4-in-1 Conductivity Sensor: EC, Salinity, TDS and Temperature Selection

If you need EC, salinity, TDS and temperature from one monitoring point, a 4-in-1 conductivity sensor can reduce probes and PLC channels. You must still define the conductivity range, derived-value conversion, output and acceptance method before ordering YexSensor YEX-S1PRO-ECT4.

Why Buyers Search for a 4-in-1 Conductivity Sensor

Integrators often need EC, salinity, TDS and temperature on the same PLC screen. Four separate instruments would add mounting points, cables, power feeds, addresses and maintenance tasks. The real procurement question is whether one physical conductivity cell can provide the decisions the project needs without presenting derived values as independent analytical results.

Start with the control objective. Conductivity is the primary electrical measurement and can indicate ionic loading, concentration, rinse completion, contamination or desalination performance. Salinity and TDS can be useful operational representations when the water composition and conversion model are understood. If the purchase specification requires a certified mass concentration or composition-specific salt result, a general conversion may not be sufficient.

YEX-S1PRO-ECT4 Product Fit and Limits

The official YEX-S1PRO-ECT4 information lists conductivity, salinity, TDS and temperature outputs. Conductivity ranges are 0–3000, 0–10000 or 0–30000 μS/cm; salinity and TDS ranges are 0–3000, 0–10000 or 0–30000 ppm, with customization available. Published resolution is 1 μS/cm or 1 ppm, conductivity accuracy is ±1.5%, temperature accuracy is ±0.1°C and response time is 10 seconds.

The probe uses a titanium electrode, 316L stainless steel plus ABS housing, IP68 protection, automatic temperature compensation, 12–24 VDC power and approximately 0.4 W. It supports RS485 Modbus RTU or optional 4–20 mA, selected as the ordered output. Installation uses a 3/4 NPT connection for immersion, pipe or tank arrangements.

Primary Measurement Versus Derived Outputs

Conductivity depends on ion concentration, ion mobility and temperature. Two waters can have the same conductivity but different chemical composition. A TDS or salinity output therefore depends on the configured conversion and may not equal a gravimetric TDS result or a composition-specific salinity method in every matrix. Buyers should request the conversion basis and validate it with representative samples if those displayed values drive decisions.

Temperature compensation normalizes conductivity behavior but does not remove every process effect. Confirm the reference temperature and compensation approach used by the controller. Store uncompensated or compensated status in the commissioning record so future operators do not compare values generated under different assumptions.

Technical Parameters and Procurement Checks

Where One Probe Works—and Where It Does Not

A combined probe can suit natural water, process water, wastewater and salinity trending where all fields come from one representative sample. It reduces hardware and synchronizes temperature with derived values. It is useful when PLC channels, power, enclosure space or maintenance access are limited.

It is not a replacement for ion-specific analysis, laboratory gravimetric TDS, seawater methods required by a contract, or independent redundancy. It is also unsuitable when the conductivity range cannot cover the process, the electrode is exposed to incompatible chemicals, solids continually bridge the cell, or the location dries out. In those cases, use another range, protected bypass, different principle or separate reference method.

Range and Acceptance Planning

Collect minimum, normal, alarm and credible upset conductivity data. A narrow range can clip cleaning or contamination events, while an unnecessarily wide range may provide less useful resolution. Select the EC range first, then confirm that the requested salinity and TDS display ranges and conversions remain meaningful for the same water.

Factory and site acceptance should verify every register, unit, sign, decimal position and quality state. Compare conductivity with a traceable reference across multiple points and compare salinity or TDS only against the agreed project method. Define the permitted difference and the action taken when online and reference results disagree.

Installation, Data Quality and System Integration

A sensor is only one part of the measurement point. The project also needs a representative location, rigid or retrievable mounting, cable protection, suitable power, a controller or gateway, documented communication settings and safe maintenance access. Install the measuring end in continuously renewed water and keep it away from direct chemical injection, trapped air, settled deposits and unrepresentative dead zones unless the approved design specifically requires that location.

For RS485 Modbus RTU, confirm power polarity, A/B convention, device address, baud rate, parity, stop bits and the register map supplied with the ordered revision. Use a unique address for every device on a shared bus, appropriate topology and termination, and separation from variable-frequency-drive or motor cables. If optional 4–20 mA is selected instead, define the engineering-unit scaling, fault behavior and PLC analog-input isolation before the purchase order is released.

Store the raw reading, unit, configured range, temperature, quality flag and maintenance state together. A number without context can appear valid after dry exposure, cleaning, a range change or communication recovery. Define warning, action, out-of-range, maintenance and communication-loss states separately. Use persistence or rate-of-change rules when bubbles, cleaning movements or hydraulic transitions can create short harmless spikes.

Commissioning should include mechanical inspection, stable-value confirmation, reference comparison, alarm simulation and communication-loss testing. Record the model, serial number, range, output, cable length, protocol revision and initial reference results.

Lifecycle Cost, FAT and Responsibility Boundaries

Evaluate ownership cost over the planned service period. Include mounting hardware, flow cells or bypass piping, junction boxes, controller inputs, gateways, standards, cleaning labor, consumables, replacement sensing parts, travel and downtime. A lower probe price can become the more expensive option if it requires unsafe weekly retrieval or if missing protocol documents delay PLC commissioning. Ask each supplier to separate included equipment from recommended accessories and customer-supplied items.

