Remote actuation capability is important because the initial release of hazardous aterial can occur without a fire. If hazardous material is released, the operator may find it difficult to enter the area safely to isolate and shut down the equipment. Conversely, with remote actuation, the operator can isolate the equipment from a safe location.
Locate pushbuttons a minimum of 50 feet from the actuator and valve and outside the fire-hazardous area zone.
Placing a protective shroud over the stop pushbutton helps to prevent accidental activation.
In the field, make pushbuttons easily visible and label them clearly and permanently (white letters on a red background) with a sign or nameplate.
In panels and consoles, arrange all pushbuttons or switches carefully to avoid operator confusion. Operators, under the stress of an emergency situation, may shut down the wrong equipment if shutdown switches, for different process units or equipment, look the same and are grouped together. Physically separate the shutdown switches and label their functions boldly.
For maintenance safety, make sure pushbuttons can be locked in the de-energized position.
If pushbuttons are part of an automatic shutdown system, the action which they initiate should latch the system so that the EBV does not return to its original position when the pushbutton is released.
The capability to actuate electric motors may be required both on the electric motor actuators and from at least one set of remote pushbuttons. The remote pushbuttons must be able to override the local pushbuttons on the motor. The location of the remote open, close, and stop pushbuttons will vary with design requirements. These pushbuttons may be required in the plant, in the control house, or at both locations.
The open and close pushbuttons for electric motors should require two actions to activate, such as pushing in and turning to the maintained position. Activating the stop pushbutton should require only the push action. Consider installing a protective shroud over the stop pushbutton to prevent accidental activation.