Extended Operational and Trade Vocabulary

Marine Auxiliary Machinery and Pumps glossary

The auxiliary-machinery vocabulary: marine boilers and economizers (the Aalborg Mission series), exhaust-gas boilers, pumps, separators, and the steam-plant and heat-recovery terms. Grounds each term in the auxiliary system or the machinery maker it belongs to, complementing the marine-engineering section.

573 defined terms.

Showing 250 on this page (page 1 of 3).

A

Aalborg Industries: Danish marine boiler manufacturer founded in 1919, now operating as Alfa Laval Aalborg after the 2007 acquisition.
Aalborg Mission OL: Oil-fired auxiliary boiler series from Alfa Laval Aalborg used on tankers and bulk carriers for steam generation.
Aalborg Mission OS: Combined oil-fired and exhaust gas boiler from Alfa Laval Aalborg integrated as a composite unit.
Aalborg Mission XS-TC: Smoke-tube exhaust gas economizer from Alfa Laval Aalborg fitted in the funnel uptake of the main engine.
Aalborg Mission XW-TG: Water-tube exhaust gas boiler designed by Alfa Laval Aalborg for higher steam pressures.
Aalborg OC-TCi: Composite oil-fired and exhaust gas boiler from Alfa Laval Aalborg for combined heat recovery and burner firing.
Aalborg OL: Vertical cylindrical oil-fired auxiliary boiler with annular furnace from Alfa Laval Aalborg.
Aalborg OM-TCi: Combined vertical oil-fired and exhaust gas heated boiler used on small to medium tankers.
Aalborg OS-TCi: Smoke-tube auxiliary boiler with side-fired burner integrated with exhaust gas section.
Aalborg XW: Water-tube exhaust gas economizer used downstream of low-speed two-stroke main engines.
AC Motor-Driven Pump: Pump unit driven by an alternating current induction motor through direct, belt, or flexible coupling.
Accumulator Tank: Pressurized vessel that maintains hydrophore pressure in fresh water, sanitary, or hydraulic systems.
Acid Cleaning: Chemical descaling of boiler water side, evaporator tubes, or heat exchanger surfaces using inhibited acid.
Activated Carbon Filter: Polishing stage in fresh water generator and potable water systems for taste, odor, and chlorine removal.
Activated Sludge Process: Biological sewage treatment using aerated bacteria culture to oxidize organic matter in marine STPs.
Aeration Tank: Compartment in a biological sewage treatment plant where activated sludge is mixed with diffused or mechanically supplied air.
Aerobic treatment: Treatment relying on dissolved oxygen, generally not used for ballast water disinfection because BWMS often deoxygenate water.
Air bottle: Starting air receiver, typically two of 30 bar working pressure for main engine and one for auxiliaries.
Air Compressor: Reciprocating or screw machine that delivers compressed air for starting, control, service, and instrument duties.
Air Cooler (Compressor): Intercooler or aftercooler that removes heat of compression between or after compressor stages.
Air receiver: Pressurized vessel storing starting air at typically 30 bar.
Alarm Set Point: Configured threshold at which an OWS 15 ppm OCM, salinity cell, or low-suction switch trips an audible alarm.
Alfa Laval Aalborg: Boiler and combustion business unit of Alfa Laval headquartered in Aalborg, Denmark.
Alfa Laval AQUA Blue: Low-temperature plate evaporator with optimized titanium plates for higher distillate output.
Alfa Laval Aquamar: Vacuum-type fresh water generator from Alfa Laval used as a simplified plate evaporator.
Alfa Laval JWP: Jacket Water Plate fresh water generator series using engine jacket water as the heat source.
Alfa Laval JWP-16-C: Plate-type fresh water generator producing roughly 16 m3/day from jacket water.
Alfa Laval JWP-26-C: Mid-size plate-type single-stage evaporator from Alfa Laval.
Alfa Laval JWP-36-C: Larger jacket water plate evaporator suited to VLCCs and large bulkers.
Alfa Laval MAB: Manual sludge discharge purifier series for fuel and lube oil cleaning on older tonnage.
Alfa Laval MAPX: Hydraulically operated self-cleaning centrifugal separator for fuel oil and lube oil duty.
Alfa Laval MFPX: Modular high-speed separator for marine fuel and lube oil applications.
Alfa Laval MIB: Small manual purifier originally produced for diesel engine lube oil cleaning.
Alfa Laval Mini-City: Compact plate fresh water generator for small vessels and offshore units.
