Industrial Waste Water Treatment

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TPI oil water separator ext

Tilted Plate Interceptor Oil Water Separator – TPI Series

The TPI Series steel Coalescing Oil Water Separators are designed for applications where a coalescing oil water separator design is desired using coalescing media but suspended solids are excessive for high performance coalescing designs. The industrial duty TPI design has many features such as adjustable water weir, integral inlet diffuser, A-36 carbon steel or stainless steel construction and many options to provide engineers, system integrators and end users with convenience and flexibility in oil separator system configuration choices. Customization & modifications to fit your project needs are offered. Typical performance is 50 ppm or less, 60 micron free, non-emulsified oil droplet.

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The TPI Series steel tilted plate interceptor coalescing oil water separators are designed per API-421 1st Edition, February 1990, Section 4 Parallel Plate Separators. This design is based on 60 micron oil droplet size with an expected performance of 50 mg/L or less.

TPI plate pack angle can be provided from 45° – 60° and a plate spacing of 0.75-2″. Pan America provides its Wave Plate™ TPI pack which allows more surface area per plate pack than a standard flat plate pack. The TPI separator design is recommended for applications where high solids loadings are expected. The TPI design can handle solids better than higher performance coalescing designs.

Pan America always recommends pre-settling solids prior to all coalescing separators as a rule so that the oil separator equipment will function at peak performance as coalescing separators are first and foremost designed as oil water separators. As a rule, if significant solids loading is expected a 60º plate angle should be used in order to exceed the angle of repose of most solids and improve solids movement. For applications where a high performance coalescing oil water separator design is desired using coalescing media.

The TPI design has many features such as adjustable water weir, integral inlet diffuser, A-36 carbon steel or stainless steel construction and many options to provide engineers, system integrators and end users with convenience and flexibility in oil separator system configuration choices. Customization & modifications to fit your project needs are offered. Typical performance is 50 mg/L or less, 60 micron free oil droplets. 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 hydrocarbon 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.


Specification Summary:
System model
Number of model sizes 
Process  types
Volume range offered     

Design Specification Summary

Design criteria
Influent chamber
Separation chamber      
Solids hopper  
Clean water effluent chamber  
Water baffle  
Weir plate   
Oil skimmer 
Oil reservoir 
Media pack     
Lifting lugs                         

Materials of Construction

Surface preparation(steel)
Coatings (steel)                                         

Standards used    

TPI oil water separator
Tilted Plate Interceptor
Oil separation, TSS settling
5 – 2500 GPM


50 mg/L or less 60 micron free oil droplet
API-421, 1990, section 4 parallel plate separators
Influent diffuser or overflow weir
To contain TPI media pack(s)
Located under and after separation chamber and TPI packs
Located after separation chamber
Water flows over this baffle to exit tank
Vertically adjustable weir plate to maintain operating water level
Fixed or adjustable weir plate integrated into the oil reservoir, located in the separation chamber
Located in separation chamber for temporary storage of skimmed oils
Single or multiple, Wave Plate or flat plate separation packs
Multiple section vapor retaining, gasketed with polyethylene gasket and attached via zinc plate fasteners
NPT couplings up to 3″, 4″ & larger: 150# ANSI B16.5 FF flange
Steel skid base of channel, beam or tube construction
(4) Minimum, located at lifting points on sidewalls of tank


A-36 carbon steel, 304/316 SS, FRP, polyethylene, polypropylene
A-53 black steel, 304/316 SS, FRP, PVC
Dye penetrant on steel construction
Interior surfaces shall be prepared to an SSPC-SP10 near white metal blast. Exterior surfaces shall be prepared to an SSPC-SP6 commercial blast.
Interior coating shall be coated with Ameron High Build Coal Tar Epoxy Amercoat 78HB (16 mils DFT).
Exterior coating shall be coated with Ameron epoxy primer, Amerlock 2, (5-8 mils DFT).  Final coat to be Ameron Amershield Aliphatic Polyurethane Enamel coat (5 mils DFT)Surface color to be Green RT-2203.
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 Operational Theory

Coalescing Oil Water Separators: Coalescing Oil Water Separators are passive, physical separation systems designed for removal of oils, fuels, hydraulic fluids, LNAPL and DNAPL products from water. Pan America Environmental’s designed performance can be described by a combination of Stoke’s 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.

