Sullair 3007 Installation and maintenance instructions

KEEP FOR
FUTURE
REFERENCE
OPERATOR’S MANUAL AND PARTS LIST
®SULLAIR
®
PART NUMBER:
©SULLAIR CORPORATION
Starting Serial Number:
003-139556
I NDUSTRIAL
A IR C OMPRESSOR
3000, 3700, 4500,
3000 V , 3700 V , 4500 V
30, 37 & 45 KW /40, 50 & 60HP
Air-Cooled Standard & 24 KT
02250155-601

AIR CARE
SEMINAR TRAINING
Sullair Air Care Seminars are courses that provide hands-on instruction in the proper operation, maintenance
and service of Sullair equipment. Individual seminars on Industrial compressors and compressor electrical
systems are presented at regular intervals throughout the year at a dedicated training facility at Sullair's
corporate headquarters in Michigan City, Indiana.
Instruction includes discussion of the function and installation of Sullair service parts, troubleshooting of the
most common problems, and actual equipment operation. The seminars are recommended for maintenance
and service personnel.
For detailed course outlines, schedule and cost information contact:
Sullair Corporate Training Department
: 1-888-SULLAIR or
219-879-5451 (ext. 5363)
www.sullair.com
- Or Write -
Sullair Corporation
3700 E. Michigan Blvd.
Michigan City, IN 46360
Attn: Service Training Department

®SULLAIR
®
®SULLAIR®
3700 Operator’s Manual and Parts List iii
3700 Operator’s Manual and Parts List
TABLE OF CONTENTS
1 - SAFETY............................................................................................... 1
General................................................................................................ 1
Personal Protective Equipment ........................................................... 1
Pressure Release................................................................................ 2
Fire and Explosion............................................................................... 2
Moving Parts ....................................................................................... 3
Hot Surfaces, Sharp Edges and Sharp Corners ................................. 3
Toxic and Irritating Substances ........................................................... 3
Electrical Shock................................................................................... 4
Lifting................................................................................................... 4
Entrapment.......................................................................................... 5
2 - DESCRIPTION..................................................................................... 7
Introduction.......................................................................................... 7
Description of Components ................................................................. 8
Sullair Compressor Unit, Functional Description................................. 8
Compressor Cooling and Lubrication System, Functional
Description ........................................................................................ 10
Compressor Discharge System, Functional Description ................... 10
Control System, Functional Description ............................................ 11
START MODE - 0 TO 50 PSIG
(0 TO 3.5 BAR)............................................................................ 11
FULL LOAD MODE - 50 TO 100 PSIG (3.4 TO 6.9 BAR)........... 12
MODULATING MODE - 100 TO 110 PSIG (6.9 TO 7.6 BAR) .... 12
UNLOAD MODE - IN EXCESS OF 110 PSIG (7.6 BAR)............ 13
LOAD/NO LOAD CONTROL....................................................... 13
AUTOMATIC OPERATION ......................................................... 13
Air Inlet System, Functional Description............................................ 13
3 - SPECIFICATIONS............................................................................. 15
Table of Specifications ...................................................................... 15
Lubrication Guide .............................................................................. 17

®SULLAIR®
iv 3700 Operator’s Manual and Parts List
Application Guide .............................................................................. 17
Lubrication Change Recommendations and Maintenance -
Fluid Filter and Separator.................................................................. 18
4 - INSTALLATION................................................................................. 25
Mounting of Compressor................................................................... 25
Ventilation and Cooling ..................................................................... 25
Air-Cooled Compressors ............................................................. 25
Service Air Piping.............................................................................. 26
Pipe Sizing .................................................................................. 26
Use of Auxiliary Receiver / Sump............................................... 26
Isolation Valve(s)......................................................................... 26
Fluid Containment ....................................................................... 27
Coupling Alignment Check ................................................................ 27
Fluid Level Check.............................................................................. 27
Electrical Preparation ........................................................................ 27
Motor Rotation Direction Check ....................................................... 28
Fan Motor Rotation Check ................................................................ 28
5 - WS Controller................................................................................... 29
Controller Layout............................................................................... 29
Controller Keypad.............................................................................. 29
LED Display....................................................................................... 29
LED Lights......................................................................................... 31
6 - MAINTENANCE ................................................................................ 33
General.............................................................................................. 33
Daily Operation.................................................................................. 33
Maintenance After Initial 50 Hours of Operation ............................... 33
Maintenance Every 2000 Hours........................................................ 33
Fluid Maintenance ............................................................................ 34
Filter Maintenance............................................................................. 34
Fluid Filter Element Replacement ............................................... 34
Air Filter Maintenance ...................................................................... 34
Air Filter Element Replacement................................................... 35
Separator Maintenance .................................................................... 35
Separator Element Replacement ................................................ 35
Oil Return/Sight Glass Maintenance ........................................... 35
Pressure Regulator Adjustment .................................................. 36
Water Condensate Drain Maintenance ....................................... 36
Control Line Strainer ................................................................... 36
Shaft Coupling Maintenance ....................................................... 37
Troubleshooting - Introduction........................................................... 37
Troubleshooting Guide...................................................................... 38

