akreel
Member
Many of you have experienced this before. Operators tend to get into a rut. If somebody posts a handy little cheat-sheet on how to operate a piece of equipment, the operators will follow it without ever wondering why.
I am currently working on an upgrade project at a local waste water plant (the OTHER one you people from Wisconsin are thinking of). While investigating a panel that I'd like to demolish, I found a signal converter: 4-20mA --> pulse. The pulse output is an input (plant flow) to a sampler (a solenoid-operated device that grabs a few mL of water and dumps it into a jug). On the sampler itself there is a manual mode and two automatic modes, time based or flow based.
There is a cheat-sheet on the sampler, explaining how many pulses to set the counter for at various levels of plant flow. I found this odd, because I thought a "flow based" sample should be based on a fixed number of pulses (X pulses per gallon). After looking closer at the chart, I found something even more interesting. For each doubling of plant flow, the pulse count was doubled. The chart converts flow pacing back to time based sampling!
Why would this be done? My best guess is, someone didn't like finding the gallon bucket overflowing and created a cheat-sheet to control the number of samples per day.
I am currently working on an upgrade project at a local waste water plant (the OTHER one you people from Wisconsin are thinking of). While investigating a panel that I'd like to demolish, I found a signal converter: 4-20mA --> pulse. The pulse output is an input (plant flow) to a sampler (a solenoid-operated device that grabs a few mL of water and dumps it into a jug). On the sampler itself there is a manual mode and two automatic modes, time based or flow based.
There is a cheat-sheet on the sampler, explaining how many pulses to set the counter for at various levels of plant flow. I found this odd, because I thought a "flow based" sample should be based on a fixed number of pulses (X pulses per gallon). After looking closer at the chart, I found something even more interesting. For each doubling of plant flow, the pulse count was doubled. The chart converts flow pacing back to time based sampling!
Why would this be done? My best guess is, someone didn't like finding the gallon bucket overflowing and created a cheat-sheet to control the number of samples per day.
