APX1-C2 pH ORP Controller Adds Dual SPST Relay Control for Dosing and Alarm Automation

Automating chemical dosing and alarm response no longer requires a separate control box. The APX1-C2 online pH/ORP controller from Daruifuno includes two SPST relays with a 3 A 250 V AC contact capacity, enabling it to drive pumps, valves, and alarms directly from live pH and ORP readings.

Versatile Control Functions

Each relay can be assigned to a different duty through the controller's function menu:

• Main value control — the relay responds to the pH or ORP measurement
• Temperature control — the relay responds to the measured temperature
• Wash relay — periodic on/off cycling for sensor cleaning, in either Hold or Constant wash state

Configurable Alarm Logic

Switching between alarm behaviors is intuitive. When the On value is set above the Off value, the relay works as a high alarm; when the On value is below the Off value, it becomes a low alarm. This makes the instrument equally suited to dosing control and to protective shutdown logic.

Complete Output Package

Ready for Real Processes

From wastewater neutralization to CIP cleaning control, the APX1-C2 gives operators dependable relay-based automation in a single panel-mount instrument.

Typical Application Scenarios

In a neutralization skid, relay one can energize an acid or caustic dosing pump while relay two drives an alarm beacon. In a cooling or process water loop, the wash relay can trigger a cleaning cycle on a fixed schedule while the second relay guards against over-temperature. In each case, the APX1-C2 replaces dedicated timer and alarm hardware, simplifying the panel and reducing cost.

Measurement Backbone

Control decisions are only as good as the measurement behind them. The controller monitors pH from 0 to 14 pH and ORP from −2000 mV to 2000 mV with pH accuracy of ±0.02 pH and ORP accuracy of ±2 mV, supported by NTC10K or PT1000 automatic temperature compensation. Two active 4–20 mA outputs mirror the live values for recorders and PLCs.

Integrates With Your Network

With RS485 Modbus RTU and JSON output, relay events and measured values can be logged centrally, giving managers clear visibility into dosing performance and alarm history across the plant.

Contact Daruifuno for relay wiring diagrams, pricing, and OEM options.