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Multi-Parameter Input Transmitter For pH/ORP


Process Display & Transmitter | DPU91_pH

Process Display & Transmitter

See All Models Below

1 year warranty CE
  • Large Auto-Sensing Backlit Display
  • “Dial-Style” Digital Bar Graph
  • Intuitive and “User-Friendly” Interface
  • Optional Field Upgradable Relays
  • Warning LED Indicator
  • Custom 13-Character Label Capabilities
  • Factory Reset Capability
Industrial pH Instrumentation and Electrodes - View related products


The DPU91 transmitter provides a single channel interface for many different parameters including flow, pH/ORP, conductivity/resistivity, salinity and temperature. The DPU91-BC transmitter has the added capability of supporting the batch module for batching control. The extra-large (100 mm²) backlit display can be viewed at 4 to 5 times the distance of traditional transmitters. The display shows separate lines for units of measure, main and secondary measurements as well an analogue bar graph.

The DPU91 is offered in both panel or process-mount versions. Both models can run on 12 to 32 Vdc power (24 Vdc nominal) and have 4 to 20 mA outputs. Designed for complete flexibility, plug-in modules allow the unit to easily adapt to meet changing application needs. Optional modules include relay, direct conductivity/ resistivity, batch and a PC communications configuration tool. The unit can be used with default values for quick and easy installation or can be customised with labels, adjustable minimum and maximum dial settings, units of measure and resolution.

