“Open/closed lock valve or open / closed valve car seal” is not a form of valve. It’s a valve’s “health.” A lock or a Car-Seal can be applied to any door.
These apps would be known as an “add-on after-marker.”
A locking mechanism or Car-Seal may be attached to any regular valve (Gate, Globe, Ball, Spark, Needle, Diaphram, Orbit, Butterfly, etc.). Any valve that had these instruments on them, by comparison, can have them withdrawn and then they are just valves.
LO or LC:
Using LO / LC valves is often correlated with health. This system provides a means of ensuring that, during normal operation, all vital manual valves stay in their desired position and are not worked erroneously.
Maintaining such a system requires comprehensive and thorough processes to control valve location and lock maintenance. From my view, a strong safety policy within the company also takes place.
The inlet and exit of Pressure Safety Valves (PSVs) and relief valves would be an example of Locked Open (LO) valves. In addition, these isolation valves on a PSV’s inlet and outlet must remain open throughout normal operation in order to protect the equipment they are installed on.
In normal operation, maloperation / accidental closing of these valves could have catastrophic consequences. Which is why they must be kept in their open position.
An example of a Locked Closed (LC) valve would be in line with the closed drain system for repair. Throughout normal operation, the absorption of flammable hydrocarbons in the maintenance closed drain pipe is risky, therefore the drain line isolation valve must be shut throughout normal operation. This is why they must be kept in their closed position
Locked open / closed means just that, i.e. to open a padlock that is kept secure and opened only against work permits, etc. This appears to be for safety critical valves-for example, insulation valves for pressure relief valves-to keep them open or closed and to stop someone from adjusting the location without permission.