As the days get shorter and the nights longer, facilities fire up their boilers for comfort heating. Water treatment professionals will begin their seasonal routine checking programs and products making sure it is viable and re-ordering expired chemicals. As well, pre-startup includes checking and servicing feed pumps, controllers, and probes ensuring all are in good working order and sensors are calibrated.
Treatment Program Monitoring
AquaPhoenix recommends fresh pH buffers, conductivity and Fluorescein dye standards for inline-probe calibration. Use an inline-probe cleaning kit containing brushes, swabs and cleaning solution. Standard solutions which approximate certain control parameters should be used. Look at expiration dates on all solutions which may be left over from last season. Allow enough time to re-stock products if any have expired. Typical standards are: Conductivity = 100, 1000, 1500, 2,000, 2,500 and 3,900µS; pH = 4, 7 and 10; Fluorescein = 10, 50, 100, 250 and 500ppb. Follow the equipment manufacturer’s calibration instructions.
When the boiler is off-line, remove your in-line conductivity probe being used for automatic blowdown control and clean it. Use a mild acidic solution and a city water rinse with a soft brush or cloth removing scale which would create inaccurate readings.
Optimum deaerator operation and performance is critical in preventing severe boiler system corrosion. The oxygen scavenger and Dissolved Oxygen (DO) levels are key performance indicators. A properly cooled sample is key for both sulfite, typically used in low pressure boiler systems, and DO tests. If the sulfite drop test sample is hot, the starch indicator will get cooked and you can’t reach the colored end-point. As a DO sample cools, oxygen absorbs back into solution giving a false-high result. AquaPhoenix recommends using a bottom-up flow through sample vial when testing DO.
Proper care of your sensors and equipment will ensure accurate readings and long probe life. pH meters, probes and electrodes are particularly sensitive. For boiler or condensate tests, ensure the sample is cooled. Rule of thumb, the sample should be comfortable to touch. Most manufacturers recommend a sample temperature of less than 130oF. Use an electrode storage solution when done testing. Do not use DI water as a storage solution because it will permanently damage the electrode.
Test Kit Check
Checking your test kit and gear is critical. After all, good accurate testing leads to good overall program performance. Fresh pH buffer, electrode storage solution, conductivity and Fluorescein dye standards should be at the top of your list. Clean and calibrate pH meters, conductivity instruments and Fluorometers to be certain they function properly. Use an electrode cleaning solution for pH sensors.
Key boiler program reagents are sulfite, phosphate, conductivity neutralizer, filming amine, neutralizing amine, and hardness. The reagent solutions should not be layered or separated and without floaters or precipitated solids.
For drop count tests, order a new reagent bottle or replace the dropper tip. This will insure free flowing, uncontaminated, and calibrated drop sizes. Changing the dropper tips is cheap and easy insurance for good testing.
AquaPhoenix recommends cleaning and checking colorimeter/photometer calibrations. A handheld-device cleaning kit with specially formulated cleaning solution, swabs and brushes is ideal. When cleaning a photometric instrument, use a solution which will not damage the light transfer cell. Glass cleaners, alcohol, or wipes may leave a residue or discolor the inner surfaces of the instrument. Check each wavelength to be certain it is functioning. There are iron, copper, phosphate or molybdenum standards for the DR890, DR900, Pyxis SP900 series, and Lovibond units.
In the fall, anticipate on-coming cold weather. The further north your location means shipping becomes more difficult. Nitrite reagents, pH buffers, and conductivity standards cannot freeze. If this happens, throw them away because they won’t go back into solution.
Finally, check your glassware or plastic-ware. The titration vials should be clean and the calibration lines/numbers visible. If the sample size is off by a slight margin, test results could be off by 10-30%.
So, fall is time to get ready for boiler season. Early preparation is the key to a smooth transition.