0.01pH Resolution 3-Point Calibration Glass Electrode Online pH Sensor Digital pH Probe for Water Treatment

The DPH890 is a digital online pH sensor built on the glass electrode method. A pH-sensitive glass bulb develops a potential that follows the hydrogen ion activity of the water, a reference half-cell supplies a stable comparison potential, and the electronics inside the stainless steel 316 and POM body convert the difference into a temperature-compensated pH value before sending it out over RS485 Modbus RTU. Nothing in that chain depends on a separate transmitter, a screened analog cable or an external temperature probe.

The measurement specification is the part most engineers check first, so here it is in plain terms. The span is 0.00~14.00 pH with 0.01 pH resolution. Accuracy is stated as 0.1% of the measuring range or ±0.02 pH, whichever is larger, and the temperature channel is 0.0~50.0 °C with ±0.5 °C accuracy. That accuracy statement matters: at the low and high ends of the scale the percentage term dominates, which is the honest way to specify a glass electrode rather than quoting a single best-case number. 

Calibration is deliberately flexible in controller. Three calibration points are supported — by default 4.01, 6.86 and 9.18 pH — and each point value can be edited inside a permitted window (3.5~4.51 pH, 6.36~7.5 pH and 8.68~10.5 pH) so you can calibrate with the buffers you actually keep in stock. Zero point, slope 1, slope 2 and a separate main measurement offset are all individually adjustable, which lets a maintenance team compensate for normal electrode ageing instead of replacing the sensor early. 

The DPH890 is a digital online pH sensor built on the glass electrode method. A pH-sensitive glass bulb develops a potential that follows the hydrogen ion activity of the water, a reference half-cell supplies a stable comparison potential, and the electronics inside the stainless steel 316 and POM body convert the difference into a temperature-compensated pH value before sending it out over RS485 Modbus RTU. Nothing in that chain depends on a separate transmitter, a screened analog cable or an external temperature probe.

The measurement specification is the part most engineers check first, so here it is in plain terms. The span is 0.00~14.00 pH with 0.01 pH resolution. Accuracy is stated as 0.1% of the measuring range or ±0.02 pH, whichever is larger, and the temperature channel is 0.0~50.0 °C with ±0.5 °C accuracy. That accuracy statement matters: at the low and high ends of the scale the percentage term dominates, which is the honest way to specify a glass electrode rather than quoting a single best-case number. 

Calibration is deliberately flexible in Daruifuno pH controller . Three calibration points are supported — by default 4.01, 6.86 and 9.18 pH — and each point value can be edited inside a permitted window (3.5~4.51 pH, 6.36~7.5 pH and 8.68~10.5 pH) so you can calibrate with the buffers you actually keep in stock. Zero point, slope 1, slope 2 and a separate main measurement offset are all individually adjustable, which lets a maintenance team compensate for normal electrode ageing instead of replacing the sensor early. 

Signal conditioning is configurable too in the pH controller . The sampling buffer can be set to level 2, 4, 8, 16 or 32, so the same sensor can give a fast response in a dosing line or a smoothed reading in a basin with surface agitation. Power and communication are electrically isolated inside the sensor.

1. Digital measurement at the electrode: the high-impedance glass signal is converted and linearised inside the stainless steel body, so the value that reaches the controller is already temperature compensated and immune to cable length.
2. Clear accuracy statement: 0.01 pH resolution with 0.1% FS or ±0.02 pH accuracy (whichever is larger) and ±0.5 °C on temperature — figures a validation engineer can work with.
3. Three-point calibration with editable buffers: calibrate at 4.01 / 6.86 / 9.18 pH by default, or enter your own buffer values inside the permitted windows and use the standard solutions you already stock.
4. Individual zero, slope and offset adjustment: trim zero point (-50~50), slope 1 and slope 2 (45~60) and the main measurement offset (-14~14) to compensate for ageing before replacing the electrode.
5. Automatic temperature compensation: use the built-in element where temperature moves
6. Isolated RS485 Modbus RTU: pH at register address 2 and temperature at address 4 as 32-bit floats, with a published address map and worked command frames in the user manual.
7. Rugged IP68 body in stainless steel 316 and POM: about 500 g, Φ37 mm by 261 mm, rated to 1 bar, supplied with 10 m of cable in customizable length.

• Process water and circulating water: loops where a stable 0.01 pH trend is used for dosing control.
• Drinking water treatment: coagulation and disinfection stages, clear water tanks and network monitoring points.
• Wastewater treatment: aeration basins, neutralisation tanks and effluent channels.
• Pure water systems: reverse osmosis permeate and demineralised water with the pure water coefficient enabled.
• Electroplating, electronics and PCB lines: rinse baths and wastewater neutralisation where a stainless body is required.
• Chemical, food and pharmaceutical processes: reaction tanks, CIP return lines and process water loops.

1. Five installation variants are available: side wall installation for tank and channel walls, top flange mounting through a tank cover, flow-through installation in a bypass or sample line, submerged installation on a rail or bracket, and pipeline installation threaded into a tee. Whichever variant you choose, keep the barrel within ±30° of vertical - never horizontal or inverted.
2. Keep flow across the glass bulb between roughly 0.001 and 0.5 m/s; avoid dead legs and direct injection points.
3. Wire by colour: red V+ (DC 9~24 V), black V-, white RS485 A, green RS485 B. The aviation plug version is pre-wired.
4. Soak the electrode in 3 mol/L KCl solution for at least 30 minutes before the first calibration, and keep the protection cap wet in storage.
5. Calibrate with fresh buffers, then record zero point and slopes in the maintenance log as the baseline for the next service.
6. Inspect monthly, check calibration monthly, replace the sensor yearly depending on the process.

The DPH890 user manual (Version 1.0) is supplied with every sensor and issued as a PDF with the quotation on request. It contains the specification table, dimensional drawing, installation accessory list, wiring colour table, the complete Modbus RTU address map with data formats and initial values, worked command frames for reading values and for each calibration step, the maintenance cycle and a fault-finding table. 

Model DPH890, digital pH sensor, stainless steel 316 and POM body, RS485 Modbus RTU, 10 m cable. Please confirm cable length, connection method (separate cable or aviation plug) and which installation accessory set is required (side wall, top flange, flow-through, submerged or pipeline). Advise your process temperature, pressure and pH range and our engineer will confirm the configuration.