I would like to ask the experts here; I don’t understand the valve control logic shown in the drawings. Please give me some guidance!
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It’s my first post – were the images added? In this data sheet, what is the emergency state of the emergency shut-off valve when there is a loss of air or power supply? What exactly is that emergency state?
It is a double-acting piston actuator; the valve position remains locked in the event of an air supply failure, and it remains locked as well in the event of a power supply failure. The operating mode is normally open, with the solenoid valve remaining energized continuously.
It’s open during normal operation; so in an emergency situation, it should be closed, right? What is the landlord trying to say?
Thank you for the reply! Please check the air source fault indicator and solenoid valve power loss indicator in the data table. How to achieve it?
An emergency situation refers to an emergency in production. The isolation valve is activated through the interlock system to carry out emergency intervention in the production process. In the event of a fault in the air supply for the shut-off valve or a loss of power to the solenoid valve, the shut-off valve remains in a certain position. It refers to the state of the valve when the air supply is lost. An emergency state and a fault state of the shut-off valve are two different concepts.
Thank you for the reply! The solenoid valve in the data sheet is designed for continuous excitation; the valve is normally open, and the actuator is of double-acting type. Note that the solenoid valve is a two-position three-way valve. In other words, when the solenoid valve is powered, it controls the air supply and the valve opens. So how do you close the valve? Is it necessary to cut off power to the solenoid valve in order to close the valve in the air circuit? What is the state of a power supply failure? Is it also a situation of no power supply? The data sheet specifies that it should be in a locked state – how can one distinguish between an electromagnetic valve losing power and a power supply failure?
It seems there is a problem with this specification sheet; a single two-position three-way solenoid valve cannot enable two-way control of the valve’s opening and closing.
Note that in the event of a air supply failure, the pneumatic cut-off valve remains in a locked state, rather than being closed.
In my opinion, the reason for choosing two three-way solenoid valves is to lock the valve in place. 1. The operation of a double-acting cylinder requires a change in the air supply direction. Under normal conditions, air enters one cylinder while it exits from another; in the diagram, the on/off state of the coil is used to change the operation of the solenoid valve, thereby determining which cylinder receives the air supply and thus enabling the opening and closing of the valve ； 2. Under the conditions of 1, in the event of a loss of air or power supply, the valve cylinder and solenoid valve remain in a closed state, thereby keeping the valve position locked ； I’m not sure if this understanding is correct; I hope my colleagues can offer some guidance.