Dense Phase

Dense phase conveying is commonly used when conveying materials that are either abrasive or fragile. Dense phase systems transfer material at lower speeds, higher pressures and higher product-to-air ratios than dilute phase systems of similar rates and distances. They are less commonly used than dilute phase systems, as the capital investment is typically more than a corresponding dilute phase system if there is no need to be concerned about breakage or wear.


At the heart of most high pressure systems is a dense phase transmitter or DPT (often commonly referred to as a "Pressure Vessel" or "Blow Pot"). The DPT is where the product is filled and pressurized to begin the convey cycle. Smoot's dense phase transporters are controlled by our patented "bypass valve" and operate without cumbersome and expensive compressed air line "boosters". The bypass valve controls the material-to-air ratio by diverting the convey air around the pot if convey pressures start to build to high. This is usually a result of too much material in the line, causing the material-to-air ratio to start to slide out of balance. By diverting the air around the pot, material flow is slowed and the ratio is reduced by air going directly to the convey line.

Dense phase transmitters, when compared to rotary valves, offer both advantages and disadvantages in their use.

On the positive side:

  • They do not leak
  • They can operate at high pressure
  • They fit nicely into a batch weighing application
  • They are much less subject to the effects of wear

On the negative side:

  • They require a lot more height to install
  • They are not continuous
  • They come with a much higher capital cost

Another typical distinction between dense phase and dilute phase systems is the air source. Dilute phase systems are often powered by positive displacement (or "PD") blowers (~15 PSIG). Dense phase systems are more commonly powered by higher pressure (~100 PSIG) and higher horsepower air compressions, making them more costly to operate.

Dense Phase Map


Dense Phase Transmitter

Dense Phase Transmitter

A key feature of a Smoot dense phase conveying system is the exclusive air management system. By using a pressure control regulator, airflow control orifice and bypass valve, total air flow to the system and product-to-air ratio (the combination of air flow and conveying rate) are automatically controlled at the vessel.

Bin Vents

Bin Vents

The filter receiver receives product and separates the material from the convey air.

Slide Diverter Valves

Slide Diverter Valves

The Smoot Slide Diverter Valves feature a unique sealing method that uses regulated compressed air applied to the sealing rings, which results in an air-tight seal between the inlet and outlet ports. The unique model design features minimal line deflection and full port flow from low pressure drop.

Spare Parts & Components

Spare Parts & Components

Searching for the right solution? The Smoot Service Center offers a complete line of pneumatic conveying components and spare parts. Our customer service professionals have the knowledge and expertise necessary to bring top-flight service for an incredible range of products.

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Dilute Phase Systems
Dense Phase Systems
Eco Phase Systems
Rotary Airlocks
Slide Diverter Valves
Pneumatic Conveying Components
General Information

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