Bladder low pressure type accumulators consist of a welded cylindrical pressure vessel made of steel.
The accumulator is subdivided into a gas and fluid side by an elastic bladder mounted in the interior of the vessel.
The bladder is charged with nitrogen to the specified gas charge pressure P0 by means of gas valve.
When the fluid is pressed into the accumulator, the gas in the bladder is compressed and hence the pressure increased. The gas volume reduces and on the fluid side, the fluid can flow into the accumulator. As soon as the pressure on the fluid side falls below the gas pressure, the accumu- lator is emptied.
The special oil valve (anti-extrusion plate) prevents draining of the blad- der into the oil channel and thus the bladder from being destroyed. When the minimum operating pressure is reached, a small oil volume is to be maintained between the bladder and the fluid volume (approx. 10% of the nominal capacity of the hydraulic accumulator), in order that the bladder does not hit the valve during every expansion process.
Gas valve consists of external caps, sealing cap, filling valve, gas valve body and rubber coated washer. These parts can be replaced separately. The nameplate shows the technical data and features of the hydraulic accumulator.
PRESSURE TEST (PT): 1.43 x PS
0.7 – 1 – 1.5 – 3 – 5 – 10 – 15 – 20 – 25 – 35 – 55 litres
WORKING TEMPERATURE: -40 ÷ +150 °C
COMPRESSION RATIO (Po : P2): max. 1 : 4 FLUID VISCOSITY RANGE: 10 ÷ 400 cSt RECOMMENDED VISCOSITY: 36 cSt FLUID CONTAMINATION DEGREE:
class 21/19/16 according to ISO 4406/99
– carbon steel shell painted with rust inhibitor RAL 8012 – nickel coating 25 – 40 μ
– stainless steel AISI 316L
– phosphated or galvanized carbon steel in compliance with Directive 2002/95/EC (RoHS) to resist to corrosion
– stainless steel AISI 316L – nickel coating 25-40 μ
– P = Nitrile rubber (NBR)
– F = Low temp. nitrile rubber
– H = Nitrile for hydrocarbons
– K = Hydrogenated nitrile (HNBR) – B = Butyl (IIR)
– E = Ethylene-propylene (EPDM) – N = Chloroprene (Neoprene)
– Y = Epichlorohydrin (ECO)
– V = Fluorocarbon (FPM)
See Table 3.3c and/or Chapter 1.5
FILLING VALVE CONNECTION:
– 5/8”-UNF std – 7/8” UNF
– 1⁄4” BSP
FLUID PORT CONNECTION: see 3.3db – 3.3eb – 3.3ec – 3.3fb FLOW RATE: see Table 3.3db
WEIGHT: see Table 3.3db