- No moving parts = zero maintenance : Designed to be fail-proof in harsh environments.
- Flexible & customizable : Molded fiberglass allows unique layout for exact system integration.
- High-efficiency separation : Down to 10ppm of free oils—meets compliance and discharge limits.
- Built for real-world challenges : Works with fuels, crude, hydraulic oils, DNAPL, LNAPL, and more.
- Compact, lightweight & powerful : Up to 50 GPM capacity in an above-grade, self-supported system.
IN STOCK. READY TO SHIP. BUILT TO WORK.
Stop waiting 12–16 weeks for equipment you need now. Our Coalescing Oil Water Separators are stocked and ready to ship — helping you reduce disposal costs, separate oil efficiently, and keep operations moving without delays.
Ask what’s in stock today.
Coalescing Oil Water Separator Features
Industrial Fiberglass Oily Water Separators — 10 ppm Performance | No Moving Parts | Built for Harsh Environments
SkimOIL ® ’s ROSF Series Coalescing Oil Water Separators are lightweight, rugged, and engineered for long-term performance with virtually zero maintenance. With molded fiberglass construction, high-efficiency coalescing media, and flexible chamber configurations, these separators deliver reliable 10 ppm effluent quality while integrating easily into industrial, remediation, wash rack, and stormwater systems.
01
Design
- Molded fiberglass construction: Corrosion-proof FRP body built for long life in industrial, marine, and outdoor environments.
- Flexible internal layout: Horizontal or vertical chamber division options, combined or separated, to match exact system requirements.
- Built-in oil reservoir: Integrated oil storage chamber allows temporary capture of skimmed oils before removal.
- Compact & lightweight: Above-grade, self-supported design fits tight spaces and is easy to transport, place, and integrate.
- Media-packed separation chamber: Flopak coalescing media maximizes surface area for superior droplet rise and oil removal efficiency.
02
PERFORMANCE
- High-efficiency separation: Removes free and dispersed oils down to 10 mg/L (10 ppm) for discharge compliance.
- Handles real-world contaminants: Effective with fuels, hydraulic oils, crude, DNAPLs, LNAPLs, machining oils, lube oils, bunker C, and more.
- Solid + oil separation: Removes 30-micron oil droplets and manages 40–100 mg/L TSS loads depending on configuration.
- API-421 + coalescing plate theory: Designed using proven OWS engineering standards to ensure predictable, repeatable performance.
- Gravity flow up to 50 GPM: Five model sizes available, supporting a wide range of industrial flow demands.
03
INSTALLATION
- Zero moving parts: Eliminates mechanical failure points, making the system nearly maintenance-free.
- Above-grade, plug-and-play setup: Self-supported FRP tank installs quickly—ideal for remediation, wash racks, and temporary or mobile systems.
- Simple cleaning & inspection: Large, single-piece vapor-retaining cover provides easy access for periodic checks.
- Optional pumps & automation: Choose influent feed pumps, sludge or oil pumpout systems, or level sensors as needed.
- Long-life components: FRP construction, PVC piping, gasketed cover, and Flopak media make long-term operation dependable.
WHY THIS COALESCING SEPARATOR MATTERS
When uptime and simplicity matter, this unit delivers dependable oil removal without the babysitting. Molded fiberglass construction and zero moving parts mean fewer breakdowns and long-term reliability. Install it, connect it, and let it do the work — consistent 10-ppm performance, day after day.
Overview
These small (up to 50 gpm) fiberglass industrial oil water separators (OWS) have the unique capability to be modified to fit the application, in that it has a built in oil reservoir which typically has a horizontal plate that separates it from the effluent chamber. These two chambers can be divided horizontally or vertically, or combined to fit your system needs. This unit will typically deliver an effluent quality of 10ppm or less of unemulsified oil particles over 30 micron. We can do it because they are molded fiberglass.
These are great little oil water separators with a flow range all the way up to 50 gpm gravity flow. If you are going to be pumping—we need to talk about it and the limits. Call us (314) 579-9755.
NO MOVING PARTS—it’s hard to screw this one up.
The ROSF Series Fiberglass Coalescing Oil Water Separators are designed for above grade applications where a high performance coalescing oil water separator is desired using coalescing media. The lightweight, compact ROSF oil water separator design has many features and options to provide engineers, system integrator and end users with convenience and flexibility in system integration choices for groundwater remediation, wash rack, storm water runoff and other projects.
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Removes
Products removed: motor oils, fuels (vehicle/jet), fuel oils, hydraulic fluids, immiscible machining oils, lube oil, transmission fluid, bunker c, DNAPL, LNAPL, vegetable based oils, crude, air compressor lube & other petroleum based derivatives (BTEX etc.). Model sizing is based on the oil/fuel specific gravity, droplet size removal desired and other parameters of the waste stream.
