV 08l

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 6
To Turn The Air Compressor On:
Fully close the Water Drain Valve (10A).1. (See Assy. Diagram A.)
Pull on the Pressure Relief Valve (5A) briey to ensure that it does not stick.2.
Turn the Air Flow Valve (6A) to its “OFF” position.3.
Connect the air hose (not provided) to the Air Flow Valve (6A) of the Air Compres-4. sor. Then, connect the other end of the air hose to the pneumatic tool (not pro-
vided) that is to be used.
5. To extend the life of your air tools and equipment, it is recommended to install
an oiler and water lter in series (available from Harbor Freight Tools) with the Air
Output Line of the Air Compressor.
Note: Plug the Power Cord of the Air Compressor into a 230 V~ electrical source.
Pull6. up on the “ON/OFF” Power Switch (1A) to turn the Air Compressor on.
(Push down on the “ON/OFF” Power Switch to turn the Air Compressor off.)
Allow sufcient time for the Tank Pressure Gauge (4A) to indicate 7. 80 PSI before
using the Air Compressor.
Turn the Air Flow Valve (6A) to its “ON” position to allow air to the pneumatic tool.8.
With the Air Compressor turned on, the operation is automatic and under the con-9. trol of the automatic switches inside the box under the Power Switch (1A).
NEVER open the power switch box or adjust the controls within.
To Adjust The Air Output To The Pneumatic Tool:
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 (3A) and
the Tool Pressure Gauge (4A). The reading on the Tank Pressure Gauge dictates
the maximum/minimum air pressure at which the Tool Pressure Gauge may also
be set.
With the Air Compressor running, and the air hose and pneumatic tool hooked up1. to the Air Compressor, pull up on the Tool Pressure Adjuster (2A). Turn the Tool

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 7
Pressure Adjuster clockwise to increase the air output to the tool, up to the work-
ing air pressure (115 PSI) as indicated on the Tank Pressure Gauge (3A). Never
exceed the maximum PSI for the tool being used or any component of the air
system.
Turn the Tool Pressure Adjuster (2A)2. counterclockwise to decrease the air output
to the tool.
To Use The Tank Pressure Relief Valve:
The Tank Pressure Relief Valve Ring (5A) is used when decompression is needed1.
quickly and efciently. It is also designed to release automatically if the compres-
sor pressurizes up to or beyond it’s safe limit.
To decompress the Air Tank (9A) pressure, press the “ON/OFF” Power Switch (1A)2. down to turn off the Air Compressor.
Pull out on the Tank Pressure Relief Valve Ring (5A) to immediately release air3. pressure in the Air Tank (9A).
To Empty Moisture From The Tank:
The Water Drain Valve (10A) is located underneath the Air Tank (9A), and should1. be used daily to release all trapped moisture through this valve. If this is not done,
condensation may cause Air Tank corrosion. (See Assy. Diagram A.)
WARNING: Do not open the Water Drain Valve (10A) so that more than four threads are
showing.
Push down on the “ON/OFF” Power Switch (1A) to turn off the Air Compressor.2. Then, unplug the Air Compressor’s Power Cord from the electrical outlet.
You may wish to lay a pan under the drain to collect the dirty water trapped within.3. Slowly and carefully unscrew (no more than four threads) the Water Drain Valve
(10A) until the compressed air and condensation begins to be released from the Air
Tank (9A). Allow sufcient time for all of the air and condensation to escape from
the Air Tank. Then, rmly retighten the Water Drain Valve.
IMPORTANT!
IF THE MOTOR STOPS UNEXPECTEDLY, the overload breaker may have
sensed an over-current condition, and stopped the motor to protect it. If this oc-
curs, shut off the pressure switch and wait at least 5 minutes. Release the air pressure
in the tank to ease restarting. Then press the breaker button to reset it, and turn on the
pressure switch. To help prevent this, ensure that this compressor is set up on a dedi-
cated circuit (one with no other equipment running on it), and that the distance from the
compressor to the circuit breaker panel is as short as possible. Extension cords should
not be used, and the outlet should not be far from the panel.

