DOTX45-Series

Supported Applications

The Omega DOTX-45 Series is a 2-Wire Isolated Dissolved Oxygen Transmitter System designed for the continuous on-line monitoring of dissolved oxygen in solution. The system pairs with the DOE-45PA sensor, which utilizes a polymer membrane-covered galvanic sensing element to measure dissolved oxygen levels and percent saturation.

Operating Conditions & Performance

The DOTX-45 transmitter operates within an ambient temperature range of -20 to 60°C (-4 to 140°F) with a storage temperature capability from -30 to 70°C (-22 to 158°F). The system is rated for humidity levels up to 95%, non-condensing. Process measurement occurs within a temperature range of -5 to 55°C (23 to 131°F), with the sensor internally compensated for membrane permeability changes using a Pt100 or selectable Pt1000 element.

Performance specifications include a measuring range of 0 to 40 ppm and 0 to 200% saturation. The system demonstrates repeatability of 0.1% of span or better, with stability rated at 0.1% of span per 24 hours (non-cumulative). Non-linearity is specified as 0.1% of span. Response time for the sensor reaches 90% in less than 3 minutes, while the transmitter response time achieves 90% of a step input in 4 seconds at the lowest setting.

The system supports pressure ratings from 0 to 150 psig @ 25°C (77°F) and requires a minimum flow rate of 6 mm (0.02") per second for accurate measurement.

Key Performance Metrics

• Measuring Range: 0 to 40 ppm; 0 to 200% saturation
• Sensitivity: 0.05% of span
• Temperature Drift: Span or zero, 0.02% of span/°C
• Warm-Up Time: 4 seconds to rated performance
• Supply Voltage Effects: ±0.05% of span

Configuration Options

The series offers configurable options for power, output signaling, and mounting configurations to accommodate diverse installation requirements.

Housing & Enclosure

• Enclosure Rating: NEMA 4X (IP66), weatherproof and corrosion resistant
• Material: Polycarbonate with stainless steel hardware
• Dimensions: 112 H x 112 W x 89 D mm (4.4 x 4.4 x 3.5 in)
• Mounting Options: Wall, panel, pipe, DIN rail, or integral-sensor mounting
• Conduit Openings: Two PG9 openings and one 1 NPT center opening; cordgrips and plug included

Sensor & Wetted Materials

• Sensing Principle: Membrane covered galvanic (3-electrode amperometric)
• Cathode Material: Platinum
• Anode Material: Lead
• Membrane Thickness: 50 microns; FEP (fluorinated ethylene propylene) material
• Electrolyte: Potassium chloride based
• Wetted Materials: 316 SS, FKM, Noryl
• Sensor Cable Length: Standard 9.1 m (30'); supports sensor-to-transmitter distances up to 305 m (1000')

Electrical & Output Options

• Power Supply: Loop-powered 2-wire DC, 16 to 35 Vdc; optional integral power supply card for 115 VAC operation available via specific model variants.
• Output Signal: Standard 4 to 20 mA isolated analog output. Models with relays (e.g., DOTX-45-115VAC-R2) support dual 4-20 mA outputs and SPDT relay operation.
• Isolation: 600V galvanic isolation
• Cable Type: Belden twisted-pair, shielded (sensor-to-transmitter)
• Filtering: Adjustable damping from 1 to 99 seconds additional time constant to 90% step input

User Interface & Diagnostics

• Display: Large, high-contrast super-twist LCD with a 4-digit main display (19.1 mm / 0.75" characters) and a 12-digit secondary dot-matrix display.
• Keypad: 4-key membrane type with tactile feedback
• Diagnostics: Includes sensor membrane puncture/tear diagnostic, output hold, alarm, simulation features, and system condition messages.

Key Product Differences

The series is available in distinct configurations based on power requirements and relay functionality. The standard DOTX-45 model functions as a loop-powered 2-wire transmitter operating on 16 to 35 Vdc with a single 4 to 20 mA output.

The variant DOTX-45-115VAC-R2 is designed for AC power operation, featuring an integral alarm relay and dual 4-20 mA output capability. This model supports the optional integral power supply card for 115 VAC.

The sensing element DOE-45PA** is sold separately from the transmitter unit. Initial purchase of the sensor requires the addition of DOE-45PA-DOE electrolyte solution and DOE-45PA-RM membranes to ensure operational readiness. Additional accessories include replacement lead electrodes, membrane holders (316 SS), submersible sensing modules, and unregulated power supplies.