ROSF Fiberglass Series Separator Brochure / R/OS/X Steel Series Separator Brochure / SSC/OWS/EX Stainless Steel Series Separator Brochure / Sheen Coalescing Pack (SCP)
Performance
Oil/fuel removal : 10 mg/L or less of oil droplets 30 micron and larger of non-emulsified, free and dispersed oils Solids (TSS) : 40 -100 mg/L
Influent concentration basis: Oils 1250 mg/L or less influent loading TSS 400 mg/L or less influent loading
Specifications
Specification Summary: ROSF oil water separator System model: Coalescing Separator Number of model sizes: 5 Process types: Oil separation, TSS settling Volume range offered: 5 – 50 GPM
Design Specification Summary
- Performance: 10 mg/L or less 30 micron free, dispersed and non-emulsified oil droplet
- Design criteria: Elements of API-421, 1990 & current coalescing media design theory
- Influent chamber: Influent diffuser or overflow weir Separation chamber: To contain Flopak media pack(s) Solids hopper: Located under and after separation chamber and media packs
- Clean water effluent chamber: Located after separation chamber
- Water baffle: Water flows over this baffle to exit tank Weir plate: Vertical fixed weir plate to maintain operating water level
- Oil skimmer: Adjustable rotary weir located in the separation chamber
- Oil reservoir: Located in separation chamber for temporary storage of skimmed oils
- Media pack: Flopak separation packs Cover: Single piece vapor retaining, gasketed with polyethylene gasket and attached via zinc plate fasteners
- Fittings: NPT couplings up to 3″, 4″ & larger: 150# ANSI B16.5 FF flange
- Base: Self-supporting FRP base Lifting lugs: No lifting lugs provided
Materials of Construction
- Tanks: FRP
- Piping: PVC
- Testing: Hydrostatic testing
- Surface preparation (FRP): Interior surfaces prepared prior to molding.
Coatings (FRP): Exterior coating shall be white gel coat, 25 mil DFT. Interior coating shall be coated with a clear veil.
Standards Used
Elements of AWS D1.1/1.1M, API, API-650, API-421, ANSI, IEC, AWS D1.6, UL, UL-508, UL-845, SSPC, ASME, CSA, NEMA, NFPA79, NEC
Oil Water Separator Theory
Coalescing Oil Water Separators are passive, physical separation systems designed for removal of oils, fuels, hydraulic fluids, LNAPL and DNAPL products from water. Designed performance can be described by a combination of Stokes Law and current coalescing plate theory, wherein, the oil droplet rise rate and other parameters dictate the surface area required for gravity & coalescent separation.
Separation Process : The water/oil mixture enters the separator and is spread out horizontally, distributed through an energy and turbulence diffusing device. The mixture enters the Flopak media where laminar and sinusoidal flow is established and the oils impinge on the media surface. As oils accumulate they coalesce into larger droplets, rising upward through the pack corrugations until they reach the top of the pack, where they detach and rise to the water’s surface. At the same time solids encounter the media and slide down the corrugations, falling into the v-hopper under the Flopak media.
Applications
- Groundwater Remediation
- Refineries
- Vehicle Wash Racks
- Military Wash Racks
- Industrial Process Water
- Steel Mills
- Stormwater Treatment
- Shipping Ballast & Bilge Water Treatment
- Tank Farms
- Petro-Chemical
- Power Generation
- Heat Treating
Options
- Slotted Pipe Scum Skimmer
- Influent Feed System
- Effluent Pumpout
- Sludge Pumpout System
- Oil Pumpout System
- Sludge Auger
- Freeze Protection
- Retpak Secondary Coalescer
- Oil Sight Glass
- External Sight / Level Glass
- Elevation Stand
- High Temperature Design
- Alternate Media Construction
- External Storage/Feed Tanks
- Effluent Filter Systems
- Specialty Filter Systems
- Carbon Filtration Systems
- Emulsion Cracking Systems
- pH Adjustment Systems
- System Containerization
- Trailer Mounting
- Field Skid Mounting
- Skid Mounted System
- Vent Scrubber
- Level Sensors
- Class 1 Div 1 & 2 Compliance
- Oil Monitor
- Seismic Design
Frequently Asked Questions
What is the ROSF Fiberglass Coalescing Oil Water Separator?
The ROSF series is a compact, high-efficiency fiberglass oil water separator designed for industrial applications. It removes free, dispersed, and non-emulsified oils down to 10 mg/L, with no moving parts—making it low-maintenance, durable, and ideal for harsh environments.
What types of applications is this separator suitable for?
These separators are versatile and work well in groundwater remediation, vehicle and military wash racks, refineries, stormwater treatment, tank farms, shipping ballast & bilge water treatment, and other industrial processes handling fuels, crude, hydraulic fluids, and petroleum-based oils.
Can the separator be customized to fit my system?
Yes. The molded fiberglass construction allows flexible design modifications, including vertical or horizontal chamber divisions, media pack arrangements, and optional accessories like scum skimmers, pumpouts, secondary coalescers, and effluent filters—so you can tailor it precisely to your system requirements.
How does the ROSF separator handle emulsified or high-solids water?
The system is designed to separate free and dispersed oils effectively. While it excels with non-emulsified oils 30 microns and larger, high TSS (total suspended solids) or emulsified oils may require pre-treatment or optional enhancements such as Retpak secondary coalescers or effluent filters to achieve optimal performance.
What are the available sizes and flow capacities?
The ROSF series is available in five standard model sizes, supporting flow rates from 5 to 50 GPM. Custom sizing is possible depending on influent oil/fuel concentration, droplet size, and system integration needs. For flows above 50 GPM or pump-assisted systems, we recommend contacting us to discuss system limits.
Need Customization?
- Customization & modifications are available.