The eSelect M1 pH(Rx) is a versatile, multi-function instrument designed for measuring pH or Redox (Rx) parameters. This device, part of the eSelect M series, offers high-quality performance in terms of measurement and a comprehensive set of functions to meet various requirements.
Function Description
The eSelect M1 pH(Rx) serves as a control unit for chemical dosing pumps, peristaltic pumps, and other equipment. Its primary function is to monitor and control pH or Rx levels in a system, such as swimming pools or water treatment plants. The instrument can switch between pH and Rx measurement modes through simple programming, requiring the use of the appropriate electrode.
It features two main operating modes for its output relays:
- ON-OFF Mode: This mode activates or deactivates the output relays based on whether the measured value is above or below the selected setpoint. It is compatible with most ON-OFF devices and is cost-effective. However, due to high output frequency, slight discrepancies between the real measurement in the system and the display may occur, influenced by factors like chemical concentration and injection point distance.
- Proportional - PWM Mode (Pulses Width Modulation): This mode offers more accurate control by activating output relays with timed pulses. The pulse width and cycle duration are adjusted based on the distance from the setpoint, allowing for precise dosing. This mode is particularly useful for applications requiring fine-tuned control of chemical additions.
The instrument also includes several safety and control functions:
- MIN/MAX Alarm: Allows setting minimum and maximum values beyond which an alarm is triggered, enhancing safety by alerting operators to out-of-control parameters.
- Hysteresis: Prevents rapid oscillations around the setpoint in ON-OFF mode by defining a range within which the output relays remain stable, protecting connected devices from excessive switching.
- Delay Output Response: Blocks output relays for a programmable period (up to 999 seconds) to ensure sensor measurements are stable before activation, leading to better chemical balance.
- Overdose Time Alarm: Sets a period within which the setpoint must be reached. If not met, the instrument blocks all output operations (including mA metering pumps), displays an alarm, and activates the alarm relay (Relay 4), preventing excessive chemical dosing.
- Maximum Metering Time: Ensures dosing operations are completed within a specified time limit (up to 999 minutes). This function allows for continuous dosing based on setpoints or for setting a specific duration for dosing.
- Start-Up Delay: Stops output relays when the unit is switched on, allowing the sensor to polarize and ensure correct measurements.
- Flow Sensor ("Proximity Sensor"): Disables all outputs if there is no water flow in the probe socket (and potentially in the system), preventing chemical addition when not needed (disabled by default).
- AUX Output: Controls various remote ON-OFF devices via a real-time timer, allowing for precise programming of minutes, hours, days, and weeks. This makes the instrument highly versatile for managing other system functions beyond chemical parameter measurement.
Important Technical Specifications
- Measurement Parameters: pH or Rx (Redox).
- Power Supply: 100/240 V a.c. 50/60 Hz single-phase (with maximum ±10% fluctuations permitted); 12/24 V on demand.
- Case Material: ABS plastic.
- Display: Wide and elegant, ensuring easy viewing.
- Connectivity:
- RS485 / Ethernet external module connection (Modbus protocol with ETATRON SmartApp® Software) for remote control via PC, smartphone, or tablet.
- Digital input for level probe (for chemical tank control).
- Proximity sensor input.
- PT100 temperature sensor input.
- BNC connector for pH or Rx electrode.
- Outputs:
- Relay outputs for setpoint values (ON-OFF or PWM proportional).
- Analog outputs in current (4-20 mA1 / 4-20 mA2) for data loggers, PLCs, recorders, or mA metering pumps.
- Auxiliary ON-OFF output (Relay 3) with timer programming.
- Alarm ON-OFF relay output (Relay 4) for external signaling.
- Temperature Compensation: Manual (0-100°C) or Automatic (via PT100 sensor).
- Operating Temperature: Maximum 40°C.
Usage Features
The eSelect M1 pH(Rx) offers two types of programming menus to cater to different user needs:
- Basic Programming Menu: Simplified for household applications, such as small swimming pools or basic water treatment systems.
- Expert Programming Menu: Provides complete programming options, including advanced functions for more accurate control and detailed safety settings, suitable for professional applications and installers.
The instrument's design emphasizes ease of use, with a self-explanatory menu and clear display. The ability to switch between pH and Rx measurements with a single instrument reduces inventory complexity and ordering issues for operators.
Maintenance Features
- Electrode Cleaning and Maintenance: Deposits on the electrode can cause reading errors. Cleaning methods vary by deposit type:
- For thin deposits, shaking the electrode or spraying with distilled water is recommended.
- Organic or stubborn deposits require chemical removal.
- Mechanical cleaning of the bulb should be a last resort, as it can cause irreparable damage.
- If cleaning doesn't restore electrode effectiveness, it may be aged and require replacement. The mV value displayed during calibration helps assess electrode efficiency.
- Electrode Reconditioning (pH and Rx): Specific chemical treatments can be performed to recondition the electrode:
- Immerse the tip in 0.1N hydrochloric acid, then 0.1N sodium hydroxide, followed by rinses. Repeat three times.
- For persistent issues, immerse in 20% ammonium bifluoride solution.
- For severe cases, immerse in 5% hydrofluoric acid, then 5N hydrochloric acid, followed by rinses.
- Calibration: Periodic calibration of the pH electrode is crucial for accurate measurements and overall chemical-physical balance. New or good condition buffer solutions and a reliable test kit are recommended.
- Data Reset: A "DATA RESET" function allows resetting the instrument to factory settings. This should only be used if parameters are incorrect, programming issues arise, or a fresh start is desired. Overuse is discouraged as it may affect instrument efficiency.
- Troubleshooting: The manual provides a detailed troubleshooting guide for common issues such as a blank display, fixed measurement readings, fluctuating measurements, or calibration failures, offering possible causes and solutions.
- Electrical Safety: The instrument is built to professional standards. Any internal repairs must be carried out by qualified and authorized personnel. Proper electrical installation, including earthing and voltage protection (UPS recommended), is essential for safety and longevity. The device is protected against voltage fluctuations within its specified range (100-250 VAC ±10% or 9-24VDC).
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