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Your benefits with LESER’s
Change-over Valve

Read here why spare relief valve installations are important and how our latest product contributes to safe and efficient plant operation.


LESER Change-over Valve

On LESER's Youtube channel you will find videos on the operation of the change-over valves Type 330 Compact and Type 320 Flow.

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Challenges: The design of a spare relief valve installation needs to ensure a maximum permissible inlet pressure drop at 3% of the safety valve’s set pressure. This especially should be ensured when dealing with additional piping components, long inlet lines or in combination with high capacity safety valves. Many solutions available in the market need unstandardized modifications in order to adapt to plant conditions, making the pressure drop calculation difficult, sometimes even impossible.

LESER’s solution: To suit a wide variety of application requirements, our  Change-over Valve is available in two types. Both designs have an improved flow path that minimizes the inlet pressure drop. Type 330 Compact is adapted to pressure drop requirements in basic applications. Type 320 Flow fulfills more demanding pressure drop requirements. In addition, the size of the plant piping on the respective system is no challenge for LESER’s Change-over Valve: Its inlet nozzle can easily be adapted to our customers’ needs.


Challenges: A stable safety valve functioning is crucial for the safety of the plant and the environment. Therefore, the inlet pressure drop should not exceed 3% of the set pressure of the safety valve. Many spare relief valve installations in the market use unstandardized modifications e.g. complex and extensive piping, making the calculation of the inlet pressure drop unreliable. This again threatens the stable safety valve functioning and therefore the safety of the plant.

LESER’s solution: LESER’s Change-over Valve has an optimized flow path ensuring minimal pressure drop. Besides, LESER’s Change-over Valve has a clearly defined resistance coefficient for each configuration, allowing a reliable and precise calculation of the inlet pressure drop. Those resistance coefficients are calculated and optimized via computational fluid dynamics (CFD) simulations and were measured and validated during tests by an independent test lab. It allows for reliable and precise calculation of the inlet pressure drop ensuring stable safety valve functioning. The result: safety and 24/7 availability of the plant.


Challenges: For spare relief valve installations with isolation valves the planning process is extensive and complex, as many pipe components are needed. This makes the whole installation unpredictable in terms of dimensions, possibly resulting in a complex and inefficient planning.

LESER’s solution: Due to the high flexibility of our Change-over Valve, we offer the optimal, scalable solution according to plant needs. With the high degree of standardization, the dimension of each individual solution is precisely predictable. This makes planning of installations and plants significantly easy and more efficient.


Challenges: The typical lockable combinations of Change-over Valves available in the market often have a number of limitations. Some require the same nominal size of the Change-over Valve at the inlet as at the outlet of the safety valve. Therefore, the adaption of different sizes requires unstandardized modifications by using additional reducers, weldings or pipings. The downside to this solution: Overall dimensions of the installations will grow in an unpredictable way. There are no standard solutions for lockable combinations including differently sized Change-over Valves in the market.

LESER’s solution: With our flexible and optimized lockable combination LESER’s Change-over Valves are adaptable to different inlet and outlet sizes of the safety valve. The unique features of our smart coupling like standardized flange distances through different sets of elbows make it easily possible to combine a smaller and bigger sized Change-over Valve also with different pressure ratings if required. Like this, no additional reducers, weldings or pipings are needed. The result: We offer the most economical solution for lockable combinations in the market.

for plant safety and availability

Challenges: Some spare relief valve installations do not guarantee fail-safe operation. Here, it may occur that two safety valves are closed at the same time leaving the pressurized system unprotected. In the case of an impermissible overpressure increase, this would lead to severe damages to the plant personnel, and the surrounding environment.

LESER’s solution: Our Change-over Valve has a simple switch-over for an easy and fail-safe operation. By turning the hand wheel, the disc moves from one site to another on a circular path. Like this, a complete closure of both sides is impossible, always protecting the plant by one safety valve for continuous plant availability.


Challenges: Oftentimes, the spare relief valve installation needs to be available fast or at a certain time in order to ensure reliable installation within the shutdown time. Some solutions in the market only offer delivery times of 20 weeks not always reliably meeting the due date.

LESER’s solution: In line with our reputation for fast and convenient deliveries, we were able to reduce our distribution times for Change-over Valves significantly. By working with high stock levels and individual supply chains, we can supply our Change-over Valves at the same time as our safety valves. You receive one complete, optimized combination from one supplier.


Challenges: In order to ensure that the plant is running continuously and reliably, spare relief valve installations need to ensure proper functioning even under extreme conditions.

LESER’s solution: The durable design keeps the Change-over Valves maintenance-free. This durability was proofed during lifecycle tests with 1.000 changeovers. In addition, the Change-over Valve was tested for various application conditions such as cold or hot media, media with particles and under high operating pressure. This tested design ensures reliable operation at all time.


LESER has subsidiaries in Europe, America, the Middle East and Asia, and further representatives in more than 80 countries. Thanks to our extensive experience and our 100% focus on safety valves, LESER is one of the top companies in its market - the largest producer in Europe and one of the leading companies worldwide. LESER - The Safety Valve Company