Mercer International logo representing oil water separator services and technology in Albany, NY. design center

Above Ground Oil Water Separators

Up to 2,000 GPM Total | ~454 m³/h | ~68,572 BPD

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Above ground oil water separator system in industrial setting, 2,000 GPM capacity, split-flow configuration.

OPERATING TIER

High Flow Industrial Oil Water Separator Solutions

Mercer separators at this capacity are widely used in produced water treatment trains handling frac flowback and early-life production, where high flow rates, elevated oil loading, and variable water quality challenge traditional equipment. These systems are frequently deployed as a direct replacement for above-ground storage tanks (ASTs) and gun barrel separators, offering a compact, engineered solution with predictable hydraulic and separation performance. The 2,000 GPM design utilizes an internal split-flow configuration that divides influent into two independent 1,000 GPM treatment trains within a single vapor tight vessel, maximizing effective tank volume while controlling internal velocities.

The dual-train split-flow design provides critical operational flexibility and API 421 compliance. By dividing flow between two parallel paths, velocity through each coalescer remains below the API-recommended 3 ft/min limit, promoting effective droplet coalescence and minimizing oil re-entrainment during peak flowback conditions. Each train can be isolated independently, allowing operators to clean or service one side while the other remains in operation—maintaining continuous processing without the downtime, footprint, or inefficiencies associated with AST-based settling or gun barrel systems.

At this level, engineering review is not optional. It is fundamental to performance.

Large blue Mercer oil water separator being lifted into place at industrial facility, API 421 compliant separator installation.

Built To Scale

System Configurations (Up to 2,000 GPM)

Systems approaching the 2,000 GPM class are engineered using Mercer’s large-system design philosophy, which may include:

  • split-flow, clean-in-place internal architecture
  • large-flow-optimized Multi-Pack™ coalescer assemblies
  • instrumentation designed to diagnose conditions and trigger automated oil and solids evacuation
  • deliberate access provisions for inspection, isolation, and cleaning

Final configuration is established through engineering review.

Above-ground oil water separator, 2000 GPM configuration, split-flow design, industrial wastewater treatment system.

2000 GPM Configuration

Please Note: Exact materials, dimensions, and configurations vary by application. Carbon steel construction is typically introduced at higher flow ranges where structural requirements dictate.

FIELD-PROVEN SYSTEMS

Installed in Real Operating Environments

At this scale, separators are part of core plant infrastructure.

The installations shown represent Mercer systems operating at or near the 2,000 GPM class in environments where downtime, fouling, or performance uncertainty is unacceptable.

Large-scale Mercer oil water separator, 2000 GPM class, in industrial setting, demonstrating field-proven system design.

US Army Corps of Engineers

Washington

Above Ground

2000 GPM

Above-ground oil water separator system inside a US Army Corps of Engineers facility, Washington, showcasing Mercer's 2000 GPM configuration.

US Army Corps of Engineers

Washington

Above Ground

1350 GPM

Above-ground Mercer oil water separator at Detroit Edison, Michigan, 2000 GPM industrial wastewater treatment system.

Detroit Edison

Michigan

Above Ground

2000 GPM

Above-ground oil water separator system on trailer, 2000 GPM Mercer separator installation at Con Edison, New York.

Con Edison

New York

Above Ground

2000 GPM

Above-ground oil water separator installation at San Antonio Refinery, Texas, 2000 GPM Mercer system.

The San Antonio Refinery

Texas

Above Ground

2000 GPM

Mercer 2,000 GPM above-ground oil water separator installation at a refinery in Calumet, Texas, with crane lifting separator unit.

Calumet

Texas

Above Ground

2000 GPM

TRUSTED BY INDUSTRY LEADERS

Installed at Facilities Operated By

A small sampling of companies with Mercer separators operating at or near the 2,000 GPM class.

