pHACIDITY / ALKALINITY
Describes the acidity or alkalinity of the sample.
Read it correctly
pH is not a chlorine concentration or a purity measurement.
MEASUREMENT & CONTROLpH, FAC & ORP
pH, FAC & ORP
in HOCl generation.
Compare measurement options and define the monitoring included in your generator proposal.
Read each value
for what it measures.
Keep the measured quantity, reporting basis and units together when comparing results.
FACFREE AVAILABLE CHLORINE
Free available chlorine, measured by a defined method.
Read it correctly
Usually reported as mg/L as Cl₂. Free chlorine and total chlorine are different measurements.
ORPOXIDATION-REDUCTION POTENTIAL
The potential measured by an electrode system, reported in mV.
Read it correctly
ORP depends on the sample chemistry and electrode system. It cannot be converted universally into FAC.
Match the method
to the sample.
Choose a measurement system for the sample you will test, not simply for the number you want to display.
A method suited to a low-concentration use point may not cover the generated solution directly.
Measured parameter
Confirm that the method measures free chlorine when FAC is the required result.
Working range
Check the range against the expected sample concentration, including relevant operating variation.
Sample conditions
Review method limitations and any required sample preparation with the instrument documentation.
Routine supplies
Confirm reagents, standards or other consumables, where applicable, and their local availability.
Compare results
on the same basis.
Before comparing two readings, check that the records describe comparable samples and methods.
What a useful measurement record identifies
- Sample identification
- Where and when the sample was collected.
- Method & instrument
- The test method, instrument and working range.
- Result & reporting basis
- The measured quantity, units and any applicable preparation factor.
- Relevant conditions
- Temperature, pH or other conditions needed to interpret that result.
If results differ, compare these details before concluding that the generator output has changed.
Look beyond the display.
Review which operating records and protective functions belong to your proposed configuration.
Operating records
Review the recorded fields available in your proposed interface and how your team will use the operating history and exported data.
Equipment protection
Confirm which alarms and protective shutdown functions are provided for water shortage, feed depletion and a full tank on the selected equipment.
A few important distinctions.
Can a pH/ORP display replace a FAC test?
No. Use a method appropriate to free available chlorine when FAC is the required measurement.
Is ORP a universal chlorine-concentration converter?
No. ORP depends on the electrode system and sample chemistry; there is no universal mV-to-FAC conversion.
Does an online reading mean automatic adjustment?
No. Monitoring, alarms, recording and feedback control are separate functions to specify in the proposed package.
Define the monitoring
your project needs.
Start with your application, expected sample range and reporting needs. We can discuss the measurement and control options.