Alfa Laval MMPX: Compact self-cleaning centrifugal separator for lube oil duty on medium engines.
Alfa Laval MOPX: Self cleaning paring disc purifier widely fitted for HFO and lube oil treatment.
Alfa Laval P-Flex: Range of disc-stack separators designed for variable HFO, MGO, and biofuel feeds without gravity disc changes.
Alfa Laval P605: P-Series high-speed disc-stack centrifugal separator for marine fuel and lube oil.
Alfa Laval P615: Larger P-Series fuel and lube oil separator with EPC 60 control system.
Alfa Laval PureBallast: UV-based ballast water treatment system.
Alfa Laval PureBilge: Centrifugal oily water separator certified to MEPC.107(49) 15 ppm.
Alfa Laval PureDry: Waste oil treatment unit that converts sludge from separators into recoverable fuel and dry solids.
Alfa Laval PureNOx: Water cleaning unit used with EGR systems to remove sulfates and soot before water reuse.
Alfa Laval PureSewage: Membrane bioreactor sewage treatment plant compliant with MEPC.227(64) including special area standards.
Alfa Laval S separator: Modern hermetic centrifugal separator using EPC 60 control for fuel and lube oil cleaning.
Alfa Laval S-Series: Disc-stack separator family that succeeded the P-Series for modern marine engine room duties.
Alfa Laval S921: S-Series separator widely used for HFO and lube oil purification on two-stroke main engines.
Algae Fouling: Biological growth on sea chests, condenser tubes, and seawater strainers requiring periodic cleaning.
Alkalinity Test: Boiler water test measuring P and M values to control caustic and carbonate concentration.
Allweiler: German pump manufacturer (now part of CIRCOR) producing screw, progressing cavity, and centrifugal pumps for marine use.
Allweiler SM: Twin-screw pump series for cargo, transfer, and stripping service.
Allweiler SN: Three-screw pump series widely applied as fuel oil booster and lube oil pumps.
Ambient Air Compressor: Compressor drawing intake air from the engine room atmosphere through a suction filter and silencer.
Ammonia Refrigerant: R-717 used in industrial fish factory and large refrigeration plants for its high efficiency.
Anaerobic Treatment: Sewage process operating without free oxygen, sometimes used in retention or holding tanks.
Annular Furnace: Combustion space of vertical cylindrical auxiliary boilers such as the Aalborg OL series.
Anode (Sacrificial): Zinc or aluminum element fitted in coolers, fresh water generators, and pump casings to limit galvanic corrosion.
Anti-foaming agent: Silicone or polyacrylate additive used to suppress foam during bunkering and tank stripping.
API Pump: Pump manufactured to API 610 standard, occasionally specified for offshore and FPSO duty.
Apollo Goessling: German manufacturer of gear pumps used on marine fuel oil and lube oil services.
Aquamarine Sewage: Generic term for STP units treating black water from accommodation toilets.
Aspirator: Venturi-based eductor used to draw vacuum on fresh water generators by motive seawater flow.
Astern Pump: Service pump arranged for reversed flow during astern operation of certain steam turbine systems.
Atlas Copco: Swedish manufacturer of marine air compressors, including the LE and LF reciprocating ranges.
Atlas Copco GA: Oil-injected rotary screw compressor series used for service and instrument air.
Atlas Copco LE: Oil-lubricated reciprocating piston compressor range for low-pressure service air.
Atlas Copco LF: Oil-free reciprocating piston compressor for instrument and breathing-quality air.
Atomizer: Burner component that breaks fuel oil into fine droplets for efficient combustion in marine boilers.
Automatic Filter: Self-cleaning back-flushing filter fitted upstream of fuel injection systems and purifiers.
Auxiliary boiler: Oil-fired boiler for steam at sea when waste-heat is insufficient.
Auxiliary Cooling Pump: Electrically driven pump providing cooling water at port when main engine pumps are stopped.
Auxiliary Feed Pump: Standby feed water pump arranged in parallel with the main boiler feed pump.
Auxiliary Steam Header: Distribution manifold downstream of the auxiliary boiler serving fuel heating, accommodation, and tank heating.
Axial Flow Pump: Pump with propeller-type impeller producing high flow at low head, used for ballast and cooling water duties.

