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Product quality, operational safety and energy efficiency are of prime im- portance. Conveying distance, throughput, configuration of the system and the order of processes are decisive when considering whether to use over or negative pressure. Pneumatic conveying systems have established themselves in all kinds of sectors of bulk material processing. Both conveying systems – pressure and suction conveying – have undergone consistent development. Today both systems provide possibilities to transport product gently from A to B with minimum attrition. That is why a plant manufacturer may find it difficult to decide on which conveying method suits his process best. Pneumatic Conveying: Pressure or Suction Conveying? Pressure Conveying Loading of product in normal atmos- pheric conditions, e.g. directly from open hopper Transport from several loading points to one receiving vessel is possible Limited contamination of work envi- ronment if leakage occurs Discharging of product from receiving vessel in normal atmospheric condi- tions From one starting point to several re- ceiving vessels Dense phase conveying Long conveying distances Smaller tube diameters Smaller air compressors and filters Not necessarily suitable for dense phase conveying Conveying over short distances (ap- prox. 80 m) limited Larger tube diameters Larger compressors and filters Product can be compacted long-term if pressure is too high Space required when loading can be quite large depending on selection of pressure conveying process (rotary valve – pressure vessel) Disadvantages Suction Conveying Advantages

Pneumatic Conveying: Pressure or Suction Conveying?€¦ · Both conveying systems – pressure and suction conveying – have undergone consistent development. Today both systems

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  • Product quality, operational safety and energy efficiency are of prime im-

    portance. Conveying distance, throughput, configuration of the system

    and the order of processes are decisive when considering whether to use

    over or negative pressure.

    Pneumatic conveying systems have established themselves in all kinds of

    sectors of bulk material processing. Both conveying systems – pressure

    and suction conveying – have undergone consistent development. Today

    both systems provide possibilities to transport product gently from A to

    B with minimum attrition. That is why a plant manufacturer may find it

    difficult to decide on which conveying method suits his process best.

    Pneumatic Conveying: Pressure or Suction Conveying?

    Pressure Conveying

    Loading of product in normal atmos-•

    pheric conditions, e.g. directly from

    open hopper

    Transport from several loading points •

    to one receiving vessel is possible

    Limited contamination of work envi-•

    ronment if leakage occurs

    Discharging of product from receiving •

    vessel in normal atmospheric condi-

    tions

    From one starting point to several re-•

    ceiving vessels

    Dense phase conveying•

    Long conveying distances•

    Smaller tube diameters•

    Smaller air compressors and filters•

    Not necessarily suitable for dense •

    phase conveying

    Conveying over short distances (ap-•

    prox. 80 m) limited

    Larger tube diameters•

    Larger compressors and filters•

    Product can be compacted long-term •

    if pressure is too high

    Space required when loading can be •

    quite large depending on selection

    of pressure conveying process (rotary

    valve – pressure vessel)Dis

    adva

    ntag

    es

    Suction Conveying

    Adv

    anta

    ges

  • For further information: www.gericke.net

    Trials carried out at our Test Centre

    provide valuable information

    The material to be conveyed can be

    tested with both conveying systems

    in realistic conditions at our Gericke

    Test Centre. Laboratory tests provide

    information concerning general flow

    characteristics such as fluidisation ca-

    pacity or compressibility of a product

    and facilitate selection of the right

    system.

    Trend-setting configuration

    The number of places in total where the conveying process begins and

    ends can determine the type of conveying selected. If for example several

    systems are to be supplied from one silo, one would probably decide on a

    conveying process with overpressure the reason being that several recei-

    vers can be supplied from one point.

    If however one machine is to be filled from several reservoirs, this is a case

    where suction conveying comes into play. This process means that the ma-

    terial can be suctioned to one point from various loading points.

    Modification of product characteristics

    Varying forces affect the material to be conveyed depending on whether it

    is conveyed using suction or pressure. Negative and positive differences in

    pressure can have an impact on central product characteristics. The forces

    during the conveying process as well as the residence time in the vessel

    (pressure conveying) or in the receiving vessel (suction conveying) must be

    taken into consideration.

    Pressure as physical difference between suction and pressure systems

    There are advantages in connection with both systems. One difference

    remains: The suction pneumatic system has a maximum usable pressure

    difference of 1 bar whereas pressure conveying systems can theoretically

    use unlimited pressure. In practice, most pressure conveying systems ope-

    rate with 1-4 bar overpressure.