Gibson Energy logo showcasing Mercer International's trusted customer base Martin Midstream Partners logo demonstrating trusted oil water separator clients. Schlumberger logo demonstrating trusted customer partnerships for Mercer International oil water separators.
ExxonMobil logo demonstrating Mercer International's trusted customer base.
Buckeye Partners logo demonstrating Mercer International's trusted customer base. Oxy logo showcasing Mercer International's trusted customer base and oil water separator solutions. Hess logo demonstrating trusted customer and Mercer International oil water separator system user.
INEOS Oligomers logo, demonstrating Mercer International's trusted customer base.
Hartsfield-Jackson Atlanta International Airport logo demonstrating Mercer's trusted customer base. Penske logo demonstrating Mercer International's trusted customer base.
Firefly Aerospace logo demonstrating trusted equipment for Mercer International oil water separators.
Blue Origin logo showcasing a feather design, demonstrating trusted partnerships for Mercer International oil water separators.
Raytheon Technologies logo demonstrating trusted customer partnerships for Mercer oil water separators. U.S. Department of Homeland Security logo demonstrating trusted Mercer oil water separator clients.
Stellantis logo representing a trusted customer of Mercer International oil water separators. Daimler logo showcasing Mercer International's trusted customer base.
Cummins logo representing a trusted customer of Mercer International oil water separators. Harley-Davidson Cycles logo representing trusted customer partnerships and equipment reliability.
TechnipFMC logo demonstrating Mercer International's trusted customer base. Mercer International logo showcasing SELECT, demonstrating trusted oil water separator systems. Chevron logo representing industry leader trust in Mercer oil-water separators.
BWC Terminals logo showcasing bulk liquid storage, a trusted Mercer International customer.
Church & Dwight logo showcasing Mercer International's trusted customer base. Indorama Ventures logo, showcasing Mercer International's trusted customer base. DuPont logo showcasing trusted customer and engineering firm partnerships.
Formosa Plastics logo demonstrating Mercer International's trusted customer base.
UPS logo demonstrating Mercer International's trusted customer base. Blue Origin logo showcasing a feather design, demonstrating trusted partnerships for Mercer International oil water separators.
Lockheed Martin logo demonstrating Mercer International's trusted customer base
Pratt & Whitney logo demonstrating trusted customer and United Technologies Company.
U.S. Army Corps of Engineers logo demonstrating Mercer's trusted customer base. Naval Sea Systems Command (NAVSEA) logo demonstrating Mercer International's trusted customer base.
Mercer International logo showcasing trusted oil water separator systems CEMEX logo representing a trusted customer of Mercer International oil water separators.
Goodyear logo representing Mercer International's trusted customer base and reliable oil water separator systems. Toyo Tires logo representing Mercer International's trusted customer base.
CSX logo representing a trusted customer of Mercer International oil water separators. Canadian Pacific logo representing a trusted customer of Mercer oil water separators. Norfolk Southern logo representing trusted Mercer International customer and transportation infrastructure partner.
Siemens logo demonstrating trusted customer relationships for Mercer oil water separators.
Con Edison, Inc. logo showcasing Mercer International's customer base in the electrical and power utilities sector. DTE Energy logo showcasing Mercer International's trusted customer base. PECO logo, an Exelon Company, showcasing Mercer International's trusted customer base.
Calpine logo showcasing Mercer International's trusted customer base.
Hydro-Québec logo showcasing trusted Mercer International customer. NRG logo showcasing Mercer International's trusted customer base and oil water separator solutions.
Xcel Energy logo showcasing trusted customer and industry partnerships for Mercer oil water separators.
Southern Company logo showcasing trusted customer and Mercer oil water separator client.
Frito-Lay logo demonstrating Mercer International's trusted customer base. Mercer International customer logo: The Cleveland-Cliffs Foundation, demonstrating trusted oil water separator clients.
Barrick logo representing Mercer International's trusted customer base and reliable oil water separator systems. Kinross logo demonstrating Mercer International’s trusted customer base.
Mercer International logo showcasing trusted customer Black & Veatch. Fluor separation technology component in Mercer oil-water separators.
Union Pacific logo showcasing Mercer International's trusted customer base. BNSF Railway logo representing trusted customers and industries served by Mercer International. CN logo showcasing customer credibility and trusted oil water separator systems.
GE logo demonstrating trusted customer partnerships for Mercer International oil water separators.
New York Power Authority logo, demonstrating Mercer International's trusted customer base in electrical and power utilities. Georgia Power logo demonstrating trusted customer and electrical utility partnership. Mercer International logo showcasing Allegheny customer partnership and oil water separator reliability.
Duke Energy logo representing trusted customer and industry partner for Mercer International oil water separators.
NextEra Energy logo showcasing Mercer International's trusted customer base. Reliant logo representing Mercer International customer credibility and oil water separator performance.
Bacardi logo representing trusted customer organizations and Mercer International's oil water separator solutions.
Coca-Cola logo showcasing trusted customer partnerships for Mercer International oil water separators.
AM/NS Calvert customer logo demonstrating trusted oil water separator clients. Nucor Tubular Products logo demonstrating trusted customer relationships for Mercer oil water separators.
Centerra Gold logo showcasing trusted customer of Mercer International oil water separators. Bechtel logo showcasing trusted customer partnerships for Mercer oil water separators.
Hyundai Engineering & Construction logo, demonstrating Mercer International's trusted customer base. GFL logo representing trusted customer partnerships and Mercer International's oil water separator solutions.
Gibson Energy logo showcasing Mercer International's trusted customer base Martin Midstream Partners logo demonstrating trusted oil water separator clients. Schlumberger logo demonstrating trusted customer partnerships for Mercer International oil water separators.
ExxonMobil logo demonstrating Mercer International's trusted customer base.
Buckeye Partners logo demonstrating Mercer International's trusted customer base. Oxy logo showcasing Mercer International's trusted customer base and oil water separator solutions. Hess logo demonstrating trusted customer and Mercer International oil water separator system user.
INEOS Oligomers logo, demonstrating Mercer International's trusted customer base.
Hartsfield-Jackson Atlanta International Airport logo demonstrating Mercer's trusted customer base. Penske logo demonstrating Mercer International's trusted customer base.
Firefly Aerospace logo demonstrating trusted equipment for Mercer International oil water separators.
Blue Origin logo showcasing a feather design, demonstrating trusted partnerships for Mercer International oil water separators.
Raytheon Technologies logo demonstrating trusted customer partnerships for Mercer oil water separators. U.S. Department of Homeland Security logo demonstrating trusted Mercer oil water separator clients.
Stellantis logo representing a trusted customer of Mercer International oil water separators. Daimler logo showcasing Mercer International's trusted customer base.
Cummins logo representing a trusted customer of Mercer International oil water separators. Harley-Davidson Cycles logo representing trusted customer partnerships and equipment reliability.