B

Back Pressure (Boiler): Resistance to flue gas flow imposed by economizer, scrubber, and uptake fittings.
Back Pressure Valve: Control valve maintaining minimum pressure in OWS discharge or sludge transfer lines.
Bag Filter: Cloth or felt filtration element used for sludge dewatering and bilge water polishing.
Ballast pump: Centrifugal or self priming pump moving ballast water, increasingly replaced by submersible types.
Ballast Stripping Pump: Smaller pump or eductor used to remove residual ballast water from tank bottoms.
Bellows-Type Compressor: Specialty compressor using metal bellows for leak-tight handling of refrigerants or process gases.
Belt-Driven Pump: Pump connected to its driver through V-belts or flat belts, common on small auxiliary services.
Bilge alarm: 15 ppm oily water discharge monitor.
Bilge Eductor: Jet pump using seawater or steam motive flow to drain hold or compartment bilges.
Bilge Hat: Suction strainer screen fitted to bilge wells to prevent solids from entering the bilge pump line.
Bilge Holding Tank: Tank for collected bilge water; sounded and inspected for MARPOL compliance.
Bilge Injection Valve: Direct-suction valve allowing the main seawater pump to draw from the engine room bilge in emergencies.
Bilge Main: Common piping that connects bilge wells to the bilge pump suction manifold.
Bilge Pump: Dedicated reciprocating or centrifugal pump used to empty bilges; SOLAS requires at least two on cargo ships.
Bilge Separator: Common synonym for an oily water separator (OWS) treating engine room bilge water.
Bilge Tank: Reception tank for collected bilge water awaiting treatment or discharge.
Bilge well: Recess at low point of engine room floor collecting drainage to the bilge system.
Biocide: Chemical substance that controls harmful organisms, used in antifouling paints and certain BWMS.
Biomaster: Trade name of the RWO biological sewage treatment plant.
Bitzer: German manufacturer of refrigeration compressors widely used in reefer plants and reefer container units.
Bitzer 4FES: Semi-hermetic reciprocating compressor common in vessel provision rooms.
Bitzer CSH: Semi-hermetic screw compressor used in larger reefer and air-conditioning plants.
Bitzer Octagon: Semi-hermetic reciprocating compressor platform suited to R-404A and R-134a duty.
Black water: Sewage as defined in MARPOL Annex IV.
Blowdown: Removal of concentrated boiler water to control TDS, performed as bottom or surface blowdown.
Blower (Boiler): Forced draft fan supplying combustion air to oil-fired auxiliary boilers.
Boiler Drum: Cylindrical pressure vessel of a water-tube boiler housing the water-steam interface.
Boiler Feed Pump: High-pressure multistage centrifugal or reciprocating pump supplying water to the boiler at working pressure.
Boiler Mountings: Safety and operational fittings such as safety valves, water level gauges, and stop valves.
Boiler Trim: Auxiliary fittings including blowdown, sample, and feed connections on a boiler shell.
Boost Pump: Auxiliary pump raising suction pressure to a main pump or fuel injection system.
Bornemann: German manufacturer (now part of ITT) of twin-screw pumps for crude oil and viscous duty.
Bornemann SLH: Twin-screw pump series used as cargo and stripping pump on chemical tankers.
Bornemann W: Twin-screw multiphase pump range used in offshore service.
Bowl (Separator): Rotating drum of a centrifugal separator that develops the gravitational field separating phases.
Brominator: Inline halogenation device used to disinfect distillate from a fresh water generator.
Brunvoll: Norwegian manufacturer of tunnel thrusters, azimuth thrusters, and CP propeller systems for offshore vessels.
Bunker Pump: Pump dedicated to receiving or transferring fuel during bunkering operations.
Burner: Combustion unit of a marine boiler comprising atomizer, ignition, and air register.
Burner management system: BMS, sequence and safety logic for boiler firing including purge and flame supervision.
Butterfly valve: Disc type valve common on sea water and ventilation lines, operated by lever or actuator.
Bypass Filter: Side-stream filter that polishes a portion of the lube oil flow continuously.