TABLE OF CONTENTS
®SULLAIR®
3700 Operator’s Manual and Parts List v
7 - PARTS LISTS.................................................................................... 41
Procedure For Ordering Parts ........................................................... 41
Recommended Spare Parts List ....................................................... 43
Compressor, Frame and Drive - 3000 and 3700 Models .................. 44
Compressor, Frame and Drive - 4500 Model .................................... 46
Air Inlet System ................................................................................. 48
Air Piping - Air-Cooled....................................................................... 50
Fluid Piping - Air-Cooled ................................................................... 52
Cooling and Lubrication System - Air-Cooled 18"/60Hz
Fan, Standard Cooler ........................................................................ 54
Discharge, Sump and Piping System................................................ 56
Moisture Drain ................................................................................... 58
Pneumatic Control System - Standard .............................................. 60
Pneumatic Control System - With Sequencing ................................. 62
Control System and Electric Parts - 230/460
WYE-Delta......................................................................................... 64
Enclosure - Air-Cooled ...................................................................... 66
Decal Section - Air-Cooled ................................................................ 68

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®SULLAIR
®
®SULLAIR®
3700 Operator’s Manual and Parts List 1
3700 Operator’s Manual and Parts List
Section 1
SAFETY
1.1 GENERAL
Sullair Corporation and its subsidiaries design and
manufacture all of their products so they can be
operated safely. However, the responsibility for safe
operation rests with those who use and maintain these
products. The following safety precautions are offered as
a guide which, if conscientiously followed, will minimize
the possibility of accidents throughout the useful life of
this equipment.
The compressor should be operated only by those who
have been trained and delegated to do so, and who have
read and understood this Operator’s Manual. Failure to
follow the instructions, procedures and safety
precautions in this manual may result in accidents and
injuries.
NEVER start the compressor unless it is safe to do so.
DO NOT attempt to operate the compressor with a
known unsafe condition. Tag the compressor and render
it inoperative by disconnecting and locking out all power
at source or otherwise disabling its prime mover so
others who may not know of the unsafe condition cannot
attempt to operate it until the condition is corrected.
Install, use and operate the compressor only in full
compliance with all pertinent OSHA regulations and/or
any applicable Federal, State, and Local codes,
standards and regulations.
DO NOT modify the compressor and/or controls in any
way except with written factory approval.
While not specifically applicable to all types of
compressors with all types of prime movers, most of the
precautionary statements contained herein are
applicable to most compressors and the concepts
behind these statements are generally applicable to all
compressors.
1.2 PERSONAL PROTECTIVE
EQUIPMENT
Prior to installing or operating the compressor, owners,
employers and users should become familiar with, and
comply with, all applicable OSHA regulations and/or any
applicable Federal, State and Local codes, standards,
and regulations relative to personal protective
equipment, such as eye and face protective equipment,
respiratory protective equipment, equipment intended to
protect the extremities, protective clothing, protective
shields and barriers and electrical protective equipment,
as well as noise exposure administrative and/or
engineering controls and/or personal hearing protective
equipment.
NOTE
OPERATOR IS REQUIRED TO
READ ENTIRE INSTRUCTION
MANUAL.
SU_0000005

