Gardner Denver ELECTRA-SCREW ESG User manual

13-9-601
1st EDITION
ELECTRA-SCREW@
STATIONARY
COMPRESSORS
@30 HP-
IMoDEL
040 HP-
MODEL
●50 HP-
MODEL
ESG
ESH
ESJ
13-9-601

WARRANTY
Subject to the terms and conditions hereinafter set forth, Gardner-Denver Company (the
Company) warrants products and parts sold by it, insofar as they are of its own manufacture,
against defects of material andworkmanship, under useandservice accordance with Company's
written instructions, recommendations and ratings for installation, operating, maintenance and
service of products, for aperiod of three months from the date of initial use, provided that such
three month period shall in no case extend beyond one year from the date of shipment by
Company. THIS WARRANTY IS LIMITED TO THE REPAIR OR REPLACEMENT, AS
COMPANY MAY ELECT, OF ANY DEFECTIVE PARTS, REGARDING WHICH, UPON
DISCOVERY OF THE DEFECTS, THE PURCHASER HAS GIVEN IMMEDIATE WRITTEN
NOTICE. Installation and transportation costs are not included. Company shall have the option
of requiring the return to it of the defective material, transportation prepaid, for inspection.
Because of varying conditions of installation and operation, all guarantees of performance are
subject to variation of 3% COMPANY DOES NOT WARRANT THE MERCHANTABILITY
OF ITS PRODUCTS AND DOES NOT MAKE ANY WARRANTY, EXPRESS OR IMPLIED,
OTHER THAN THE WARRANTY CONTAINED HEREIN. Company has not authorized
anybody to make any representation or warranty other than the warranty contained herein.
FOREWORD
Gardner-Denver ELECTRA-SCREW@ compressors are the result of advanced engineering and skilled
manufacturing. To be assured of receiving maximum service from this machine, the owner must exercise
care in its operation and maintenance. This book is written to give the operator and the maintenance
department essential information for day-to-day operation, maintenance and adjustment. Careful adherence
to these instructions will result in economical operation and minimum downtime.
TABLE OF CONTENTS
GENERAL INFORMATION .......................................................
CONTROLS AND INSTRUMENTS. .................................................
LUBRICATION –OILCOOLER, OIL FILTER AND SEPARATOR ..........................
AIR FILTERS .................................................................
COUPLING ...................................................................
INSTALLATION ...............................................................
STARTING AND OPERATING PROCEDURES ..........................................
MAINTENANCE SCHEDULE ......................................................
TROUBLE SHOOTING ...........................................................
COMPRESSOR OVERHAUL .......................................................
SECTION 1
SECTION 2
SECTION 3
SECTION 4
SECI’ION 5
SECTION 6
SECTION 7
SECTION 8
SECTION 9
SECTION 10
13-9-601 Page i

INDEX
NOTE: Numbers preceding dash are Section Numbers –numbers following dash are Page Numbers.
Addition of Oil Between Changes ................
Aftercooler ..............................
Aftercooler (Heat Exchanger Water Piping) . . , . . . . . . .
Air Filter .......................4–1.7–1.
Air Filter, Heavy-Duty .......................
AIR FILTERS (SECTION 4).... ..............
Air flow ...............................
Air& Oil Discharge Temperature ................
Air-Oil Systems Flow Diagram.. ................
Air Pressure Adjustment (Automatic Start-Stop) .......
Air Pressure Adjustment (Dual) ...,...,.........
Air Pressure Adjustment (Duomatic) . . . . , . , . . . . . . .
Air Pressure Gauge .........................
Air Receiver, Auxiliary, .....................
Air Receiver-Oil Reservoir .....................
Air Receiver Pressure Adjustment (Constant Speed) . . . . .
Alignment of Compressor &Motor.., ............
Alignment, Coupling . . . . . . . . . . . . . . . . . . ..5–1.
Assembly ...............................
Automatic Blowdown System. .................
Automatic Blowdown Valve.. .................
Automatic Start-Stop Control System. ......,......
Automatic Start-Stop (Duomatic) ................
Auxiliary Air Receiver .......................
Blowdown System, Automatic .......,..,.......
Blowdown Valve, Automatic. ..................