C

Calorifier: Steam or electric heated vessel producing domestic hot water from fresh water.
Cam-Operated Pump: Reciprocating pump where the plunger is actuated by a rotating cam, used in some fuel and dosing applications.
Cargo Pump: Pump used to load or discharge bulk liquid cargo on tankers, available in steam, electric, or hydraulic drive.
Cargo Pump Room: Compartment for cargo pumps on tankers; gas-hazardous zone.
Carrier Transicold: US-headquartered manufacturer of container reefer units, including PrimeLINE, PrimeLINE Plus, and NaturaLINE.
Cascade Filter: Series of separators or filters arranged to progressively clean fuel or oil.
Cascade Tank: Observation tank in steam systems where returned condensate is checked for contamination before reuse.
Cast Iron Pump Casing: Common pump body material for non-corrosive seawater alternatives or oil services.
Caustic Embrittlement: Boiler damage mechanism caused by stressed metal exposed to concentrated caustic solution.
Cavitation: Vapor bubble formation when local pressure falls below vapor pressure.
Centrifugal pump: Rotodynamic pump with impeller, used for sea water, ballast, fire, and bilge service.
Centrifugal separator: Rotating bowl device that uses density difference to remove water and solids from fuel, with disc stack configurations dominating marine practice.
Check Valve: Non-return valve protecting pumps and lines from reverse flow.
Chemical Dosing Pump: Small positive displacement pump injecting boiler, cooling water, or sewage treatment chemicals.
Chlorination Unit: Disinfection unit using sodium hypochlorite or chlorine tablets for potable water and sewage effluent.
Cleaver-Brooks: US manufacturer of fire-tube and water-tube boilers used in marine and industrial applications.
Closed Cooling System: Fresh water cooling circuit isolated from seawater, treated with corrosion inhibitor.
Coalescer: Filter element that merges fine water droplets for separation.
Coffin: US manufacturer of marine pumps including the Coffin DE turbine-driven feed pump.
Combined Steering Gear: Steering arrangement with two power units that can operate together or independently per SOLAS Ch II-1.
Composite Boiler: Auxiliary boiler combining oil firing and exhaust gas heating in a single shell.
Compressed Air Reservoir: Air receiver for storage of compressed air used in starting, controls, and services.
Condensate pump: Pump returning condensate from observation tank or hotwell to feed system.
Conductivity meter: Instrument used to measure soluble salt levels on blasted steel via the Bresle method.
Constant Pressure Governor: Speed governor for steam pumps maintaining constant discharge pressure regardless of demand.
Control Air Compressor: Oil-free compressor supplying instrument and control air to pneumatic systems.
Cooler (Lube Oil): Plate or shell-and-tube heat exchanger maintaining lube oil temperature into the engine.
Cooling Sea Water Pump: Pump circulating seawater through the main and auxiliary coolers.
Copes-Vulcan: US manufacturer of feed water control valves and boiler regulating equipment.
Cornell Pump: US manufacturer of self-priming and trash pumps used in some auxiliary marine duties.
Counter-Flow Heat Exchanger: Arrangement where two fluids flow in opposite directions to maximize temperature differential.
Crank Mechanism (Pump): Drive mechanism converting rotary motion to reciprocating plunger or piston motion.
Crossover Pipe: Connection between two systems or pumps allowing emergency cross-supply.
Cryogenic Pump: Pump designed for low-temperature service such as LNG transfer on gas carriers.
Cumberland Pump: Historical brand of marine reciprocating pumps used on legacy vessels.
Cycle Stop Valve: Solenoid valve isolating the OWS discharge during alarms exceeding 15 ppm.
Cyclone Separator: Device using rotational flow to separate solids or liquid droplets from a gas stream.

