What’s the pressure differential across that pump?  It’s simple if we have pressure gauges on the inlet and outlet right?

           Δp = inletPSIG – outletPSIG

Some might say, “hey, I can calculate that in my head.” Sure you can, but why would you want to?  Take these simple readings: 42.12 – 39.87. What’s the difference? Ok, it’s… uh, it’s 2.something, let’s see 2.25? Right. But, why work so hard? Any decent tool for recording observation data for your operational logs should allow you to express these things in a template that will automatically calculate values for you so that you only need to enter the actual source readings/observations.

Going further, the tool you choose should give you one place to setup your equations, and it should work consistently on all the devices you use, whether desktop or mobile

Also, not every calculation is as trivial as a simple difference. So, you definitely need some help getting these right versus doing them in your head. The tool you choose should support more complex calculations, as well as, allowing for complex functions and nested parenthetical grouping.

Here’s a slightly more complex example: calculating salt rejection in reverse osmosis. Let’s say we have a couple of conductivity measures that we’ve converted to total dissolved solids (TDS) values, one of the feedwater (feedTDS) and one of the permeate water (permTDS). In that case. the formula for salt rejection % is:

        saltRejectPct = ((feedTDS-permTDS)/feedTDS)*100

The tool you use should be just that straightforward with regard to expressing your calculation.

And, the tool you choose should allow you to set the expected range for calculated values, just like manually entered values. So, let’s say you want to be alerted if the Salt Rejection percentage is less than 80%, that should be trivial to do.

Finally, the tool you choose should allow annotation of calculated values. There may be a good reason why a calculation is out-of-range, and it sure would be helpful to get that commentary along with the calculated value.

Here’s an example from LogBook, where calculations are easily added to your templates.

Whether you have a reverse osmosis system or not, calculations can be valuable during your inspections, walkdowns or rounds. They help keep operators focused on the important metrics they need to be paying attention to versus fiddling around with a calculator or spreadsheet.

To learn more about how LogBook can be helpful for any type of inspection or recording of operational metrics, check us out at trylogbook.com.