Blowdown Valve Piping ......................
3–2
6–1
6–2
8–1
4–1
4–1
1–1
3–6
3–1
2–6
2–6
2–9
2–2
6–1
3–4
2–3
O–8
7–1
o–2
3–5
2–2
2–6
2–8
6–1
3–5
2–2
6–2
Canopy Enclosure ..........................
Capacities, Oil, ...........................
Check, Compressor Oil System. ...,.,...........
Check, Daily .............................
Check List, Service .........................
Check Valve (Oil Reservoir) ...................
Circuit Breaker ...........................
6–1
3–2
3–6
7–1
8–1
2–2
2–1
Cleaning &Draining Oil System. ................3–2
Clearance Chart -Unit Cold.... ...............10–4
Cold Ambient Operation .....................3–2
Compression Principle .......................1–1
Compressor .............................1–1
Compressor Lubricants ......................3–2
Compressor Oil, ..........................7–1
Compressor Oil Cooler –Radiator Type. ........... 3–3
Compressor Oil Cooler –Water-Cooled Heat Exchanger . . 3–3
Compressor Oil Filter .......................3–3
Compressor Oil Inlet Temperature. ............... 3–6
Compressor Oil Separator..,.. ................ 3–4
Compressor Oil System ......................3–1
Compressor Oil System Check.... . . . . . . . . . . . . ..3–6
Compressor Outline ........................1–4
COMPRESSOR OVERHAUL (SECTION 10). . . . . . . . . 10–1
Condensate Ejector Drain .,... . . . . . . . . . . . . . . ..6–1
Constant Speed Control System ................. 2–2
Constant Speed (Duomatic Control). . . . . . . , . . . . . . . 2–8
Control Piping ...........................6–1
CONTROLS &INSTRUMENTS (SECTION 2). . . . . . . . 2–1
Control System (Automatic Start-Stop). . . . . . . . . . . . . 2–6
Control System (Constant Speed) ....,....,...... 2–2
Control System (Dual) .......................2–6
Control System (Duomatic) .................... 2–8
Control Valve, Oil Flow (Duomatic Unit Only). .,,.... 3–5
Control Valve, Water Flow (Heat Exchanger) ......... 3–4
Control Voltage ...........................2–1
coupling ...............................5–1
COUPLING (SECTION 5) ..,,... . . . . . . . . . . ..5–1
Coupling Alignment ....................5–1. 7–1
13-9-601
Daily Check .............................7–1
Differential Group, Pressure, ,.................. 3–5
Dimensions ..............................10–9
Disassembly Instructions . . . . ... . . . . . . . . . . . . . ..10–1
Discharge Pressure Valve, Minimum .......,....... 2–2
Discharge Service Line .......................6–2
Discharge Temperature, Air&Oil. ............... 3–6
Drain, Condensate Ejector.. ..................6–1
Draining &Cleaning Oil System . . . . . . . . . . . . . . . . . 3–2
Drain, Oil Reservoir ........................6–1
Dual Control System .......... ., ............2–6
Duomatic Control System .....................2–8
Dust Cup (Heavy-Duty Air Filter) ...,............ 4–1
Ejector Drti, Condensate ....................6–1
Electrical ...........................6–3.7–1
Electrical Wiring (Automatic Start-Stop) ........ 2–5, 2–6
Electrical Wiring (Constant Speed). ........,.. 2–3, 2–4
Electrical Wiring (Dual) ..................2–7. 2–8
Electrical Wiring (Duomatic) ...............2–9, 2–10
Element, Filter (Heavy-Duty) ....,.,.,.......... 4–1
Element Life, Filter (Heavy-Duty) ..,............. 4–2
Fan ..................................3–6
Filling Oil Reservoir ........................3–3
Filter, Air, .....................4–1.7–1.8–1
Filter, Compressor Oil .,..... . . . . . . . . . . . . . . ..3–3
Filter Element (Heavy-Duty) ...................4–1
Filter Element Life (Heavy-Duty) ................ 4–2
Filter, Heavy-Duty Air, ......................4–1
FILTERs, AIR (SECTION 4)...... . . . . . . . . . . ..4–1
Fits ..................................10–9
Flow Diagran -Air-Oil Systems ... ., . . . . . . . . . ..3–1
Foundation .............................6–1
