Oil Water Separators

April 22, 2014

Below Ground Oil Water Separator Design
Featuring one of our oil water separator designs to be placed under ground.

Our single wall or double wall below ground parallel corrugated plate oil/water separators meet and exceed API 421 requirements, removing essentially all free and dispersed non-emulsified oil droplets in the waste


  • Parking Lots
  • Re-fueling Facilities
  • Marinas
  • Military Installations

Performance Standards

Below Ground Oil Water Separator Design and Installation.
Installing a below ground oil water separator.
  • Utilizes patented, revolutionary, non- plugging coalescing plates which
    remove free oil droplets as small as 20 microns
  • Will not need to use secondary polishing packs
  • Will achieve discharge of 5 ppm or less in accordance with CEN EN 858-1
  • Performance guarantee based on influent characteristics
  • Warranted for (5) years on material and workmanship and (30) years
    against external and internal corrosion

How does it work?

Construction Standards

  • Construction in accordance with UL58
  • Corrosion protection in accordance with UL1746, FRP, STi P3 or urethane
  • Single wall or double wall construction with interstitial space for leak detection
  • Meets NFPA 30 local requirements

With these separators, we can provide analysis, which indicates that the
separator will be provided with the required square feet of projected plate
separation area to achieve the specified performance under laminar flow
(i.e. Reynolds Number of less than 500) conditions. This service includes
calculations signed by a registered professional engineer.

Model # Average Flowrate (GPM) Approximate Capacity (Gallons) Dimensions Diameter x Length (FT)
WB-QB-342 10-30 350 3.5 x 6
WB-QB-548 30-50 500 3.5 x 9
WB-QB-1048 50-100 1000 4 x 11
WB-QB-2064 100-200 1500 5 x 12
WB-QB-2564 200-300 2000 5 x 21
WB-QB-2572 300-400 2500 6 x 12
WB-QB-3272 400-500 3200 6 x 15
WB-QB-4072 500-800 4000 6 x 19

Frequently Asked Questions

March 5, 2014

In some locations such as power plants or older factories, there may be a need to install a larger oil water separator in a constrained space. There may be room for the separator, but the entrance to the separator area may be a maze of twisted steps and narrow hallways.  If this is the case, we have the ability to custom engineer an oil water separator that can be built in place, piece-by-piece.

Constrained Location Oil Water Separator
Our Built In Place Oil Water Separators are designed for those constrained locations that seem impossible. Wash Bay Solutions provides an advanced solution for this very need.

Applications include:

  • Power Plants
  • Refineries
  • Factories
  • Industrial plants

Available in a range of dimensions and flow rates, these separators can be constructed of stainless steel or carbon steel that corrosion protection applied at the factory.

To ensure each piece will be made to accommodate the facility, we will prepare detailed sub-assembly drawings for your approval prior to starting construction. Then, detailed construction drawings and instructions will be provided for onsite installation.

Like all of our separators, these constrained space oil/water separators will remove 99.9% of free and dispersed non-emulsified oil droplets in the waste stream.


  • Removes free oil droplets as small as 20 microns
  • Reduces effluent free oil concentration to 10 ppm or less
  • High flow rates in a compact design
  • Low maintenance costs
  • Solids storage capability

All of our systems are constructed of heavy-duty components for maximum life and performance.  They can be customized with hoppers or oil storage compartments and a variety of skimming, monitoring, and pumping packages.

March 5, 2014

Are you washing with dirty water?

Many industries have parts washing systems that are critical to their production. Often used on a continuous basis, they remove heavy oils, dry lubes and machining particles off production parts. Many of these wash systems require constant cleaning and filtration to not to re-contaminate the parts. 

Our oil water separator systems will remove 99.9% of free and dispersed non-emulsified oil droplets in the wash water  – greatly improving the quality of the cleaning water and extending the time before having to dump and re-charge. They will also help drop out particles from the wash water.

Oil Water Separator
Featuring an image of one of our oil water separator designs.

Available in a range of dimensions and flow rates, our oil water separators can be can be integrated easily with the existing parts washing systems and customized with a variety of skimming, monitoring, and pumping packages.  All of our systems are constructed of stainless steel and heavy-duty components for maximum life and performance. 


  • 99% Removal of all free oil
  • Small foot-print – compact design
  • Low maintenance costs
  • Solids storage capability
  • Easily integrated into existing systems

Above Ground Oil/Water Separators

OWS Model # Dimensions
W x H x L (ft)
Max Flowrate, GPM


1 x 2 x 4 3


2 x 2 x 4 6


3 x 2 x 4 9


1 x 2 x 5 6


2 x 2 x 5 12


3 x 2 x 5 18


1 x 3 x 5 12


2 x 3 x 5 24


3 x 3 x 5 36


2 x 3 x 7 60


3 x 3 x 7 90


4 x 3 x 7 120

March 3, 2014

Oil Water Separator for Vehicle Washing Solutions
Here is one of our oil water separators specifically designed for the vehicle washing industry to help remove dirt and oil.

Our oil water separators have been specially developed for treating wash water from commercial vehicle washing operations.  Used in a variety of applications, our vehicle washing oil water separator systems will remove 99.9% of free and dispersed non-emulsified oil droplets in the wash water with discharge to the sewer or a treatment plant.


  • Equipment Washing
  • Car Washing
  • Truck & Bus Washing
  • Forklift Wash Facilities
  • Aircraft Washing
  • Locomotive Washing
  • Marinas

Available in a range of dimensions and flow rates, our oil water separators can be can be customized with a variety of skimming, monitoring, and pumping packages.  All of our systems are constructed of stainless steel or coated carbon steel and heavy-duty components for maximum life and performance. They can also be easily adapted to handle a range of input water variations including high salt content and acids.


