PARSHALL FLUME GENERAL COMMENTS

The Parshall Flume was originally designed for use in streams and open channels. It is still frequently installed in open channels. However, it is also suitable for in-line applications when proper end adapters are used to transition flow into and out of the flume. The flume uses a simple power equation, and can be used with any of the meters available today.

ADVANTAGES

1.     The Parshall flume has one of the widest flow range capabilities and is available in standard flume sizes that will handle small flows down to a few gallons per minute or very large streams as high as 335 MGD.

2.     The flume design accelerates flow as it passes through the throat thus making it “self-cleaning”.

3.     Within its flow range, the Parshall flume provides greater incremental flow resolution than other types of flumes.

4.     Plasti-Fab has developed special adapters designed to reduce entrance velocity and turbulence in many common flow measurement applications.

DISADVANTAGES

1.     The Parshall flume is a larger style of flume which at times may limit the number of sites where it can be used.

2.     The Parshall flume has good flow resolution, but is often not the best choice for low flows.

3.     The Parshall flume may be more expensive depending on site and installation requirements.

Application Notes: Also see “General Flume Design Data”

1.     The 1” and 2” Parshall flumes are not recommended for sanitary waste or other high solids streams because of potential clogging.

2.     Higher heads generated by a Parshall flume may cause upstream hydraulic problems in some cases.

To calculate submerged flow in a Parshall flume measurements at Ha and Hb are used to find the submergence percentage, Hb / Ha = % submerged flow. For flumes with throat sizes 1” through 6” submergence takes place approximately at ± 55%. For flumes 9” though 30” submergence occurs at ± 65%. For larger flumes, submergence ranges from 70% - 80%. If submerged flow readings are unavoidable, a stilling well must be installed at the Hb point to get proper secondary readings.

ROTATING SCUM SKIMMERS

The FRP Rotating Scum Skimmer is designed for rectangular basins. Typical sizes range from 6 ft. to 20 ft. in length, and will be 6 inches to 18 inches in diameter. Most are manually operated with a lever.

FRP Rotating Scum Skimmers provide exceptional corrosion resistance under some of the worst operating conditions. Typically they are found in primary and industrial process clarifiers. Normal maintenance consists of routine plant washdown.

OPERATION

The scum skimmer is operated by rotating the slots below the surface of the water such that the top layer of water and debris flows into the scum skimmer. Rotation is most often done with a simple bar handle, but handwheel mechanisms, or electric operators are also available.

MATERIALS

The Plasti-Fab scum skimmer is fabricated of fiberglass reinforced plastic with stainless steel hardware.

LOCATIONS

Typical applications include: grease and scum in primary basins; surface oil in oil/water separators; foam and process debris in industrial basins; byproduct decant in certain industrial separation basins; and/or the removal of leaves and other floating organic debris in water plant sedimentation and chlorination basins.

WHY BUY PLASTI-FAB?

• Lightweight, easy to install or retrofit.

•  Can be custom designed and built for any installation or retrofit.

• Will not corrode. It is the material of choice when replacing corroded steel skimmers

COPOLYMER STOP LOGS

Stop logs were originally wooden planks that were set into a groove in a head wall, and stacked to vary the upstream water level.  Today, most stop logs used in    municipal and industrial projects are made of fiberglass, plastic, or a corrosion-resistant metal.  Stop logs permit incremental changes in water level that are not possible using stop gates or slide gates.

Plasti-Fab has been building stop logs for over 15 years.  The Heavy Duty Copolymer Stop Log has a one-piece molded cover that totally encapsulates the internal structural steel matrix and has no seams, glued joints, or cut edges.  Water and chemicals are completely sealed out. Plasti-Fab is the best choice, giving high quality log at a competitive price.  Stop logs can vary in thickness from 1 inch to 6.5 inches or more, depending upon the width of the log and the expected head or water depth to be held back.

Stop logs require individual handling, and for this reason are usually considered for lower use applications where they may remain in place indefinitely or where they can be installed briefly during annual maintenance.  They do have some special advantages:

a.     Stop logs require less lifting force than a large stop gate or slide gate.

b.     They are less costly because an operator, stem, and associated hardware are not needed.

c.     Stop logs are interchangeable.  With careful design, a number of openings can be built to share and optimize their use.

d.     Stop logs can be designed to close off openings up to 20 feet wide.

e.     Stop logs can range in height from 6 inches to 24 inches to more closely control water level.  Common sizes will be 12 inches to 16 inches in height.

f.      Stop logs have an indefinite life cycle due to FRP resistance to corrosion.

g.     Stop logs operate in extreme environments well below freezing and above 130 degrees and 100% humidity.

h.     Stop logs are ultraviolet stabilized for long-term exposure to sunlight.                                            

Stop logs must be heavier than the buoyant force of the surrounding liquid or they will float.  The weight of the stop log also provides the only seating force to seal between individual logs.  This means all but the smallest logs will require some type of lifting device to remove them from the guide.  Smaller logs, up to 3 feet wide, can be fitted with stainless  steel lifting eyes, and can be raised by one or two people using lifting hooks.  Large stop logs are fitted with stainless steel lifting pins that protrude from both sides of the log. A heavy duty lift beam with automatic latching mechanism is recommended for these applications.  The lift beam will be raised with an overhead winch, davit crane, back hoe, or other convenient tool.

The Importance of Using Scum Skimmer and Corrosion Preventive Products

It is important to use composite fiber glass materials that can control the fluid control equipments for the industry and other infrastructures. The expert team of corrosion resistant equipments can provide good solution for water and wastewater systems. All such professionals provide the best solution for all corrosion equipments and accordingly control the fluids. There are special plastic and other fiber glass materials that can be used just to avoid the corrosion and increase the service period. 

Scum Skimmer

Such materials are effective against corrosion and functions smoothly in all environmental conditions. So it is important to use corrosion free or resistant materials for various engineering composites. Here are some materials that come along with various benefits:

●     Parshall Flume is a specialized engineered material that helps in acting as a corrosion resistant for different engineering designs and available in various shapes.

●     FRP Shelter is completely suitable for all conditions and requires no maintenance. The materials are nonconductive and are normally not susceptible to ruts or any types of decay. Such items are available in different shapes and styles.

●     Scum Skimmer is easily installed and needs low maintenance cost, easily installed and effective with their designs. The materials that are engineered with such composites do not corrode so easily enhancing the life period of the material.

For increasing the longevity of engineered goods it is important to use corrosion free materials that can help in enhancing the service period. All such materials are suitable for corrosion and tough natural conditions.