Gauge, Air Pressure ........,. ,.............z–2
Gauge, Oil Level ..........................3–2
Gauge, Oil Temperature ......,...............2–2
Gauges &Instruments .......................2–2
Gear Data (Drive &Driven) ..,. . . . . . . . . . . . . . ..10–7
General (Controls &Instruments) ................ 2–1
GENERAL INFORMATION (SECTION 1) .......... 1–1
General (Installation) . . . . . . . . . . . . . . . . . . . . . ..6–1
Heat Exchanger Type Compressor Oil Cooler . . . . . . . . . 3–3
Heavy-Duty Air Filter .......................4–1
High Air Temperature Shutdown Switch .....,...... 2–I
High Oil Reservoir Pressure Shutdown Switch. ......,. 2–1
Honrmeter ..............................2–2
INFORMATION, GENERAL (SECTION 1). ......... 1–1
Inlet Line ..............................6–2
Inlet Pressure, Oil ............ .............3–6
Inlet Screen &Tube (Heavy-Duty Air Filter) . . . . . . . . . 4–2
Inlet Temperature, Compressor Oil ............... 3–6
Inlet Valve (Constant Speed).,.. ............... 2–3
Inlet Valve(Duomatic) ......................2–8
INSTALLATION (SECTION 6) ................ 6–1
INSTRUMENTS &CONTROLS (SECTION 2). ....... 2–1
Instruments &Gauges .......................2–2
Page ii

Light Test, Operating . . . . . . . . . . . . . . . . . . . . . ..7–1
Location (Installation )........ ...............6–1
Lubricants, Compressor ......................3–2
Lubrication, Cooling &Sealing. ................. 1–1
LUBRICATION –OIL COOLER, OIL FILTER
&SEPARATOR (SECTION ).............. 3–1
Maintenance of Air Filters ..........,..... 4-1, 4–2
MAINTENANCE SCHEDULE (SECTION 8) . . . . . . . . 8–1
Minimum Discharge Pressure Valve ............... 2–2
Minimum Operating Pressure (Automatic Start-Stop). .... 2–6
Minimum Operating Pressure (Constant Speed) . . . . . . . . 2–3
Minimum Operating Pressure (Dual) ..,........... 2–8
Minimum Operating Pressure (Duomatic) . . . . . . . . . . . . 2–9
Mixing Valve, Thermostatic (Radiator-Type Oil Cooler) . . . 3–3
Mode, Operating . . . . . . . . . . . . . . . . . . . . . . . . ..7–1
Motor Protection Devices ..................... 2–1
Oil& Air Discharge Temperature ................ 3–6
Oil-Air Systems Flow Diagram. .................3–1
Oil Capacities ............................3–2
Oil Change Interval .........................3–2
Oil, Compressor ...........................7–1
Oil Cooler, Compressor –Radiator Type ........... 3–3
Oil Cooler, Compressor –Water-Cooled Heat Exchanger . . 3–3
Oil Cooler Oil Pressure Drop... ................3–6
Oil Filter -Compressor ......................3–3
Oil Flow Control Valve (Duomatic Only) ........... 3–’5
Oil Inlet Pressure ..........................3–6
Oil Inlet Temperature, Compressor ............... 3–6
Oil Level Gauge ...........................3–2
Oil Pressure Drop, Oil Cooler... ...............3–6
Oil Quality ..............................3–2
Oil Reservoir -Air Receiver ...................3–4
Oil Reservoir Check Valve... .................2–2
Oil Reservoir Drain .........................6–1
Oil Reservoir -Filling ......................3–3
oil Reservoir Pressure Shutdown, High ............. 2–1
Oil Return ..............................3–5
Oil Separator, Compressor ....................3–4
Oil Specifications .........................3–1
Oil System ..............................3–1
Oil System Check, Compressor. ................. 3–6
Oil System-Draining&Cleaning ...............3–2
Oil Temperature Gauge . . . . . . . . . . . . . . . . . . . . ..2–2
On-Off Switches ..........................2–1
Operating Air Pressure Adjustment (Automatic Start-Stop) .2–6
Operating Air Pressure Adjustment (Dual) ........... 2–6
Operating Air Pressure Adjustment (Duomatic) . . . . . . . . 2–9
Operating Light Test ........................7–1
Operating Mode ...........................7–1
Operating Pressure, Minimum (Auto Start-Stop). .,..... 2–6
