The CS526 isolated pH probe makes reliable, accurate pH measurements in aqueous solutions. It can be submersed or inserted into tanks, pipelines, and open channels. This probe has a serial, TTL output that represents a 2 to 12 pH range.Read More
|pH Range||2 to 12|
|Power Requirements||5 Vdc|
|Current Consumption||15 mA (maximum)|
|Accuracy||±0.2 pH (over 10° to 40°C)|
|Operating Temperature Range||10° to 40°C|
|24 h Drift||< 0.15 pH (after 15 min. soak in pH 7 at 25°C)|
|Allowed Water Pressure||0 to 700 kPa (0 to 101.5 psi)|
|Cable Type||Three-twisted pair, 24 AWG cable with Santoprene jacket|
|Sensor Material||Polyetheretherketone (PEEK)|
|Maximum Cable Length||100 m (328 ft)|
|Diameter||16 mm (0.63 in.)|
|Length||102 mm (4 in.)|
|Weight||318 g (11.2 oz) with 3.05 m (10 ft) cable|
Number of FAQs related to CS526: 15
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The CR300 and CR310 dataloggers do not support TTL logic, which is what the CS526-L sensor uses. A TTL to RS-232 converter (supplied by the user) could be used, however.
The source and the drain are two of the three electrodes contained within the ISFET chip, and they behave in much the same way. The third electrode in the ISFET chip, the gate, has an electrical field that influences the current that flows between the source and the drain. The electrical potential in the ISFET pH sensor is measured between the reference electrode and the source.
An ISFET chip pH sensor has three main components:
In an ISFET chip pH sensor, the chemical coating on the gate electrode can vary depending on the model and manufacturer of the pH sensor. Depending on which chemical coating is used and what elements are present in the sample solution, there may be some ion interference.
PolyEtherEtherKetone (PEEK) is a plastic material that has very good thermal stability and chemical resistance properties. This material was chosen for use in the manufacture of the CS526-L because of its natural resistance to organic acids (acetic, carbonic, citric, tartaric, etc.) and its hydrolysis resistance to fresh and saltwater.
The CS526-L pH sensor uses an ISFET chip instead of pH-sensitive glass, which is used for many other pH sensors. The ISFET chip is a transistor coated with a chemically sensitive material. One of the ISFET chip’s electrodes (the gate) and the reference electrode are submersed in the same sample solution. A circuit path is established between the two electrodes. The difference in electrical potential between the two electrodes is directly proportional to the sample solution’s pH. Thus, by measuring the electrical potential, the pH is measured.
Silver is the best electrical conductor of all the metals because it has the lowest electrical resistance. The silver wire, coated in silver chloride, is relatively insensitive to changes in temperature.
A reference electrode can become contaminated when poisoning ions such as lead, iron, chrome, cyanide, or sulfide enter the reference electrode and react either with the silver wire or with the electrolyte solution.
The contamination may not become apparent until the silver-chloride coating is completely dissolved and the electrical potential from the reference electrode has changed greatly. If this occurs, the reference electrode must be replaced.
Cleaning and/or calibration may be required when the measurements are scattered, drifting occurs, or there is physical evidence of fouling. Measurements for pH must be monitored regularly to check for scattering. However, just because the results are scattered does not necessarily indicate the need for an adjustment. For example, there may be a change in the water source that causes the scattering. As a sensor ages, however, the scattering of the measured values tends to increase.
To check the performance of a pH sensor, use it to measure a buffer solution in the correct range. If the value returned is within the specified range, the sensor does not need to be calibrated.
Most Campbell Scientific sensors are available as an –L, which indicates a user-specified cable length. If a sensor is listed as an –LX model (where “X” is some other character), that sensor’s cable has a user-specified length, but it terminates with a specific connector for a unique system:
If a sensor does not have an –L or other –LX designation after the main model number, the sensor has a set cable length. The cable length is listed at the end of the Description field in the product’s Ordering information. For example, the 034B-ET model has a description of “Met One Wind Set for ET Station, 67 inch Cable.” Products with a set cable length terminate, as a default, with pigtails.
If a cable terminates with a special connector for a unique system, the end of the model number designates which system. For example, the 034B-ET model designates the sensor as a 034B for an ET107 system.