Insert Means Flexibilily

Flexibility during Installation 

FlowCon's insert-based solutions can be installed in any orientation (360° mounting) with no negative impact on functionality. During installation of the valve housing, this design flexibility enables highly compact construction and efficient use of available space, particularly in confined plant rooms and retro-fit applications. The absence of pipe layout constraints simplifies installation and reduces the need for additional pipework adaptations.

In addition, adjustable inserts can be set to the required maximum flow either before installation or after being placed in the valve housing. If flow requirements change, the setting can be re-adjusted easily while the system remains in operation, allowing the flow capacity to follow original flow requirement and still be able to adapt to later system modifications. This makes the insert-based solution a very flexible choice.

For any of FlowCon's dynamic balancing- and PICV inserts, flow setting and selected differential pressure checks can then be carried out fast and efficiently as a final step as p/t ports are installed in the housing, minimizing on‑site handling and avoiding time consuming commissioning.

Flexibility during Maintenance

An insert‑based valve design provides easy serviceability. This modular approach allows targeted maintenance activities to be performed efficiently and directly on the insert, minimizing system down-time and eliminating the need for pipe disassembly or re-balancing. During maintenance, simply remove the insert for inspection, cleaning, or replacement as required, while the valve housing and pipework system remain untouched. Following maintenance, the insert can be re-installed or replaced, restoring the valve’s flow balance and control functionality.

By decoupling insert maintenance from the pipe-work, insert‑based solutions keep on supporting easy serviceability throughout the lifetime of the valve, contributing to predictable long‑term system performance, and align with lifecycle‑oriented maintenance strategies.

Flexibility at End-of-Life

Insert‑based valve designs support a lifecycle-oriented approach by enabling physical separation of materials at end‑of-life, in line with principles for Design for Disassembly and Design for Recycling as referenced in ISO 14040- and ISO 14044‑based life cycle assessments.

At end‑of‑life, the insert can be removed independently of the valve housing, allowing differentiated handling of sub-components according to material composition. Valve housings are either all DZR brass or all AISI 316L stainless steel and can be re-used directly or recycled – this also goes for the assigned flushing caps mentioned under Flexibility during Flushing. Spring‑based inserts are manufactured exclusively from stainless steel, facilitating direct allocation through established metal recycling streams with high material recovery rates. Diaphragm‑based inserts are engineered for controlled disassembly with a simple twist by hand, enabling separation into distinct sub‑components (composite material, EPDM, brass and stainless steel), thereby supporting accurate material sorting and recycling in accordance with waste hierarchy principles.

By enabling disassembly and material separation at component level, insert‑based solutions reduce end-of‑life complexity, improve re-useability and re-cyclability, and support transparent lifecycle modelling. This contributes to improved data quality in LCA studies, facilitates more precise allocation of environmental impacts, and supports documentation requirements within ESG reporting frameworks and circularity strategies.

This insert solution is founded on the well-proven ‘moving cup’ technology, originally developed within the FlowCon Group in 1960. This mechanically simple yet robust principle forms the basis for a reliable, constant flow insert design with decades of field-proven performance.

Operating Principle

The insert functions as a pressure‑independent maximum flow limiter, known as FlowCon's stainless steel insert range. Flow balance is governed by the fundamental relationship:

Materials and Design

The insert is manufactured entirely from stainless steel, ensuring high durability and corrosion resistance. Precision laser‑cut orifices provide accurate flow control and exact flow balancing. In combination with the spring mechanism, the laser‑cut geometry creates a self‑cleaning effect: any debris trapped in the orifices is removed through a knifing action as the cup moves. 

The self‑cleaning design minimizes clogging and supports long‑term operational reliability with reduced maintenance. Combined with pressure compensating performance, robust materials, and tamper-proof pre-setting, the spring‑based insert delivers consistent and dependable flow control throughout the system lifetime and makes it ideal for constant flow systems as a pre-set maximum flow limiter.