Operating Pressure, Minimum (Constant Speed) . . . . . . . . 2–3
Operating Pressure, Minimum (Dual) .............. 2–8
Operating Pressure, Minimum (Duomatic) . . . . . . . . . . . 2–9
OPERATING PROCEDURES &STARTING (SECTION 7) 7–1
Outline, Compressor . . . . . . . . . . . . . . . . . . . . . . ..1–4
OVERHAUL –COMPRESSOR (SECTION 10) ., . . . . . 10-1
Pilot, Subtractive ..........................2–2
Piping.................. ...............7–1
Piping, Blowdown Valve ......................6–2
Piping, Control ...........................6–1
Piping, Water (Water-Cooled Units) ............... 6–2
Pressure Adjustment, Air Receiver Section (Constant Speed) 2–3
Pressure Adjustment, Operating Air (Automatic Start-Stop) 2–6
Pressure Adjustment, Operating Air (Dual). . . . . . . . . . . 2–6
Pressure Adjustment, Operating Air (Duomatic). . . . . . . . 2–9
Pressure Differential Group... ................. 3–5
Pressure Drop, Oil Cooler Oil ..................3–6
Pressure Gauge, Air . . . . . . . . . . . . . . . . . . . . . . . ..2–2
Pressure, Minimum Operating (Automatic Start-Stop) . . . . 2–6
Pressure, Minimum Operating (Constant Speed) ........ 2–3
Pressure, Minimum Operating (Dual) ....,......... 2–8
Pressure, Minimum Operating (Duomatic) . . . . . . . . . . . 2–9
Pressure, Oil Inlet .........................3–6
Pressure Shutdown, High Oil Reservoir . . . . . . . . . . . . . 2–1
Pressure, System ..........................7–1
Pressure Valve, Minimum Discharge ............... 2–2
Radiator Type Oil Cooler .....................3–3
Rebuilding Data . . . . . . . . . . . . . . . . . . . . . . . . ..10–9
Receiver, Auxiliary Air.... ..................6–1
Reservoir Drain, Oil ........................6–1
Reservoir (Oil) Check Valve... ................2–2
Rotation ...............................7–1
Running Clearances .........................10–9
Safety Devices ............................2–1
Safety Valve .............................2–2
Screw Torque Tightening Recommendations. .........10–3
Sectional View of Compressor . . . . . . . . . . . . . . . . . . 10–3
Separator, Compressor Oil...... . . . . . . . . . . . . . . . 3–4
Service Check list .........................8–1
Service Liue, Discharge.......................6–2
Shutdown Switch, High Air Temperature ........... 2–1
Shutdown Switch, High Oil Reservoir Pressure ........ 2–1
Shutoff Valve, Water (Water-Cooled Heat Exchanger) .... 3–4
Specifications, Oil ..........................3–1
STARTING &OPERATING PROCEDURES (SECTION 7) 7–1
Starting unit -cold ........................7–1
Starting Unit -Hot ........................7–1
Stopping Unit ............................7–1
Subtractive Pilot ..........................2–2
Switch, High Air Temperature Shutdown ........... 2–1
Switch, High Oil Reservoir Pressure Shutdown . . . . . . . . 2–1
Switches, ’’On-Off’’ ........................2–1
System Pressure ...........................7–1
Temperature, Air& Oil Discharge . . . . . . . . . . . . . . . . 3–6
Temperature, Compressor Oil Inlet ............... 3–6
Temperature Gauge, Oil ......................2–2
Temperature Shutdown Switch, High Air . . . . . . . . . . . 2–1
Thermostatic Mixing Valve (Radiator Type oil Cooler) ... 3–3
Timed Automatic Start-Stop (Duomatic) . . . . . . . . . . . . 2–8
Torque Tightening Recommendations ..............10–3
TROUBLE SHOOTING (SECTION 9). ............ 9–1
Valve, Automatic Blowdown. ..................2–2
VaIve, Check (Oil Reservoir) ...................2–2
Valve, Inlet (Constant Speed) .................. 2–3
Valve, Inlet (Duomatic Control) .......,......... 2–8
Valve, Minimum Discharge Pressure ............... 2–2
Valve, Oil Flow Control (Duomatic Only) . . . . . . . . . . . 3–5
Va.lve Piping, Blowdown ......................6–2
Valve, Safety ............................2–2
Valve, Thermostatic Mixing (Radiator-Type Oil Cooler) . . . 3–3
