holset st676 and st773 air compressor oil carryover. september, 1997

8/20/2019 Holset ST676 and ST773 Air Compressor Oil Carryover. September, 1997

http://slidepdf.com/reader/full/holset-st676-and-st773-air-compressor-oil-carryover-september-1997 1/14

L

- e Servlce Bulletln-/

Subject

Holset ST676 and ST773 Air Compressor Oil Carryover

BulletinNo. 3666221 Date:

September 1

This service bulletin will explain the plumbing necessary to control oil carryover in the Holset Twin CylindeCompressor.

Oil carryover has been experienced on Holset twin cylinder air compressors in certain high air use applicationsas bulk unloading, central tire inflation systems, and mining. In most cases, the problem has been c1eterminedin the air system plumbing downstream from the air compressor. .

The following information describes and illustrates the makeup of air systems (by applications) that will allow for poperation of a Holset twin cylinder air compressor. The systems described were developed to address oil carrissues and have demonstrated the ability to function properly in the field. Most air systems in service, as of theof this publication, do not meet these guidelines and may need to be modified to function properly. Refer ttroubleshooting tree on page 4. However, if a current system is not generating complaints of oil carryover or redcompressor life, it should not be changed.

The following guidelines will aid in troubleshooting oil carryover in a system with a twin cylinder air compress

HOLSET ST MODEL COMPRESSOR PWMBING by APPLlCATION CATEGORIES (DURATION and PRESS

'"Meeting the objective of providing Goal, clean, dry air to the regí of the system is economically achieved by thof a pressure-governed "receiver" tank. The cooling of the air, which will condense water and oil vapors so thebe periodically eliminated from this tank, greatly improves the performance of a downstream air dryer for brakecentral tire inflation (CTI)system. It algo provides significant moisture and contaminant reduction for air flowing d(not going through the brake system air dryer) to a bulk tank trailer or other vehicle system which requires high-voair pressure. Cummins Engine Co. recommends the use of an appropriate high volume filler to remove any rem

contamination prior to air delivery to a bulk trailer tank or other system.

Discharge air temperature at the compressor can be ayer 204°C [400OF].A good cooling arrangement will reducair temperature to well below 65.6°C [150°F] at the dryer inlet. Low spots/condensation traps must be avoided. and oil condensation should be eliminated before reaching the air dryer or other filler.

While many components and plumbing arrangements are possible to do this, Cummins Engine Co. recommendfollowing as a consistent and economical approach.

. Compressor inlet may be naturally aspirated (take air al, or near, the engine air cleaner) or turbocharge

. Use a 1 inch Nominal, or larger, discharge line. Teflon lining is recommended. Steel or copper provides

heat transfer.. Use a mínimum of 4.56 m [15 tí] of length before receiver tank. Avoid elbow fittings by using bends.

. Use a 2500 cubic inch mínimum size receiver tank with 175 psig safety valve.

. Use a heated "automatic" drain valve instead oí, or in addition lo, a manual drain for both the receiver and stanks.

-"

Cummlns Englne Company, Ine., Columbus, Indiana 47202-3005Cummlns Englne Company Ud., Daventry, Northants, England NN11 5NURegistered Office:46.50 Coombe Road, New Malden, Surrey KT3 40LRegistered No. 573951 EnglandCopyri\)ht @ 1997Cummlns Englne Company, Inc.AII rights reserved

.



Holset ST676 and ST773 Air Compressor Di! Carryoverpage 2

. Control the compressor trom the receiver tank pressure with the governor set at 10 psig above the governopressure setting which controls the dryer trom the supply tank pressure.

. Use a minimum 1 inch Nominal hose or tube between receiver tank and trailer tank.

. Use a minimum 3/4 inch Nominal hose trom receiver tank to air dryer.

. Use an air dryer which will maintain near system pressure at the dryer inlet while the dryer is in the purge modThis is necessary to maintain air pressure on the exhaust valves. A tilter such as CR Turbo-2000 (ChicagRawhide) with a purge tank is recommended because ot demonstrated effectiveness. The WABCO SS Twin ha

been alternately used with success. However,several other dryers tailed to pertorm properly during controllebench tests due to an overstated capacity claim. Overstated capacity claims are common and may be impossibto determine short ot signiticant bench testing.

