pHionics STs pH Transmitter

The STs series of submersible water quality transmitters have an integrated preamp and an isolated 'true 2-wire', 4-20 ma transmitter. Two independent channels simultaneously transmit a pH and temperature signal -- two wires for pH and two wires for temperature. The compact design afforded by the patented pHiConn (TM) keyless connection system -- and the 316SS (titanium optional) and Delrin construction -- make the rugged sensor/transmitter ideal for applications such as process control, data acquisition, wastewater treatment, and, groundwater monitoring, The units can be submersed to 200 feet (approximately 100 psi). Individual units can be combined to make redundant or multiparameter modules using the pHionics' patented pHiKLIP (TM) array system. The pHiKLIP (TM) system also allows for the units to be used in in-line (insertion) applications without fear of blow-out. As with all pHionics' designs, the sensor/transmitters are designed with 'ease of service' as a primary goal.

The 'true 2-wire', 4-20 ma STs series sensor/transmitters send a current proportional to the parameter being measured on the same two wires that provide the power (7 to 40 volts dc). Current transmission allows for long runs of inexpensive cable or wire (up to three miles) that is virtually noise-free without any signal loss that is common to voltage (IR drop) or digital (capacitance affecting 'rise/fall' timing). The seven volt operation allows the units to be powered by 12 volt battery systems with 5 volts of compliance, making them compatible with RTU's and solar powered applications. The units are intended for calibration via software supplied with the datalogger, PLC, or through the DCS.

The pH signal on Channel 1 is automatically temperature compensated -- providing a Nernstian correction to yield the true pH output regardless of temperature changes. This is not to be confused with the temperature channel of the transmitter, which provides an independent, isolated, 4-20 ma output proportional to the 0 to 50 C range on Channel 2. The auto-polarity correction feature directs the applied supply voltage to allow for proper operation regardless of wire hookup. The Red and Black wires are for channel 1 -- pH, and the White and Green wires are for channel 2 -- temperature.

The sensor cartridge has a fast, glass electrode, that is easily cleaned, and a double-junction, gel-filled reference system that combines for accurate and long life in tough process applications -- as well as simple groundwater monitoring applications. The cartridge can be replaced in 15 seconds -- further reducing costs.

 

 

Features and Benefits:

• Isolated outputs on all pHionics transmitters
  • No ground-loops -- will operate in tough process applications
    
    
•  0-50 Celsius temperature channel on all transmitters
  • A temperature transmitter at no additional cost
    
    
•  'True 2-wire' 4-20 ma output
  • No third wire required -- which can result in damage due to improper wiring
    
    
• Reversible input protection and correction
  • Transmitter cannot be wired incorrectly – will work even if wires are reversed – preventing damage to transmitter
    
    
• Small, 3/4" (19mm) diameter
  • Ideal for submersion in wells, and lower mounting costs, at higher pressures
    
    
•  Automatic temperature compensation of pH
  • Corrects for Nernstian temperature changes from is opotential point
    
    
•  Sensor (electrode) life of three years in typical applications
  • Resulting in a low cost of ownership (approx $10/mo) 
• Insertion (in-line) or submersion capability
  • Insertion (in-line) or submersion capability
    
    
•  Patented, field replaceable sensors and cables
  • The entire transmitter does not have to be scrapped, if only one or two components are damaged
    
    
•  Kevlar^TM (DuPont) reinforced, shielded, water-blocked, polyurethane jacketed cable -- standard
  • Added pull strength, low noise, and limited water damage due to compromised cable or transmitter -- not simply 'marine grade'
    
    
•  Optional titanium housing and FEP jacketed cables
  • For the extremely difficult applications
    
    
•  Double o-ring seals
  • Provide exceptional sealing for reliability on cable and sensor seals
    
    
• No potting -- Fully engineered transmitter with rebuildable components -- no potting required to conceal poor design
  • No premature failures due to poor sealing and curing of potting compounds – plus allows for the capability of easily replacing the cable, housing, or electronics – or simply exchanging the cable for a different length. Reduced weight.

 

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 Model Code Details