Falling Stream Sampling Systems

Falling Stream Samplers are a general product category that covers a wide range of sampler designs. The key characteristic all these designs have in common is that sample material is collected from a main process flow that is either in a free-falling condition or traveling through some trajectory, such as at the discharge of a conveyor.


Falling Stream Samplers tend to be simpler in design and function, and usually offer highly reliable operation with relatively low maintenance requirements. This style of sampling is well suited to high flow rate applications where minimal downtime is a requirement, such as loadout systems.

Using a Falling Stream Sampler does have some limitations. This type of sampler requires some amount of vertical clearance for installation (this height varies by machine type and application), and they are sometimes more invasive and expensive to install. There are many applications for Falling Stream Samplers. McLanahan has a range of product offerings, as well as the ability to develop custom designed Falling Stream Samplers, to meet the needs of your specific requirements. 

How Falling Stream Sampling Systems Work

Falling Stream Samplers come in all manner of shapes, sizes, and configurations, but regardless of the machine in question, the basic function of this type of machine is essentially the same. A sample cutter is parked on one side of a moving material flow. When a sample increment is to be collected, the cutter drive assembly (which varies by machine type) will move the cutter through the material flow at a constant speed, collecting a sample increment.

For diverter type cutters (i.e. sample material is directed from the material flow to another area), the sample increment is directed into a sample discharge area of the sampler where it is either collected for offline use or passed into the next piece of equipment installed in the sampling system. Once the cutter clears the material flow, the sampler drive stops the cutter on the opposite side of the material flow. The next increment is collected by moving the cutter back in the direction of the first parked position.

If the sampler in question has a bottom dump type cutter, the sample cutter will pass through the moving material flow at a constant speed, collecting material inside it. Once the cutter reaches the other side of the material flow, the cutter will open to release this material back into the main flow. The cutter will then pass back through the material flow, collect the sample increment, and stop back in its original parked position and empty the sample increment into a discharge chute. Material is then collected for offline use or directed to the next machine in the sampling system. It is also important to note that some bottom dump samplers may have a sample discharge point on both sides of the material flow. In this case, the operation would be as described with the diverter type cutter.

Falling Stream Sampler drive units vary by machine type but are usually one of three types of drives. These are gear-reducer driven rack and pinion, gear-reducer driven chain and sprocket, and hydraulic cylinder.

Regardless of cutter or drive type, the basic, simple operation and reliability remains the same.

Why McLanahan Falling Stream Sampling Systems

McLanahan offers many types of falling stream sampling equipment to cover the wide range of possible applications involving this style of machine. Some common types of Falling Stream Samplers for both dry materials and slurry applications are baffle plate type (in either vertical or tangential entry configurations), overhead carriage (with multiple cutter options like bottom dump and reverse spoon), traveling hopper, Vezin, double Vezin, arcual and other, less common types. Falling Stream Samplers can easily be incorporated into new projects. Additionally, all Falling Stream Samplers offered by McLanahan can be, and often must be, engineered for integration into existing operations.

The basic design and simple back-and-forth mode of operation characteristic of Falling Stream Samplers limits the number of mechanical components. Limited components and simple operation allows for long service life and minimal maintenance. Maintenance that is eventually required is facilitated by appropriately sized and located access and inspection doors, easy replacement of common wear items (cutter lips, track rollers), and sealed-for-life bearings that eliminate the need for regularly accessing components.

Regardless of your application requirements, if a Falling Stream Sampler is suited to your application, McLanahan has a sampler offering to meet your needs.

Horizontal Carriage Bottom Dump Samplers

Horizontal Carriage Bottom Dump Samplers are one type of Falling Stream Sampling System. They feature a horizontal carriage arrangement in which the cutter is oriented to the side of the drive. The cutter moves with the drive from one end of the machine to the other through a falling stream of material, collecting a sample as it does so and depositing it via the bottom of the cutter.

Frequently Asked Questions About Falling Stream Sampling Systems

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If one of the various Falling Stream Sampler options is not well suited to a particular application, a Cross Belt Sampler could be used. If the application in question is related to sampling from trucks, railcars, or stationary lots, Auger Sampling Systems could also be considered.

Falling Stream Samplers can be widely applied throughout many industries, including coal, coke, crushed ore, concentrates, potash, sand, stone, gravel, salt, bauxite, wood pellets and more.

Features & Benefits
  • Many types of samplers are available to match a wide range of sampling requirements
  • Robust design for applications up to 20,000stph (18,200mtph)
  • Simple design and operation offers long-term reliability and minimum maintenance requirements
  • Replaceable liners and wear components are fabricated using enhanced wear-resistance materials
  • Multiple drive configurations are available (rack and pinion, chain and sprocket, belt and pulley, hydraulic cylinder, linear electric actuator)

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