Valve design modification

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The built-in drain devices designed and supplied by conventional steam turbine manufacturers are air-operated valves; when the pressure of the compressed air supply or the power supply is lost, all of these built-in pneumatic drain valves will open automatically. The solenoid valve should be turned off while in normal operation. But I think it might be fine for solenoid valves to remain powered for short periods of time, as there are many of them; however, operating them under power for extended periods is unsafe. Their service life is reduced when they remain powered continuously. Even if their quality is high, the working environment and temperature around these valves remain harsh. Therefore, I think it would be better to change the valve type to one that closes when air is supplied and opens when air is lost, and closes when power is lost. (The pneumatic drain valve’s air supply control solenoid coil cuts off the air supply when energized, thereby releasing the pressure in the cylinder and restoring the valve to its normally open state.) When the unit loses load, if there is no pressure in the air supply used for instruments, this mechanism ensures that the drain valve can open. The power distribution cabinet is equipped with two power sources, along with power monitoring and alarm functions, thus providing redundancy and reducing the likelihood of power outages. There is also an issue with the original design: if the solenoid valve of the main steam drain valve fails or gets damaged under full load, the valve may open suddenly. Drain valves typically open under low load conditions, when pressure and temperature levels are low; however, if a drain valve opens accidentally under full load, the potential hazards are significant, in my opinion ； It disrupts the vacuum in the condenser, posing a threat to and testing the materials of the drain pipes and the condenser itself. The normal operation of the system involves increasing the load from low to full capacity; at low loads, all drain valves must be open. Any valves that cannot be opened due to power issues are excluded from use. The chance of a trip occurring after all valves are closed when the load exceeds 20% is very low. At low loads, when the load is below 20%, the drain valves open automatically. If there are still some drain valves that have not opened, they can be opened manually. The worst that can happen is that both power supplies in the power cabinet fail simultaneously, but this generally does not occur; if it does, it represents a serious accident, as not only will the drain valves not function properly. Based on my analysis, it is either a body-type valve or a air-operated valve; the latter can open when air is lost and close when power is lost, which is more reliable. I would appreciate it if experts could offer their opinions, provide support, or discuss the feasibility of this plan. Thank you! I would appreciate it if experts could offer their opinions, provide support, or discuss the feasibility of this plan. Thank you!