WorldWide Drilling Resource

45 WorldWide Drilling Resource ® SEPTEMBER 2015 Accumulator Safety Accumulators are devices which store energy in the form of fluid under pressure. Because of their ability to store excess en- ergy and release it when needed, accumu- lators are useful tools for improving hydraulic efficiency. Industrial hydraulic accumulators are typically classified as hydropneumatic. This type of accumulator applies a force to a liquid by using compressed gas. The two most common types of hydropneumatic accumulators are the bladder type and the piston. The name of each type indicates the device separating gas from liquid. A hydropneumatic accumulator has a fluid compartment and a gas compartment, with a gas-type element such as a bladder separating the two. The bladder is charged through a gas valve at the top of the accumulator, while a poppet valve at the bottom prevents the bladder from extruding into the pressure line. The poppet valve is sized so the maximum volume metric flow cannot be exceeded. To operate, the bladder is precharged with nitrogen to a pressure specified by the manufacturer according to the operating conditions. When the system pressure exceeds the gas precharged pressure, the poppet valve opens, and hydraulic fluid enters the accumulator. The changing gas volume in the bladder determines the useable volume or useful fluid capacity. Accumulators store energy that can be used during power failure or when ad- ditional energy is needed. In certain situations, additional flow may be needed. An accumulator can be used to supplement the flow rate of a pump. Hydraulic systems are very complex, and identifying stored energy locations in hydraulic systems can be difficult and dangerous. The energy of hydraulic fluid under pressure and the loads this energy supports is extremely hazardous. The accidental release of this energy has been the cause of many injuries and death throughout all industries. Researchers have developed this safety topic to bring a respected understanding of fluids under pressure, including an in-depth study of hydraul ic accumulators, their design, application, and dangers. Accumula- tors from the per- spective of safety are the most dan- gerous compo- nent in a hydraulic system. The phys- ical exposure to the accidental release of this stored energy can be fatal. When discharging and charg- ing an accumulator in a confined area, you should ALWAYS monitor oxygen levels. Ni- trogen does not contain oxygen, it has no taste or smell, and will displace breathing air. Always consult an expert when workingwith accumulators ~ the life you save may be your own. Eric Eric may be contacted via e-mail to michele@ worldwidedrillingresource.com Hydraulic Training by J. Eric Freimuth Hydraulic Training Associates 9 &15*/( 3)& %1*--*/( */%42318 2*/$& : 9!)&/ *3 $0.&2 30 ; < 6& ,/06 3)& : 2&"-&% #&"1*/( %1*-- #*32 '01 &" !&23 1"/,'013 --*/0*2 0$"3*0/ "7 0-- 1&& ."*- 3&&+"8 .*%6&23 /&3 4< /*2'3* "& > > > > ,'< ? /2+ '6* /3+6 /3+6 ')1/3- " " !8=2+ /7843 4* 4* ')1/3- !+8 5)7 !8'3*'6* $'2:+ 9((+6 6':+2 $'2:+ 9((+6 !+'87 9((+6 $'2:+ 37+687 #6+8.'3+ $'2:+ 37+687 $'2:+ !56/3- ! ! $'2:+ 4:+6 '71+8 ? !;/:+2 ')1/3- ? !+6/+7 ? !+6/+7 ? !+6/+7 ? !+6/+7 ? !+6/+7 ? !+6/+7 < /3+6 < /3+6 < /3+6 < /3+6 < /3+6 6/)+7 !9(0+)8 "4 .'3-+ %/8.498 48/)+ !@ @ < < < < <