Stokes Law: This equation relates the terminal settling or rise velocity of a smooth, rigid sphere in a viscous fluid of known density and viscosity to the diameter of the sphere when subjected to a known force field (gravity). The equation is:

V = (2gr²)(d1-d2)/9µ
V = velocity of rise (cm sec-¹),
g = acceleration of gravity (cm sec-²),
r = “equivalent” radius of particle (cm),
dl = density of particle (g cm -³),
d2 = density of medium (g cm-³), and
µ = viscosity of medium (dyne sec cm-²).

Coalescence: Gravity separation utilizes the difference in specific gravity between the oil and water. Oil separates from a fluid at a rate explained by Stoke’s Law. The formula predicts how fast an oil droplet will rise or settle through water based on the density and size of the oil droplet size and the distance the object must travel. Our separators are built to exploit both variables of Stokes Law.

With the use of our Flopak media oil only need rise a short distance before encountering the oleophilic, coalescing media plates inside the separation chamber as opposed to rising a great distance in gravity separation. Upon impinging on the plates the oils coalesce (gather) into larger droplets until the droplet buoyancy is sufficient to pull away from the media and rise to the water’s surface. The design will meet particular design criteria as indicated below:

o The hydraulic distribution of the influent flow must assure full usage of the cross-sectional area of the media to fully utilize the plate pack’s surface area.
o Flow control and direction must be determined to prevent hydraulic short circuiting around, under or over the media pack.
o A laminar flow condition must be maintained (Reynolds “Re” number less than 500) in order to assist droplets to rise. Per the American Petroleum Institute’s (API) Publication 421 of February 1990.
o Horizontal flow through velocities in the separator must not exceed 3 feet per minute or 15 times the rate of rise of the droplets whichever is smaller.
o The media containment chamber design, plate design/angle and spacing sufficient to facilitate removal of accumulating solids. Plates are to be smooth surfaced and angled at 60 deg.

Flopak Coalescing Media Design

Pan America’s Flopak coalescing media provides a laminar flow path that creates a quiescent zone to facilitate the impact with and attachment of oils to the media surface by reducing wastestream turbulence and velocity. This control of the wastestream creates a more ideal environment for oil removal. By virtue of our Flopak media design, solids will also collide with the media and settle to the separator bottom to some degree. Due to oil typically being lighter than water, they (oil) will rise up the coalescing plate. As the oil droplets rise up the plate they will coalesce or come together with other droplets, creating progressively larger droplets. Once the droplet size is sufficient or the droplet reaches the top of the media plate the droplet pulls away from the plate and rises to the water surface. To some degree, the solids replicate this process in reverse (settling).

Gravity Separation vs. Coalescing Plates

Two types of oil water separator exist today in varying types of design, but all are dependent on these two types of design.
The first and oldest type is gravity or conventional separation, simple separation via gravity (density differential between two immiscible liquids leads to one of them rising above the other). This design, when designed properly (or even improperly) provides a certain tank length, width and depth that provides a wide, quiet spot in the pipeline to give oils time to rise. This design (also known as an API separator) generally provides a discharge oil concentration of 100 ppm based on a 150 micron droplet size. The API type design relies on a large water volume. This correlates to a tank size that can be 5 times the size of an equally sized coalescing separator.

The coalescing design is known by many names i.e. parallel plate, corrugated plate, slant rib coalescer so on and so forth. However, the concept, operation and design are generally the same. The coalescing concept is based on having a large surface area in contact with the wastestream (coalescing plates). The more surface area provided, the more enhanced the separation process will typically be. By using the coalescing media, the size of the tank is reduced and a higher performance is attained than by gravity separation. Pan America’s Flopak coalescing design provides a discharge oil concentration of 50 PPM or less with an oil droplet size of 60 droplet.

