FAQs & Technical Support for Steriflow Sanitary Valves

Valve flow coefficient (Cv) indicates the flow capacity of a control valve at a given valve position. The required Cv for an application is determined by operating conditions such as flow rate, pressure differential, fluid properties, and temperature. The valve’s available Cv is determined by factors including valve size, port size, trim design, and valve position.

Proper valve sizing is critical for reliable and efficient control. Oversizing a control valve to provide additional “safety margin” is a common cause of poor performance. An oversized valve may operate too close to the closed position during normal conditions, resulting in unstable control, excessive cycling, increased trim wear, and reduced usable range. Ideally, the selected Cv should allow the valve to operate within approximately 10% to 90% of its available travel over the expected operating range.

To optimize control valve performance:

Select the appropriate flow characteristic for the process. Equal-percentage trim is generally suited to applications with varying pressure drop, particularly where much of the system pressure drop occurs outside the control valve. Linear trim is typically better suited to applications where pressure drop remains relatively constant and occurs primarily across the valve.
Size the valve using actual minimum, normal, and maximum operating conditions rather than selecting it based only on worst-case conditions. The selected trim should provide adequate controllability across the expected range of flow rates and pressure differentials.
Evaluate the valve for cavitation, flashing, excessive velocity, and noise using established ISA/IEC valve-sizing methods rather than relying on rule-of-thumb sizing.

Valve sizing software can help identify potential problems before a valve is selected. The Jordan Valve, LowFlow Valve, and Steriflow Valve JVCV/SFCV Max sizing software evaluates operating conditions and provides warnings when conditions such as cavitation, flashing, or excessive noise may occur with the selected valve and Cv. Engineers can then evaluate alternative valve sizes, Cv values, trims, or operating conditions to achieve more reliable and efficient control.

One of the most common control valve sizing mistakes is oversizing. Selecting a valve Cv based only on the maximum possible flow condition can result in a valve that operates near the closed position during normal operation, causing poor control resolution, instability, and increased valve wear. To avoid oversizing, evaluate minimum, normal, and maximum flow and differential pressure conditions when selecting the valve and trim.

Steriflow Valve’s JVCV/SVCV Max sizing software allows engineers to evaluate multiple operating conditions when sizing sanitary control valves. This helps identify a Cv and trim that can provide effective control across the expected operating range rather than sizing for a single extreme condition.

Another common mistake is failing to evaluate cavitation and flashing in liquid applications with significant pressure drop. These conditions can cause noise, vibration, erosion, and premature valve damage. Steriflow’s sizing software evaluates operating conditions and provides warnings for potential cavitation, flashing, excessive outlet velocity, and predicted noise before the valve is specified.

Selecting the wrong flow characteristic can also result in poor controllability. Equal-percentage trim is generally appropriate when system pressure drop varies and a significant portion of the pressure drop occurs outside the control valve. Linear trim is generally better suited to applications where the pressure drop remains relatively constant and occurs primarily across the valve.

Actuator selection should also be considered as part of the valve-sizing process. An improperly sized actuator or unsuitable response speed can affect control performance even when the valve body and Cv are correctly selected.

Using established ISA/IEC sizing methods and valve sizing software rather than rule-of-thumb estimates helps engineers avoid these common sizing mistakes and select a sanitary control valve that provides stable, reliable performance throughout the expected operating range.

Steriflow Valve offers sanitary check valves designed specifically for pharmaceutical, biopharmaceutical, and other high-purity applications. Selecting the right Steriflow check valve requires considering line size, flow rate, installation orientation, cracking pressure, process media, temperature, and material compatibility.

Start with the line size and expected flow range. Cracking pressure — the differential pressure required to open the check valve — should also be appropriate for the application. A cracking pressure that is too high can restrict flow and create unnecessary pressure drop, while improper selection can contribute to unstable operation or chattering.

Steriflow offers sanitary check valves for several piping orientations and applications:

• SVC Series Downflow check valves are designed for vertical liquid drain lines. They remain open to allow drainage and close when water-based process fluid backs up and rises in the drain line.

• SVC Series Upflow check valves are designed for vertical piping with upward flow.

• SHC Series check valves are designed for horizontal piping installations.

Steriflow sanitary check valves feature springless, crevice-free designs that eliminate the springs and associated entrapment areas found in traditional spring-loaded sanitary check valves. This helps reduce potential particulate generation and supports cleanability in aseptic and high-purity processes.

For material selection, 316L stainless steel is appropriate for most sanitary and high-purity applications. Hastelloy C-22 is available for applications involving more aggressive process or buffer chemistries where additional corrosion resistance is required. Product-contact seal and seat materials should also be selected for chemical and temperature compatibility and meet applicable FDA and USP Class VI requirements.

Steriflow sanitary check valves are designed in accordance with applicable ASME BPE valve design guidelines and are compatible with CIP, SIP, and autoclave processes.

For final selection, consider line size, flow requirements, installation orientation, cracking pressure, process media, temperature, cleaning and sterilization requirements, and material compatibility.

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