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 8
INSPECTION, MAINTENANCE, AND CLEANING
WARNING: Disconnect the Air Compressor from its electrical supply source before per-
forming any inspection, maintenance, or cleaning.
BEFORE EACH USE,1. inspect the general condition of the Air Compressor. Check
all air ttings for leaks. Check for loose screws, misalignment or binding of mov-
ing 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 vibra-
tion occurs, immediately disconnect the Air Compressor from its electrical supply
source and have the problem corrected before further use.
Do not use damaged equipment.
DAILY:2. Check the Air Compressor oil level. If necessary, ll with a premium qual-
ity, 30-weight, non-detergent oil. NOTE: When checking the oil level, make sure to
unscrew (do not pull) the Oil Breather (14B). (See Assy. Diagram B.)
DAILY:3. Purge the Air Tank (9A) of all air and moisture to prevent corrosion. To do
so, slowly and carefully unscrew (no more than four threads) the Water Drain Valve
(10A) until the compressed air and condensation begins to be released from the Air
Tank. Allow sufcient time for all of the air and condensation to escape from the Air
Tank. Then, rmly retighten the Water Drain Valve. (See Assy. Diagram A.)
EVERY 100 HOURS OF USE:4. Clean the Air Filter (7A) with a mild solvent. Then,
dry and reattach the Air Filter. NOTE: Replace the Air Filter if it is too dirty to prop-
erly clean. (See Assy. Diagram A.)
EVERY 500 HOURS OR 12 MONTHS:5. Drain and replace the old oil with new, pre-
mium quality, 30-weight, non-detergent oil. When the Oil Drain (16A) is removed,
the old oil needs to be collected and disposed of in full accord with all applicable
waste disposal ordinances.
TO CLEAN6. : wipe with a damp cloth, using a mild detergent or mild solvent.
WHEN STORING7. : Keep the Air Compressor in a clean, dry location.
PLEASE READ THE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS DIAGRAM IN THIS
MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER NOR 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 MANUFACTURER 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 REPLACE-
MENT PARTS THERETO.

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 9
PARTS LIST A / ASSEMBLY DIAGRAM
Part Description Qty.
1A ON/OFF Power Switch 1
2A Tool Pressure Adjuster 1
3A Tank Pressure Gauge 1
4A Tool Pressure Gauge 1
5A Pressure Release Valve 1
6A Air Flow Valve 1
7A Air Filter 1
9A Air Tank 1
10A Water Drain Valve 1
11A Quick Release Coupler 1
Part Description Qty.
12A Rubber Wheel 2
13A Washer 2
14A Nut 2
15A Fitting 1
16A Oil Drain Plug with Gasket 1
17A Foot 2
18A Unloader Valve 1
19A Polyurethane Unloader Tube 1
20A Copper Air Tube 1
1A
2A
3A
4A
5A
7A
9A
10A
12A
13A 14A
6A
15A
11A
16A
17A
18A 19A
20A
(Rear View with motor cover removed.)

SKU 93271 For technical questions, please call 1-800-444-3353. PAGE 10
Note: Some parts are listed and shown for illustration purposes only, and are not avail-
able individually as replacement parts.
PARTS LIST B / ASSEMBLY DIAGRAM B
Part Description Qty.
1B Bolt 4
2B Cylinder Case 1
3B Gasket 1
4B Valve Seat 1
5B Gasket 1
6B Cylinder 1
7B Compression Ring 2
8B Oil Scraping Ring 1
9B Piston 1
10B Gasket 1
11B Piston Pin 1
12B* End Cover 1
13B Crankshaft Retainer 2
14B Oil Breather 1
15B Connecting Rod 1
16B Gasket 1
17B Bolt 6
18B Front Cover 1
19B Gasket 1
Part Description Qty.
20B Oil Window 1
21B Crankshaft Bolt 1
22B Crankshaft 1
23B Crankshaft Case 1
24B* Stator 1
25B* Bearing 2
26B* Armature 1
27B Capacitor 1
28B Radiating Fan Wheel 1
29B Retainer Ring 1
30B Bolt 4
31B Screw 2
32B Radiating Cover 1
33B* Seal Washer 1
34B Motor Assembly 1
35B Overload Switch 1
*Not available individually. Must be ordered as
entire Motor Assembly (See part #34B).