Valve, Water Flow Control (Heat Exchanger) . . . . . . . . . 3–4
Valve, Water Shutoff (Water-Cooled Heat Exchanger) . . . . 3–4
Voltage, Control ..........................2–1
Water Flow .............................6–4
Water Flow Control Valve (Heat Exchanger) ......... 3–4
Water Piping (Water-Cooled Units). ......,........ 6–2
Water Shutoff Valve (Water-Cooled Heat Exchanger). . . . . 3–4
Wiring Diagram (Automatic Start-Stop) ............. 2–5
Wiring Diagram (Constant Speed) . . . . . . . . . . . . . , . . 2–4
Wiring Diagram (Dual Control) .................. 2–7
Wiring Diagram (Duomatic Control). . . . . . . . . . . . . . . 2–10
Wiring, Electrical ......................6–3.7–1
13-9-601 Page iii

SECTION 1
GENERAL INFORMATION
COMPRESSOR –The Gardner-Denver Model “ES”. Electra-Screw@ compressor is asingle stage, positive displacement
rotary machine using meshing helical rotors to effect compression. The input drive shaft and helical drive gear are supported
in the gear case by high capacity ball bearings; the drive gear meshes with adriven gear mounted on the main rotor shaft
to drive the rotors. Both rotors are supported between large capacity antifriction bearings located outside the compression
chamber. Single-width cylindrical roller bearings are used at the inlet end of the rotors. Two heavy-duty single row angular
contact ball bearings at the discharge end locate each rotor axially and carry all thrust loads.
COMPRESSION PRINCIPLE (Figure l-l) –Compression is accomplished by the main and secondary rotors synchronously
meshing in aone-piece cvlinder. The main rotor has four helical lobes 90° apart. The secondary rotor has six matching
helical grooves 60 apart to allow meshing
%— aoToa
.
with main rotor lobes.
FIGURE 1-1. –COMPRESSION CYCLE
The air inlet port is located on top of the compressor near the drive shaft end. The discharge port is near the bottom at
the opposite end of the compressor cylinder. Figure 1-1 is an inverted view to show inlet and discharge ports. The com-
pression cycle begins as rotors unmesh at the inlet port and air is drawn into the cavity between the main rotor lobes and
secondary rotor grooves (A). When the rotors pass the inlet port cutoff, air is trapped in the interlobe cavity and flows
axially with the meshing rotors (B). As meshing continues, more of the main rotor lobe enters the secondary rotor groove,
normal volume is reduced and pressure increases. Oil is injected into the cylinder to remove the heat of compression and
seal internal clearances. Volume reduction and pressure increase continues until the air/oil mixture trapped in the interlobe
cavity by the rotors passes the discharge port and is released to the oil reservoir (C).
AIR FLOW (Figure 1-3) –Air enters the air filter and passes through the inlet unloader valve to the compressor. After
compression, the air/oil mixture passes into the oil reservoir where more than 9970 of the entrained oil is removed by velocity
change and impingement and drops back into the reservoir. Amultiple element final separator removes the balance of the
oil and returns it to the system through tubing connecting the separator and compressor. The air then passes through the
reservoir check valve, the air receiver section and the minimum pressure valve to the plant air lines.
LUBRICATION, COOLING AND SEALING –Oil is forced by air pressure from the oil reservoir through the oil filter,
oil cooler and thermostatic mixing valve (mixing valve is not used with the water-cooled oil cooler), and discharges into
the compressor main oil gallery. Aportion of the oil is directed through internal passages to the bearings, gears and shaft
oil seals. The balance of the oil is injected directly into the compression chamber to remove heat of compression, seal
internal clearances and lubricate the rotors.
