A "Green" Company Since 1990

MaxiSep™ "Enhanced Gravity" Oil/Water Separators

Follow this link "Oil Water Separator Design Parameters" for information on the accurate design and sizing of Oil Water Separators and Separation Systems

HydroFlo Enhanced Gravity Oil/Water Separators separate free non-emulsified oil, hydrocarbons, diesel, gasoline, and fuels, from water.

Our separators are designed specifically around the data presented in API pub 421 "Design and Operation of Oil/Water Separators". By following all the API design parameters, the HydroFlo enhanced gravity oil/water separators are the most efficient oil water separators available.

We can outfit our separators with various sizes of our proprietary DynaPac™ cross corrugated coalescing media, as well as unlimited varieties of parallel plate media. This allows us to tailor the design of our oil water separator to meet your specific application.


The internal media (whether DynaPac™ cross corrugated coalescing media or parallel plate media) can be flushed with water and reused for years of efficient, trouble free use.

One of the advantages of our design is that the recovered product will typically have a residual water content of less than 3%.

One of the greatest advantages of the HydroFlo line of oil/water separators is the ability to easily add additional features as they become necessary. As your process or discharge requirements change, you can install different media, add a sludge auger or add a surface drag skimmer. You can even add an air dissolving recirculation system and convert the entire separator into a dissolved air flotation system. HydroFlo oil/water separators are the most flexible separators available anywhere, able to be configured to meet any of your current demands and your changing demands of the future.

Standard Features:

  • Adjustable effluent weir troughs
  • Epoxy coated ASTM A-36 carbon steel tank
  • Factory tested
  • PVC plate packs
  • Seamlessly integrates with other HydroFlo offered wastewater products
  • Stand alone operation
  • Standard units can be manufactured for flows from 5 gpm to 3000 gpm and above, in a single above grade tank
  • Structural steel support legs

Available Options:

  • Access platforms with ladder or stairs
  • Automatic sludge pump out packages
  • Chemical pretreatment systems
  • Concrete tank designs for large in ground installations
  • Duplex systems for redundancy
  • Effluent monitoring
  • Effluent sampling
  • Explosion-proof design
  • Flash mix/flocculation tanks with mixers
  • 304 or 316 stainless steel construction
  • Influent equalization
  • Influent / effluent lift stations
  • Instrumentation and controls
  • Removable covers with gaskets
  • Integral mechanical sludge thickener
  • On board reagent storage (day tanks)
  • Pilot size units for on-site testing
  • Potable water design
  • SCADA system monitoring
  • Special coatings and plate materials
  • Sludge handling and dewatering


Equipment Design Data & Sizing Calculations

• Standard Engineering

"Common" Engineering
  Applicable to all HydroFlo
  Manufactured Equipment

Installation, Operation & Maintenance Manuals

Standard IO&M Manual

General IO&M
  Applicable to all HydroFlo
  Manufactured Equipment

There are many considerations to be taken into account when designing an enhanced gravity oil/water separator. The following needs to be taken into account as a minimum:

  1. Inlet flow distribution

  2. Length to height to width ratios (for proper overall flow distribution)

  3. Cross sectional velocities (actual, not nominal)

  4. Laminar flow conditions

  5. DynaPac™ Cross Corrugated coalescing media or parallel plate media "Reynolds" calculations (for quiescent flow distribution)

  6. Effluent flow distribution

  7. Total projected surface area

These basic design considerations all contribute to the complete utilization of the separation media. Follow them properly and the results will be consistent, equal flow distribution through the separation chamber and the media pack. These are the earmarks of a thoughtful, wholly engineered, fully developed oil/water separator design.

HydroFlo strives to be the benchmark by which all others are judged. By paying total attention to every detail of the separators design, we can supply you with the finest oil/water separator available anywhere.

Equipment Criteria:

The separator shall be a specially fabricated rectangular channel tank. The separation process shall be fully automatic requiring no moving parts. The design of the separator shall satisfy the requirements of API PUBLICATION 421, Feb. 1990 on DESIGN & OPERATION OF OIL/WATER SEPARATORS and Stokes' law. Performance enhancement shall be achieved by the use of DynaPac™ cross corrugated coalescing media.