The diaphragm‑based solution is built on a rolling diaphragm principle that maintains a constant differential pressure across a defined effective area. This FlowCon signature-design was first introduced in the early 1990s, when FlowCon invented the PICV concept, and later evolved into the well-known diaphragm‑based insert concept, with more than 25 years of proven field performance.

Operating Principle

This diaphragm‑based insert design is available as a range of automatic balancing inserts, ABV inserts (FlowCon E-JUST and Composite), a range of pressure independent control valve-inserts, PICV inserts (FlowCon Green and GreEQ) and a range of differrential pressure control valve-inserts, DPCV inserts (FlowCon EDP, ADP and SDP). For the ABV- and PICV inserts, flow balance follows the fundamental relationship:

To maintain a constant flow (Q), the differential pressure (ΔP) across the effective orifice area is kept constant, independent of changes in system differential pressure.

DPCV inserts, on the other hand, control a ΔP_circuit which is beyond the scope of this Topic Letter.

Functional Performance

Automatic flow balancing is achieved through the interaction between the internal spring and the rolling diaphragm. P1 (valve inlet) and P3 (valve outlet) represent the system pressures, with P1-P3 being the total pressure drop across the valve. The internal P2 is set by the diaphragm acting in reaction to P1, which is let to the upper diaphragm chamber through an internal tube. As system differential pressure increases, the diaphragm rolls downward, reducing the outlet orifice area to maintain a constant ΔP (P1-P2). When pressure decreases, the diaphragm rolls upward again, increasing the openings and still maintaining ΔP (P1-P2) constant. This continuous mechanical response, i.e. the dynamic pressure independent balancing, ensures a constant and stable flow regardless of system pressure fluctuations. 

The adjustable versions of diaphragm‑based insert solutions allow precise setting of the required design flow. Both ABV- and PICV inserts (FlowCon E-JUST, Green and GreEQ) feature stepless setting across 41 defined setting positions through a multiturn micrometer setting, covering the full range between lowest and highest settable maximum flow. This enables a clear and repeatable setting position matching design flow.

In addition, the PICV insert design ensures full control performance, delivering 100% valve authority and 100% usable stroke, independent of the selected flow setting. This is achieved by separating the adjustment and control functions: the flow setting is established through a horizontal rotational adjustment, while the actuator performs control through a vertical, linear movement. As a result, the actuator stroke remains fully effective across the entire flow range, ensuring accurate, stable, and proportional control at both partial load and full load.

Once the desired flow is set, the insert can be rendered tamperproof by fitting a top cover (ABV inserts) or an actuator (PICV inserts), protecting the flow setting from unintended adjustment. A wide insert range for both ABV- and PICV variants ensures straightforward and reliable selection across a wide spectrum of applications.

Materials and Design

The three primary functional components are the essential patented rolling diaphragm made of EPDM, a stainless steel spring and the adjustment unit from glass‑reinforced PPS, which together form the core regulating mechanism. The central head nut linking the setting scale with the dynamic regulating assembly is manufactured from brass. Other wetted composite parts of the insert are also produced from glass‑reinforced PPS, ensuring high mechanical strength and long‑term dimensional stability. Non‑wetted components, including the scale and other external elements, are manu-factured from ABS, PC, and POM. All materials are specifically selected for durability and dimensional accuracy.

In summary, FlowCon’s diaphragm‑based insert design applies a mechanically simple yet highly precise pressure independent principle to ensure stable and repeatable flow control. By maintaining a constant differential pressure across a defined area, and by assigning flow adjustment and control modulation to two independent mechanical move-ments, the solution delivers full valve authority, long‑term reliability, and consistent performance. Combined with high-performing materials, the diaphragm‑based insert provides dependable operation throughout the system lifetime.

This Topic Letter has outlined the technical benefits when selecting insert-based solutions. By separating the valve housing from the dynamic balancing and pressure independent control function, inserts can offer advantages in terms of configurability, serviceability, and lifecycle flexibility - without compromising flow accuracy or control stability. Insert-based solutions will support precise hydraulic balancing, predictable control behavior, and efficient system operation. For further technical evaluation or application-specific guidance, FlowCon remains available to support you and your HVAC project.