Set compressor Governor to 130 PSI cut-out

,1,1,1,1,1,1,1,1,1::::::::~)

Mount governor clase to compressor

Engine Air Filter

15 FT mino ot11nch ID hose

150 PSI

Safety valva

Receiver Tank

Tetlon interior/wire braid exterior

Optional Turbo Inlet

Automatic

Spitter Draintor

Supply Tank

12800042

Governed receiver tank

The above "universal" arrangement ot the governed receiver tank is most effective tor al! applications.



,

I

Holset ST676 and ST773 Air Compressor Oil CarryPa

Long Duration, Low Pressure

Pressurizing the trailer tank to facilitate the unloading of bulk material is an example of long-duration, but low presair delivery around 20 psig. The balance of the mission is primarily on-highway operation with the brake system aprimary air consumption requirement. Little or no boost is available from the engine when pumping-off. During drtime, a ST Model Compressor willlikely pump for approximately ten seconds to satisfy the brake system, so na

aspiration is not a detriment to air delivery and it minimizes the air discharge temperature during the pump-off mNOTE: Lower temperatures in the compressor cylinder means that oil is less likely to be vaporized and swept awith the air.

Do not duct the air for the pump-off through the brakesystem air dryer. One dryer with a "Nominal capacity" of aro20 standard cubic feet per minute (scfm) is adequate for the pumping time required to supply a three-axle tractor a two or three-axle trailer brake system.

Long Duration, High Pressure

Central Tire Inflation (CTI) is an application that requires approximately 20 minoof pumping to a pressure of appmately 110psig to feed the inflation controller at approximately 18 scfm. The ST models deliver 18 scfm when natuaspirated. Turbocharged inlet air is an option, but provides little useful advantage and may increase system opera

temperatures.

Short Duration, High Pressure

Linehaul applications using an ST model for short duration, high pressure needs (perhaps for multiple trailers, or awill benefit from the reliable approach of using the "universal" ST plumbing arrangement. This includes a govereceiver tank, natural aspiration, and an air dryer which maintains pressure in the discharge line. Turbocharging air is an option with the "universal" arrangement, but provides litlle useful advantage and can increase syoperating temperatures.

Troubleshooting

A WARNING A

Troubleshooting can present risks of severa personal injury and death. Troubleshooting should be performby trained, experienced technicians only.

Refer to the Troubleshooting Symptom Trees on pages 4 and 5.



Holset ST676 and ST773 Air Compressor Di! CarryoverPáge 4

Air Compressor Pumping Excess Lubricating Oil into the Air System

This is symptom tree TOO7.

Cause Correction

Contaminants are not being drained trom thesystem on a regular basis

. Orain the reservoirs daily. Reter to the Opera-

tion and Maintenance Manual or the OEMService Manual.

OK...

Air dryer desiccant cartridge is saturated ....... Replace the desiccant cartridge on the airdryer. Reter to the OEM service manual.

OK...

Air intake system restriction to air compressoris excessive

.......

Replace the air compressor air cleaner (itinstalled). Check the air intake piping. Checkengine air intake restriction it the air compres-sor inlet is plumbed to the vehicle or equip-ment intake system.

OK...

Engine crankcase pressure is excessive .......Check tor excessive blowby. Reter to theCrankcase Gases (Blowby) Excessive symptomtree in the base engine Troubleshooting andRepair Manual.

OK...

Air compressor crankcase ventilation system isplugged

OK

. . . . . . . Check and clean the compressor crankcasebreather and vent tube.

...

Coolant tlow to or trom the air compressor isnot adequate

. . . . . . . Check the coolant supply and drain lines tor

obstructions. Verify that the supply lines arethe correct part numbers.

OK...

Air governor is maltunctioning .......

Check the air governor tor correct operation.Make sure the air governor is located less than

two teet trom the qir compressor. Reter to theMaster Repair Manual, Holset Air Compres-sors, Bulletin No. 3666121, and the OEMservice manual.

OK...

Unloader valve is maltunctioning ....... Check the unloader valve and unloader boay

seal. Reter to the Holset Air Compressor ,Bulletin No. 3666121.

OK...

(Continued)



Holset ST676 and ST773 Air Compressor Dil Carryopag

Air Compressor Pumping Excess Lubricating Oil into the Air System (Continued)

Cause Correction

Air dryer model is not correGífor use with twin

cylinder air compressors

Use only an air dryer that maintains nearsystem pressure in the air discharge line

during unloaded operation. Refer to theinformation on the Turbo/CR2000 and theWabco SS Twin in this Service Bulletin.

