pH Measurement in Refining Crude Unit Overhead
Challenging application for pH sensors
Reduce Sensor Cleaning & Extend pH Sensor Life
pH is monitored on the separator outlet and used to control the addition of neutralization chemicals to maintain the distillate pH at acceptable levels. Salt impurities accumulate in distillate and create corrosive acidic conditions, leading to short sensor life and frequent cleanings due to the trace oil in the water. Rosemount™ 3500P pH Sensors have oil resistant electrolyte and refillable reference for maximum sensor life. Retractable sensor options are also available for easy cleaning and replacement. The Rosement 3500P pH Sensor features high-temperature glass, poison-resistant electrolyte and a double reference junction to provide maximum sensor life.
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Product Solutions
The Rosemount 3500P pH / ORP Sensor, with integral cable, incorporates several design innovations that prolong the life of the sensor in difficult applications. The pH/ORP sensor features a rebuildable double junction reference cell that allows for wide application flexibility by using different reference electrolyte solutions. The resulting sensors live longer, respond faster and drift less thereby minimizing maintenance and lowering the total cost of ownership.
- Rebuildable design allows pH / ORP sensor use in applications of elevated temperatures, fouling, coating and poisoning
- Fast, accurate, and stable pH/ORP measurement
- SMART preamplifier allows automatic recognition of pH sensors by Rosemount 1066, 1057, 1056 and 56 transmitters
Materials of Construction
Wetted Materials: Platinum (ORP only), titanium, Ryton, PTFE, glass, and user-specified O-ring material (EPDM, FKM, or FFKM)
Temperature Range
41 to 248 °F (5 to 120 °C)
Maximum Pressure
100 psig (790 kPa)
The Rosemount 3400HT High-Performance pH / ORP Sensor, with integral cable, incorporates several design innovations that prolong sensor life in difficult hot processes. High temperatures, fouling, coating and poisoning conditions cause increased deterioration of the glass sensing membrane. Use the Rosemount 3400HT pH/ORP sensor to lower your total cost of ownership and reduce sensor replacement.
- Rebuildable reference junction and electrolyte allow pH / ORP sensor use in applications of elevated temperatures, fouling, coating and poisoning
- Versatile mounting options feature either a 21" or 36" titanium tube sensor length
- SMART enabled to eliminate field calibration
Maximum Process Pressure
400 psig (2859 kPa [abs])
Max Pressure at Retraction or Insertion: 64 psig (542 kPa [abs])
Max Pressure at Retraction or Insertion: 64 psig (542 kPa [abs])
Materials of Construction
Wetted Materials: Platinum (ORP only), titanium, Ryton, PTFE, glass, and user-specified
O-ring material (EPDM, FKM, or FFKM)
O-ring material (EPDM, FKM, or FFKM)
Temperature Sensor Types
Platinum RTD 100 Ohm
The Rosemount 3400HTVP High Performance pH / ORP Sensor incorporates several design innovations that prolong sensor life in difficult hot processes. High temperatures, fouling, coating and poisoning conditions cause increased deterioration of the glass sensing membrane. Use the Rosemount 3400HTVP pH/ORP sensor to lower your total cost of ownership and reduce sensor replacement.
- Rebuildable reference junction and electrolyte allow pH / ORP sensor use in applications of elevated temperatures, fouling, coating and poisoning
- Versatile mounting options feature either a 21" or 36" titanium tube sensor length
- SMART enabled to eliminate field calibration
Maximum Process Pressure
400 psig (2859 kPa [abs])
Max Pressure at Retraction or Insertion: 64 psig (542 kPa [abs])
Max Pressure at Retraction or Insertion: 64 psig (542 kPa [abs])
Materials of Construction
Wetted Materials: Platinum (ORP only), titanium, Ryton, PTFE, glass, and user-specified
O-ring material (EPDM, FKM, or FFKM)
O-ring material (EPDM, FKM, or FFKM)
Temperature Sensor Types
Platinum RTD 100 Ohm
Rosemount 5081 Explosion-proof Transmitter is a single channel loop powered device that can accept input from pH/ORP sensors, conductivity (contacting and toroidal) sensors and amperometric (dissolved oxygen, chlorine, and ozone sensors).
- Robust explosion-proof design constructed with heavy duty cast aluminum
- Faster installation using Quick Start programming
- Intrinsically safe, non-incendive, and explosion-proof hazardous area location approvals
Measurement Range
Varies by sensor type. See Product Data Sheet for details.
Operating Temperature
-4 - 149 °F (-20 - 65 °C)
Power Supply
Minimum power supply voltage is 12 Vdc. Maximum power supply voltage is 42.4 Vdc (30 Vdc for intrinsically safe operation). Power supply voltage should cover the voltage drop on the cable plus the external load resistor required for HART® communications (250 Ω minimum).
