New universal gas charging kit for accumulators from Hydrotechnik

25 September, 2015

Accumulators are typically used alongside hydraulic power packs as an auxiliary power storage device to quickly and safely operate a system. For example, in the case of wind turbines, they rotate the blade to a null position in extreme wind conditions.

Accumulators can also be used as the power to start very large diesel engines in the marine industry. The power that can be stored in an accumulator is immense and can be applied at full power immediately.

Critical maintenance issue

Moreover, accumulators can be used as the energy source to activate the brake calipers on wind turbines. The brake force holding time required can be as long as several days, which means that the accumulators must have enough pre-charged gas pressure beforehand to ensure the turbine is held under control. It is therefore a critical maintenance issue that all accumulators have the correct nitrogen gas pre-charge pressure at all times.

Wind turbines commonly use piston type accumulators because of their smaller footprint and high pressure performance. Piston accumulators are commonly fitted with Minimess gas charging valves due to their high pressure capability, leak free design and safe ease of use. Other typical applications for accumulators are:

• Emergency and safety: An accumulator which is kept constantly under pressure is valuable in the event of an electrical power failure as it can provide flow and pressure to perform an additional function or complete a machine cycle.

• Shock or pulsation dampening: An accumulator can be used to cushion the pressure spike from sudden valve closure, the pulsation from pumps or the load reaction from sudden movement of parts connected to hydraulic cylinders.

• Leakage compensation: An accumulator can be used to maintain pressure and make-up for lost fluid due to internal leakage of system components including cylinders and valves.

• Thermal expansion: An accumulator can absorb the pressure differences caused by temperature variations in a closed hydraulic system.

• Energy conservation: An accumulator can be used to supplement a pump during peak demand thereby reducing the size of the pump and motor required. The accumulator is charged during low demand portions of the pump cycle time and then discharges during the high demand portions of the system.

• Noise reduction: An accumulator is effective at reducing hydraulic system noise caused by relief valves, pump pulsations, system shock and other circuit generated noises.

• Improved response times: An accumulator (bladder type) has virtually instantaneous response time that can provide fluid very quickly to fast-acting valves such as servos and proportionals to improve their effectiveness.

Hydrotechnik UK recognises that there are many types of accumulators in the market and to address the needs of service engineers worldwide they have developed the universal World Wide kit.