CORE TECHNOLOGY

The Heart of the System: The Multi-Pack™ Coalescer

A tank provides residence time.

Mercer’s Multi-Pack™ coalescer is a purpose-engineered separation system designed to remain effective, adjustable, and serviceable under sustained high-flow operation typical of large parallel systems.

Mercer Multi-Pack™ coalescer plate arrangement in an above-ground oil water separator, illustrating flat, steep-angled plates and herringbone configuration. Mercer Multi-Pack™ coalescer plate packs with herringbone configuration for oil-water separation. Mercer Multi-Pack™ coalescer separation system with flat, steep-angled plates and herringbone configuration. Large coalescing plate pack assemblies for an oil water separator staged in the shop Rows of large gray coalescing plate packs lined up on a shop floor Large oil water separator with open top bays showing coalescer packs under handrail Open separator tank shell with baffle supports, weir structure and piping on a trailer Tall coalescing plate pack with corrugated plates in a fabrication shop

1. Flat, Steep-Angled Plates

The Multi-Pack™ uses flat, steep-angled plates rather than corrugated or honeycomb media. Flat plates support predictable droplet capture while allowing solids to shed cleanly instead of lodging in pockets that quietly choke performance over time.

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2. Field-Adjustable Plate Spacing

Plate spacing can be adjusted beyond or below standard spacing to tune separation performance to actual conditions—oil type, temperature and viscosity effects, solids behavior, and desired maintenance intervals.

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3. Herringbone Plate Configuration

Plates are arranged in a herringbone configuration that organizes internal flow paths and segregates areas where oils rise from areas where solids settle. This stabilizes hydraulics when flows cycle on and off, which is common in low-GPM applications.

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4. Dedicated Chimney Zones for Oil and Solids

As oil coalesces and solids shed from the plates, they enter dedicated Chimney Zones™ designed for separation—not turbulence. These quiescent chambers allow oils to rise and solids to settle without re-entrainment, even during solids spikes.

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5. Ease of Cleaning with No Replacement Parts

The Multi-Pack™ is fully removable as a single assembly. Operators can remove the pack, visually inspect it, clean it, and return it to service without dismantling internals or replacing disposable media.

There has never been a Multi-Pack™ removed from a tank where operators could not see through to the opposite side before cleaning begins. Surface films may be present. Clogged pockets are not.

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Problems This System Class Is Designed to Solve

Solids Fouling at Sustained High Flow

Conventional corrugated plastic or tube-style media foul rapidly under sustained solids loading, leading to performance loss and impractical cleaning.

Strangled Water Columns

Legacy storage tanks and gun barrel systems operate with feet—not inches—of oil accumulation and solids at the bottom, compressing the effective water column and degrading separation.