Write a factory acceptance checklist that verifies the ordered model, range, output, cable, connector, displayed units, Modbus communication and supplied documents. The site acceptance test should add installation inspection, comparison with the agreed reference method, alarm and interlock simulation, power-cycle recovery, communication-loss behavior and maintenance-state handling. Define who approves the sensor after cleaning or calibration and who may change ranges, addresses or setpoints.

Plan critical spares according to site access and consequence of failure. A remote station may need a complete exchange probe, while an accessible plant may hold cleaning tools, standards, seals or sensing elements.

How to Request a Comparable Quotation

Send the monitoring objective, process drawing, water source, minimum, normal and credible maximum values, temperature, pressure, pH, salinity or conductivity, suspended solids, oil or biological fouling risk, cleaning chemicals, mounting, cable length, power, PLC or gateway, output signal, quantity and destination.

Require line-item confirmation of the exact model, ordered range, measured and calculated outputs, housing and wetted materials, cable, connector, thread, mounting accessories, optional cleaning, controller, calibration materials, spares, drawings, protocol document, warranty, lead time and exclusions. Compare the installed and maintainable measurement point rather than the probe price alone. This makes quotations technically comparable and reduces change orders during commissioning.

Frequently Asked Questions About 4-in-1 conductivity sensor

Does one probe independently measure all four parameters?

The probe directly senses conductivity and temperature; salinity and TDS are related outputs based on conductivity and configured conversion logic. Confirm the calculation basis before using derived values for contractual decisions. For procurement, require the quotation and register list to label conductivity and temperature separately from calculated salinity and TDS outputs. Record the calculation status in SCADA so operators do not treat every displayed value as an independent analysis.

Which conductivity range should be ordered?

Choose 0–3000, 0–10000 or 0–30000 μS/cm from representative minimum, normal, alarm and upset samples. Request customization only with actual water data and an acceptance method. Ask YexSensor to print the selected range, resolution, output and conversion settings on the quotation so bidders cannot price different configurations. Also provide the reference temperature and expected cleaning or contamination peaks when selecting the range.

Can the TDS value replace gravimetric laboratory TDS?

Not automatically. Conductivity-to-TDS conversion depends on water composition and the selected factor. Validate representative samples if TDS drives compliance, dosing or product release. If laboratory TDS is contractual, include paired-sample acceptance points and the permitted difference in the purchase specification. Keep the agreed factor and laboratory method in the commissioning record for later comparisons.

Can YEX-S1PRO-ECT4 connect to a PLC?

Yes. It supports RS485 Modbus RTU or optional 4–20 mA, selected at ordering. Confirm address, baud rate, register map, units and analog scaling before commissioning. State whether the order needs digital or analog output, then request the matching wiring diagram, protocol revision and commissioning test values. Test both valid readings and failure states after power cycling before the PLC loop is accepted.

Is the complete sensor made from titanium?

No. The official construction identifies a titanium electrode and 316L stainless steel plus ABS housing. Request a wetted-material drawing if the water is corrosive. For corrosive water, request a wetted-material drawing covering the electrode, housing, seals, connector and mounting hardware—not only a marketing material label. Confirm that brackets and fasteners are also compatible with the process water and cleaning chemicals.

Where should the sensor be installed?

Use continuously renewed representative water with the measuring end immersed, adequate clearance and safe retrieval. Avoid dead zones, direct dosing points, trapped air and heavy deposits. Attach the installation drawing to the RFQ and require confirmation of immersion depth, 3/4 NPT connection, orientation, flow and removal clearance. The approved drawing should also show cable strain relief and how technicians retrieve the probe safely.

When are separate sensors preferable?

Use separate instruments when independent redundancy is required, parameters need different locations, a specific analytical method is mandatory, or the single range and conversion model cannot cover the project. If redundancy or different locations are required, ask for separate line-item alternatives so lifecycle cost can be compared with the combined probe. Compare installation, maintenance and spare-channel costs rather than using sensor quantity as the only criterion.

What should be tested during commissioning?

Verify EC against a traceable reference, every Modbus register, temperature compensation, derived-value factors, alarms, communication loss and restoration after cleaning. Require FAT and SAT documents to name the reference instrument, test points, conversion factors, alarm simulation and pass/fail tolerance before shipment. Acceptance records should preserve raw values, units and configured factors for each tested point.

What belongs in the RFQ?

Include the water matrix, EC data, required displayed outputs, conversion basis, range, temperature, pressure, mounting, cable, output, controller, reference method, quantity and destination. When requesting a quotation, this information lets YexSensor confirm YEX-S1PRO-ECT4 suitability and prevents an ambiguous four-parameter request from becoming a range or unit mismatch. Ask for separate prices for the probe, mounting, controller documents, standards, spares and commissioning support.

Final Thoughts

If you need synchronized EC, salinity, TDS and temperature data, review the YEX-S1PRO-ECT4 configuration with YexSensor. Send your water data, range, conversion method, installation and PLC requirements for a comparable quotation.