Don’t alarm what you won’t act on

Spent last night babysitting an alarm flood on a feed pump start. HMI lit up like a pinball machine: low suction pressure, seal pot low, motor overload warm, min-flow not proven, discharge low-flow… Operators were riding ACK like it was a solution. Well, there’s your problem: five alarms screaming about one condition - no NPSH at cold start.

The fix wasn’t more alarms. We added permissives: no start unless tank level > X, suction block proved open, min-flow valve open limit made, and VFD ramp extended. We pushed the “low suction pressure” nag down to an event during start sequence, kept a single high-value trip to protect equipment, and tightened the min-flow recycle control. Net result: zero nuisance, zero cavitation, no heroics.

My rule: if it needs immediate operator action, alarm. If it can damage equipment or violate process limits, interlock it. If it’s just FYI, log it. Five ways to say the same thing is noise.

How do you draw the line between alarm, event, and hard interlock on rotating equipment starts? Any favorite permissives you won’t go without?