PHTX45-Series

Supported Applications

The Omega PHTX-45 is a microprocessor-based, loop-powered, fully isolated transmitter system designed for industrial pH and ORP measurement. The series supports applications requiring high reliability in harsh environments, with diagnostics included for electrode breakage and sensor failure.

Operating Conditions & Performance

The PHTX-45 operates within an ambient temperature range of -20 to 60°C (-4 to 140°F) and a process temperature range of -5 to 95°C (23 to 203°F). Storage is supported from -30 to 70°C (-22 to 158°F), with ambient humidity rated at 0 to 95%, non-condensing. The transmitter provides measurement ranges of 0 to 14.00 pH and -1000 to 2000 mV (ORP) with a resolution of 0.01 pH or 1 mV.

Performance specifications include an accuracy sensitivity of 0.05% of span, repeatability of 0.1% or better, and non-linearity of 0.1% of span. Temperature drift is specified at 0.02% of span/°C for both span and zero. The transmitter response time is 4 seconds to 90% of step input at the lowest setting, with a warm-up time of 4 seconds to rated performance.

Key Performance Metrics

• Sensitivity: 0.05% of span (transmitter); 0.002 pH or 0.2 mV for sensors
• Stability: 0.1% of span per 24 hours, non-cumulative (transmitter); 0.02 pH or 2 mV per 24 hours, non-cumulative (sensor)
• Input Impedance: Greater than 1013 Ω
• Sensor to Transmitter Distance: 914 m (3000') with preamp; 9.1 m (30') without preamp

Configuration Options

The series is configured as a two-wire device powered by 16 to 35 Vdc, outputting a 4 to 20 mA signal. The enclosure features NEMA 4X and IP65 ratings with polycarbonate construction and stainless steel hardware, measuring 112 H x 112 W x 89 mm D (4.4 x 4.4 x 3.5"). Mounting options include wall, panel, pipe, DIN rail, and integral-sensor configurations.

Electrical & Display Features

• Display: Large dual display with a high-contrast super-Twist (STN) LCD; 4-digit main display (19.1 mm / 0.75" seven-segment character) and 12-digit secondary display (7.6 mm / 0.3" 5 x 7 dot matrix).
• Keypad: 4-key membrane type with tactile feedback, polycarbonate with UV coating.
• Conduit Openings: Two PG9 openings and one to 1 NPT center opening; cord grips and plug included.

Sensor & Wetted Materials

The PHE-45P pH electrode utilizes wetted materials including PEEK, ceramic, titanium, glass, FKM, and EDPM. A 316 stainless steel body option is available with 316SS components. The ORE-45P ORP sensor includes platinum or gold in addition to the standard material set.

Key Product Differences

The PHTX-45 series encompasses distinct transmitter and electrode models:

• PHTX-45: pH Transmitter unit.
• PHE-45P: pH Electrode with a 3 m (10') sensor cable, featuring Pt1000 temperature compensation via a 6-conductor plus 2 shields configuration.
• ORTX-45: ORP Transmitter unit.
• OER-45P: ORP Sensor with a range of -1000 to 2000 mV.

Available accessories include the PHTX-45-SMH submersion mounting hardware (1.8 m / 6'), the PHTX-45-RK pH/ORP sensor regeneration kit, and buffer solutions PHA-4, PHA-7, and PHA-10.