The FOX HB – HBX – HBR Series Bladder Accumulator – Repairable is designed with a high-strength forged steel body, carefully sandblasted and painted to ensure excellent long-term durability in demanding industrial environments. This range of hydropneumatic accumulators is divided into two main construction configurations: the HB series, developed as an internationally repairable bottom-repair solution , and the HBR series, specifically designed for top repair operations. The maximum working pressure (PS) reaches 350 bar for the standard models of both variants. However, for higher hydraulic requirements, the HB series is available in special versions capable of operating at 480 bar and even 690 bar. Each unit undergoes rigorous testing; the test pressure (PT) corresponds to the maximum pressure multiplied by a safety factor of 1.43, 1.3 or 1.5. A significant advantage of the HB series lies in its complete interchangeability: the models are dimensionally and technically compatible with accumulators from other brands belonging to the same category.

Operating and Installation Specifications

Equipped with a standard 5/8″ UNF nitrogen valve , the accumulator uses a standard bladder fully suitable for contact with mineral oils and non-aggressive fluids. The permitted operating temperature range (TS) is very wide and extends from -20°C to +80°C. The versatility of the component is also reflected in the installation options, which may be horizontal or vertical, provided that the nitrogen valve is always facing upward.

Compression Ratio and Use as a Dampener

To ensure maximum performance and preserve the mechanical integrity of the hydraulic system, the recommended compression ratio is P2/P0 = 2.5 , although there is a maximum tolerated technical limit of P2/P0 = 4. Operating parameters directly affect the mechanical lifespan of the accumulator, whose useful cycle count is inversely proportional to the increase in compression ratio. In specific applications, when the unit functions as a pulsation dampener, the nitrogen precharge pressure must necessarily fall within a range between 60% and 80% of the working pressure, carefully calibrating the value according to the type of pump used and the operating temperature of the fluid.

Customization Options and International Compliance

The HB and HBR series offer a wide range of customization options to meet dedicated system requirements. It is possible to request internal coatings in different materials, bladders made from special compounds (HNBR, EPDM, FPM), as well as the implementation of stainless steel nitrogen valves. For the hydraulic section, SAE 3000, SAE 6000, ANSI B16.5, UNI/DIN flanged connections and special custom-made connections are available. The high quality standards and safety are certified by the numerous regulatory compliances available upon request, covering the main global markets: from European CE (PED) and ATEX directives to ASME VIII, KOSHA, SELO standards, as well as naval and offshore certifications such as DNV / RINA and Lloyd’s / ABS.

Summary Technical Table

Feature Value
Maximum working pressure (PS) 350 – 480 – 690 bar (depending on series/version)
Test pressure (PT) PS x 1.43 / 1.3 / 1.5
Body Forged steel, sandblasted and painted
Operating temperature (TS) From -20°C to +80°C
Standard bladder Suitable for mineral oils and non-aggressive fluids
Installation Horizontal or vertical (nitrogen valve facing upward)
Recommended compression ratio P2 / P0 = 2.5
Maximum compression ratio P2 / P0 = 4
Standard nitrogen valve 5/8″ UNF

Product Codes

Model Nitrogen Volume (L) Max Pressure (Bar) Max N2 Precharge (Bar) Hydraulic Connection Max Flow Rate (L/min) Weight (Kg)