Measuring Conductivity, Resistivity and Salinity with the Multi- Parameter Input Transmitter

The DPU91 transmitter provides a single channel interface for various types of parameters, including flow, conductivity/resistivity, pH/ORP, temperature, and salinity. The DPU91-BC transmitter has the additional capability to support the batch module for batching control.

The DPU91 transmitter has the extra-large (3.90 x 3.90") autosensing backlit display that can be viewed at 4 to 5 times the distance compared to conventional transmitters. The well-illuminated display and large characters lower the risk of misinterpreting or misreading the displayed values.

Separate lines for main, units, secondary measurements, and “dial-style” digital bar graph are shown in the display. The DPU91 transmitter is available in field or panel-mount versions, and both of these configurations can operate on 12 to 32 VDC power (24 VDC nominal) and provide 4 to 20 mA outputs.

Designed for full flexibility, plug-in modules enable the unit to easily adapt to varying needs of customers. Batch, relay, direct conductivity/resistivity, and a PC communications configuration tool are available as optional modules. The unit can be used together with default values for easy and fast programming or can be modified with adjustable minimum and maximum dial settings, labeling, unit and decimal measurement options.

Intuitive and “user-friendly” interface

“Dial-Style” digital bar graph

Large auto-sensing backlit display

Warning LED indicator

Custom 13-character label capabilities

Factory reset capability

Optional field upgradable relays

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), kO, MO

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)

Open Collector: 1

Overvoltage Protection: 48 V transient protection device current limiting for circuit protection and reverse-voltage protection

Relay Specifications (DPU91-R)

Dry-Contact Relay:

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 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