First, let’s DEFINE what we mean when we use the term “remotely operated shutoff valve.” I have come to love the UK’s HSE definition, which is:
A valve DESIGNED, INSTALLED, and MAINTAINED for the primary purpose of achieving rapid isolation of plant items containing hazardous materials in the event of a failure of the primary containment system (including, but not limited to, leaks from pipework, flanges, and pump seals). Closure of the valve can be initiated from a point remote from the valve itself. The valve should be capable of closing and maintaining tight shutoff under foreseeable conditions following such a failure (which may include fire).
Manual valves should never be used when the employee affecting the isolation would be in danger. This is a significant consideration in deciding when to use Remotely Operated Shutoff Valves (ROSOVs). Manual valve isolation may be acceptable when rapid isolation is NOT required to prevent a major accident. However, manual valves are often fitted mainly for maintenance work and are unlikely to be the safest or most effective option for emergency isolation.