, .

OK..

Air temperatura is excessive or air systemcomponents are restricted.

. Make sure the air system is plumbed correctly

Refer to the system that you are using.iClthisbulletin. . -

OK..

Air compressor is excessively worn or internallydamaged

.Replace or rebuild the air compressor. Replacthe desiccant element on the air dryer (ifequipped). Refer to the manufacturer'sinstructions.



Holset ST676 and ST773 Air Compressor Di! Carryover

Cummins Engine Company, Ine. reeommends the following plumbing arrangements for the sueeessfulapplieation of the Holset ST676 and Holset ST773 models.

ST676/ ST773 for Bulk Trailer Unloading (Long Duration, Low pressure)

System assumptions that need consideration in actual applications.

. Engine speed is 1800 rpm.

. Altitude of operation is sea level.

. The brake system air use will not exceed 2 scfm.

. Ambient operation from -40°C to 49°C [-40°F to 120OF].

. The receiver tank and air dryer will discharge water and oil.

. The air supply tanks remains free of water and oil.

. A measurement of dryer inlet temperaturas of greater than 65.6°C [150OF] indicates that more exhaust aircooling is required.

System Requirements

. The compressor inlet is plumbed to the angina intake manifold that is turbocharged, or to (or near) the anginaair cleaner for natural aspiration.

. The compressor inlet line is a mínimum 1 inch Nominal.

. The compressor can be either a ST676 or ST773.

. Thegovernor is mounted on the compressor or on the angina.

. The length of the line from the governor unloader port to the compressor unloader port is to be equal to or lessthan 609.6 mm [2 tI]. Shorter is better.

. The exhaust line to the receiver tank is a mínimum of 4.54 m [15 ft]. of 1 inch Nominal. Longer is better. Teflonlined, copper or steel can be usad.

. The exhaust line is downward sloping to the receiver and supply tanks.

. The compressor governor cut-out setting does not exceed a maximum of 130 psig. Lower is better.

. The line from the governor reservoir (RES) outlet is a mínimum of 1/4 inch Nominal and has a downward slopeto the receiver tank.

. Receiver tank is 2200 to 2800 cubic inches.

. A safety valva with a 175 psig rating is installed on the receiver tank.

. A heated automatic spitter, or daily-serviced manual drain valva is installed on the receiver tank.

. Use a mínimum 3/4 inch Nominalline from the receiver tank to the air dryer.The length is as necessary to providea 65.6°C [150°F] maximum temperatura at dryer inlet port.

. Use a CR Turbo-2000 air dryer.

. The air governor gansas the air supply tank and unloads the CR Turbo 2000 dryer.

. Set the CR Turbo 2000 dryer governor cutout at 10 psig below compressor governor.

. The normal chargeable tank volume(s) does (do) not exceed 6000 cubic inches.

. Use mínimum 1 inch Nominallines to the bulk trailer tank.

. The receiver tank pressure during a bulk uniDad operation does not exceed 30 psig maximum.

. A high volume (30 scfm min.) final filler is usad for added filtration prior to the bulk trailer tank .

---



1

Holset ST676 and ST773 Air Compressor Di! CarryPa

ST676/ ST773 fer Bulk Trailer Unloaing 2 SCFM Normal Useage

Engine Air Filter Min 1/4 ID Gov Line (Down lo Condenser Tank)Gov Sel Compresaor Govemorlo

Center Unloader Valve (Sld) 130 Pai Cutoul

Maximum Air Supply Volumis 6000 Cubic Inches

3/4IDline Brake

SyatemTank

Bulk Unloading Presaurrecontrolled lo 30 Pai Max

=:--11lnch IDLineFilter

Inlet air Options: HeatedSpitter

-Naturally Aspirated (Recommmended)

-Turbocharged

30 SCFM minimum

flow capacily

Oto 18 SCFM System Air Demand

1280004



Holset ST676 and ST773 Air Compressor Dil Carryoverpage 8

ST676/ ST773 for Central Tire Inflation Systems or Continuous Flow Dperation (Long Duration, High pressure)With Two CA Turbo-2000 Air Dryers




. Ambient operation is from -40°C to 49°C [-40OF to 120OF].

. The accessory air use from the air supply tank(s) will not exceed 18 scfm.


. The receiver tank and air dryer will discharge water and oil.

