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Industrial pH Two Wire 4-20 mA Transmitters LCD Display w/NEMA-4X Housing Model Available
PHTM-014, PHTM-212, PHT422i

pH Two Wire 4-20 mA Transmitters
Isolated or Non-Isolated Models Available
4 to 20 mA Output

The PHTM Series pH two wire transmitter is designed to provide a standard 4 to 20 mA current output which is proportional to the pH being measured. Its small size and encapsulated construction allow for easy installation and will accommodate any pH electrode with a BNC connector. Temperature compensation is either manual or automatic with use of any 1000 ohm Platinum RTD.

The PHTM-014 covers the full 0 to 14 pH range. The PHTM-212 with a 2 to 12 pH input is the popular choice for use with recorders or any application where it is convenient to divide the 4 to 20 mA output into ten divisions.

The PHTM-ORP is for an ORP electrode input with a range of 0 to 1000 mV.
The PHT422I features include a NEMA-4X housing, an integral LCD display for continuous pH reading or for a direct corresponding readout in milliamps, using a convenient push-button switch. The 4-20 mA output signal may be scaled in the field to meet specific pH ranges in any 1 to 14 pH unit increment. Temperature compensation is manual using a fixed resistor or automatic using any of NEWPORT's 700 Series thermistors.


PHT422I Isolated 4-20 mA Transmitter.
pH Electrodes purchased separately.


Range: 0 to 14 pH, 2 to 12 pH, 0 to 1000 mV

PHTM-014: 0 to 14 pH
PHTM-212: 2 to 12 pH
PHTM-ORP: 0 to 1000 mV
PHT442I: Any 1 to 14 pH unit, user selectable output

Accuracy: ±0.02 pH

PHTM: ±1.0 mV
Operating Temperature

PHTM-014, PHTM-212, PHTM-ORP: -25 to 70ºC (-13 to 158ºF)
PHT422I: -10 to 60ºC (14 to 140ºF)

Temperature Compensation

Manual: fixed resistors
  • PHTM-014, PHTM-212, 1000 ohm RTD
  • PHT422I NEWPORT 700 Series thermistor
Connector: BNC
Input Impedance: >1013 Ohms
Power Input: 12 to 80 Vdc (24 Vdc recommended)

PHTM-014: Non-isolated 4 to 20 mA
PHTM-212: Non-isolated 4 to 20 mA
PHTM-ORP: Non-isolated 4 to 20 mA
PHT422I: Isolated 4 to 20 mA

Input to Output Isolation: PHT422I, 600 V maximum


PHTM-014, PHTM-212, PHTM-ORP: 57.4 H x 38.1 W x 38.1 mm D (2.25" x 1.5" x 1.5")
PHT422I: 125 H x 74.2 W x 99.6 mm D (4.92" x 2.92" x 3.92")

PHT422I: 3 1/2 digit LCD
Display Resolution
PHT422I: 0.01 pH

Product Selection (Specify Model Number)
 Part Number   Availability   Price    Description   
 PHTM-014 in-stock    $260.00     Non-isolated 4 to 20 mA pH transmitter, 0 to 14 pH range  
 PHTM-212 Consult Sales    $260.00     Non-isolated 4 to 20 mA pH transmitter, 2 to 12 pH range  
 PHTM-ORP 3 Weeks    $260.00     Non-isolated 4 to 20 mA pH transmitter, 0 to 1000 mV range  
 PHT422I in-stock    $475.00     Isolated 4 to 20 mA pH transmitter with integral display, NEMA 4X enclosure  
 PSS-D12B in-stock    $218.00     12 or 24 Vdc power supply  
All dollar amounts on this site are shown in US currency.

 Note: Each unit comes complete with operator's manual.
 Ordering Example: (1) PHT422I isolated 4 to 20 mA pH transmitter with integral display and NEMA 4X enclosure, (1) PSS-D12B power supply = $693

Keywords: Industrial pH Two Wire 4-20 mA Transmitters, 2-wire transmitter

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