SECTION 1
®SULLAIR®
23700 Operator’s Manual and Parts List
1.3 PRESSURE RELEASE
A. Install an appropriate flow-limiting valve between
the service air outlet and the shut-off (throttle)
valve, either at the compressor or at any other
point along the air line, when an air hose
exceeding 13mm inside diameter is to be
connected to the shut-off (throttle) valve, to
reduce pressure in case of hose failure, per
OSHA Standard 29 CFR 1926.302(b)(7) and/or
any applicable Federal, State and Local codes,
standards and regulations.
B. When the hose is to be used to supply a manifold,
install an additional appropriate flow-limiting valve
between the manifold and each air hose
exceeding 13mm inside diameter that is to be
connected to the manifold to reduce pressure in
case of hose failure.
C. Provide an appropriate flow-limiting valve at the
beginning of each additional 23m of hose in runs
of air hose exceeding 13mm inside diameter to
reduce pressure in case of hose failure.
D. Flow-limiting valves are listed by pipe size and
flow-rated. Select appropriate valves accordingly,
in accordance with their manufacturer’s
recommendations.
E. DO NOT use air tools that are rated below the
maximum rating of the compressor. Select air
tools, air hoses, pipes, valves, filters and other
fittings accordingly. DO NOT exceed
manufacturer’s rated safe operating pressures for
these items.
F. Secure all hose connections by wire, chain or
other suitable retaining device to prevent tools or
hose ends from being accidentally disconnected
and expelled.
G. Open fluid filler cap only when compressor is not
running and is not pressurized. Shut down the
compressor and bleed the sump (receiver) to zero
internal pressure before removing the cap.
H. Vent all internal pressure prior to opening any line,
fitting, hose, valve, drain plug, connection or other
component, such as filters and line oilers, and
before attempting to refill optional air line anti-icer
systems with antifreeze compound.
I. Keep personnel out of line with and away from the
discharge opening of hoses or tools or other
points of compressed air discharge.
J. Use air at pressures less than 2.1 bar for cleaning
purposes, and then only with effective chip
guarding and personal protective equipment per
OSHA Standard 29 CFR 1910.242 (b) and/or any
applicable Federal, State, and Local codes,
standards and regulations.
K. DO NOT engage in horseplay with air hoses as
death or serious injury may result.
1.4 FIRE AND EXPLOSION
A. Clean up spills of lubricant or other combustible
substances immediately, if such spills occur.
B. Shut off the compressor and allow it to cool. Then
keep sparks, flames and other sources of ignition
away and DO NOT permit smoking in the vicinity
when checking or adding lubricant or when
refilling air line anti-icer systems with antifreeze
compound.
C. DO NOT permit fluids, including air line anti-icer
system antifreeze compound or fluid film, to
accumulate on, under or around acoustical
material, or on any external surfaces of the air
compressor. Wipe down using an aqueous
industrial cleaner or steam clean as required. If
necessary, remove acoustical material, clean all
surfaces and then replace acoustical material.
Any acoustical material with a protective covering
that has been torn or punctured should be
replaced immediately to prevent accumulation of
liquids or fluid film within the material. DO NOT
use flammable solvents for cleaning purposes.
D. Disconnect and lock out all power at source prior
to attempting any repairs or cleaning of the
compressor or of the inside of the enclosure, if
any.
E. Keep electrical wiring, including all terminals and
pressure connectors in good condition. Replace
any wiring that has cracked, cut, abraded or
otherwise degraded insulation, or terminals that
are worn, discolored or corroded. Keep all
terminals and pressure connectors clean and
tight.
F. Keep grounded and/or conductive objects such as
tools away from exposed live electrical parts such
as terminals to avoid arcing which might serve as
a source of ignition.
G. Remove any acoustical material or other material
that may be damaged by heat or that may support
combustion and is in close proximity, prior to
attempting weld repairs.
H. Keep suitable fully charged Class BC or ABC fire
extinguisher or extinguishers nearby when
servicing and operating the compressor.
I. Keep oily rags, trash, leaves, litter or other
combustibles out of and away from the
compressor.
J. DO NOT operate the compressor without proper
flow of cooling air or water or with inadequate flow
of lubricant or with degraded lubricant.