Separation Cell:

The separation cell is designed using elements of American Petroleum Institute's publication 421 Feb. 1990 “Design of Oil-Water Separators” to ensure the best possible use of particle rise rate performance. The separation cell is a rectangular “V” bottom tank manufactured from carbon steel with an effluent surface baffle, 304 stainless steel full width adjustable overflow weir, effluent collection chamber with flanged outlet nozzle and recycle suction port, and angled float beaching plate.

  1. Influent Diffusion Chamber
    The flow shall enter the separator submerged, through an influent diffusion chamber. Dispersion across the depth and width of the DYNAPAC™ is to be achieved through the use of a non-clog diffuser. Heavy solids that fall out of suspension here shall be channeled to the sludge collection chamber.
  2. Separation Chamber
    The Separation Chamber shall be fitted with DYNAPAC™ cross corrugated coalescing media. Adequate space is to be left before and after the chamber to prevent short circuiting through the pack. A total of ____ cubic feet of coalescing media is provided with ½, ¾, or 1-1/4” spacing providing _______ft3 of coalescing surface area.
  3. Sludge Collection Chamber
    The sludge collection chamber shall be located directly beneath the coalescing media pack and provide ample storage capacity for the settled sludge. The sides of the chamber shall be sloped at 45 degrees to insure easy and complete removal of the settled sludge.
  4. Oil Trough
    The oil trough shall be located at the influent end of the separation chamber and incorporate an angled float/oil skimming plate.
  5. Effluent Chamber
    The aqueous phase leaving the DYNAPAC™ shall pass under the oil retention baffle and up over the adjustable 304 stainless steel effluent weir, which shall maintain the liquid level throughout the separator.
  6. Removable Lids
    The entire separator shall be covered with bolt down removable lid
  7. Coalescing Media
    The coalescing media pack shall be fabricated of oleophilic cross corrugated coalescing media manufactured by HydroFlo Tech.

Surface Skimmer (Optional):

Provide a removable float skimming system with frame assembly and drive motor, sprockets, chains and full width stainless steel skimming blades. The skimmer blades are mounted on swivel pins that are fastened to the skimmer chains and maintain the blades in a down position at all times. The conveyer chains are provided with drive sprockets on a full width shaft at the drive end and four independent idler sprockets at the return end. The skimmer system frame shall provide a sprocket tension adjustment device and the carrying and return tracks for the chain. The entire system shall be self supporting with side and end channels, and cross members with lifting lugs that permit removal of the skimmer assembly as a complete unit for easy cleaning and service. The skimmer drive system is provided with a hollow shaft gear reducer that is maintenance free.

Bottom Sludge Auger (Optional):

The ribbon flight auger is made from 304 stainless steel, has converging flights to gently move settled sludge toward the sludge outlet nozzle and is driven at 3-5 RPM by an industrial duty TEFC motor with gear box speed reduction.

Control Package (Optional):

All HydroFlo Tech oil/water separation systems are fully automated. Control packages (depending on your specific requirements) are available in either basic relay logic controls, or a full state of the art PLC with touch screen HMI and our sophisticated treatment algorithms. The relay logic controls package allows basic reconfiguration of the original system settings, while the PLC based package allows maximum flexibility to change the process parameters, as well as tight control that minimizes chemical usage. We can include a variety of options including digital data logging of critical process parameters, Ethernet access to process data, communication with Building Management Systems, and even remote system access using cellular wireless technology.

All enclosures are NEMA 4X. Where metallic enclosures are used, they are provided with epoxy or polyester finishes for corrosion resistance. All conduit is plastic coated where possible. Low voltage 24VDC is used throughout to minimize service personnel exposure to high voltage. All panels are OSHA LOTO and NFPA 79 compliant. Additionally UL-508 listing is available.

Effluent Monitoring: As mandated by the local controlling authority, the effluent quality must be continuously monitored. A two pen recorder is to be used to monitor effluent flow rate and pH. The recorder is to be equipped with a flow totalizer. Any effluent pH deviations will trigger an alarm and system discharge will be halted.

System Packaging:

The system is supplied as a completely fabricated "turnkey" package. All devices are pre-wired and plumbed.

You need to make the plumbing connections to and from the system and a single electrical connection point for incoming power. The disconnect on the MCP provides OSHA Lock Out / Tag Out and NFPA 79 compliance. For systems requiring compressed air, only one connection is required and a valve is supplied for OSHA LOTO.