The FOX HST-Plastic Series Diaphragm Pulsation Dampener represents an advanced technical solution for pulsation control within hydraulic circuits. Designed to maximize flow stability, this dampener requires a nitrogen precharge pressure between 60% and 80% of the working pressure, a value that must be calculated in close relation to the type of pump used and the operating temperature of the system. The component offers a recommended compression ratio of 2.5 (P2/P0), with a maximum operationally tolerated limit of 4. It is essential to underline that the mechanical life of the device, measured strictly in number of cycles, is always inversely proportional to the increase in this compression ratio.

Construction Features and Materials

The versatility of the series lies in the wide range of materials available for the internal diaphragm, including technical options such as NBR, HNBR, EPDM, FPM, HYTREL, and Alcryn, allowing maximum chemical and mechanical compatibility with various operating fluids. The nitrogen charging valve supplied as standard features a 5/8″ UNF connection. The construction design of the dampener allows installation in both horizontal and vertical orientation; however, in the latter case, the nitrogen valve must face upward to ensure correct operation. The standard maximum working pressure (PS) of the component is 10 bar, while the test pressure (PT) corresponds to PS multiplied by the safety coefficients 1.43 or 1.5.

Versions and Operating Temperatures

The external body construction versions are available in different polymer variants, each specifically designed to tolerate strict operating temperature ranges:

  • The standard version identified as HSTP, made of PP (Polypropylene), is fully suitable for operating temperatures between 0°C and +70°C.
  • The HSTPVC variant, made of PVC-U material, reliably covers a temperature range from -5°C to +50°C.
  • The HSTPVCC model, made of PVC-C, raises the maximum supported temperature threshold, operating safely between -5°C and +60°C.
  • For the most extreme thermal conditions, the HSTPVDF version in PVDF handles temperatures from -20°C to +80°C without critical issues.

Connections, Options and Regulatory Compliance

In addition to flexibility in the choice of construction materials, the entire range offers several advanced hydraulic connection solutions. Versions equipped with an integrated flange connection or a flange compliant with strict international ANSI B16.5 and UNI/DIN standards are available. To meet special system requirements, configurations with special connections can always be requested. In order to drastically reduce management costs and machine downtime, the line includes completely maintenance-free variants identified by the dedicated code HSTP-SMF. In addition, for applications requiring higher resistance, a high-pressure construction version capable of continuous operation up to 15 bar is available on request. Finally, to fully meet global safety directives, the product can be supplied in compliance with top-level certifications such as CE (2014/68/EU-PED), KOSHA, SELO, EN 14359, PD5500, EN 13445, DOSH, NR-13, AS1210/4343, ARH, BV, Lloyd’s/ABS, DNV/RINA, and CU-TR 032/2013.

Technical Summary Table of Main Characteristics