Models: TPI Series OWS

Separator models



*Maximum flow rate is based on an oil specific gravity (SG) of 0.75.
*Flow rate & model size changes with the SG of your oils.

Influent Feed System:

Air operated, diaphragm pump with air controls or progressive cavity pump, sump level switches & Nema 4 control panel, base mounted, 115/230/460V power offered. Electric diaphragm pumps available.

Effluent Pumpout:

Centrifugal pump with level switches & Nema 4 control panel, base mounted, 115/230/460V power offered. OS Effluent chamber must be expanded to accommodate pumpout or provision of an external pumpout tank.

Sludge Pumpout System:

Air operated, diaphragm pump with air controls & Nema 4 control panel, auto on/off timer, base mounted, 115V/1ph/60Hz power req’d. Progressive cavity pump system also available. 1 – 100 GPM.

Oil Pumpout System:

Air operated, diaphragm pump with air controls, level switches & Nema 4 control panel, base mounted, 115V/1ph/60Hz power req’d. Electric gear or progressive pump systems available. 1 – 100 GPM (larger if required)

Sludge Auger:

OS separator V-hopper(s) can be provided with a sludge auger. System consists of stainless steel shafts with coated steel screw auger(s) driven by a slow speed gear motor drive assembly. The auger extends the full length of the solids hopper(s) and conveys solids to the sludge outlet. A Nema 4 on/off control box is provided, power required: 230 or 460V/3ph/60Hz.

Freeze Protection:

Immersion heaters mounted through tank wall. Each heater has an independent thermocouple well, 0-100 deg. F thermostat and Nema 1 (or optional Nema 4) housing. 230/460V/3ph/60Hz power req’d.

Retpak Secondary Coalescer:

High surface area, reticulated, secondary coalescing media for polishing flow after standard Flopak media.

Oil Sight Glass:

Two automatic, brass valves with tempered sight glass and protection rods mounted in oil reservoir. If glass is broken check ball stops outflow from reservoir.

External Sight / Level Glass:

An externally mounted clear PVC sight tube is provided with multi-point level switch for indication or pump control of oil or water. Switch is removable for cleaning and inspection.

Elevation Stand:

Epoxy coated steel stand or legs to elevate tank to desired level. Standard deck height is 30″. Full platforms & walkways with ladders or stairways can be designed where required or desired.

High Temperature Design:

Flopak coalescing media and any piping is constructed of a combination of CPVC &/or polypropylene (or other materials) for temperature resistance up to 200? F.

Alternate Media Construction:

Standard Flopak media is PVC. HPVC, polypropylene, glass-coupled polypropylene and 304/316 stainless media is available. Contact PAE to determine proper media type for your application. Media plate spacing is available in 1/2″, 3/4″ & 1.2″.

External Storage/Feed Tanks:

A wide variety of tank volumes can be supplied for your water, product and sludge holding needs. Flat bottom and cone bottom designs constructed in polyethylene, fiberglass, steel & stainless steel can be provided.

Effluent Filter Systems:

Solids filter systems can be provided to remove filterable solids from the separator effluent. Contact Pan America to determine proper filtration needs for your application.

AQAM Filter Systems:

AQAM (Alkyl Quaternary Ammonium Montmorillonite) filter systems can be provided to remove trace hydrocarbons, sheens, DNAPLs, slightly soluble chlorinated hydrocarbons and high molecular weight organics from the separator effluent. Contact Pan America to determine proper filtration needs for your application. Can be used to protect and increase GAC lifespan.

Carbon Filtration Systems:

GAC carbon filters can be provided to remove contaminants after the separator. Contact Pan America to determine proper system needs for your application.