. The air supply tanks remain absent of water and oil.

. A measurement of dryer inlet temperaturas of greater than 65.6° e; [150° F] indicates that more e~haust aircooling is required.

System Aequirements

. The compressor inlet is to be plumbed to naturally aspirated air from the angina inlet filler or from the anginaintake manifold that is turbocharged.

. The compressor inlet line is to be mínimum 1 inch Nominal.


. The governor is to be mounted on the compressor or on the angina.

. The length of the line from the governor unload port to the compressor unload port is to be less than or equalto 609.6 mm [2 ft]. Shorter is better.

. The exhaust line to the receiver tank shall be a mínimum of 4.56 m [15 ft.] of 1 inch Nominal. Teflon lined, copperor steel can be usad, longer is better.

. The exhaust line is to be always downward sloping to the receiver tank.

. The compressor governor cut-out is to be set to a maximum of 130 psig (Iower is better).

. The governor reservoir (RES) line is to be 1/4 inch Nominal having a downward slope to the receiver and supplytanks.

. Receiver tank of 2200 to 2800 cubic inches.

. A safety valva with 175 psig rating is installed in the receiver tank.

. A heated automatic spitter, or daily serviced manual drain is installed in the receiver tank.

. Use mínimum 3/4 inch Nominal tubing from the receiver tank to the air dryer. The length is as necessary toprovide 65.6° C [150° F] maximum temperatura at the dryer inlet port.

. CR Turbo-2000 air dryer - 2 required.

. The governor gansas the air supply tank and unloads both dryers.

. The dryer governor cutout is to be set at 10 psig below compressor governor.

. The normal chargeable tank volume(s) does not exceed 8000 cubic inches.

-



1

Holset ST676 and ST773 Air Compressor Dil Carryoverpage 9

ST676/

ST773 for Central Tire Inflation Systems

Engine Air Filter

Inlet air Options:

~ NaturallyAspirated~ Turbocharged

Oto 18 SCFM

Receiver Tank

30 SCFM minimum

flow capacity

System Ai r Demand

Maximum Air Supply Volumeis 8000 Cubic Inches

18 SCFM max

Accessory Port' '.

J<,heck Valve

,Primary Tank

Brake

Checkvalve Syslem

,Secondary Tank

2 SCFM Normal Useage

tor Brake System

12800044



Holset ST676 and ST773 Air Compressor Oil Carryoverpage 10

ST676/ ST773 for Central Tire Inflation Systems, or Continuous Flow Operation (Long Duration, High pressure)With one WABCO Dryer


. Air compressor speed is 1800 rpm.


. Ambient operati9n is from -40°C to 49°C [-40OFto 120°F].



. The receiver tank and air dryer discharge water and Gil.

. The air supply tanks should remain free of water and Gil.

. A measurement of dryer inlet temperatures of greater than 65.6°C [150OF] indicates that more .exhaust acooling is required.

System Requirements

. The compressor inlet is plumbed to naturally aspirated air at the engine inlet air filter or from the engine intakmanifold that is turbocharged.

. The compressor inlet line is a mínimum 1 inch Nominal.


. The governor is mounted on the compressor or on the engine.

. The length of the line from the governor uniDad port to the compressor uniDad port is less than or equal to 609mm [2 ft]. Shorter is better.

. The exhaust line is a mínimum of 4.56 m [15 ft.] of 1 inch Nominal. Teflon lined, copper or steel can be usedlonger is better.

. The exhaust line is always downward sloping to the receiver tank.

. The compressor governor cut-out is set to a maximum of 130 psig. Lower is better.

. The governor reservoir (RES) line is 1/4 inch Nominal having a downward slope to the receiver and supply tank

. Receiver tank of 2200 to 2800 cubic inches.

. A safety valve with 175 psig rating is installed on the receiver tank.

. A heated automatic spitter, or daily serviced manual drain is installed in the receiver tank.

. Use 3/4 inch Nominal tubing from the receiver tank to the air dryer. The length is as necessary to provide 65.6°[150OF] maximum temperature at dryer inlet port.

. The WABCO dryer must have a 1 (one) mm regeneration orífice. A 3-way normally open solenoid is.requireto operate the purge function.

. The normal chargeable tank volume(s) does not exceed 8000 cubic inches.