SAFETY
®SULLAIR®
3700 Operator’s Manual and Parts List 3
K. DO NOT attempt to operate the compressor in
any classification of hazardous environment
unless the compressor has been specially
designed and manufactured for that duty.
1.5 MOVING PARTS
A. Keep hands, arms and other parts of the body
and also clothing away from couplings, fans and
other moving parts.
B. DO NOT attempt to operate the compressor with
the fan, coupling or other guards removed.
C. Wear snug-fitting clothing and confine long hair
when working around this compressor, especially
when exposed to hot or moving parts.
D. Keep access doors, if any, closed except when
making repairs or adjustments.
E. Make sure all personnel are out of and/or clear of
the compressor prior to attempting to start or
operate it.
F. Disconnect and lock out all power at source and
verify at the compressor that all circuits are de-
energized to minimize the possibility of accidental
start-up, or operation, prior to attempting repairs
or adjustments. This is especially important when
compressors are remotely controlled.
G. Keep hands, feet, floors, controls and walking
surfaces clean and free of fluid, water or other
liquids to minimize the possibility of slips and falls.
1.6 HOT SURFACES, SHARP EDGES
AND SHARP CORNERS
A. Avoid bodily contact with hot fluid, hot coolant, hot
surfaces and sharp edges and corners.
B. Keep all parts of the body away from all points of
air discharge.
C. Wear personal protective equipment including
gloves and head covering when working in, on or
around the compressor.
D. Keep a first aid kit handy. Seek medical
assistance promptly in case of injury. DO NOT
ignore small cuts and burns as they may lead to
infection.
1.7 TOXIC AND IRRITATING
SUBSTANCES
A. DO NOT use air from this compressor for
respiration (breathing) except in full compliance
with OSHA Standards 29 CFR 1910 and/or any
applicable Federal, State or Local codes or
regulations.
B. DO NOT use air line anti-icer systems in air lines
supplying respirators or other breathing air
utilization equipment and DO NOT discharge air
from these systems into unventilated or other
confined areas.
C. Operate the compressor only in open or
adequately ventilated areas.
D. Locate the compressor or provide a remote inlet
so that it is not likely to ingest exhaust fumes or
other toxic, noxious or corrosive fumes or
substances.
E. Coolants and lubricants used in this compressor
are typical of the industry. Care should be taken to
avoid accidental ingestion and/or skin contact. In
the event of ingestion, seek medical treatment
promptly. Wash with soap and water in the event
of skin contact. Consult Material Safety Data
Sheet for information pertaining to fluid of fill.
F. Wear goggles or a full face shield when adding
antifreeze compound to air line anti-icer systems.
G. If air line anti-icer system antifreeze compound
enters the eyes or if fumes irritate the eyes, they
should be washed with large quantities of clean
water for fifteen minutes. A physician, preferably
an eye specialist, should be contacted
immediately.
H. DO NOT store air line anti-icer system antifreeze
compound in confined areas.
ADANGER
INHALATION HAZARD!
Death or serious injury can result from
inhaling compressed air without using
proper safety equipment. See OSHA
standards and/or any applicable Federal,
State, and Local codes, standards and
regulations on safety equipment.
SU_0000006

SECTION 1
®SULLAIR®
43700 Operator’s Manual and Parts List
I. The antifreeze compound used in air line
antifreeze systems contains methanol and is
toxic, harmful or fatal if swallowed. Avoid contact
with the skin or eyes and avoid breathing the
fumes. If swallowed, induce vomiting by
administering a tablespoon of salt, in each glass
of clean, warm water until vomit is clear, then
administer two teaspoons of baking soda in a
glass of clean water. Have patient lay down and
cover eyes to exclude light. Call a physician
immediately.
1.8 ELECTRICAL SHOCK
A. This compressor should be installed and
maintained in full compliance with all applicable
Federal, State and Local codes, standards and
regulations, including those of the National
Electrical Code, and also including those relative
to equipment grounding conductors, and only by
personnel that are trained, qualified and
delegated to do so.
B. Keep all parts of the body and any hand-held tools
or other conductive objects away from exposed
live parts of electrical system. Maintain dry
footing, stand on insulating surfaces and DO NOT
contact any other portion of the compressor when
making adjustments or repairs to exposed live
parts of the electrical system. Make all such
adjustments or repairs with one hand only, so as
to minimize the possibility of creating a current
path through the heart.
C. Attempt repairs in clean, dry and well lighted and
ventilated areas only.
D. DO NOT leave the compressor unattended with
open electrical enclosures. If necessary to do so,
then disconnect, lock out and tag all power at
source so others will not inadvertently restore
power.
E. Disconnect, lock out, and tag all power at source
prior to attempting repairs or adjustments to
rotating machinery and prior to handling any
ungrounded conductors.
1.9 LIFTING
A. If the compressor is provided with a lifting bail,
then lift by the bail provided. If no bail is provided,
then lift by sling. Compressors to be air-lifted by
helicopter must not be supported by the lifting bail
but by slings instead. In any event, lift and/or
handle only in full compliance with OSHA
standards 29 CFR 1910 subpart N and/or any
applicable Federal, State, and Local codes,
standards and regulations.
B. Inspect points of attachment for cracked welds
and for cracked, bent, corroded or otherwise
degraded members and for loose bolts or nuts
prior to lifting.
C. Make sure entire lifting, rigging and supporting
structure has been inspected, is in good condition
and has a rated capacity of at least the weight of
the compressor. If you are unsure of the weight,
then weigh compressor before lifting.
D. Make sure lifting hook has a functional safety
latch or equivalent, and is fully engaged and
latched on the bail or slings.
E. Use guide ropes or equivalent to prevent twisting
or swinging of the compressor once it has been
lifted clear of the ground.
F. DO NOT attempt to lift in high winds.
G. Keep all personnel out from under and away from
the compressor whenever it is suspended.
H. Lift compressor no higher than necessary.
I. Keep lift operator in constant attendance
whenever compressor is suspended.
J. Set compressor down only on a level surface
capable of safely supporting at least its weight
and its loading unit.
ADANGER
All field equipment must be tested for
electrostatic fields prior to servicing or
making contact with the machine using
the following or equivalent test
equipment:
• 90-600 VAC: Volt detector such as Fluke
Model 1AC-A
• 600-7000 VAC: Voltage detector such as
Fluke Networks Model C9970
It is the responsibility of each
organization to provide/arrange training
for all their associates expected to test for
electrostatic fields.
SU_0000020

