Product category:
Hydraulic Components
News Release from: Parker Hannifin | Subject: Pressure Directive and Accumulators handbook
Edited by the Engineeringtalk Editorial
Team on 28 August 2001
Legislation on hydraulic accumulators
explained
The Pressure Equipment Directive and Hydro-Pneumatic Accumulators is the title of an invaluable new 12-page, A5, handbook produced by Parker Hannifin, to highlight new European legislation
The Pressure Equipment Directive and Hydro-Pneumatic Accumulators, is the title of an invaluable new 12-page, A5, handbook produced by Parker Hannifin, to highlight how new European legislation will affect designers, specifiers and end users of hydraulic accumulators From 30th May 2002, most items of pressure equipment with a maximum operating pressure greater than 0.5 bar manufactured in EC member states must meet the requirements of the European Pressure Directive (PED) 97/23/EC
Since November 1999, there has been a transition period during which pressure equipment can be manufactured either to the requirements of the PED or to the national rules which were in place at that date.
This transition period ends on 29th May 2002.
Featuring the very latest information available on the PED, the new handbook provides answers to the most commonly posed questions: What is the PED?; What does it cover?; What are its requirements?; What are the benefits? (for both the OEM manufacturer and for the customer); What industries are affected?; Who is responsible for compliance?; What is the timescale?; What should I look for?; and, most importantly, What do I have to do?.
The PED is one of the most important and far-reaching changes in industrial legislation to affect the European hydraulics industry, and arises from the European Community's programme for the elimination of technical barriers to trade.
Its purpose is to harmonise national laws of member states regarding the design, manufacture and conformity assessment of pressure equipment and assemblies of pressure equipment.
The Directive requires that all pressure equipment and assemblies within scope - such as accumulators - must be safe when placed on the market and put into service.
Safe pressure equipment and assemblies are defined as those which, when properly installed and maintained and used for their intended purpose, will not endanger the health and safety of persons and property.
Accumulators are frequently relied upon, for example, to provide shock absorption during valve closure in hydraulic power systems or fluid transmission lines or when loads start, stop or are reversed in machinery such as camshaft grinding machines.
Shock absorption is also desirable when loads are carried on lift trucks, tractor shovel loaders and earth moving equipment and to compensate for load reactions on the pressure rolls of papermaking machines and printing presses.
Accumulators are used on mobile equipment to eliminate 'pitching' oscillations which could cause the operator to lose control of the vehicle.
These oscillations can be set up in articulated wheel loaders and end loaders, for example, when running with no load.
Accumulators are also employed to maintain system pressure, compensating for pressure losses due to leakage and increases due to thermal expansion, or for holding pressure while a pump does other work.
In the case of emergencies such as power or pump failure, accumulators also serve to maintain pressure until a turbine can be stopped or where fluid power is needed to withdraw tools to avoid work spoilage.
An accumulator can provide power for emergency valve closure, to ensure fail-safe operation of systems and processes.
In other applications, accumulators are a valuable means of storing energy and are often used on electric circuit breakers and switchgear and on hydraulic starters for diesel engines.
They may be used to dispense fluid in a pressurised lubrication system and to supplement pump delivery in die casting and injection moulding equipment.
By incorporating accumulators into the design of hydraulic systems, designers can also reduce the size of the hydraulic power pack required, thereby reducing both noise levels and energy consumption in the system. Request a free brochure from Parker Hannifin ...
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