Managing industrial gas flows is rarely straightforward. When a process deviates from standard conditions — for example, in terms of temperature, pressure, or gas composition — an off-the-shelf product is no longer sufficient. Custom damper solutions are the answer to this reality: they are designed to operate reliably where standard products fail. In this article, we walk through what customization means in practice for special processes, how process conditions drive technical requirements, which parameters are critical for design, and what mistakes in damper selection recur most frequently.

The article is structured progressively: we begin with defining the concept and move toward concrete technical details and practical decision-making support. The goal is that a process engineer or procurement manager, after reading this article, can critically assess when a custom damper system is necessary and from what starting points the design should begin.

What do custom damper solutions mean in special processes?

A custom damper system means a shut-off or control damper whose structure, materials, and operating principle have been designed to meet the individual conditions of a specific process, rather than relying on standardized size ranges or one-size-fits-all solutions. In special processes, this distinction is decisive.

The design starting point for standard dampers is a typical use case: moderate temperature, clean or low-impurity gas flow, and stable operating pressure. When any of these assumptions does not hold, the damper may leak, seize, or wear prematurely. In special processes — such as flue gas lines in biomass plants, industrial drying processes, or exhaust gas ducts on ships — conditions often deviate significantly from these baseline assumptions.

A concrete example clarifies the matter: in the drying process of a plasterboard factory, the gas flow contains moisture, dust, and corrosive compounds simultaneously. A standard damper sized for dry airflow begins to corrode within a few months. A custom damper solution, on the other hand, starts precisely from these process conditions: materials, seals, and bearings are selected to withstand the actual operating environment, not an imaginary ideal situation.

Customization does not mean that every component is manufactured from scratch on a blank slate. In practice, it means that the basic structure can remain familiar and tested, but critical parameters — such as shaft sealing, blade material, and actuator coupling — are adapted to the real requirements of the process. Sammet® dampers represent this approach: structural reliability combined with process-specific adaptation.

How do process conditions define damper requirements?

Process conditions are the starting point of damper design. Every condition variable sets technical boundary conditions that constrain material choices, sealing solutions, and structural geometry. When these variables are known precisely, requirements specification is a straightforward process. When they are known inadequately, errors are inevitable.

Temperature and its range of variation

Operating temperature is often the first parameter to come up. The damper’s materials — particularly the metal alloys of the blades and shaft, as well as sealing materials — must be selected to withstand both the normal operating temperature and any peak values during start-up and shutdown situations. In high-temperature processes, such as flue gas lines in power plants, thermal expansion of steel must be taken into account in the structural dimensional tolerances. If the damper is sized too tightly for a cold structure, it may seize in hot operation.

The range of temperature variation is often just as important as the absolute maximum value. A process in which temperature repeatedly varies between 80 and 400 degrees stresses structures through thermal fatigue in a way that a stable high temperature does not.

Gas composition and impurities

The chemical composition of the gas flow determines the level of corrosion risk. Sulfur dioxide, hydrogen chloride, and moisture in combination form acidic condensate that rapidly corrodes conventional steel structures. Flue gas produced in biomass combustion often contains ash and dust, which mechanically wear seals and bearings.

Here lies a common area of underestimation: gas composition is not constant over the process lifecycle. Fuel quality varies, process conditions change, and gas impurity concentrations can rise significantly, for example during process upsets. A custom damper system accounts not only for normal operation but also for realistic exceptional situations.

Pressure and tightness criteria

Process pressure and its variations directly affect the required tightness of the damper. In high differential pressure environments, leakage class is a critical design parameter. The European standard EN 1751 classifies dampers into leakage classes, but in special processes the required class must always be defined on a process-specific basis, not by default.

Key technical parameters in customization

In the previous section, we discussed how process conditions set the boundary conditions. Now we delve into the concrete technical parameters that are defined in practice during customization. These parameters form the core of the design document and guide all material and structural choices.

Material requirements

The choice of blade material is often the single most important decision in customization. Ordinary carbon steel is sufficient for clean and dry airflow, but stainless steel, special alloys, or coated structures are essential in corrosive or high-temperature applications. Sealing materials — such as graphite, silicone rubber, or PTFE — are selected based on temperature and chemical compatibility.

Flow engineering sizing

The aerodynamic performance of the damper — particularly pressure drop at various positions and flow uniformity — must be sized for the actual flow profile of the process. Clean Flow technology is an example of how flow engineering design can be taken beyond the standard: the patented geometry maximizes flow uniformity and minimizes pressure drop, which is especially important in processes where gas flow non-uniformity causes process upsets.

Actuator and control logic

The mechanical structure of the damper is only part of the whole. The choice of actuator — electric or pneumatic — and its integration into the process automation system must be customized according to the process control requirements. The requirements of a fast-responding control damper differ entirely from those of a simple shut-off damper. An incompatible actuator can render an otherwise correctly sized damper inoperable.

Installation geometry and connection dimensions

Customization also covers physical integration into the existing ductwork. Flange dimensions, installation orientation, and required maintenance space must be defined according to the actual installation environment. In industrial modernization projects, this is often a critical constraint: the new damper must fit in place of the old one without extensive structural modifications.

The most common mistakes in damper selection for special processes

Building on the principles discussed earlier, we can now identify the mistakes that are repeatedly made in damper selection. These mistakes most often do not stem from incompetence, but from insufficient knowledge of process conditions or from the fact that choosing a standard solution feels adequate — until it proves inadequate.

Sized for normal conditions, not the actual operating profile

The most common mistake is sizing the damper to the nominal values of the process without accounting for the conditions during start-up, shutdown, and upset situations. During start-up, temperature can vary rapidly and gas composition can deviate significantly from normal. A damper that performs well during steady-state operation may be damaged precisely during these transitional situations.

Underestimating the impact of gas impurities

Ash, moisture, and corrosive compounds together represent a many times more challenging environment than each one individually. Process designers often assess each impurity factor separately, but the combined effect can be more severe than expected. For example, the combination of moisture and sulfur dioxide forms sulfurous acid, which corrodes structures considerably faster than either one alone.

Selecting a damper without a consultative process

Dampers for special processes cannot be selected from a product catalog without a thorough investigation of process parameters. This is perhaps the single most important lesson: the right damper selection always requires a dialogue about the actual conditions of the process. Suppliers of standard dampers often sell the closest suitable product, whereas a supplier of a custom solution starts by asking what actually flows through the duct and under what conditions.

Neglecting maintainability during the design phase

The technical performance of a damper at the moment of installation does not tell the whole story. Seal replacement, bearing maintenance, and actuator calibration are recurring operations throughout the entire service life. If maintenance points are located in hard-to-reach places or if spare parts are not available, the total cost rises significantly above the original purchase price. In customization, maintainability must be built in during the design phase, not added afterward.

Selecting custom damper solutions for special processes is above all the result of information gathering and technical dialogue. The right questions about process conditions, gas composition, and operating profile lead to the right choices. Wrong assumptions lead to premature failures, costly shutdowns, and ultimately reinvestment.

If your process conditions raise questions about whether a standard product is suitable or whether a custom solution is needed, contact our design team for a consultative assessment. We will review your process parameters and help define what kind of damper system meets your actual requirements.