OC Laboratory

Event Coordinator

Allan Clum
General Manager
Mount Pleasant Water Works

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Questions accepted up until 9/25/2023. Questions can be asked at the pre-competition meeting on Monday, October 2, in Chicago.

Can you provide the Mass Balance Test that was used at WEFTEC 2022?

2022 US Mass Balance Exam

2022 Metric Mass Balance Exam

Will there be any changes to the 2023 Lab Event?YES there will be a minor change.  New Event Description has been published, see above.
I think you’ll enjoy the change and it adds a realistic skill to the challenge – good stuff.
After the target reference sample is calculated and mixed in the volumetric flask the description states
10.Pour volumetric flask into 100ml beaker and measure using meter
11.Measure reference standard using TDS Measurement Procedure listed above
Do we have to label the 100ml beaker, label the volumetric flask, or prerinse the beaker with the reference standard?
Will you account for the TDS of the dilution water used at each competition?The source of the dilution water (if deionized or distilled water is not used) will impact the final concentration of the dilution.  Event coordinators may choose to use tap water to keep the setup simple.  If tap water is used, the head judge will need to account for the TDS in the dilution water to ensure the target concentration is properly adjusted. (i.e. target 500 us/cm + tap water 100 us/cm = meter reading of 600 us/cm)2/2/23

A pipette bulb will be needed for calibration prep, correct? Wasn't listed in new purchase list.

Will there be 3 pipet bulbs one for each pipet?

2 bulbs are listed on the equipment list.  No additional bulb will be provided or added to equipment list.2/9/23
How many Conductivity Calibration Pouches will we have? The supplies list 20/pk.One pouch at start of event.  Additional pouches will be available if needed.2/27/23
With the new conductivity standard process:
1. Will the 100 mL beaker need to be rinsed out with the sample solution we create?
2. When the packet of 12.88mS is used should we dump the remaining amount in the 5000 mL waste beaker and place the package in the trash bin?
3. Should the new 100 mL beaker we are pouring the volumetric flask into, be labeled TDS STD?
4. Will we be filling this 100 mL beaker up to approximately the 100 mL mark?
1.  Rinsing the 100 ml beaker is not identified in the steps and will not be a penalty.  However, rinsing may increase accuracy.

2.  Yes

3.  Please refer to recent procedure update.  Yes, beaker and volumetric need to be labeled – Ref Std

4.  Fill to appropriate level to ensure adequate coverage of the probe.

The 12.88 mS conductivity calibration solution is temperature variable and is referenced at 25C. Are we going to perform the target reference calculations based on room temperature correction or will the judges compensate for the difference in the final reading?

The judges will compensate

Will the pans been pre labeled like past years? Yes3/23/23

Before the changes were made to this year's lab event, the rules stated:

"NOTE: Care should be taken to use fresh standard when calibrating the meter. Using old standard or diluted standard can result in a calibration error. If a calibration error occurs during the competition, move forward with the event steps as noted in the measurement procedure and record error in the result area of the benchsheet."

Now that getting an actual reading to hit the target range on the reference standard is critical to our final time of the run, if we get an "error" while calibrating, would that be cause to stop the event and reset?

The meters will be checked prior to the event.  Proper calibration will be critical for teams. If there is equipment failure during the event the head judge will be responsible for verifying.