Holset ST676 and ST773 Air Compressor Dil Carrypag

ST676/ ST773 for Central Tire Inflation Systemsor Continuous Flow Operation

Engine Air Filter Min 1/4 ID Gov Line (Down to Condenser Tank)Gov Set Compressor Govemorto

Center Unloader Valve (Std) 130 Psi Cutout

Maximum Air Supply Volumis 8000 Cubic Inches

3-way Normally apeo Solenoid Valve

Wired to Ignition Circuit

Oul..8.. In

lnaure Dryer has 1 MM

orficea in regen circuit

Inlet air Options:

~ Naturally Aspirated

~ Turbocharged

flow capacity

Oto 18 SCFM

18 SCFM max

Accessory Port"

2 SCFM Normal Useage

tor Brake System

System Ai r Demand

128000



Holset ST676 and ST773 Air Compressor Dil Carryover

ST676 / ST773 for Special Applications--Mining, Dff-Highway, Construction (Short Duration, High pressure)




. The ambient operation is from -40° e to 49°e [-40OF to 120OF].



. The receiver tank and air dryer will discharge water and Gil.

. The air supply tanks remain absent of water and Gil.

. A measurement of the dryer inlet temperatures of greater than 65.6°e s[1500 F] indicates that more exhaust aircooling is required. '

System Requirements

. The compressor inlet is plumbed to naturally aspirated air from the engine inlet air filter or from the engine intakemanifold that is turbocharged.

. The compressor inlet line is 1 inch Nominal


. The governor is mounted on the compressor or on the engine.

. The length of line from the governor uniDad port to the compressor uniDad port is less than or equal to 609.9mm [2 ft.]. Shorter is better.

. The exhaust line is a mínimum of 4.56 m [15 ft] of 1 inch Nominal. Teflon lined, copper or steel can be usedlonger is better.

. The exhaust line is always downward sloping to the receiver tank.

. The compressor governor cut-out is set to a maximum of 130 psig. Lower is better.

. The governor reservoir (RES) line is to be 1/4 inch Nominal having a downward slope to the receiver and supplytanks.

. A receiver tank of 2200 to 2800 cubic inches.

. A supply tank of 2200 to 2800 cubic inch.

. A safety valve with a 175 psig rating is installed on the receiver tank.

. A heated automatic spitter, or daily serviced manual drain must be installed in the receiver tank.

. Use 3/4 inch Nominal tubing from receiver tank to air dryer. The length shall be as necessary to provide65.6°e[150°F] maximum temperature at dryer inlet port.

. eR Turbo-2000 air dryer - 2 required

. The governor senses the air supply tank and unloads both dryers.

. The cutout is set at 10 psig below the compressor governor.

. The normal chargeable tank volume(s) does (do)not exceed 8000 cubic inches.



"

Holset ST676 and ST773 Air Compressor Dil CarryPag

5T676/ 5T773 for Central Tire Inflation 5ystems--Mining, Off-Highway, Construction

Engine Air Filter Min1/4 IDGov Line (Downto CondenserTank)Gov Set Compressor Governor to

Center Unloader Valve(Std) 130Psi CutoutSet Govemor To

CR T2000 120 Psi Cutout

Gov

Inlet air Options:

~ Naturally Aspirated

~ Turbocharged

Heated Spitter Spitter

Oto 18 SCFM System Air Demand

18 SCFM max

Sys~,~ Use

12800



Holset ST676 and ST773 Air Compressor Dil CarryoverPagé 14

The following parts kit has been released to aNominal in implementing the guNominalelines of this bulletin on problemair systems.

Parts Kit Number 3559604

Quantity Description1 2500 cubic in. Receiver Tank1 Manual Drain Valva

1 175 psig Safety Valva1 Air Governor

ManufacturerMidwestMidlandControl DevicesMidland

3/8 in. NPT

r--14 in. Diameter

I~ !I

3/8 in. NPT

3/8 in. NPT

>-1~-.-6¡;;-'--.~. l-"

i ! ¡ ~in.

_o_o_o>-°to_o_oio_o_o~o OtO_o.

! i i 4in.! i i .1.~ ~- _.t._.

3/8 in. NPT

iiI

_o_o_o_o_o_o_~~~~~~~o~~:_o

!

_o_._o_o_o_o~o~~~o~.~:_._oI

IiI

iiii

17 in.

3/8 in. NPT

Front View Rear View

12800047

2500 cubic inch Receiver Tank

holset st676 and st773 air compressor oil carryover. september, 1997

Documents