FAQ - Pressure Relief Valve
The trigger/opening action is highly dependent on the pinch valve’s nominal width and the initial/closing pressure. The sensitivity of the trigger/opening action decreases proportionally to the pinch valve’s nominal width. The sensitivity of the trigger/opening action increases proportionally to the initial/closing pressure. Please contact our sales team for details.
In this case, the valve is no longer functional and the defective sleeve must be immediately replaced.
In principle, every air-operated pinch valve can be used as a pressure relief valve. The series VMP air-operated pinch valves are not recommended, however, because their design includes two 0-ring seals, which result in an additional minimal potential leakage.
An AKO pinch valve used as a pressure relief valve offers all of the benefits of a pinch valve. These primarily include its free passage, protection against clogging, ease of maintenance, high service life and low wear and the additional fact that unlike bursting disk valves, for example, the AKO pressure relief valve does not need to be replaced following one-time activity.
The pressure switches primarily allow the operating pressures to be indicated as they rise and fall again. Therefore, 2 pressure switches are ideally recommended. In addition to this, the switching states of the pressure relief valve are electrically monitored.
LV = Air available
LNV = Air not available
The type LV does not include the routine manual repumping of compressed air by the constant compressed air supply. This type is therefore preferable when control air is available.
The additional pressure regulating valves and the permanent air supply with the type LV always keep the pinch valve closing pressure constant. With the type LNV, the compressed air in the pinch valve is stored and must therefore be regularly checked and repumped. The modes of action are otherwise identical. We differentiate as to whether air is available on site (LV) or not available (LNV). The design of the excess pressure unit is based on this.
The pressure switch plays an even more important role for the LNV type because it can additionally be used to signal the pending repumping.
In line with the benefits of the pinch valves, the pressure relief valve can also be used for a large number of media. Its advantages such as free passage, for example, make the pressure relief valve especially suitable when suspensions, contaminated liquids, fibrous media and highly viscous media are used. Please contact our sales department for the most suitable pinch valve specification and excess pressure unit.
A pneumatically activated pinch valve is closed by a predefined closing/control pressure. The predefined closing/control pressure of the pinch valve depends on the desired normal state of your system’s operating pressure. The pinch valve’s pre-defined closing/control pressure can be computed from the operating pressure + 2 - 2.5 x the pinch valve differential pressure. If the operating pressure rises above the normal state, then the pinch valve sleeve starts to open and the undesired excess pressure can escape in the bypass through the opening pinch valve. The pinch valve closes automatically if the operating pressure drops again. The built up units allow the pressures to be read and retain the air in the pinch valve for a specific time period. With AKO pressure relief valves, any desired air-operated pinch valve is combined with a pressure control unit (referred to as an overflow unit).
The maximum operating pressure depends on the pinch valve type. The data on the respective data sheet (3.5 to 6 bar) apply here.
Yes, the pressure relief valves reclose automatically as soon as the excess pressure is relieved and the normal system operating pressure reset.