The Flopak coalescing media systems are designed to remove non-emulsified, free & dispersed oils and fuels from water. Flopak is a standard feature of our high performance oil water separators and are also offered for replacement or retrofitting of existing tanks to improve performance and increase flow rates. Removal efficiencies have been as low as <1 mg/L down to non-detect. Typical, regular performance is in the 3-10 mg/L range depending on waste stream characteristics.
Pan America Environmental can provide review of your existing tank to replace existing media or engineer the fitting of Flopak into a tank for the first time via modifications to optimize tank design for the best oil separation environment.
Our Retpak secondary coalescing media can be provided to high-density surface area in a small cubic area to add to your existing media or in conjunction with Flopak to increase small droplet capture.
Coalescing Media Specification
The Pan America Environmental Flopak Series Coalescing Medias are designed to separate non-emulsified, free and dispersed oils and fuels. By virtue of the media design readily settleable solids can also be removed depending on solids type and loading.
1.01 Flopak Construction & Dimensions
Flopak Media Modules – Media modules are fabricated from PVC (or other material)sheets and completely corrugated at an angle of 60 degrees from the horizontal to form a cross-corrugated pattern between adjacent sheets, creating a continuous and horizontal redistribution of wastewater. Modules will be either 1 ft. (0.305 m) or 2 ft. (0.610 m) high, drugstore 2 ft. (0.610 m) wide, and either 2 ft. (0.610 m) 4 ft. (1.219 m) or 6 ft. (1.829 m) long.
1.02 Media Design
Flopak Media Module shall be 100% cross-flow and completely corrugated at an angle of 60 degrees from the horizontal to form a cross-corrugated pattern between adjacent sheets, providing a continuous and horizontal redistribution of wastewater. The module shall ensure adequate redirection points by providing a minimum of 720 impact or redistribution points per cu. ft. (25,424 per m3) of module. Random, vertical and tilted plate media are not acceptable.
b. The flute height for each corrugation in the Structured Flopak Media Module shall be 0.75 in. (19 mm). There shall be a minimum of 16 sheets per each 12-in. (0.305 m) wide module.
c. Each Flopak Media Module must provide a minimum surface area of 48 sq. ft. / cu. ft. (157 m / m3) with a minimum of 95% void-to-volume ratio.
d. Each module shall have a minimum bearing capacity of 400 lbs. / sq. ft. (1952.8 kgs. / m). Modules in the top layer shall have a minimum bearing capacity of 1000 lbs. / sq. ft. (4882 kgs / m__). In addition, media modules shall be capable of withstanding a minimum loading of 40 lbs. / sq. ft. per foot (195.3 kgs / m per 0.3 m) of media height above the module as placed in the tank.
e. The maximum allowable deflection shall be 1.5 percent at a test temperature of 75°F (24°C).
f. The finished modules shall be suitable for normal wastewater temperatures between 40°F and 130°F (PVC material).
1.03 Shipping Handling & Storage
1. Flopak Media Modules shall be shipped and delivered to job site on pallets for ease of handling and to prevent damage.
1. All material and equipment shall be shipped, stored, handled, and installed in such a manner as to not degrade quality or serviceability.
2. Flopak Media Modules shall not be stacked more than 8-ft. (2.4 m) high (one over the other) unless prepacked in Pan America Environmental media pack frame system. All modules shall be stored on the shipping pallets.
3. All modules shall be stacked such that the sheet planes are in a vertical position.
4. A light colored cover shall cover all modules required to be stored in the open beyond two months. Ideally these covers should be double sided such as a white on black. The white side, facing out, is used to reflect light away. Clear covers are prohibited. Black is not recommended. Black will absorb heat and if the cover comes in direct contact with the media, this heat can be quickly transferred to the media.
5. Covers cannot be wrapped tightly around the media. There should be at least a 6-in. (150 mm) air gap between the cover and top of media. The ends of the cover should be securely anchored on all sides with at least a 12-in. (300 mm) air gap at the bottom. These covers should provide shading while allowing air to pass through to prevent heat build-up.
6. Modules should be checked at least once a week. Covers can become loose over time due to wind or rain and must be re-secured. A check of the stored area should be done to make any minor repairs to the cover or to restack any modules that may have fallen.
7. Media Modules exposed to extended non-operational periods in the tank shall be adequately protected to prevent damage by temperature, weather and UV conditions.
1. Media Modules shall remain on shipping pallets until ready to install.
2. Abusive handling of the material shall not be permitted.
3. Media Modules may get brittle at low temperatures or softer at high temperatures. Therefore, care should be used in the handling of modules.
1. The material of construction shall be flame resistant, self-extinguishing, rigid corrugated PVC (or other material) sheets that are conducive to oil separation and UV protected. The media modules shall be resistant to rot, fungi, bacteria and inorganic/organic acids and alkalies as commonly found in wastewater.
2. The media sheets shall be of uniform thickness and free from holes, air bubbles, foreign matter, undispersed raw material or other manufacturing defects that may adversely affect their performance.
3. The media sheets shall be prime, rigid, conforming to commercial standard ASTM D1784:12454B.
Pan America Environmental, Inc.
2309 N. Ringwood Rd., Ste G McHenry, IL 60050 USA 815.344.2960 Fax: 847.487.9218
Pan America Environmental warrants its products to be free of defect in materials and workmanship for a period of one year from the date of shipment.
Oil Water Separator 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 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.
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 Stokes 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:
&NBSP;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 waste stream turbulence and velocity. This control of the waste stream 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 waste stream (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 10 PPM or less with an oil droplet size of 30 or as small as a 20 micron oil droplet.
Flopak, Retpak, Tiltpak, HD-Q pak, GPP Pac
Number of model sizes Per application
Media type Coalescing
– Frac water
– Produced water
– Biodiesel plants
– Machining coolant
– Petrochemical plants
– Groundwater remediation
– Hydroelectric plant seal water
– Storm water treatment
– Carwash water
– Military wash rack water
– Aircraft wash
– Heavy equipment wash
– Tank truck wash
– Locomotive/train wash
– Steel mill water
– Tank bottom water treatment
– DNAPL/LNAPL removal
– Stamping press water
– Aircraft maintenance
– Ballast water
– Bilge water
Performance 5 &10 mg/L or less of oil droplets 30 micron and larger of non-emulsified, free and dispersed oils