Annunciator Bypass Setup
Overview
A unit can be configured to have one or more bypass (on / off bypass) valves that are automatically actuated by the system.
Note that this is different from proportional recycle valves which can gradually recycle gas. For those types of valves see Dual Recycle Setup.
Basic Bypass Setup
To assign an output (and optionally feedback inputs) to use a normal Bypass valve, see Annunciator Valve Setup which talks about the output to valve assignment page. That page is also used to specify if the valve is powered to open or powered to close.
Once an output is assigned to run a bypass, in general the system will open the valve for startup and then close the valve when it is time to load the unit. The exact timings of both depend on a few other settings on the Bypass setup page under Brain -> Outputs Setup -> Bypass Logic.
Settings on this page:
- On panel power up, bypass should be...: Choose the state to have the bypass when the panel powers up
- On normal stop, bypass should be...: Choose the state for the bypass after a normal manual stop
- On fault stop, bypass should be...: Choose the state for the bypass after a fault shutdown
- After load delay, prompt user to load: If set to Yes, then after load delay a button appears in the corner telling the user the unit can be loaded. Selecting the button gives the option to close the bypass. If this setting is set to No, then the bypass will close automatically after load delay.
If the bypass is closed when the unit needs to be started then it will open during startup before pre-lube.
Note that if the bypass is set to close automatically after load delay (the last setting above is set to NO) then the process pressures should have low kills set to 'C' class to make sure the sequence doesn't fault out as the bypass is closing.