  • 99% Removal of all free oil and settable solids
  • Versatile design
  • Low installation and maintenance costs
  • Solids storage capability
  • Easily modified for existing site systems

Vehicle Wash Oil/Water Separators

OWS Series # Typical Application Average Flowrate, GPM
Above Ground Systems
WB-GS Series Low Flow, hand wash 3-20
WB-GM Series Medium Flow 20-60
WB-AG Series Medium Flow, Low Solids 30-2000
WB-HP Series Medium-High Flow, Medium Solids 30-350
WB-SPT Series Medium Flow, High Solids 10-150
Below Ground Systems
WB-QB Series Medium-High Flow, Low Solids 35-4000

November 14, 2013

Clarifier Oil Water Separator in Mexico
The clarifier oil water separator used for the mining company in central Mexico.

Problem: A gold mine in central Mexico was modifying their vehicle maintenance facility and adding a wash bay for their heavy mining trucks and vehicles covered with solids, dirt, oil, and grease. The mining company contacted an engineering firm in Arizona who then contacted us for our wash bay expertise.

Solution: We worked with the engineering firm to help design the wash bay with the proper pad layout to accommodate the enormous vehicles, substantial wash water volumes and large amounts of solids. We also had to account for rainwater volumes since their wash bay was uncovered.

Our SPT-50 Clarifier Oil Water Separator System was a perfect fit since it was designed for treating wash water from industrial washing operations with large solids concentrations. It includes a stainless steel clarifier oil water separator that has both a clarifier section, which will remove all settable solids and an oil water separator section, which will remove all non-emulsified oil from the waste stream.

During construction of the wash pad and installation of the SPT-50, we continued to work with the engineering company so insure all tasks were completed properly. We provided all manuals and documentation in both Spanish and English so that as little information as possible was lost in translation. The client has reported that the SPT-50 has been working very well since installation.

September 18, 2012

In many cases, a below ground oil water separator is the best option due to space restrictions and layout. You can use gravity to drain into a below ground system and then into the sanitary sewer system so there is no need for pumps and controls. In other cases, a below ground system has been previously specified and it is not possible to change the specifications.

May 9, 2012

The HD Q-PAC media has vastly superior properties compared to the traditional media used in oil-water separators. These properties result in a more efficient and effective separation than that attained by traditional coalescing media, for a variety of reasons.

In a typical oil-water separator with traditional media, incoming oily water slowly flows from the inlet through a media comprised of a series of parallel, inclined plates. As the oil droplets in the water coalesce with other oil droplets on the media surface, the oil droplets grow in size and travel up the plates to the water surface. This design, however, allows some water droplets to by-pass the plates and flow through the separator, requiring secondary polishing filters to achieve the required effluent characteristics. The shapes and configurations of tradition coalescing media also traps particles and sludge on the media itself, resulting in a sludge build-up and a reduction of effective flow through the separator.

The HD Q-PAC media provides improved performance in oil-water separators over traditional media due to the following properties:

– A larger amount of surface area per cubic foot of media allows for greater oil drop coalescence. HD Q-PAC media has 132 ft2/ft3 surface area for oil droplets to contact. Other typical coalescing media have about 48 ft2/ft3 to 68 ft2/ft3.

– A more efficient first step separation reduces the need for a second polishing step. HD Q-PAC media removes 99.9% of oil droplets 20 microns in size and larger. This meets EPA Method 1664 Revision A and European Standard EN 858-1.

– An open design eliminates trapping of particles and subsequent clogging of water channels. Oil water separators with HD Q-PAC media require fewer maintenance shut-downs and separates oil and water faster.

– Where higher-than-normal operating temperatures are required, HD Q-PAC media outperforms its competitors. HD Q-PAC media works effectively in temperatures up to 212°F, versus a maximum temperature of about 120°F for competing media.

April 7, 2012

Oil Water Separators are designed to effectively remove floating solids and non-emulsified oil from an oil and water mixture on a beginning to end flow process through the separator. The mixture of oil and water enters one end of the separator and slowly flows toward the other end. If oil and water are mixed and not emulsified, the oil originally exits the water in different sizes of droplets. When the drops of oil are large enough and the flow is laminar, or moving in a smooth and gentle flow with no turbulence, the oil droplets will separate before reaching the end of the separator tank.

Since the calculations of Stokes’ Law are supported on a zero velocity flow, a Reynolds number lower than 500 guarantees optimal separation. The majority of oil water separators commonly use the parallel corrugated plate design which causes oil droplets to enlarge in size and ascend to the surface of the water. Flow of oil and water through the oil water separator follows several main steps after entering the separator:

  • Mixture particulates, heavier sludge drops from liquid and is confined in sludge hopper.
  • Lighter weight particles from mixture travel up inclined plates.
  • Inclined plates begin separating the mixture.
  • Some oil will rise to the top of the separator.
  • Particulates drop down into sludge hopper.
  • Remaining mixture travels on through coalescing media packs.
  • Most remaining small oil particles attach to media and coalesce with retained droplets.
  • Retained droplets form larger oil droplets.
  • Larger oil droplets float, rising to top of separator.
  • Oil volume reaches a certain level and is pumped or drained to a storage tank.
  • Clean water travels on to a chamber and goes through a final polishing pack.
  • Clean water is discharged from the separator.

It is especially essential for the flow of the liquid through the oil water separator to be laminar to act in accordance with Stokes Law. To achieve this type of flow, a design that is cross-fluted and having an internal structure of connecting channels between adjoining plates can be used. With this design and the enlarged surface area, the effectiveness of the oil water separation process is greatly enhanced.

North Carolina


At WashBaySolutions.com, we have been specializing in high tech, custom-engineered solutions to complex washing and wastewater issues since 1991.
+ 1 800-453-8639




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