OPERATING TIER
Mercer’s low-flow separator series delivers industrial-duty performance in a compact footprint, incorporating the same proven features as Mercer’s standard separators that have built the company’s strong reputation for reliability. These units are widely used in vehicle wash operations, automotive repair shops, dealerships, transportation agencies, and utilities as stand-alone treatment or as primary treatment ahead of larger systems, valued for dependable operation and ease of maintenance. They have also been successfully applied across diverse industries, including scrap yards, chemical and fertilizer processing, boiler and bilge water treatment, hydraulic fluid leakage control, and food and beverage processing for grease, fat, and oil removal.
This low-flow family is an ideal candidate for Mercer’s Test For Free and Guarantee program. Its proven design, predictable performance, and straightforward installation allow customers to evaluate real-world results with minimal risk, while its versatility and consistent treatment outcomes make it well suited to quickly demonstrate value and build confidence for broader adoption.
Built To Scale
At this scale, separators are no longer “background equipment.”
The installations shown represent Mercer systems operating in the 20–30 GPM range at facilities where wastewater treatment is part of daily operations and reliability matters.
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
A small sampling of companies with Mercer separators operating within the 20–30 GPM family range.
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
TRUSTED BY INDUSTRY LEADERS
A small sampling of companies with Mercer separators operating within the 20–30 GPM family range.
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 MoreAt this flow range, separators often appear to work—until they don’t.
In the 20–30 GPM range, separators don’t typically fail suddenly—they fade. Fouling accumulates, oil removal drops, maintenance escalates, and uncertainty replaces confidence, often while the system remains in service with compromised internals.
The Multi-Pack™ is built to stop that progression. With predictable solids shedding, stable oil capture, and full visual access for inspection and cleaning, it ensures separation performance is provable and recoverable—not assumed.
At this flow range, recurring solids loading quickly fouls corrugated plastic or tube-style media, reducing separation efficiency and making cleaning impractical.
Systems without solids removal considerations require frequent monitoring, disruptive cleanouts, or early replacement to maintain performance.
Separators selected strictly by nameplate flow often perform briefly and fail once real-world conditions—solids, temperature, oil variability—assert themselves.
Fleet maintenance and wash facilities generate oil-laden wastewater with recurring solids loading. Mercer systems are selected to remain serviceable between cleanings while maintaining discharge compliance.
Light-to-moderate industrial processes and utility support areas require predictable separation performance without constant operator attention.
This family has also been applied in fuel handling areas, service depots, and municipal support facilities where access and long-term reliability drive equipment selection.
All 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
Engineered for Service Life
A significant number of Mercer systems in the 20–30 GPM range have been in service for decades and continue operating without interruption. These systems remain fully functional, managing oil and solids under actual process conditions.
This longevity is driven by internal components designed for handling solids, consistent oil removal, and the absolute lowest maintenance over time—not disposal or replacement of plastic junk.
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
Above Ground
20 & 30 GPM
INDUSTRY APPLICATIONS
Above-ground oil-water separators in the 20–30 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.
Light-to-moderate industrial processes and utility support areas require predictable separation performance without constant operator attention.
Learn more
This family has also been applied in fuel handling areas, service depots, and municipal support facilities where access and long-term reliability drive equipment selection.
Learn more
Fleet maintenance and wash facilities generate oil-laden wastewater with recurring solids loading. Mercer systems are selected to remain serviceable between cleanings while maintaining discharge compliance.
Learn MoreAt this flow range, separator performance is rarely limited by plate media — it is limited by assumptions. Mercer engineers review real flows, solids, oil chemistry, and operating constraints to confirm whether this configuration is appropriate before equipment is selected.Talk to Mercer to validate your application and avoid undersized or over-engineered solutions.
Talk to Mercer about your application.As flow rates increase, hydraulic balance and solids management become more critical. These units use the same proven coalescing internals as smaller models, but with proportionally sized inlet calming zones, plate packs, and access features to ensure performance is maintained at higher throughputs.
Maintenance is governed less by flow rate and more by solids loading, oil type, and operating discipline. Facilities with washdown grit, biological growth, or variable loading may require more frequent inspection than sites with consistent, well-characterized influent.
Yes. Above-ground systems in this range are often specified with allowance for future process changes, including additional solids management, oil recovery accessories, or instrumentation. Mercer designs these systems to be serviceable and adaptable, not locked into a single operating snapshot.
Tell us about your project and we’ll provide the right configuration drawings for your site and flow conditions.
Head to the design center
Provide your project details and we’ll share the full technical specs relevant to your operating conditions.
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