SAFETY
®SULLAIR®
3700 Operator’s Manual and Parts List 5
K. When moving the compressor by forklift truck,
utilize fork pockets if provided. Otherwise, utilize
pallet if provided. If neither fork pockets or pallet
are provided, then make sure compressor is
secure and well balanced on forks before
attempting to raise or transport it any significant
distance.
L. Make sure forklift truck forks are fully engaged
and tipped back prior to lifting or transporting the
compressor.
M. Forklift no higher than necessary to clear
obstacles at floor level and transport and corner at
minimum practical speeds.
N. Make sure pallet-mounted compressors are firmly
bolted or otherwise secured to the pallet prior to
attempting to forklift or transport them. NEVER
attempt to forklift a compressor that is not secured
to its pallet, as uneven floors or sudden stops may
cause the compressor to tumble off, possibly
causing serious injury or property damage in the
process.
1.10 ENTRAPMENT
A. If the compressor enclosure, if any, is large
enough to hold a man and if it is necessary to
enter it to perform service adjustments, inform
other personnel before doing so, or else secure
and tag the access door in the open position to
avoid the possibility of others closing and possibly
latching the door with personnel inside.
B. Make sure all personnel are out of compressor
before closing and latching enclosure doors.

SECTION 1
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63700 Operator’s Manual and Parts List
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®SULLAIR
®
®SULLAIR®
3700 Operator’s Manual and Parts List 7
3700 Operator’s Manual and Parts List
Section 2
DESCRIPTION
2.1 INTRODUCTION
Your new Sullair flood-lubricated rotary screw air
compressor will provide you with a unique experience in
improved reliability and simplified maintenance.
Compared to other types of compressors, the Sullair
rotary screw is unique in mechanical reliability, with “no
wear” and “no inspection” required of the working parts
within the compressor unit.
Read Section 6, MAINTENANCE to see how
surprisingly easy it is to keep your air compressor in top
operating condition.
Figure 2-1
1. Fluid Filter
2. Moisture Separator
3. Sump Tank
4. Fluid Fill Sight Glass
5. Fluid Fill
6. Starter Box
7. Controller
8. E-Stop Button
9. Compressor Unit
10. Cooler Fan Motor
11. Cooler
12. Motor
13. Air Inlet Filter
F i g u r e 2 - 1
Overall Component Layout - Air-Cooled Model
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












 
3!?

