5 replies to this topic

[Lyne]

Hello everyone,

Please why we should not use motor operated valves in ESD application? Is it related to the safe fail position?

Thank you

Edited by Lyne, 25 April 2024 - 11:42 PM.

[breizh]

Hi,

Probably because the power supply is not reliable. 

What is the frequency of power outage at your location?

Check for standard in your area or local regulation.

Breizh 

[Lyne]

It's a probable scenario that we provide an emergency power generation utility, what I'm confused about it is the fail safe position of MOV, could it be achieved in case of a power failure by using a spring return? I checked many company standards where they don't allow the use of MOV in an ESD application but without mentioning the reason behind it

[seuenergy]

My think is that the possible reason behind this could be the combination of safety and reliability. IA driven system seems more safer and reliable than electrical system. 

[Pilesar]

Emergency shutdown devices (ESD) must fail so as to leave the process in a safe condition. Motor operated valves fail in a way that the valve does not move from its current position. A spring return does not change the position of a motor operated valve. ESD should not require any outside force to operate. It is the outside force on the ESD that prevents it from activating.

[fallah]

Hello everyone,

Please why we should not use motor operated valves in ESD application? Is it related to the safe fail position?

Thank you

 

Hi,

 

Motor operated valve (MOV) is an ordinary ball valve or any other type of valve that operated by an electric actuator. In general, the MOV is used as isolation valve in big lines sizes for equipment which requires regular access. The MOV is also used on any valve that the total energy required to open or close the valve manually is large. No specific reason regarding why MOV is used except from ease of operation standpoint.

 

On the other hand, the valves used in ESD and safety applications, SDV and ESDV, are inactive but energized in normal operation and will be activated in emergency condition if they would be deenergized; while the MOVs are to be active and energized in normal operation hence cannot be applied in safety applications because not to follow the above mentioned rule for ESDV/SDV.