Technical field report

As a rule, flow diagrams are being prepared by planning companies, which then result in 3D system planning in further process steps. During the implementation phase, plant engineers/installation companies follow these plans and the valves are installed accordingly. Often, space conditions and application processes determine the location and installation position of the valves and pressure regulators. As a result, they are installed in a wide variety of positions in the production facilities.

Pressure regulators for inerting and tank blanketing regulate pressures in the millibar range. The corresponding tank protection systems, which consist of several different valves and stages, are defined to each other in terms of pressure. Depending on the vessel design, the individual pressure settings are very close to each other. Therefore, any overlapping of the set pressures of the respective tank protection components should be considered with caution! In addition to a massively increased inert gas consumption, other undesirable effects could also occur. These include, among others, the excessive activation of vent valves or the unintended operation of rupture disks. The following statement can always be considered: The closer the individual set points of a tank protection system are to each other, the more sensitive the system operates and the faster the individual components react. This must also be considered in relation to the installation location (indoors vs. outdoors). External temperature influences can already be responsible for changes in the pressure level within the vessel! This pressure change can then activate the components. The minimum bracing between the two set points shall be at least 15 mbar. If nitrogen shall be saved, and thus product loss, is to be minimized, the two set values should be selected further apart. This prevents nitrogen flow even due to small temperature fluctuations.

The pressure regulators are preset by the manufacturer to a fixed set pressure or already sealed. Despite this, the aforementioned problems occur in the systems. But what exactly is the reason for this? This is primarily due to their design, which allows them to regulate pressures in the millibar range. The set pressure is adjusted by using the set spring in the pressure regulator. This adjustment is made at the factory and the valve is then installed in the plant. If the installation position in the pipeline deviates from the test configuration at the manufacturer's test bench, the set pressure changes. It is important to note in this context that the installation position refers to the positioning of the diaphragm. A different installation position can lead to a pressure change of up to approximately 10-15 millibars. Depending on the design of the tank protection components, this pressure change can lead to the problems in the systems described above.

Correct adjustment and testing is an elementary part in the production of low-pressure regulators! In this case, correct adjustment also refers in particular to the correct or intended installation position in the production plant. At Zuercher Technik, each valve is individually adjusted and tested. This ensures that the pressure regulators also work acc. to the intended pressure during operation. Therefore, the installation position of the pressure regulator must always be specified in the respective order! The problem of unintentional overlapping of set pressures with other system components is avoided and solved.