When any of the required conditions is not satisfied the sounder on the panel will make an annoying noise and both solenoid valves will close. The audible alarm may be silenced by a toggle switch on the panel. Be certain to return it to the ``on'' position as soon as the fault is cleared.
The most confusing, but most common alarm condition is ``Low Pressure''. The solenoid valves will not remain open unless there is already ample pressure on the output side of both valves. This prevents us from flowing, for example, pure ethane to the drift chambers when the argon bottle is empty. The way to clear this condition is to make sure there are no other faults and that both argon and ethane manifolds are properly pressurized and fitted with non-empty bottles; then press and hold the ``override'' button for several seconds. This button forces the solenoid valves to open even if there are fault conditions present. If all is well, gas will flow through the valves and clear the ``low pressure'' condition so that the button many be released.