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  • PCS Germany (Region DACH)
  • +31 318 25 00 50

    Address Stationsstraat 72 3905JK VEENENDAAL The Netherlands

    Chamber of Commerce 73807435 (NL)

    About the FD series back pressure regulators

    Cv: 1·E-7 to 19  |  Max. Temperature: 150°C  |  Max. Pressure: 10 barg (150 PSI)


    The FD series is developed for the biopharma and sanitary industries. The FD series work similar to other Equilbar® back pressure regulators. The pressure on the inlet is controlled with a reference pressure on top of the regulator. The FD series meets the ASME BPE requirements. Some of the requirements are listed below:

    • USP class 6
    • EU 1935/2004 (on request)
    • Crevice free design
    • Electropolished
    • Surface roughness Ra < 0.5 µm .

    The FD series has been developed in a comprehensive development process to achieve optimal draining.  The instruments are suitable for Clean-In-Place (CIP) and Steam-In-Place (SIP) and can be flushed in both directions. In chromatography, dosing and injections processes, CIP is commonly required.

    The FD series is available for ultra-low pressure- and flow control application starting at a Cv of 10E-7 . Such low flow application often requires a high CIP flows. These contradicting requiementcan make it difficult to find a suitable valve. A common solution to work around this issue is to install a CIP bypass line with a pressure relieve valve. During the cleaning and rinsing process, the relieve valve reduce excess pressure. These bypass loops are adding complexity to the process design. The FD series is an excellent solution for this type of application. Because the FD series has a flow turn-ratio of 10.000:1 only a single valve eliminating the use of a CIP bypass line.


    The Equilibar® FD series is available with a maximum pressure of 10 bar gauge (150 PSI). It is equipped with two diaphragms. The top diaphragm is the actuation diaphragm. The bottom diaphragm reduces the effect of water hammering, that sometimes occurs at a specific combination of flow and pressure. The diaphragms are available in different materials like PTFE, Buna-N, FKM and EPDM (UPS class VI). The standard diaphragms allow a maximum temperature of 150°C. Higher temperatures can be achieved by applying different polymeric- or alloy diaphragms. Body materials are available in Stainless Steel, Hastelloy, Titanium, Monel and Zirconium. Other materials like PTFE or PVDF are available on request.  The valves can be supplied from ½” up to 2”  line size with tri-clamp or tube stub fittings. These regulators cover a Cv range from 10E-7 to 19 with only 5 models.


    The FD series back pressure regulators are pressure- and flow tested prior to delivery. When you require additional certification, it is possible to request a Sanitary Certification Package. The package contains verification of valve body materials, diaphragm materials, surface finish, electropolishing, lubricant materials and pressure leak testing.


    In biopharmaceutical filtration, high precision pressure control is often needed. When filtrating, a small pressure difference is controlled across a membrane or filter. The FD series are able to deliver superior precision even at a wide range of flow rates. This differential pressure can be set as narrow as 1 psi. Therefore the FD series can be an excellent solution for biopharmaceutical filtration.

    With product blending, it is important that the blending ratio is constant. These applications often involve flow meters with a flow controller that controls a pump. To reach high precision you need to have a constant back pressure. The FD series back pressure regulator is commonly used because of its high precision. A known problem is pressure fluctuations. The cause of the fluctuation cannot always be avoided and result in unstable flow control and therefore inconsistent blending ratios. When using an FD series back pressure regulator you can isolate the supply header from the main header. This solves the problem of pressure fluctuations from influencing flow control equipment.

    Single Use Design for Biopharma

    The FD Series also includes a Single Use Design (SD Series) for application in the biopharma industry.

    You can find more in-depth information about the various back pressure regulators below.

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    The working of an Equilibar Dome Loaded Back Pressure Regulator

    How to Rebuild your Equilibar Back Pressure Regulator

    Different materials that are used to make Equilibar Back Pressure Regulators and diaphragms

    Sanitary Pressure Control Across a Wide Range of Flow Rates