SECTION 2
®SULLAIR®
83700 Operator’s Manual and Parts List
2.2 DESCRIPTION OF COMPONENTS
Refer to Figure 2-1 and Figure 2-2. The components
and assemblies of the air compressor are clearly shown.
The complete package includes compressor, electric
motor, starter, compressor inlet system,
compressor discharge system, compressor
lubrication and cooling system, capacity control
system, microprocessor controller, aftercooler, a
combination separator and trap, all mounted on a
heavy gauge steel frame.
On air-cooled models, a fan draws air into the enclosure
over the fan and main motors through the combined
aftercooler and fluid cooler thereby removing the
compression heat from the compressed air and the
cooling fluid, and forces it out the top of the machine.
On water-cooled models, a shell and tube heat
exchanger is mounted on the compressor frame. Fluid is
piped into the heat exchanger where compression heat
is removed from the fluid. Another similar heat
exchanger cools the compressed air.
Both air-cooled and water-cooled versions have easily
accessible items such as the fluid filter air/oil separator
and control valves. The inlet air filter is also easily
accessible for servicing.
2.3 SULLAIR COMPRESSOR UNIT,
FUNCTIONAL DESCRIPTION
Sullair air compressors feature the Sullair compressor
unit, a single-stage, positive displacement, flood
lubricated-type compressor. This unit provides
continuous compression to meet your needs.
The 3700 Series compressors are factory-filled with
Sullube lubricant. For more information on fluid fill,
consult Section 3, SPECIFICATIONS.
Sullair 24KT compressors are filled with a fluid that
rarely needs to be changed. Use only Sullair 24KT fluid
in the event that a fluid change is required.
Sullair recommends that a 24KT sample be taken at the
first filter change and sent to the factory for analysis.
This is a free service. The sample kit with instructions
and self-addressed container is to be supplied by your
Sullair dealer at start-up. The user will receive an
analysis report with recommendations.
Fluid is injected into the compressor unit hoses and
mixes directly with the air as the rotors turn,
compressing the air. The fluid flow has three basic
functions:
1. As coolant, it controls the rise of air temperature
normally associated with the heat of compression.
2. Seals the clearance paths between the rotors and
the stator and also between the rotors themselves.
3. Acts as a lubricating film between the rotors allowing
one rotor to directly drive the other, which is an idler.
After the air/fluid mixture is discharged from the
compressor unit, the fluid is separated from the
air. At this time, the air flows through an
aftercooler and separator then to your service
line while the fluid is being cooled in preparation
for reinjection.
NOTE
With a Sullair compressor, there is no
maintenance or inspection of the internal
parts of the compressor unit permitted in
accordance with the terms of the
warranty.
SU_0000021
CAUTION
Mixing of other lubricants within the
compressor unit will void all warranties.
SU-0000022

DESCRIPTION
®SULLAIR®
3700 Operator’s Manual and Parts List 9
Figure 2-2
F i g u r e 2 - 2
Air-Cooled Cooling/Lubrication and Discharge System
DISCHARGE SYSTEM
SA_0000009
COOLING / LUBRICATION
SYSTEM

