The new EXAxt 450 series builds on the superior functionality of the industry leading Yokogawa EXA series by enhancing the EXA's proven operation and application flexibility. The Model 450 series feature a uniquely simple touch screen menu structure that offers a choice of multiple languages.
The Model PH450 provides the best pH measurement accuracy in the industry resulting from advanced temperature compensation functionality, preloaded calibration standards, stability checks and online sensor and analyzer diagnostics to provide verifiable results.
In addition to dynamic sensor checking, the Model 450 offers a wash cycle function to assure trouble free and accurate analysis with a minimum of maintenance. The EXAxt 450 also offers full application functionality with PID control on either mA output(s) or on contact output(s).
The PH450 combines pH with Temperature and ORP (Redox) measurement that can be utilized though different output functions: two mA outputs, four independent SPDT contact outputs and a digital HART signal is superimposed on mA1. This information can be used to generate additional current and contact outputs in the HIM monitor and in maintenance optimization programs like PRM or AMS.
The EXAxt 450 series provides a truly unique Human Machine Interface. The high resolution graphical display and touch screen operation provides all information clearly visible and easily accessible to the operator. Simply select the language of choice and on screen instructions assure that the best configuration for the application is obtained.
|Measuring principle||Glass electrode method|
|Input ranges||pH: -2 to 16 pH
ORP: -1500 to 1500 mV
rH: 0 to 100 rH
Temperature: -30 to 140 deg C (Pt1000)
|Transmission signals||General: Two isolated outputs of 4 to 20 mA DC with common negative. Maximum load 600 Ω. Bi-directional HART® digital communication, superimposed on mA1 (4 to 20 mA) signal.
Output function: Linear or Non-linear (21-step table) output for pH, temperature, ORP or rH.
Control function: PID control.
Burn out function: Burn up (21.0 mA) or burn down (3.6 mA) to signal failure accorded with NAMUR NE43.
Hold: The mA-outputs are frozen to the last/fixed value during calibration/commissioning.
|Contact outputs||General: Four SPDT relay contacts with display indicators.
Switch capacity: Maximum values 100 VA, 250 V AC, 5 A
Maximum values 50 W, 250 V DC, 5 A
Status: High/Low process alarms, selected from pH, ORP, rH and temperature. Configurable delay time and hysteresis. Failure annunciation.
Control function: On/Off, PID duty cycle or pulsed frequency control.
Wash: Contact can be used to start manual- or interval time wash cycles.
Hold: Contact can be used to signal the Hold situation.
Fail: Contact S4 is programmed as fail-safe contact.
|Contact input||Remote wash cycle start.|
|Temperature compensation Function||Automatic or manual. Compensation to Nernst equation. Process compensation by configurable temperature coefficient, NEN6411 for water or strong acids/bases or programmable matrix.|
|Calibration||Semi-automatic 1 or 2 point calibration using pre-configured NIST, US, DIN buffer tables 4, 7 & 9, or with user defined buffer tables, with automatic stability check. Manual adjustment to grab sample.|
|Display||Graphical Quarter VGA (320 x 240 pixels) LCD with LED backlight and touch screen.|
|Housing||Cast Aluminum housing with chemically resistant coating; Polycarbonate cover with Polycarbonate flexible window, Protection IP66/NEMA 4X/CSA Type 3S|
Ratings; 100 to 240 V AC, Acceptable range; 90 to 264 V AC
Ratings; 50/60 Hz, Acceptable range; 50 Hz ±5%, 60 Hz ±5 %
Power Consumption; 15 VA
Ratings; 12 to 24 V DC, Acceptable range; 10.8 to 26.4 V DC
Power Consumption; 10 W
|Environment and operational conditions||Ambient temperature: -20 to 55℃ (-5 to 130℉)
Storage temperature: -30 to 70℃ (-20 to 160℉)
Humidity: 10 to 90 % RH at 40℃ (100℉) (non-condensing)
|pH input||≤0.01 pH|
|ORP input||≤1 mV|
|Temperature||≤0.3℃ (≤0.4℃ for Pt100)|
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For control of batch neutralization, a pH measurement coupled with a timer-controlled chemical feed scheme provides very satisfactory results.
This system can be adapted for either acid waste or alkaline waste neutralization.
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Cyanide-bearing wastewater from mining and electroplating facilities and certain types of chemical plants is toxic and must be treated by oxidation with chlorine or chloride to bring the cyanide concentration within regulatory limits.
The treatment of wastewater from pulp and paper plants is a serious environmental concern. Yokogawa's submersion holder with an ultrasonic+air-jet cleaner (customized product) can reduce the manual cleaning frequency to just once every one or two months.
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Wastewater from electroplating facilities and certain types of chemical plants contains toxic forms of hexavalent chromium such as chromate and dichromate. The hexavalent chromium in this wastewater must be reduced before the water can be discharged. This requires a two-step process: hexavalent chromium (CR6) is reduced to trivalent chromium (CR3); and CR3 is precipitated as chromium hydroxide.
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