If your pH application involves low flow rates and a relatively small pH adjustment (say, under 10 gallons per minute and 0.5 unit change), your best bet would be to find a reliable local water treatment dealer who can test your water, and is willing to guarantee his work. If your job has larger flows or major pH changes, or if it is a wastewater, you need someone like us. This section will talk about some of the key system components we commonly use to solve pH problems.
Perhaps the most critical component in any system is the pH electrode you select. Your system will live or die according to its accuracy. Glass electrodes include specially formulated glass membranes that have been found to be very sensitive to hydrogen ion concentrations. They can detect, with accuracy, concentrations as low as 10-14 gram-ions of hydrogen per liter (pH 14). If that number is converted to more conventional units, it would be the equivalent of 0.01 parts per quadrillion by weight (million, billion, trillion quadrillion….). That’s sensitive, folks! Yet these electrodes are subject to contamination, poisoning, electrical ground loops, temperature fluctuations (up to a 0.8 pH unit variation for water between the freezing point and boiling point), chemical coating, and just plain dirt. Since they are a sensor, they do require maintenance, calibration, cleaning and care. But when they are good, they are very very good, and the right pH electrode will be crucial to your system’s performance. After a thorough search, we have chosen to partner with Sensorex, a quality electrode manufacturer. Our experience tells us that they’ll do right by you.
A second principal component would of course be the pH controller you choose. Today’s electronic controllers combine monitor and control functions, and they are really quite sophisticated. The menus programmed into them allow you to customize their operation to match your particular application. In a number of ways these controllers, once they are calibrated and correctly programmed, will be the least problematic of your system components. As a general rule, once electronic controls are up and running, they will keep doing so for a long time. We are a representative and master stocking distributor for the Liquid Metronics, or LMI, line of controllers and pumps. More stuff that works.
One or more chemical feed pumps will be the next most likely component for your system. These pumps will typically feed either acid or caustic, or both, to control your water’s pH. As with electrodes, selecting the right pump requires some care and informed decision-making (see Basic Chemical Pump Questions, Basic pH System Questions, and Jar Testing Made Easy). Electronic pumps, in particular, can be quite reliable. They can also be very flexible in their application. Once you have done some research, provided the basic information, and made a few choices, we’d be happy to help you select the appropriate equipment for your job.
There are a number of pieces of accessory equipment that you will need to pull your components together to make a complete system. Small items include cabling for your electrode and pump, tubing, pump mounting accessories, a pump calibration cylinder, specialty valves such as for back pressure or pressure relief, buffer solutions, a pH simulator, mixers, a flowmeter, chemical tanks, plumbing, etc. Larger items might include a Programmed Logic Controller (PLC), a Proportional Integrated Derivative (PID) control, or a skid-mounted package system.