SECTION 2
®SULLAIR®
10 3700 Operator’s Manual and Parts List
2.4 COMPRESSOR COOLING AND
LUBRICATION SYSTEM,
FUNCTIONAL DESCRIPTION
Refer to Figure 2-2. The Cooling and Lubrication
System (air-cooled version) consists of a fan, fan
motor, radiator-type aftercooler/fluid cooler, full flow
fluid filter, thermal valve, and interconnecting hoses.
For water-cooled models, two shell and tube heat
exchangers and a water-flow regulating valve are
substituted for the radiator-type cooler listed above. The
pressure in the receiver/sump causes fluid flow by
forcing the fluid from the high pressure area of the sump
to an area of lower pressure in the compressor unit.
Fluid flows from the bottom of the receiver/sump to the
thermal valve. The thermal valve is fully open when the
fluid temperature is below 185°F (85°C) [200°F (93°C)
for 24KT] and pressures are rated at or above 150 psig.
The fluid passes through the thermal valve, the main
filter and directly to the compressor unit where it
lubricates, cools and seals the rotors and the
compression chamber.
As the discharge temperature rises above 185°F (85°C),
due to the heat of compression, the thermal valve begins
to close and a portion of the fluid then flows through the
cooler. From the cooler the fluid flows to the fluid filter
and then on to the compressor unit.
A portion of the fluid flowing to the compressor is routed
to the anti-friction bearings which support the rotors
inside the compressor unit.
The fluid filter has a replacement element and an
integral pressure bypass valve. A message on the
controller indicates when the fluid filter needs to be
changed.
Water-cooled models have a water pressure switch to
prevent operation with inadequate water pressure.
2.5 COMPRESSOR DISCHARGE
SYSTEM, FUNCTIONAL
DESCRIPTION
Refer to Figure 2-2. The compressor unit discharges the
compressed air/fluid mixture into the combination
receiver/sump.
The receiver has three basic functions:
1. It acts as a primary fluid separator.
2. Serves as the compressor fluid sump.
3. Houses the final fluid separator.
The compressed air/fluid mixture enters the receiver and
flows through an internal baffle system. The direction of
movement is changed and its velocity significantly
reduced, thus causing large droplets of fluid to form and
fall to the bottom of the receiver/sump. The fractional
percentage of fluid remaining in the compressed air
collects on the surface of the separator element as the
compressed air flows through the separator. A return line
(or scavenge tube) leads from the bottom of the
separator element to a medium pressure region of the
compressor unit. Fluid collecting on the bottom of the
separator is returned to the compressor by a pressure
differential between the receiver and the compressor. A
visual sight glass is located on the return line to observe
this fluid flow. There is also an orifice in this return line
(protected by a strainer) to assure proper flow. The
separator system reduces the fluid carry-over to less
than 1 ppm (parts per million) or 2 ppm for 24KT. A
message on the controller indicates if abnormal
pressure drop through the separator develops. At this
time, separator element replacement is necessary.
A minimum pressure/check valve, located downstream
from the separator, assures a minimum receiver
pressure of 50 psig (3.4 bar) during loaded conditions.
This pressure is necessary for proper air/fluid separation
and proper fluid circulation.
A terminal check valve is incorporated into the minimum
pressure/check valve to prevent compressed air in the
service line from bleeding back into the receiver on
shutdown and during operation of the compressor in an
unloaded condition.
A pressure relief valve (located on the wet side of the
separator) is set to open if the sump pressure exceeds
the sump tank rating. A temperature switch will shut
down the compressor if the discharge temperature
reaches 235°F (113°C).
Fluid is added to the sump via a capped fluid filler
opening, placed low on the tank to prevent overfilling of
the sump. A sight glass enables the operator to visually
monitor the sump fluid level.
AWARNINGAWARNINGAWARNING
DO NOT remove caps, plugs, and/or other
components when compressor is running
or pressurized.
Stop compressor and relieve all internal
pressure before doing so.
SU_0000023

DESCRIPTION
®SULLAIR®
3700 Operator’s Manual and Parts List 11
2.6 CONTROL SYSTEM, FUNCTIONAL
DESCRIPTION
Refer to Figure 2-3. The purpose of the compressor
Control System is to regulate the amount of air being
compressed to match the amount of compressed air
being used. The Capacity Control System consists of a
solenoid valve, regulator valve and an inlet valve. The
functional description of the Control System is described
below in four distinct phases of operation. For
explanatory purposes, this description will apply to a
compressor with an operating range of 100 to 110 psig
(6.9 to 7.6 bar). A compressor with any other pressure
range would operate in the same manner except stated
pressures.
START MODE - 0 TO 50 PSIG
(0 TO 3.5 BAR)
When the compressor “ ” (START) pad is depressed,
the sump pressure will quickly rise from 0 to 50 psig (0 -
3.4 bar). The compressor initially starts unloaded with
solenoid valve open and inlet valve closed. It then
switches to full load when full rpm has been achieved.
During this period, both the pressure regulator and the
solenoid valve are closed, the inlet valve is fully open
and the compressor pumps at full rated capacity. The
rising compressor air pressure is isolated from the
service line in this phase by the minimum pressure valve
set at approximately 50 psig (3.4 bar).
Figure 2-3
1. Air Outlet
2. Pressure Regulator
3. Solenoid Valve
4. Air Inlet
5. Blowdown Valve
6. Minimum Pressure / Check Valve
7. Sump Tank
F i g u r e 2 - 3
Standard Control System
Art to Come
3
2
1
4
5
6
7
SA_0000010

