FAILSAFE is a much abused word. It is very dramatic because it combines the apparently contradictory concepts of failure and safety in a single word. The reality is not so dramatic. It means that GATE VALVESthe failure of a component is unlikely to cause any harm. The formal definition I prefer is:A FAILSAFE design is GLOBE VALVEone in which the most probable failure mode results in the most probably safe condition." 1. Failsafe is without meaning and content if not discribed exactly together with what to fail and what to happen. 2. Other failures present or happening together with main failure and not described are normally not taken into account. 3. Most commonly for valves is the requirement 'failsafe closed' (or open), requiring that the valve is actuated by an actuator and the actuator has a stored force to close the valve if the valve is open and power fails. Normally this will be interpreted to mean a pneumatic actuator with spring return, but could of course be other devices and variations. A pneumatic actuator with spring return will close with: a) Failure of SAFETY VALVES electrical current, but only if the solenoid valve is of type 'normally closed without current' and NOTE! the solenoid valve is connected to the actuators working air inlet/exhaust port to give this effect! b) Will close also if air pressure fails together with electrical current or air pressure fails alone. In the last case to further ensure closere solenoid valve should be operated to closed position to evcuate air from working chamber in the actuator (if nescessary). 5. You are with thisPLUG VALVES and the above comments left with the questions you usually have to place to clarify unclear product specifications: - Total process and fluid description - What standards to apply - If outside any standard please describe exact requirements and how to qualify. - How will products be tested and by whoom after installment? 6. If the MUD VALVESinquirer can not answer, you can although bid with your own interpretation and answering the questions within what you can supply. Be sure to put limitations to your bid, for instance: as described in our data sheets only, no certifications or verifying tests available. Process tests after agreement in writing before order acceptance only - or similar as suitable.

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