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 (3.90 x 3.90") autosensing backlit display can be viewed at 4 to 5 times the distance over traditional transmitters. The highly illuminated display and large characters reduce the risk of misreading or misinterpreting the displayed values. The display shows separate lines for units, main and secondary measurements as well as a “dial-style” digital bar graph. The DPU91 is offered in both panel or field-mount versions. Both configurations 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 customer 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 programming or can be customized with labeling, adjustable minimum and maximum dial settings, and unit and decimal measurement choices.

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)
Display Ranges
For PH/ORP version visit omega.com/dpu91_ph For flow version visit omega.com/ dpu91_flow
Conductivity: 0.0000 to 99999 µS, mS, PPM and PPB (TDS), kΩ, MΩ
Conductivity Temperature: -99 to 350°C (-146 to 662°F)
Temperature: -99 to 350°C (-146 to 662°F)
Salinity: 0 to 100 PPT
Environmental
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% non-condensing 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
Overvoltage Protection: 48 V transient protection device current limiting for circuit protection and reverse-voltage protection
Relay Specifications
Dry-Contact Relays: 2
Open Collector: 1
Type: SPDT N/A
Form C: N/A
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 pH/ORP models visit omega.com/ dpu91_ph. For flow models visit omega.com/dpu91_flow
Raw Conductivity/Resistivity: Input directly from signet conductivity/ resistivity electrodes via direct conductivity/resistivity module or via CDTX-2850
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 (77°F)
Resolution: 1 µS
Repeatability: ±0.2% of reading