Emulsion Cracking Systems:

Emulsion cracking systems can be provided to remove oil-in-water emulsions prior to the separator. Contact Pan America to determine proper system needs for your application.

pH Adjustment Systems:

pH adjustment systems can be provided to maintain pH levels prior to or after the separator. Contact Pan America to determine proper system needs for your application.

System Containerization:

OS separators with any options can be installed in a 20 or 40’ shipping container(s) to simplify system provision and field implementation. System would include the complete mounting, piping and wiring of the system in one or more container as required by the project.

Trailer Mounting:

OS separators can be mounted on a trailer for system mobilization. Trailer design generally includes corner leveling jacks, bubble levels, walkway, toolbox, electric or hydraulic brakes, piping and wiring of options.

Field Skid Mounting:

OS separator system can be mounted to a mobile skid with leveling for quick field mobilization.

Skid Mounted System:

OS separators can be combined with our other treatment equipment and options into a fully integrated, custom designed system completely mounted, plumbed and wired to a system skid. To simplify your need to do the wiring and plumbing on site, reducing your time frames and on site costs, we design around your requirements.

Vent Scrubber:

Separator vapors can be extracted and scrubbed prior to discharge to atmosphere to remove VOC content.

Level Sensors:

Level sensors can be provided to detect water and oil/fuels. One or more sensor points can be provided to perform various functions such as high level, low level, pump on/off based on liquid levels and level detection for DCS controls or other functions based on your needs.

Class 1 Div 1 & 2 group C & D:

Systems can be designed for use in a class 1 div 1 or 2 group C & D environment. Controls, components and wiring are changed to meet the needs of these environments. Intrinsically safe relays are also used for level sensors.

Oil Monitor:

An oil detection system can be provided to monitor effluent oil content and provide various actions based on the oil alarm setpoint. Actions might include: audible/visual alarm, redirection of influent or effluent via actuated valve, shutdown of influent pump or your custom action.

Seismic Design:

The system can be designed for zone 2, 3 or 4 installations.

Groundwater Remediation

Contaminated ground water treatment for removal of gasoline, diesel, jet fuels,LNAPL, DNAPL, motor oils, kerosene, fuel oils and more.


Removal of crudes, gasoline, diesel fuel, motor oils, transmission fluids, hydraulic fluids, jet fuels, aircraft fuels from refining processes.

Vehicle Wash Racks

Removal of gasoline, diesel fuel, motor oils, transmission fluids, hydraulic fluids, jet fuels, aircraft fuels and lubricants when washing jets, cars, trucks, heavy equipment, railroad locomotives and equipment.

Military Wash Racks

Field equipment, jet wash, tracked equipment wash uses for typical fuels and oils removal. Complete treatment systems are offered. (Also see VEW systems)

Industrial Process Water

Hydraulic fluids, machining coolant/cutting fluid tramp oil removal, compressor condensate, machined parts rinse water.

Steel Mills

Rolling mill hydraulic oil/water extraction, compressor condensate, stormwater runoff, drain water.

Stormwater Treatment

Parking lot runoff, railroad re-fueling depot runoff, gas station runoff, bridge runoff.

Shipping Ballast & bilge water treatment

Off-loading of water to shore based treatment system, bunker & diesel fuels removal.

Tank Farms

Fuel, oil storage tank farms for removal of water from tank bottoms. Stationary and mobile systems are offered.

Petro-Chemical Refineries

Chemical compounding companies, hydrocarbon based chemical bases such as cumene and other materials.

Power Generation

Heat transfer fluids, generator lube oils, hydraulic oils, fuels, sump accumulation, stationary & mobile systems offered.

Heat Treating

Heat treating facility oily wash solution can be continuously treated.


Oil/fuel removal 50 mg/L or less of oil droplets 60 micron and larger of non-emulsified, free oils
Solids (TSS) 40 -100 mg/L

Influent concentration basis:

Oils 1250 mg/L or less influent loading
TSS 800 mg/L or less influent loading

Pan America Environmental, Inc
2309 N. Ringwood Rd., Ste G, McHenry, IL 60050 USA
815.344.2960   •