Many chemical and physical processes are carried out at a pressure greater than atmospheric. This mandates specific requirements with regards to the construction of the vessel to ensure that the process is carried out in a safe and controlled manor.
Pressure vessels are routinely used in the following scenarios:
- A permanent gas is added which may be consumed in a chemical reaction, eg hydrogenation
- A solvent or liquid reagent is heated above its boiling point and a vapor pressure is created
Within these two broad scenarios there are numerous specific applications that are used such as Industrial Chemical Processing, Organic Synthesis, Catalytic Hydrogenation, Polymerization, Catalyst Evaluation, Alkaline Digestion, Pressure Leaching, Electrochemistry, Corrosion testing, Supercritical Fluids, Extraction Testing, Aerogels, and many more.
Parr Instrument Company, based in Illinois, USA, has over 100 years of experience in the design and manufacture of pressure vessels. As machining processes and computer technologies have improved, Parr has embraced these changes to ensure that their equipment gives the performance that is expected by scientists today.
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For processes that are carried out at pressure below 10 atmospheres it is possible to use suitably engineered glassware. While this limits the pressure to a maximum of 10 bar it does allow the user to clearly see what is happening on the inside of the reactor and minimize corrosive and contamination effects from contact with metal surfaces. |
When a pressure greater than 10 bar is required Parr is able to provide a solution by manufacturing vessels with volumes in the range of 25ml up to 18.75 L. Depending upon the nature of the process it is possible to stir the contents of the vessel using a magnetic-coupled drive. This allows the operator to ensure that their reactions are fully agitated. The pressures that are achievable with Parr equipment depend upon the specific design and volume. However, broadly up to 5000psi (345 bar) at 500 oC is possible for a stirred reactor and 5000psi (354 bar) at 600 oC for non-stirred is available as standard. |
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Parr has an established range of vessels which meet the needs of 90% of their customers. However, as all of Parr’s vessels are made to order, the customer, if they so wish, is able to become a part of the specification process, thus ensuring the equipment will meet their needs.
A large amount of Parr’s custom manufacture revolves around tubular flow-through reactors. All of these are made to a customer’s particular specification, drawing on their wealth of experience in this field. These can be from small narrow tubes for catalyst testing to vessels that are up to one meter long.
Parr has considerable experience in the machining and manufacture of vessels from materials other than Stainless Steel. This is required as many customer’s processes have a corrosive nature and stainless steel is not a suitable material of construction. The use of alloys such as B-2, C-276, 400, 600 and 20CB3 are common, as well as metals such as nickel, zirconium and titanium.
All of the Parr vessels can be controlled using Parr’s own control hardware. This may simply be the heating and stirring of a reactor. However using Parr’s Process Controller it is possible to control a range of ancillary equipment and processes plus log inputs from various sensors. This is accessed via a PC with a customized Graphical User Interface.
The most important issue during the design and manufacture of Pressure Vessels is adherence to the strict legislation appropriate for the end-users region. Since 2002 pressure vessels sold into EU member states must adhere to the Pressure Equipment Directive (PED). All of Parr’s equipment that is sold in the EU meets these requirements and will be supplied with the appropriate certification for that vessel type. This allows the end-user to be certain that their pressure vessel has been designed and manufactured to the highest specification.
Scientific and Medical Products has been the exclusive agent in the UK and Republic of Ireland for the Parr Instrument Company since 1979. Since then, they have supplied numerous pressure vessels of all volumes and styles to many customers throughout their area. All of their staff who work directly with Parr Instrument Company, are either engineers or industrial chemists, and as such, are able to lead both new and experienced pressure vessel users through the decision process from the purchase of a new vessel, to training and support following the purchase.
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