D

Daily Service Tank: Settled fuel oil tank supplying treated fuel directly to engines via the service pump.
De-aerator: Vessel removing dissolved oxygen from boiler feed water.
De-Oiling Tank: Sludge or bilge tank that allows oil and water to gravity-separate before further treatment.
Deep Well Pump: Submersible pump installed at the bottom of cargo tanks on chemical and product tankers.
Desalination Plant: Equipment producing fresh water from seawater by evaporation or reverse osmosis.
DESMI: Danish manufacturer of pumps and propulsion components, including aft-peak and stern-tube auxiliaries.
DESMI ESL: End-suction centrifugal pump range for general service and seawater duty.
DESMI Modulynx: Modular centrifugal pump platform for marine applications.
DESMI NSL: In-line single-stage centrifugal pump series for cooling and fresh water duty.
DESMI OptiSaveTM: Frequency converter control system that reduces seawater and fresh water pump energy use.
DESMI Rotan: Internal gear pump series used for fuel oil booster and viscous fluid duty.
DESMI S-Series: Self-priming centrifugal pump series suited to bilge and ballast duty.
Detegasa: Spanish manufacturer of OWS and STP equipment widely fitted on offshore and merchant tonnage.
Detegasa CPS: Detegasa compact STP for crew vessels.
Detegasa HDS: Detegasa OWS series including HDS 1.0 and 2.5 m3/h units.
Diaphragm pump: Pneumatic transfer pump used for high-viscosity epoxy mixing and supply to spray equipment.
Differential Pressure Switch: Sensor signaling clogging of filters, separators, or coolers.
Disc stack: Series of conical separator discs in a centrifugal purifier creating thin layers for efficient phase separation.
Discharge Head: Pressure energy required by a pump expressed as a column height of pumped fluid.
Distillate Pump: Pump removing produced fresh water from the evaporator and delivering it to storage.
Diverting Valve: Three-way valve that redirects OWS effluent back to the bilge holding tank when oil content exceeds limits.
Domestic Fresh Water Pump: Pump pressurizing the potable water system for accommodation and galley use.
Donghwa Entec: Korean manufacturer of marine boilers, heat exchangers, and FWG units.
Donghwa Entec Mini-Plate: Compact plate-type fresh water generator from Donghwa Entec.
Donkey Boiler: Historical term for an auxiliary boiler supplying steam to deck machinery at port.
Double-Acting Pump: Reciprocating pump that delivers fluid on both forward and return strokes.
Double-Bottom Tank: Hull tank used for fuel, ballast, fresh water, or sewage storage below the inner bottom plating.
Double-Stage Evaporator: Fresh water generator using two effects to recover more distillate per unit heat input.
Down-Flow Boiler: Boiler design where flue gas travels downward through the convective section.
Draft Loss: Pressure drop of flue gas across boiler banks, economizer, and stack.
Drain Cooler: Heat exchanger that recovers heat from steam condensate before disposal or return.
Drum Level Controller: System maintaining boiler water level using single-, two-, or three-element control.
Dry Lay-Up: Boiler preservation by removing all water and adding desiccant to prevent corrosion during shutdown.
DVZ-OWS: Oily water separator series from DVZ-Services achieving the 15 ppm MARPOL limit.
DVZ-Services: German manufacturer of marine oily water separators, including DVZ-SKA and DVZ-OWS series.
DVZ-SKA: Coalescer-based bilge water separator from DVZ used widely on container ships.
Dynamic Seal: Sealing arrangement that uses fluid motion or pressure differential to prevent leakage along a rotating shaft.

E

Eccentric Screw Pump: Progressing cavity pump with single helical rotor in a stator, used for sludge and viscous fluids.
Ecochlor: Manufacturer of ballast water treatment systems often paired with auxiliary water systems.
Economizer: Refrigeration circuit enhancement boosting capacity at low evaporating temperatures; standard on PrimeLINE and Star Cool.
Eductor: Jet pump using motive water to draw bilge or stripping suction by venturi effect.
Ejector: Steam or water powered jet pump used for vacuum production or pumping water with no moving parts.
Electric Motor-Driven Pump: Pump driven by squirrel cage induction motor through coupling or belt.
Electrochlorination: Production of sodium hypochlorite from seawater by electrolysis for biofouling control.
Electrohydraulic Steering Gear: Steering gear driven by electrically powered hydraulic pumps acting on rams or rotary vane actuators.
Emergency Bilge Suction: Direct suction allowing the main seawater pump to drain the engine room in flooding casualties.
Emergency fire pump: Independent fire pump per SOLAS Reg. II-2/10.
End-Suction Pump: Centrifugal pump configuration with suction nozzle on the shaft axis and discharge on the casing periphery.
Engine Driven Pump: Pump driven by mechanical takeoff from the main or auxiliary engine.
Engineering Pump Room: Dedicated space housing fresh water, sanitary, sewage, and other auxiliary pumps.
EPC 60: Alfa Laval separator control system used on P-Series and S-Series units.
Equivalent Length: Hydraulic length representing pressure loss of fittings and valves for pump system sizing.
Evac: Norwegian manufacturer of vacuum collection and sewage treatment systems for marine and offshore use.
Evac MBR: Membrane bioreactor sewage treatment plant from Evac compliant with MEPC.227(64).
Evac Vacuum Toilet: Pneumatically actuated toilet using small volumes of water and vacuum to transport black water.
Evaporator: Fresh water generator using waste heat from jacket water at low vacuum.
Evaporator Shell: Vacuum vessel of a fresh water generator containing the evaporator and condenser sections.
Exhaust gas boiler: Economizer recovering main engine exhaust heat to produce steam.
Exhaust Gas Economizer: Common synonym for an exhaust gas boiler producing steam from main engine flue gas.
Expansion tank: Header tank for cooling system.

