OPERATING TIER
Above-ground oil-water separators in the 5–10 GPM range are typically deployed where wastewater treatment supports operations rather than defining them. These systems serve maintenance bays, washdown areas, fueling points, and utility facilities where space is limited, staffing is lean, and equipment is expected to perform reliably without constant attention.
At this scale, separators rarely fail because gravity separation is flawed. They fail because internals foul quietly, inspection is deferred, and systems are selected by nominal flow rate alone—without considering solids behavior, temperature swings, or how the separator will actually be accessed and maintained.
Mercer’s 5–10 GPM above-ground separators are designed for real wastewater conditions, including free oil, suspended solids, intermittent loading, and variable operating cycles. The design prioritizes inspectability, cleanability, and long-term reliability rather than idealized influent assumptions.
Mercer has deployed systems at this scale in demanding industrial, utility, and energy environments where access, inspectability, and long-term serviceability determine whether a separator remains an asset or becomes a maintenance problem.
Built To Scale
This product family follows a compact, low-flow footprint philosophy, with internal volume and coalescer sizing adjusted by flow range and application requirements.
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
Small flows can still pose big problems.
The installations shown represent actual Mercer systems operating in the 5–10 GPM range, deployed in facilities where access, uptime, and maintenance realities drive long-term performance.
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
TRUSTED BY INDUSTRY LEADERS
A small sampling of companies with Mercer separators operating within the 5–10 GPM family range.
ENGINEERED TO SOLVE
Even modest solids loading can foul corrugated plastic or tube-style coalescers. Once solids lodge in internal pockets, oil removal efficiency drops and cleaning becomes impractical.
Small separators are often ignored because they are difficult to inspect or access. Over time, this leads to emergency cleanouts, unexpected failures, or premature replacement.
Systems selected strictly by flow rate—without considering oil type, solids behavior, temperature, or access—often appear adequate initially and fail months later in real service.
CORE TECHNOLOGY
A tank provides residence time.
Separation performance is determined by what happens inside the coalescer.
Mercer’s Multi-Pack™ coalescer is not generic media. It is a purpose-engineered separation system built around five core design elements that control oil rise, solids shedding, hydraulic stability, and real-world maintainability—especially in applications where small systems are easy to ignore until they fail.
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.
Learn MorePlate 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.
Learn MorePlates 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.
Learn MoreAs 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.
Learn MoreThe 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.
Learn MoreAll at no cost to you.
We walk your site, capture real influent data if needed, engineer a custom separator from your worst-case scenario, and validate performance before fabrication. Only after the data confirms it do we issue a written guarantee. That’s how risk is removed.
PROVEN LONGEVITY
Built to Stay in Service
Many of the systems shown below were installed years ago and remain in continuous operation today. These are not retired examples or decommissioned assets. They are active separators, still managing oil and solids under real operating conditions.
Longevity at this scale is not accidental. It is the result of internal designs that can be inspected, cleaned, and adjusted over time rather than replaced.
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
Above Ground
5 & 10 GPM
INDUSTRY APPLICATIONS
Above-ground oil-water separators in the 400–600 GPM range are deployed in operations where wastewater treatment is continuous, not intermittent, and where solids loading, oil characteristics, and maintenance access determine long-term performance more than nominal flow rate.
Large industrial plants generate continuous oil-bearing wastewater with sustained solids loading from production, washdown, and process support activities. At this scale, Mercer systems are selected for durability, full access to internals, and predictable long-term performance under non-ideal operating conditions.
Learn more
Upstream, midstream, and downstream facilities rely on Mercer separators to manage high-volume wastewater where oil type, temperature, and solids vary over time. These applications demand stable separation performance through changing operating cycles and extended run times.
Learn more
Major utility facilities, maintenance yards, and infrastructure hubs require separators capable of continuous operation with minimal downtime. Mercer systems are applied where access for inspection and cleaning is critical to maintaining compliance and protecting downstream assets.
Learn More
Large transportation hubs, fueling terminals, and logistics centers generate high-volume wastewater from fueling, equipment washing, and maintenance operations. Reliable separation and serviceability are essential to sustaining operations and avoiding unplanned shutdowns.
Learn MoreIf you are evaluating separators in this flow range, the fastest way to determine suitability is to review your actual operating conditions—not assumed averages.
Talk to Mercer about your application.Cleaning frequency depends on solids loading and operating conditions. The removable design allows rapid inspection and cleaning without extended downtime.
Yes, when solids loading and site conditions are properly evaluated.
In many applications, Mercer systems achieve 5–10 ppm free hydrocarbons. Performance depends on influent characteristics.
Tell us about your project and we’ll provide the right configuration drawings for your site and flow conditions.
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