SECTION 2
®SULLAIR®
12 3700 Operator’s Manual and Parts List
Figure 2-4
1. Air Outlet
2. Pressure Regulator
3. Solenoid Valve
4. Air Inlet
5. Blowdown Valve
6. Minimum Pressure / Check Valve
7. Sump Tank
F i g u r e 2 - 4
Sequencing Control System
FULL LOAD MODE - 50 TO 100 PSIG (3.4 TO
6.9 BAR)
When the compressed air pressure rises above 50 psig
(3.4 bar), the minimum pressure valve opens allowing
compressed air to flow into the service line. From this
point on, the line air pressure is continually monitored by
the microprocessor controller. The pressure regulator
and the solenoid valve remain closed during this phase.
The inlet valve is in the fully open position as long as the
compressor is running at 100 psig (6.9 bar) or below.
MODULATING MODE - 100 TO 110 PSIG (6.9
TO 7.6 BAR)
If less than the rated capacity of compressed air is being
used, the service line pressure will rise above 100 psig
(6.9 bar). The pressure regulator valve gradually opens,
directing air pressure to the inlet control valve, reducing
air entering the compressor until it matches the amount
of air being used. The control system functions
continually in this manner between the limits of 100 to
110 psig (6.9 to 7.6 bar) in response to varying demands
from the service line.
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DESCRIPTION
®SULLAIR®
3700 Operator’s Manual and Parts List 13
The integrated inlet valve has an orifice which vents a
small amount of air inlet when the pressure regulator
controls the inlet control valve. The orifice also bleeds
any accumulated moisture from the control lines.
UNLOAD MODE - IN EXCESS OF 110 PSIG
(7.6 BAR)
When a relatively small amount or no air is being used,
the service line pressure continues to rise. When it
exceeds 110 psig (7.6 bar), the microprocessor control
system de-energizes the solenoid valve allowing sump
air pressure to be supplied directly to close the inlet
valve. Simultaneously, the solenoid valve sends a
pneumatic signal to the blowdown valve. The blowdown
valve opens to the atmosphere, located in the
compressor intake, reducing the sump pressure to
approximately 17 psig (1.2 bar). The check valve in the
air service line prevents line pressure from returning to
the sump.
When the line pressure drops to the low setting (cut-in
pressure; usually 100 psig (6.9 bar) on low pressure
(7 bar) compressors and 125 psig (8.6 bar) on high
pressure (9 bar) compressors, 150 psig (10.3 bar) on (10
bar) compressors, 175 psig (12.0 bar) (12 bar), the
microprocessor controller energizes the solenoid valve
and allows the blowdown valve to close. The re-
energized solenoid valve again prevents line pressure
from reaching the inlet control valve. Should the
pressure begin to rise, the pressure regulator will
resume its normal function as previously described.
LOAD/NO LOAD CONTROL
If desired by the customer, the compressor can be set to
operate load/no load without modulating control. This
control mode is often selected when a large amount of
compressed air storage (air tank) is available. Using the
microprocessor keypad, select “load/no load control”
from the menu. On a machine rated for 100 psig (7 bar)
the compressor will run in the full load mode up to
100 psig (7 bar). If less than the rated capacity is
required, pressure will rise above 100 psig and the
microprocessor will de-energize the solenoid valve,
causing the compressor to run in the unload mode.
When the system pressure falls to 90 psig (6.3 bar), the
microprocessor energizes the solenoid valve, causing
the compressor to return to the full load mode. The
compressor will thus operate to keep the system
pressure in the range of 90-100 psig (6.3 - 6.9 bar).
AUTOMATIC OPERATION
For applications with varied periods of time when there
are no air requirements, the microprocessor’s
AUTOMATIC mode allows the compressor to shutdown
(time delayed) when no compressed air requirement is
present and restart as compressed air is needed.
2.7 AIR INLET SYSTEM, FUNCTIONAL
DESCRIPTION
Refer to Figure 2-5. The Compressor Inlet System
consists of a dry-type air filter, a restriction gauge
and an air inlet valve.
The restriction gauge (located on the air filter) indicates
the condition of the air filter by showing red when filter
maintenance is required.
The poppet-type modulating air inlet valve directly
controls the amount of air intake to the compressor in
response to the operation of the pressure regulator (see
MODULATING MODE - 100 TO 110 PSIG (6.9 TO 7.6
BAR) on page 12). The inlet valve also acts as a check
valve, thus preventing reverse rotation when the
compressor is shut down.
AWARNINGAWARNINGAWARNING
“The Plastic Pipe Institute recommends
against the use of thermoplastic pipe to
transport compressed air or other
compressed gases in exposed above
ground locations, e.g. in exposed plant
piping.” (I)
Sullube should not be used with PVC
piping systems. It may affect the bond at
cemented joints. Certain other plastic
materials may also be affected.
(I) Plastic Pipe Institute, Recommendation
B, Adopted January 19, 1972.
SU_0000024

SECTION 2
®SULLAIR®
14 3700 Operator’s Manual and Parts List
Figure 2-5
1. Air Inlet Filter
2. Air Inlet
3. Compressor Unit
4. Sump Tank (Mounting)
F i g u r e 2 - 5
Air Inlet System
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