F

Feed Check Valve: Non-return valve on boiler feed line preventing back-flow into the feed pump.
Feed pump: Boiler feed pump delivering water from hotwell to the boiler drum.
Feed Water: Treated water entering the boiler, typically deaerated and chemically conditioned.
Feed Water Heater: Heat exchanger raising feed water temperature using bled steam or exhaust gas.
Filtration Stage: Particulate or coalescing stage in OWS, FWG, or fuel cleaning systems.
Fire Pump: Centrifugal pump providing pressurized water to the fire main, required in number and capacity by SOLAS.
Fire-Tube Boiler: Boiler design with hot gas flowing inside tubes surrounded by water, used in small auxiliary boilers.
Flame Failure Detection: Photoelectric or ionization device shutting down the burner if combustion is lost.
Flash Evaporator: Fresh water generator in which heated seawater flashes to vapor in a low-pressure chamber.
Flow Switch: Sensor confirming fluid flow before allowing pump or heater operation.
Forced draft fan: Combustion air blower supplying boiler furnace.
Foundation Bolt: Holding-down bolt securing a pump or compressor to its seating chock.
Frascold: Italian manufacturer of refrigeration compressors used in some reefer and air-conditioning plants.
Fresh Water Cooling System: Closed-loop circuit using treated fresh water to cool main engine jackets, lube oil, and charge air.
Fresh water generator: FWG, plate or shell type evaporator producing distilled water under vacuum.
Fresh Water Hydrophore: Pressurized vessel maintaining domestic fresh water supply pressure.
Fresh Water Pump: Pump circulating cooling fresh water through the engine and coolers.
Frydenbo: Norwegian manufacturer of rotary vane steering gear and rudder propulsion systems.
FUEL Booster Pump: Pump raising fuel pressure to the level required by injection equipment, typically gear or screw type.
Fuel oil heater: Steam or electric heater raising HFO to the temperature for the specified viscosity.
Fuel oil service pump: Pump delivering fuel from service tank to booster module.
Fuel Oil Settling Tank: Tank where fuel oil is heated and allowed to settle so water and sediment separate.
Fuel Oil Supply Pump: Pump that delivers cleaned fuel oil from settling or service tank to the booster pump.
Fuel oil transfer pump: Screw or gear pump moving fuel between storage and settling tanks.
Funnel Casing: Vertical exhaust gas duct housing the economizer and silencer arrangement.
FWG: Common abbreviation for fresh water generator.

G

Gas-Fired Boiler: Auxiliary boiler designed to burn boil-off gas, used principally on LNG carriers.
Gauge Glass: Direct-reading water level indicator fitted on every boiler steam drum.
GEA Westfalia: German manufacturer of marine centrifugal separators including the OSE, OSD, and Unitrol ranges.
GEA Westfalia BilgeMaster: Centrifugal bilge water separator from GEA Westfalia meeting the 15 ppm limit.
GEA Westfalia OSD: Self-cleaning purifier series for distillate and intermediate fuel duty.
GEA Westfalia OSE: Self-cleaning lube oil separator series for marine engines.
GEA Westfalia Unitrol: Microprocessor-based separator control system from GEA.
GEA Westfalia ViscoBooster: Integrated fuel oil supply, booster, and viscosity control unit.
Gear pump: Positive displacement pump using meshing gears, used for lube oil and fuel transfer.
General Service Pump: Multi-purpose centrifugal pump providing seawater for cooling, washing, deck wash, and emergency bilge.
Gland Sealing: Sealing arrangement around the rotating shaft of a pump using packing or mechanical seal.