Water Hardness Analyzer BC300 A dosing pump meters reagent into the sample, a photometric cell detects the reaction end point, and hardness is calculated from the volume added and reported as CaCO₃. Seven reagents split the range into intervals from 0.21–2.14 to 53.4–534.0 mg/L — pick the one that covers the control band of the water you monitor.
Hardness is not a parameter where "a rough idea" will do. Softener breakthrough, boiler feedwater excursions and cooling-water scaling usually happen inside the weekly sampling interval of a laboratory. The value of an online hardness analyzer is not a more accurate reading — it is cutting "how often you find out" from a week down to one measuring cycle.
Parameters quoted from the BC300 specification page of Bebur's Water Hardness Analyzer brochure. Supply parameters follow the order-specific technical agreement and factory calibration certificate.
Interface illustration only — not live field data.
Hardness is the sum of calcium and magnesium — yet standards write it in different ways
Total hardness is the combined content of calcium and magnesium ions. China's drinking water standard expresses it as calcium carbonate (CaCO₃) in mg/L; the industrial boiler water standard uses mmol/L. The same hardness therefore reads 450 mg/L in one document and 0.030 mmol/L in another — a factor of 50 apart. The first task in online monitoring is not choosing an instrument, but pinning down the unit and the basis for judgement.
Hardness is not directly a toxicity issue, but it decides three things: whether scale forms, whether soap will foam, and when a softener breaks through. In industrial service the most immediate consequence of excess hardness is a calcium carbonate layer on heat-transfer surfaces — every additional 1 mm of scale cuts heat transfer enough to show up plainly in the energy bill; in a boiler it also means local overheating of the heating surface and a higher risk of tube corrosion. That is why boiler water standards are far stricter on make-up hardness than drinking water standards.
| Application | Standard | Hardness requirement | Unit basis and recommended range |
|---|---|---|---|
| Drinking water | GB 5749-2022, Standards for drinking water quality | ≤ 450 mg/L | As CaCO₃; mandatory national standard. 450 mg/L falls in T07 (53.4–534.0) |
| Steam boiler · make-up water, external treatment | GB/T 1576-2018, Water quality for industrial boilers | ≤ 0.030 mmol/L | ≈ 1.5 mg/L; falls in T02 (0.005–0.053 mmol/L) |
| Steam boiler · feedwater, internal treatment | GB/T 1576-2018, Water quality for industrial boilers | ≤ 4 mmol/L | ≈ 200 mg/L; falls in T06 (26.7–267.0) |
| Hot-water boiler · external treatment | GB/T 1576-2018, Water quality for industrial boilers | ≤ 0.6 mmol/L | ≈ 30 mg/L; falls in T04 (5.34–53.4) |
| Cooling water / CDU make-up | No mandatory national limit | By process control | Set by the equipment vendor and cycles of concentration; choose the range from the actual band |
Conversion basis: 1 mmol/L hardness (as CaCO₃ equivalent) = 50.04 mg/L. Values marked "≈" are conversions for reference only; formal judgement should use the unit specified in the standard.
Titrimetric colorimetry, in essence, replaces a pair of hands in the lab with photometric detection
The BC300 follows the titrimetric colorimetric route: a dosing pump meters reagent into the sample on a set programme, the reagent reacts with calcium and magnesium ions and the colour of the solution changes; a photometric sensor tracks absorbance until the reaction end point is reached; the controller then calculates hardness from the volume of reagent already added. It belongs to the same complexometric titration family as the EDTA disodium titration in GB/T 5750.4-2023, with the end point judged photometrically and the dose controlled by a pump.
Sample enters the reaction cell
At the set interval, sample is drawn into the reaction cell and the line is flushed with sample first, so residual volume from the previous cycle cannot dilute this reading.
Dosing pump meters reagent
The dosing pump delivers reagent into the sample under programme control; the dose is governed by pump stroke and frequency, and that volume is the basis for the later calculation.
Complexation and colour development
The reagent complexes with calcium and magnesium while the indicator shows a wine-red colour. Colour intensity corresponds to the total calcium and magnesium still to be consumed.
Photometric end point
The photometric unit monitors absorbance continuously; the point of abrupt colour change is the end point. Detection is not subject to the subjective differences of matching a colour chart by eye.
Calculate and display
The controller converts the accumulated reagent volume into a hardness value, shows it on the 7-inch touch screen, logs it and sends it to the host system.
Why the colour changes at the end point
The complex formed between the indicator and calcium/magnesium is less stable than the complex formed with the reagent. As reagent is added, it first takes the free calcium and magnesium in solution; past the equivalence point it also takes the calcium and magnesium bound to the indicator, which then returns to its own colour — that is the "wine red to pure blue" moment of a visual titration.