13-9-601 Section 1Page 1

13-9-601 Section 1Page 2

13-9-601 Section 1Page 3

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13-9-601 Section 1Page 4

SECTION 2
CONTROLS &INSTRUMENTS
GENERAL –The Gardner-Denver Model “ES”
systems:
Constant Speed
Automatic Start-Stop
Electra-Screw@ compressor units are available with four different control
Dual (Selective –Constant Speed or Automatic Start-Stop)
Duomatic (Selective –Constant Speed With Low Unloaded Horsepower or Automatic Start-Stop)
Unless customer specifications instruct otherwise, the Electra-Screw@ unit is prewired at the factory with all starter to
motor and control connections for the voltage specified on the order. It is necessary only to connect the unit starter to
the correct power supply and the shop air line and water line if the unit is the heat exchanger type. The standard unit is
supplied with the control system specified, an open drip-proof motor, NEMA 1starter enclosure and adust resistant control
enclosure/instrument panel.
CONTROL VOLTAGE –The control voltage for push buttons, lights, hourmeter, pressure switches, high discharge tem-
perature shutdown switch, blowdown valve, and other electrical control devices is II 5volts regardless of power supply
voltage. Atransformer in the control enclosure is connected to change the power supply voltage to 115 volt control
voltage.
CIRCUIT BREAKERS –The instrument panel for any of the four control systems incorporates two separate push-to-reset
type circuit breakers for high discharge temperature and high reservoir pressure shutdown switches (Figures 4-2, 7-2, 8-2
and 11-2). If either atemperature or pressure failure occurs, the circuit breaker button will pop up indicating which safety
device has stopped the unit.
DO NOT CONTINUE TO RESET THE CIRCUIT BREAKER IF THE SAME MALFUNCTION OCCURS WITHIN A
SHORT PERIOD. FIND AND CORRECT THE TROUBLE BEFORE RESUMING OPERA TION.
ON-OFF SWITCHES –The “On-Off” switch for the constant speed, automatic start-stop and dual control units has an
amber lighted “On” section. The timed duomatic control switch has agreen lighted “Load” section in addition to the “On”
section; the black bar on the bottom of this switch is nonfunctional. To replace the bulb (Sylvania 120 PSB or equal)
in the switch:
1. Turn power off at main breaker panel.
2. Open control panel.
3. Turn slotted locking screw on upper side of switch body counterclockwise 1/4 turn and remove switch body from
switch operator.
4. Remove old bulb located in stem of switch body and insert new bulb.
5. Reassemble switch body to operator and lock in” place by turning locking screw 1/4 turn clockwise.
SAFETY DEVICES –All four control systems incorporate these safety devices:
Motor Protection Devices –Overload heaters are furnished for the starter in the voltage range specified. There are three
(3) overloads in the starter of proper size for the starter and its enclosure. When replacing or changing overloads, be sure
to select from a 3 overload heater table since the use of athird overload derates each overload for agiven enclosure due to
the extra heat. An overload from a2overload heater table would be undersize.
The overload heaters are in acommon overload block in the starter and have asingle common percentage adjustment
with a 90 to 110% range. The unit is set at the factory on the 100% mark.
High Air Temperature Shutdown –The compressor is protected from lubrication failure by ahigh discharge temperature
switch located in the discharge pipe between the compressor discharge and the oil reservoir. This switch is wired into the
motor control circuit and will shut the unit down if discharge temperature exceeds 225° F. The manual reset is located
as described in “Circuit Breakers” paragraph, and must be reset any time unit is shut down due to high air discharge
temperature.
High Oil Reservoir Pressure Shutdown –The unit is protected from high oil reservoir pressure by apressure switch located
under the control panel and wired into the motor control circuit with piping to the oil reservoir section. This switch will shut
the unit down if pressure in the oil reservoir exceeds 165 PSIG, acting as asafety valve without loss of oil. THE MAXIMUM
ALLOWABLE SETTING IS 165 PSIG. The manual reset is located as described in “Circuit Breakers” paragraph, and must
be reset any time unit is shut down due to high oil reservoir pressure.
