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Model 9121 Two-Wire pH/ORP Transmitter
Click on part number above to request an RFQ or place an order online.

Electronic ranges of 100 to 100,000 µMhos with a 1.0 cell constant
Can be powered with a single DC supply, has 0-5V and 4-2OmA output signals
Temperature compensation slope adjust allows accurate measurement in a wide variety of solutions
The Model 9121 is designed to meet the need for an inexpensive, yet versatile, two-wire transmitter which produces a 4-20ma current output signal proportional to a pH or Redox input.
This high performance pH/ORP transmitter offers reduced installation cost due to its two-wire design. It can be supplied with the high impedance input stage mounted inside its case for direct electrode connection, or this portion of the circuit maybe removed and located nearer the sensor assembly.
Model 9121 provides a well isolated 4-20ma output signal compatible with common recorders, data loggers and most process control systems.
Three field selectable operating modes-STANDBY,0-14 pH (or ±2000mv), and EXPANDED - allow easy startup and calibration using standard buffers.
Continuously variable expansion (to x10) and zero suppression (to 14 pH units) capabilities allow any 1.4 pH or greater fraction of the input range to be expanded to a full 4-20ma output - yet electrode function can still be checked using standard buffers by simply switching to the 0-14 pH range. For example, a working range of 8.0 to 12.0 pH can be readily calibrated using 7.0 and 10.0 buffers without the need for unstable (and uncommon) high pH buffers.
As an ORP instrument, the versatile continuous controls allow expansion of any 400mv (or greater) span to 4-20ma.

SPECIFICATIONS
POWER: +10 to +40V DC, 35mA quiescent current, plus 20mA for output signal
REPEATABILITY: ±0.5% of full scale
RANGE: Electronic ranges of 100 to 100,OOOµMhos, selected by dip switch and Standardization setting. Multiplying by available probe constants gives operating ranges of 1 to 2,000,OOOµMhos.
OUTPUTS: Non-isolated signals of 0 to 5V DC non-expanded, and 0 to 5V DC or 4 to 20mA expanded (Zero and Span controls allow expanded outputs to represent any 25% to 100% portion of full scale)
TEMPERATURE COMPENSATION: 0 to 100°C with slope adjust from 0 to 4%/ºC using 10KΩ@25°C thermistor
WIRING CONNECTIONS: 16 to 26 ga. wires with 3/8" long stripped ends, removable plug-in terminal strips
MOUNTING: #6 or #8 standoffs, 1/4" or longer, non-conductive recommended

(Return to 2/Wire Transmitter)
	Model 9121 Two-Wire pH/ORP Transmitter Click on part number above to request an RFQ or place an order online. Electronic ranges of 100 to 100,000 µMhos with a 1.0 cell constant Can be powered with a single DC supply, has 0-5V and 4-2OmA output signals Temperature compensation slope adjust allows accurate measurement in a wide variety of solutions The Model 9121 is designed to meet the need for an inexpensive, yet versatile, two-wire transmitter which produces a 4-20ma current output signal proportional to a pH or Redox input. This high performance pH/ORP transmitter offers reduced installation cost due to its two-wire design. It can be supplied with the high impedance input stage mounted inside its case for direct electrode connection, or this portion of the circuit maybe removed and located nearer the sensor assembly. Model 9121 provides a well isolated 4-20ma output signal compatible with common recorders, data loggers and most process control systems. Three field selectable operating modes-STANDBY,0-14 pH (or ±2000mv), and EXPANDED - allow easy startup and calibration using standard buffers. Continuously variable expansion (to x10) and zero suppression (to 14 pH units) capabilities allow any 1.4 pH or greater fraction of the input range to be expanded to a full 4-20ma output - yet electrode function can still be checked using standard buffers by simply switching to the 0-14 pH range. For example, a working range of 8.0 to 12.0 pH can be readily calibrated using 7.0 and 10.0 buffers without the need for unstable (and uncommon) high pH buffers. As an ORP instrument, the versatile continuous controls allow expansion of any 400mv (or greater) span to 4-20ma.
SPECIFICATIONS POWER: +10 to +40V DC, 35mA quiescent current, plus 20mA for output signal REPEATABILITY: ±0.5% of full scale RANGE: Electronic ranges of 100 to 100,OOOµMhos, selected by dip switch and Standardization setting. Multiplying by available probe constants gives operating ranges of 1 to 2,000,OOOµMhos. OUTPUTS: Non-isolated signals of 0 to 5V DC non-expanded, and 0 to 5V DC or 4 to 20mA expanded (Zero and Span controls allow expanded outputs to represent any 25% to 100% portion of full scale) TEMPERATURE COMPENSATION: 0 to 100°C with slope adjust from 0 to 4%/ºC using 10KΩ@25°C thermistor WIRING CONNECTIONS: 16 to 26 ga. wires with 3/8" long stripped ends, removable plug-in terminal strips MOUNTING: #6 or #8 standoffs, 1/4" or longer, non-conductive recommended