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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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Page 1: Pneumatic Conveying: Pressure or Suction Conveying?€¦ · Both conveying systems – pressure and suction conveying – have undergone consistent development. Today both systems

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

Page 2: Pneumatic Conveying: Pressure or Suction Conveying?€¦ · Both conveying systems – pressure and suction conveying – have undergone consistent development. Today both systems

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.