What each of the three common methods can and cannot do
Instruments marketed as "online hardness analyzers" do not share one principle. Knowing which class a unit belongs to matters more than comparing accuracy figures.
| Method | Principle and basis | Where it fits | Limitations |
|---|---|---|---|
| Titrimetric colorimetric used by BC300 |
Metering pump doses reagent, photometric detection of the end point; same complexometric titration family as the EDTA disodium method in GB/T 5750.4-2023 | Drinking water, boiler water, cooling water, food and beverage and medical water — anywhere the result must be comparable with the laboratory | Requires reagent; discrete measurement (5 min minimum); reagent must be replaced on schedule |
| Photometric colorimetry | Indicator develops colour, absorbance is read and converted via a calibration curve | Raw and process water with high or widely varying hardness, trend monitoring | High concentrations need dilution; colour and turbidity directly bias the reading |
| Ion-selective electrode (ISE) | Potential response of a calcium or combined calcium/magnesium electrode | Continuous trend monitoring where reagent-free maintenance is required | Weak stability at low concentrations, frequent calibration; interference from coexisting ions |
Selection tip: if hardness results must line up with third-party laboratory reports, choose a titrimetric method; if only the trend of "over or under limit" matters, colorimetric and ISE units are adequate. Write the method into the procurement technical agreement, so a mismatch in basis does not surface only at acceptance.
BC300 technical data
The table below is taken from the BC300 specification table in Bebur's Hardness Analyzer brochure. The range is not a single figure: the instrument covers 0.21–534.0 mg/L overall, while the usable interval is set by the reagent range selected — see the next table.
| Parameter | BC300 | Selection note |
|---|---|---|
| Measuring principle | Titrimetric colorimetric | Dosing pump adds reagent, photometric end point |
| Measuring range | 0.21–534.0 mg/L (ppm) CaCO₃ | Segmented across seven reagent ranges |
| Accuracy | ±5 % FS | FS = full scale, not reading |
| Repeatability | ±5 % FS | Same basis, referred to the full scale of the range in use |
| Measuring interval | 5 min minimum, several options | Shorter intervals consume reagent faster |
| Display | 7-inch LCD touch screen | History curves and alarms on screen |
| Dimensions | 300 × 300 × 180 mm | Leave room for reagent replacement |
| Weight | 4 kg | Check wall or cabinet load capacity |
| Temperature range | 5–45 °C | Hot samples need temperature conditioning |
| Humidity range | 20 %–95 %, indoor | Outdoor siting needs a protective cabinet |
| Pressure range | 0.2–2 bar | Above 2 bar, reduce pressure before the cell |
| Protection class | IP54 | Dust and splash protected, not for wash-down areas |
| Communication | Modbus RS485 | Optional WiFi / 4G wireless |
| Analog output | 0/4–20 mA | Confirm the scaling expected by the host device |
| Digital input | 1 channel | For external triggering or status capture |
| Digital output | 2 channels | Available as alarm or interlock contacts |
| Data storage | More than 1,000,000 records (32 G) | At 5-minute intervals, coverage far exceeds 10 years |
Note: accuracy and repeatability are referred to full scale (FS). On the T01 range (0.21–2.14 mg/L), ±5 % FS is about ±0.11 mg/L; on the T07 range (53.4–534.0 mg/L) it is about ±27 mg/L. When judging a tight limit, select the range that sits closest to that limit.
Seven reagents that split the range
One BC300 covers different concentration intervals by changing reagent range. The brochure already gives all four unit columns side by side, so values can be checked directly against the standard text without conversion on site.
| Reagent | mg/L | °dH | °f | mmol/L |
|---|---|---|---|---|
| T01 | 0.21–2.14 | 0.012–0.12 | 0.021–0.214 | 0.002–0.021 |
| T02 | 0.53–5.34 | 0.03–0.3 | 0.053–0.534 | 0.005–0.053 |
| T03 | 1.60–16.0 | 0.09–0.9 | 0.160–1.602 | 0.016–0.160 |
| T04 | 5.34–53.4 | 0.3–3.0 | 0.534–5.340 | 0.053–0.534 |
| T05 | 16.02–160.2 | 0.9–9.0 | 1.602–16.02 | 0.160–1.602 |
| T06 | 26.7–267.0 | 1.5–15 | 2.670–26.70 | 0.267–2.670 |
| T07 | 53.4–534.0 | 3.0–30 | 5.340–53.40 | 0.534–5.340 |
Reagent codes are WAR-Hardness-300T01 through T07 and are used with the BC300 controller. The mg/L column is expressed as CaCO₃; values are taken from the reagent information table in the brochure. Once a range is selected, the alarm threshold must sit inside that range, otherwise an over-limit condition can occur without being measurable.
Range selection example: the limit for steam boiler make-up water with external treatment is 0.030 mmol/L (about 1.5 mg/L). The upper limit of T01, 0.021 mmol/L, does not cover it, so T02 (0.005–0.053 mmol/L) is the right range. Selecting T03 or higher puts the limit below the lower end of the range, and the reading loses any discriminating value.
One hardness value, six ways to write it
Hardness is expressed differently across standards and industries. Enter any one value and the others update instantly, along with a note on which BC300 reagent range that value falls into. The conversion factors are fixed and can be used directly to check figures in technical agreements and acceptance sheets.
Reference: the total hardness limit in GB 5749-2022 is 450 mg/L (as CaCO₃), equal to 8.99 mmol/L or 25.2 °dH, which falls inside the BC300 T07 range (53.4–534.0 mg/L).