Misapplied Scale Assumptions

Systems specified solely by flow rate, without accounting for solids behavior, oil type, viscosity, temperature, redundancy, and maintenance constraints routinely underperform at this scale.

Red separator tank being lifted into an excavation at a work site

Why This Matters

At this scale, separation failures can be rather immediate.

As flow increases, small losses in hydraulic control compound quickly. Fouling accelerates, access becomes more difficult, and operators lose confidence in whether the system is still performing as designed.

The Multi-Pack™ prevents that outcome by maintaining predictable separation behavior, enabling full visual inspection, and allowing performance to be verified and restored over time — rather than assumed.

PROVEN LONGEVITY

Legacy Installations in Active Service

Built to Stay in Service

Many Mercer systems operating near this capacity class were installed years ago and remain in continuous operation today. These are not retired assets—they are active separators still managing oil and solids under real operating conditions.

Longevity at this scale reflects internal designs that can be inspected, cleaned, and maintained over time rather than replaced.

Above ground oil water separator at PSEG New Jersey facility, 2000 GPM capacity, demonstrating long-term operation and durability.

PSEG

New Jersey

Above Ground

2000 GPM

Above-ground Mercer oil water separator, 2000 GPM, in operation at PSEG New Jersey facility.

PSEG

New Jersey

Above Ground

2000 GPM

Above-ground oil water separator on trailer, 2000 GPM capacity, Con Edison installation in New York.

Con Edison

New York, US

Above Ground

2000 GPM

Above-ground oil water separator at PSEG New Jersey facility, 2000 GPM capacity, demonstrating long-term operational service.

PSEG

New Jersey

Above Ground

2000 GPM

Above-ground oil water separator at PSEG New Jersey facility, 2000 GPM capacity, demonstrating long-term operation and industrial wastewater management.

PSEG

New Jersey

Above Ground

2000 GPM

Above-ground Mercer oil water separator system, 2000 GPM capacity, in industrial setting near New Jersey bridge.

JCPL

New Jersey

Above Ground

2000 GPM

INDUSTRY APPLICATIONS

Applications Where This Family
Has Been Deployed

Above-ground 400 GPM oil-water separators in industrial setting, 5-4000 GPM capacity, continuous wastewater treatment.

Heavy Industrial & Process Facilities

Continuous oil-bearing wastewater with sustained solids loading from production, washdown, and process support activities.

Learn more
Aerial view of a refinery with distillation towers and a large water tank

Energy & Oil Handling Operations

Produced water and oil-handling environments where oil type, temperature, and solids vary across operating cycles.

Learn more
Water surging through a hydroelectric dam spillway below a cloudy sky

Utility & Infrastructure Operations

Major utility sites requiring continuous duty with predictable inspection and cleaning access.

Learn more
Petroleum storage tank farm with pipelines and a large blue valve under sunny skies

Transportation & Logistics Infrastructure

Large terminals, fueling operations, and hubs generating high-volume wastewater with operational uptime requirements.

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Next Step

At up to 2,000 GPM, oil-water separation becomes part of the facility’s long-term operating license. Mercer collaborates with owners and project teams to ensure the system is not only capable at startup, but governable, maintainable, and defensible throughout its service life. Engage Mercer during layout and system planning to avoid irreversible design decisions and protect the facility for decades to come.

Talk to Mercer about your application.

Frequently Asked Questions

Q.

Transportation & Logistics Facilities

A.

At flows approaching 4,000 GPM, oil-water separation stops being an isolated treatment function and becomes a governing constraint on site layout, drainage strategy, and operational sequencing. Decisions made here influence how the entire facility manages water for decades.

Q.

Why is modular thinking critical at very large flow rates?

A.

Single-path solutions at this scale concentrate risk. Mercer approaches large-capacity systems with modular logic so treatment capacity can be distributed, isolated, or expanded without placing the entire operation at risk during maintenance, modification, or future upgrades.

Q.

How does organizational turnover affect systems of this size?

A.

Facilities operating at this scale will outlive original project teams, operators, and even ownership structures. Mercer designs systems that remain understandable, controllable, and defensible long after institutional knowledge has changed.

Engineering drawing of a coalescing plate pack for an oil water separator showing dimensions and layouts

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Tell us about your project and we’ll provide the right configuration drawings for your site and flow conditions.

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Calculation sheet sizing the inlet zone of a coalescing plate oil water separator

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Provide your project details and we’ll share the full technical specs relevant to your operating conditions.

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