13-9-601 Section 2Page 1

Automatic Blowdown Valve (Figure 1-3) –Asolenoid valve piped into the oil reservoir section between the oil separator
and reservoir check valve and wired into the motor control circuit will release pressure from the oil reservoir each time
the motor stops on constant speed, automatic start-stop or dual control systems. On the duomatic system, pressure will
be released from the oil reservoir each time the compressor unloads or is shut down. A3/16” diameter orifice is used to
maintain blowdown time to about 45 seconds and prevent oil carry-over due to too rapid arelease of press tire. Asilencer
terminates the blowdown line to muffle air discharge noise.
Safety Valve (Figures 2-1 &4-1) installed in the air receiver section is set at the factory to 110% of the specified operating
pressure for protection against overpressure of the air receiver section. Periodic checks should be made to insure its proper
operation. Never operate the unit without aproper safety valve setting.
NEVER DISCONNECT SAFETY DEVICES THAT PROTECT THE UNIT.
INSTRUMENTS AND GAUGES (Figures 4-2, 7-2, 8-2 &11-2) –The constant speed and the automatic start-stop units
have alighted “ON-OFF” push button.
The dual control unit has alighted selector switch with “CON-OFF” and “AUTO-OFF” push buttons for thetwo modes
of operation.
The duomatic control unit has alighted “ON-OFF” push button with lighted sections which indicate “On” (compressor
running) and “Load” (compressor loaded).
All four control system instrument panels incorporate the following:
Hourmeter –Acontinuous reading (nonreset) type hourmeter displays the accumulated operating time of the unit and
provides aconvenient means for scheduling changes and servicing of oil supply, Falters, separator and other devices.
Air’ Pressure Gauge –Adirect reading air pressure gauge indicates air pressure in the air receiver section of the reservoir.
Oil Temperature Gauge –Adirect reading temperature gauge indicates compressor oil inlet temperature.
MINIMUM DISCHARGE PRESSURE VALVE (Figure I-2) –An internal
pilot operated minimum pressure valve is used in the discharge line from
the air receiver section of the reservoir to provide apositive pressure on
the oil system of the compressor and prevent excessive oil carry-over into
shop air lines even when the air service valve is fully open. The amount
of oil carry-over into the air service line depends on the operating pressure.
Anormal carry-over amount is one pint per 100 hours of operation at
100 PSIG.
The valve incorporates an orifice which, when air is flowing through it,
maintains approximately 65 PSIG in the air receiver section. Aspring-
loaded piston valve senses air pressure in the air receiver section. When
the system pressure rises above 65 PSIG, the piston spring is overridden
and the valve opens to full porting.
FIGURE 1-2. –MINIMUM DISCHARGE The valve does not require maintenance or adjustment. If the valve fails
PRESSURE VALVE to function, check piston O-rings for sealing, piston orifice for restriction,
or piston and valve seat for burrs and dirt.
CHECK VALVE (Oil Reservoir) (Figures 2-2 &1-3) –AVALVE
renewable resilient disc-type check valve between the oil reser-
voir (separator) and air receiver sections prevents backflow of Al R
air when the unit stops, unloads or is shut down. 1
FLOW
CONSTANT SPEED CONTROL SYSTEM (Figures 3-2, 4-2 &
5-2) –The Constant Speed Control system is used where BUMPER
requirements for air are high for long periods, causing the unit
to remain loaded most of the time. The “On-Off’ switch and FIGURE 2-2. –RESERVOIR CHECK VALVE
instrument panel is shown in Figure 4-2. The control is a
stepless pneumatic system which regulates the compressor inlet
to match the air demand made on the compressor. Effective from Oto 100% of compressor capacity, the system opens
the inlet valve as air is drawn from service valve, maintains aconstant valve opening as air demand levels off, or closes the
valve when the demand ceases. This system includes the subtractive pilot and inlet valve.
Subtractive Pilot –The subtractive pilot is aspring-loaded diaphragm-actuated valve that regulates air pressure from the air
receiver section to the unloader piston. The pilot admits air to the inlet valve piston when an air receiver section pressure
equal to the pilot low setting is reached. The air begins to pass through pilot to the piston, and the inlet valve begins to
close. As the air receiver section pressure increases the pilot pressure also increases on the inlet valve piston, closing the
inlet valve. At full receiver pressure (pilot unload setting) the pilot is exerting full differential pressure on the inlet valve
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