Six places that genuinely need continuous hardness readings
Whether continuous monitoring pays off depends on the cost of an excursion and the delay before anyone notices it. What these applications share: once hardness breaks through, the consequences start accumulating within hours, while manual sampling intervals are typically a day to a week.
Drinking water and municipal supply
Hardness at the plant outlet and at the network extremities affects taste, scaling in pipes and the load on downstream softening. The T07 range covers the 450 mg/L limit of GB 5749-2022, so readings can be checked directly against published water quality reports.
Boiler water and softener outlet
The limit for make-up water with external treatment is 0.030 mmol/L (about 1.5 mg/L), which calls for the T02 range. Put the sampling point after the softener and before the deaerator, on a stable flow section, so breakthrough shows up within the next measuring interval.
Cooling towers and cycles of concentration
Hardness rises with cycles of concentration and is a direct basis for judging scaling risk and blowdown timing. Used together with conductivity and pH, it describes the stability index of the water far more accurately.
CDU make-up and secondary loop water in liquid cooling
Cold-plate channels are narrow, so a calcium carbonate layer is amplified in both heat transfer and flow resistance. Make-up hardness is a must-test item when qualifying a make-up water source, and belongs to the cooling water monitoring family.
Food and beverage process water
Hardness affects formulation stability, taste and cleaning performance. Online readings serve as continuous evidence for compliance and process adjustment, not just a post-shift grab sample record.
Medical facility water
Cleaning and disinfection, laboratory work and haemodialysis all set explicit hardness requirements. Online monitoring documents continuity of water quality and reduces reliance on a single sample.
Most field deviation comes from sampling, not from the instrument
The same instrument can differ by a factor of two between two sampling arrangements of the same water. The items below are the ones most often overlooked during commissioning, and the easiest to correct.
| Interference | Effect on the reading | Engineering remedy |
|---|---|---|
| Turbidity and colour | Scattered light shifts the photometric baseline, so the end point comes early or late | Add filtration ahead of the cell; sample downstream of the filter |
| Iron, manganese, copper, zinc | Compete with the indicator for complexation, smearing the end point or inflating the reading | Add a masking agent; for water high in iron, sample after iron removal |
| pH excursion | Strong acid or alkali weakens buffering and shifts the indicator's colour-change range | Match the reagent dose setting to the alkalinity of the sample |
| Sample temperature | Affects reaction rate and the sharpness of the colour change | Keep within 5–45 °C; cool hot samples first |
| Air bubbles and flow loss | An inaccurate sample volume produces a direct proportional error | Use overflow sampling; avoid high points that trap air and dead legs in the line |
| Phosphate, silicate | In chemically dosed boiler samples these may precipitate with calcium and consume titrant | Adjust the sampling point or method around the dosing regime; cross-check with another method if needed |
Pre-commissioning checklist
Sampling point
Avoid the immediate downstream of a dosing point, gas–liquid mixing zones and branches that rarely flow; keep the sample line short with few bends.
Range and threshold
Choose the reagent range from the control band of the water being monitored (T02 for boiler make-up, for example), then set the alarm threshold inside that range and below the limit.
Cross-checking
In the first month after commissioning, compare with a laboratory titration weekly. If deviation exceeds the repeatability figure, check sampling and reagent before touching the calibration factor.
Reagent and wear parts
Log reagent batch numbers and opening dates; inspect pump tubing and lines quarterly so expired reagent does not introduce a systematic bias.
What this page does not cover: this instrument measures total hardness in conventional industrial and municipal water. Trace hardness in high-purity water (ultrapure or semiconductor-grade), samples containing large amounts of organic solvents or strong oxidants, and applications that must separate calcium hardness from magnesium hardness all call for a dedicated method or instrument, and readings from this unit should not be used as the basis for judgement.
Eight questions from selection and operation
Are results from the BC300 titrimetric colorimetric method comparable with laboratory EDTA titration?
The range reads 0.21–534.0 mg/L — is that one range or several?
Accuracy and repeatability are quoted as ±5 % FS — how much error is that in practice?
The boiler make-up water limit is 0.030 mmol/L — can this instrument measure that?
With a 5-minute cycle at best, can it drive softener regeneration interlock?
Which samples interfere with the hardness measurement?
How much data can it store, and can it connect to our existing PLC?
What are the requirements for the installation environment?
Where the figures on this page come from
The limits and method names on this page are quoted from the public texts of the standards listed below. Standards may be revised — check the version currently in force before relying on a limit.
National standard full-text system · official PDF
Standard text · special equipment information platform
Water analysis product line
limits quoted from the standards; derivations and conversions flagged separately
This page is a selection reference. It does not replace a site survey, process calculation or contractual technical agreement. Instrument specifications and range segmentation are quoted from the BC300 product brochure; supply parameters follow the order-specific technical agreement and factory calibration certificate. The readout shown on this page is an illustration, not live field data.
Confirm the range, interval and alarm threshold for your water
Send the sample conditions (temperature, pressure, expected hardness band, interfering ions) and the sampling point, and we will return the matching reagent range and the technical datasheet.