Feature Hydraulics & pneumatics Under pressure to ensure safety
There are many potential hazards surrounding hydraulic technology, therefore safety is of the highest priority when specifying, installing and maintaining hydraulic systems. Peter Söderberg, group promotion manager at Parker Hannifin, Hydraulics Group Europe, explores the risks and solutions
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lthough the burgeoning volume of health and safety legislation has received considerable media ridicule, there is, in most instances, sound logic and a genuine desire by the regulatory authorities to protect life and limb. This is espe- cially true in the manufacturing sector, where the potential for personal injury from plant and equipment is considerable. Systems driven using hydraulic technology – where high pressures are typical and relatively aggressive oils represent a possible hazard – are closely regulated to minimise the risk of injury. Such systems can cause serious injury if there is a sudden release of high pressure fluid, with the most common injuries coming as a result of pinhole leaks in hoses. The potential for hazard usually comes from the way in which hydraulic systems are installed, operated and maintained. Indeed, regardless of the construction and technical capabilities of a hydraulic hose, for example, it must be routed and installed correctly, and be protected from external damage, if it is to perform safely to its maximum operating specification.
Another example is where operators look for pinhole leaks in hydraulic lines by running a hand or finger along the line. Fluid can penetrate the skin at extreme pressures, replicating the action of an injection from a hypoder- mic syringe. While these injuries may not always appear serious, without proper care gangrene can result, so prompt appropriate medical attention is needed. In fact, surgery is often needed to remove the fluid along with long term medical care.
Increasing safety To prevent this type of accident and increase overall safety, the starting point for an effective strategy has to be based on a comprehensive risk assessment of all operating systems, considering all the possible things that could go wrong, while also allowing for the unpredictability of human nature. Risks can be minimised by following best practice guidelines, applying common sense, and ensuring that all employees are fully trained. Hands and the body, for example, need to be kept away from leaks and
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operated for the intended purpose. Manufacturers must also satisfy appropriate conformity assessment pro- cedures and equipment must bear specified markings, including the CE mark, along with adequate instructions for use. Similarly, component manu- facturers are developing technical failsafe solutions that help to protect machine operators still
nozzles that might eject fluid under high pressure. A simple check can be employed for small hydraulic leaks: moving a piece of cardboard or paper across the area will isolate the problem.
Safety also needs to be designed in from the outset. To address this, the latest hydraulic equipment from manu- facturers such as Parker Hannifin com- plies with legislation and guidelines, including the Pressure Equipment Directive (PED). Having been designed, manufactured and tested to strict safety requirements, it will be extremely safe. In particular, the PED requires manufacturers of hydraulic equipment and components within the EU to take responsibility for the compliance of their products, and makes it necessary for them to supply a Certificate of Conformity with equipment to reassure machine builders and end users that the equipment is safe when
Safety needs to be designed in to hydraulic systems from the outset
further, while minimising system build and maintenance time, and reducing assembly, production and overall costs. These standard products, combined with customer support, simplify the task of safety management for design, production and mainte- nance engineers alike.
For example, accumulators used in hydraulic circuits to store energy can now be protected by simple, integrated safety blocks. These incorporate shut off, non return, pressure limiting and pressure release functions in a compact and robust unit that can be rated for use in systems operating at up to 350 bar. By minimising the number of con- nections and by integrating controls, these devices can significantly reduce the potential for injury.
In addition, these safety blocks allow adjustments in system perfor- mance to be made simply and quickly without needing to disconnect or remove the block. This preserves the safety of engineering and maintenance personnel while also reducing system
Hydraulic solutions for F1 racing
time, reducing drag on the straight and allowing greater opportunity for overtaking. The rear wings will be replacing the 2010 season’s active front wings, which are now banned. The wings are raised and lowered by a large diameter hydraulic actuator. This needs to move very quickly and
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therefore demands a fast-acting, high flow valve to control it. To facilitate this, Lee Products has developed a 12v dc version of its three-way high flow solenoid valve, and several F1 teams have specified it. This modified valve can operate at temperatures up to 165°C, the retaining nut has been removed to save space and reduce weight, and the lead wires now exit from the rear of the valve instead of at the hydraulic end. The miniature three-way high flow solenoid valves are a natural evolution of the company’s proven piloting solenoid valves,
which are said to set new standards in reducing space, weight and power consumption. Valve elements are based on the low leakage, high reliability designs used in Lee check and shuttle valves. Features include two position, three-way, 3000 psi, 4.0 USGPM minimum flow at 3000 psid (300 Lohms), single coil and an integral safety screen with 0.004in hole size. Power consumption is 7.8 watts at 18-32v dc and they can operate within a -54° to +135°C temperature range. Special 12v dc versions are also available for motorsport applications. Lee Products
T: 01753 886664
www.leeproducts.co.uk
river-activated rear wings are returning to Formula 1, 40 years after they were banned for safety reasons. This year, drivers will be able to control the rear wing once they have been behind another driver for a set amount of
Enter 207 > 12 MARCH 2011 Design Solutions
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