Pressure vessels in powder processing
Pressure vessels are an indispensable part of many powder processing operations, particularly in pneumatic transport under positive pressure. A pressure vessel stores powder and then pushes it with compressed air through a pipeline to its destination. For engineers, buyers and QA in pharma, chemicals, food and the battery industry, pressure vessels are a reliable way to move powders over greater distances. At the same time, strict requirements apply to design, safety and certification. HECHT supplies pressure vessels that meet these requirements and integrate with your process.
What is a pressure vessel and how does it work?
A pressure vessel, also called a sender vessel or transmitter, is a closed reservoir that receives powder and discharges it under positive pressure. The operating principle is cyclical: the vessel is filled, sealed, pressurised with compressed air, and emptied as the powder is pushed through the transport line.
Unlike vacuum transport, which operates under negative pressure, a pressure vessel uses positive pressure. This makes it particularly suitable for long transport distances and high throughputs, because the available pressure is greater than under vacuum.
Applications of pressure vessels
Pressure vessels are used where distance, capacity or product properties call for positive-pressure transport.
- Long distances — transport over tens to hundreds of metres, where vacuum falls short
- High throughput — large quantities of powder per cycle, suitable for continuous production
- Dense phase transport — slow, product-friendly transport with minimal particle breakage
- Abrasive powders — controlled velocity limits pipe wear
In the battery industry and chemicals, pressure vessels are often used to move large volumes under inert conditions.
Dense phase versus dilute phase transport
A pressure vessel can convey powder through the line in two ways, with major consequences for product integrity and wear.
- Dilute phase — high air velocity, powder suspended in the air stream, suitable for free-flowing, non-friable products
- Dense phase — low air velocity, powder moves in plugs, product-friendly with minimal breakage, ideal for friable or abrasive powders
The choice determines the sizing of vessel, pipeline and compressed air supply. HECHT advises based on your product properties.
Safety and certification
A pressure vessel falls under the European Pressure Equipment Directive (PED, 2014/68/EU). This sets requirements for design, material selection, manufacture and inspection. An uncertified pressure vessel is a safety risk and not permitted in a professional installation.
- PED compliance — design and manufacture to the pressure equipment directive
- Overpressure protection — safety valves that prevent inadmissible pressure
- Material certification — traceable materials with certificates for process suitability
- Periodic inspection — re-inspection in accordance with applicable regulations
HECHT supplies pressure vessels with the required certification and documentation for your safety file.
Containment, hygiene and ATEX
Pressure vessels in pharma and food must meet hygiene and containment requirements alongside pressure ones. HECHT designs pressure vessels with polished, cleanable surfaces to GMP and EHEDG, with WIP or CIP where validated cleaning is required.
For combustible powders the pressure vessel is earthed and built ATEX-compliant. With reactive substances, as in the battery industry, nitrogen inerting can be applied to prevent explosion and unwanted reactions.
Sizing and process integration
The performance of a pressure vessel depends on correct matching of vessel volume, cycle time, pipe diameter and compressed air supply. An undersized system fails to achieve throughput; an oversized system wastes compressed air.
HECHT determines these parameters through product analysis and transport trials, and integrates the pressure vessel into the broader handling chain with dosing, filling and storage systems. The vessel thus functions not as a standalone component but as part of a coherent whole.
More about pressure vessels: in-depth articles
Want to read more about a specific topic? Below you will find all our articles on pressure vessels.
- How does a pressure vessel work?
- What are the main uses of pressure vessels?
- In which industries are pressure vessels used?
- How is the safety of pressure vessels ensured?
- What are the advantages of using pressure vessels?
- What materials are used to manufacture pressure vessels?
- How are pressure vessels maintained?
- What is the service life of a pressure vessel?
- Which regulations apply to pressure vessels?
- How is the pressure in a pressure vessel regulated?
- Why are pressure vessels important in chemical processing?
- Can pressure vessels be used to store gases?
- What is the role of pressure vessels in the food industry?
- How are pressure vessels cleaned?
- How is the correct size of a pressure vessel determined?
- What is the difference between a vertical and a horizontal pressure vessel?
- How do pressure vessels help to save energy?
- What is the function of a diaphragm in a pressure vessel?
- How are pressure vessels tested for leaks?
- What is the role of pressure vessels in the pharmaceutical industry?
- How are pressure vessels installed?
- How much does an industrial pressure vessel cost?
Frequently asked questions about pressure vessels
What is the difference between a pressure vessel and vacuum transport?
A pressure vessel operates under positive pressure and suits long distances and high throughput; vacuum transport operates under negative pressure and is inherently dust-safer in a leak.
When do I choose dense phase transport?
For friable or abrasive powders, where low velocity minimises particle breakage and pipe wear.
Must a pressure vessel be certified?
Yes, a pressure vessel falls under the PED directive and requires compliant design, manufacture and inspection.
Are pressure vessels suitable for pharma?
Yes, in GMP- and EHEDG-compliant versions with cleanable surfaces and optional WIP or CIP.
Can a pressure vessel operate under inert atmosphere?
Yes, with nitrogen inerting for reactive or combustible powders, relevant in chemicals and battery.
Related guides
Tailored advice from HECHT
A pressure vessel that fits your process requires correct sizing, the right transport phase and complete certification. HECHT analyses your distance, throughput and product properties and delivers a PED-compliant pressure vessel that is safe, hygienic and integrated into your handling chain. Contact us for a transport analysis and a tailored pressure vessel concept.