Specifications General
Input Channels: 1
Input Types: Digital serial ASCII, TTL level, 9600 bps
Frequency Range: 0.5 to 1500 Hz
Accuracy: 0.5% of reading (display)
Measurement Types: Flow, pH/ORP, conductivity/resistivity, salinity, pressure, temperature or batch
Enclosure and Display
Case Material: PBT
Window: Shatter-resistant glass
Keypad: 4 buttons, injection-molded silicone rubber seal
Display: Backlit, 7 and 14-segment
Update Rate: 1 second
LCD Contrast: 5 settings
Indicators: “Dial-style” digital bar graph, LEDs for open collector, relays and warning indicator
Enclosure: ¼ DIN, NEMA 4X/IP65
Mounting Panel: ¼ DIN, ribbed on four sides for panel mounting clip inside panel, silicon gasket (included)
Field Mounts: Specified to OMEGA™ field mount junction boxes
Weight: 0.63 kg (1.38 lb) DPU91-pH/ORP Series
Display Ranges
For flow version visit For conductivity/resistivity version visit
pH: 0.00 to 15.00
pH Temperature: -99 to 350°C (-146 to 662°F)
ORP: -1999 to 1999.9 mV
Temperature: -99 to 350°C (-146 to 662°F)
Ambient Operating Temperature:
    Backlit LCD: -10 to 70°C (14 to 158°F)
    Storage Temperature: -15 to 70°C (5 to 158°F)
Relative Humidity: 0 to 100% condensing for field mount; 0 to 95% noncondensing for panel mount
Maximum Altitude: 4000 m (13,123')
Electrical Requirements
Power to Sensors:
    Voltage: 4.9 to 5.5 Vdc @ 25°C, regulated short circuit protected
    Terminal Blocks: Pluggable screw type 14 AWG maximum wire gauge
Input Power
DC: 10.8 to 35.2 Vdc, regulated
Current Output: 4 to 20 mA (10.8 to 35.2 VDC, 30 mA max)
DPU91 without Relay Module: 200 mA @ 10.8 to 35.2 Vdc
DPU91 with Relay Module: 300 mA @ 10.8 to 35.2 Vdc
Open Collector: 1
Overvoltage Protection: 48 V transient protection device current limiting for circuit protection and reverse-voltage protection
Relay Specifications (DPU91-R optional relay module)
Dry-Contact Relays: 2
Type: SPDT Form C
Maximum Current Rating: 5 A resistive 50 mA DC
Maximum Voltage Rating: 30 Vdc or 250 Vac
Hysteresis Adjustable: Absolute in engineering units (EUs)
Latch Reset: In test screen only
Delay: 9999.9 seconds (maximum)
Test Mode: Set on/off
Cycle Time: 99999 seconds (maximum)
Maximum Pulse Rate: 400 pulses/minute
Proportional Pulse: 400 pulses/minute
Volumetric Pulse Width: 0.1 to 3200 s
Pulse Width Modulation: 0.1 to 320 s
Input Types
Digital or AC Frequency: pH/ORP input via the digital output from the PHTX-2750 pH/ORP sensor electronics For flow models visit dpu91_flow
Raw Conductivity/Resistivity: Input directly from compatible conductivity/ resistivity electrodes via direct conductivity/resistivity module or via CDTX-2850 For conductivity/resistivity models visit
Input Specifications
Digital Serial: ACSII, TTL level, 9600 bps
Frequency Input:
    Sensitivity: 80 mV @ 5 Hz, gradually increasing with frequency
    Span: 0.5 Hz to 1500 Hz @ TTL level input
Accuracy: ± 0.5% or reading maximum error @ 25°C (°77F)
Resolution: 1 µS
Repeatability: ±0.2% of reading
Place Order(Specify Model Number)
Part Number/Desc.
Multi-Parameter Display and Transmitter
Availability: 1 week
DC powered field mount multi-parameter display and transmitter (Requires FP90UM mounting kit)
Availability: 1 week
DC powered panel mount multi-parameter display and transmitter
pH and ORP Electrodes
Availability: 9 weeks
Flat surface ORP electrode, 10KΩ ID. 3⁄4 NPT
Availability: 9 weeks
Flat surface ORP electrode, 10KΩ ID, ISO 7/1 R3⁄4
Availability: 1 week
Flat surface pH electrode, 3K Balco, 3⁄4 NPT thread
Availability: 9 weeks
Bulb style pH electrode, 3K Balco, 3⁄4 NPT thread
Availability: In Stock
pH 10 buffer solutions 500 ml (1 pt)
Availability: 2 weeks
pH 10 buffer solutions 4L (1 gal)
Availability: In Stock
pH 4 buffer solutions 500 ml (1 pt)
Availability: 2 weeks
pH 4 buffer solutions 4L (1 gal)
Availability: In Stock
pH 7 buffer solutions 500 ml (1 pt)
Availability: 2 weeks
pH 7 buffer solutions 4L (1 gal)
Availability: 2 weeks
De-ionized water 500 ml (1 pt)
Availability: 1 week
De-ionized water 4L (1 gal)
Availability: 3 weeks
20 single use foil packets of de-ionized water
Availability: 1 week
5 each single use foil packets of pH-4, pH-7, pH-10 and de-ionized water
Availability: 9 weeks
Submersible sensor electronics, 3⁄4 NPT
Availability: 9 weeks
In-line sensor electronics, 15 ft cable, 3⁄4 NPT
Availability: 7 weeks
In-line sensor electronics, 15 ft cable, ISO 7/1 R3⁄4
Consult Sales  
In-line pre-amplifier, 3⁄4 NPT
Consult Sales  
In-line pre-amplifier, ISO 7/1 R3⁄4
Availability: 1 week
Submersible pre-amplifier, 3⁄4 NPT
Consult Sales  
Submersible pre-amplifier, ISO 7/1 R3⁄4
Availability: 1 week
pH/ORP simulator and system tester
Mounting and Electrical Options
Availability: 1 week
Universal mounting bracket for remote mounted display
Availability: 1 week
Field mount relay module
Availability: 7 weeks
Field mount communications module
Mounting options for use with EasyCal
Consult Sales  
Universal mount junction box with EasyCal
All amounts shown in EUR
Note: Comes complete with operator’s manual.

Electrodes and mounting kits sold separately.

Product Manuals:

Download pH/ORP Electrodes
Download pH/ORP Preamplifier
Download Installation Kits and Hardware Accessories
Download pH/ORP Sensor Electronics
Download Transmitter
Download Optional Modules for Batch Controller
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