Myron L DS Meter

Facilities, HVAC, process steam

Boilers and cooling towers concentrate dissolved minerals as water boils off or evaporates, and past a certain point that causes either scale or corrosion. Myron L notes that as little as 1/8 in. of scale can cost a boiler 18% of its efficiency and a cooling-tower heat exchanger 40%. Conductivity or TDS tracks the cycles of concentration so blowdown and bleed-off happen at the right moment — enough to protect the plant, not so much that water and treatment chemicals are wasted.

Measured here: Conductivity / TDS, pH, ORP, temperature, LSI

Electronics manufacturing

Ionic residue left on a finished board degrades insulation resistance and dielectric strength. Rather than send boards to a lab, the board is rinsed in a measured volume of extract solution — 75 parts by volume of 99% isopropyl alcohol to 25 parts deionised water — and the conductivity of that extract is read directly, giving a fast production-floor check of ionic contamination historically benchmarked against MIL-P-28809. The mixture must itself read no more than 0.166 µS/cm before use, or the result means nothing.

Measured here: Conductivity, resistivity

Laboratory, pharmaceutical, electronics, plating

Ion-exchange resin strips cations and anions from water until its exchange capacity is spent. Because the purity of DI water is defined by what little remains dissolved in it, resistivity is the natural measurement — it climbs as purity rises and falls sharply as a bed exhausts. Monitoring resistivity continuously is what tells you to regenerate or swap a bed before off-spec water reaches the process.

Measured here: Resistivity, conductivity / TDS

Wastewater, stormwater, surface water

Discharge to waterways, to municipal sewers and increasingly stormwater runoff all sit under permit limits, and demonstrating compliance means measuring at many points rather than one. Conductivity, pH, ORP, dissolved oxygen and nitrate together characterise both the health of a receiving water and the quality of an effluent, and handheld instruments make it practical to sample where the water actually is.

Measured here: Conductivity / TDS, pH, ORP, dissolved oxygen, nitrate, temperature

Commercial printing

In lithography the dampening (fountain) solution has to be held at the right concentration: too weak and the non-image area dries out, giving tinting, scumming and blanket piling; too strong and the ink over-emulsifies, weakening colour and changing its body and flow. pH was the traditional test, but most modern fountain solutions are buffered, so pH barely moves even when strength changes a lot. Conductivity tracks concentration directly and is now the more reliable control.

Measured here: Conductivity, temperature, pH

Nurseries, greenhouses, turf, irrigation

Three on-site tests tell a grower most of what a lab would: electrical conductivity, pH and alkalinity. EC reads the total dissolved fertiliser salts, so it shows whether feed strength and soil salinity are where they should be; pH governs whether those nutrients are actually available to the plant; and alkalinity determines how strongly the irrigation water will push the growing medium’s pH over time.

Measured here: Conductivity / EC, pH, alkalinity, temperature

Controlled-environment agriculture

With no soil to buffer it, the nutrient solution is the entire root environment, and managing it is the whole job. Conductivity gives the dissolved nutrient strength and pH governs which of the seventeen required elements the roots can actually take up. Both drift as plants feed and as water evaporates, so they are checked and corrected far more often than in soil growing.

Measured here: Conductivity / TDS, pH, temperature, dissolved oxygen

Desalination, industrial, medical, drinking water

Conductivity is the standard way to judge RO water quality and membrane performance, because comparing feed against permeate gives percent rejection directly. ORP and pH matter for membrane life rather than product quality: membranes are attacked by oxidisers such as chlorine, bromine, ozone and peroxide, so a high ORP signals a need for pretreatment while a low one can indicate biological activity and fouling. Reading ORP on the reject stream, where concentration is highest, shows even trace oxidisers or reducers.

Measured here: Conductivity / TDS, resistivity, ORP, pH, temperature

Wet processing, dyeing, finishing

Wet spinning, sizing, desizing, scouring, bleaching, mercerisation, dyeing and printing all depend on aqueous chemistry, and pH is the primary control in every one of them — it governs how effectively oxidising and reducing agents work and how dye takes up. Holding pH, conductivity or salt concentration, ORP and temperature to target conserves chemicals and energy, keeps shade and quality consistent, and reduces the effluent load that has to be treated before discharge.

Measured here: pH, conductivity / TDS / salt concentration, ORP, temperature