Platinum Sensing Pin
The HI769828-1 ORP sensor uses a platinum sensor for redox measurements. An ORP sensor must be chemically inert; it cannot be oxidized or reduced itself. It must also have the proper surface characteristics to promote rapid electron exchange, a property known as high exchange current density. Two noble metals have proven to work well for this purpose: pure platinum and pure gold are both used in the construction of ORP sensors. The platinum sensor is often preferred because it is mechanically simpler and safer to produce.
The PEI (polyetherimide) electrode body is suitable for a wide range of applications and excels in field measurements due to its durability. The shielding around the spherical glass tip minimizes breakage due to accidental bumping or dropping of the electrode. The PEI plastic is a high quality plastic that is chemically resistant to many harsh chemicals.
Double Junction Reference
A double junction electrode has an internal compartment surrounding the reference wire. Silver ions are present in the electrolyte of the internal compartment, which houses the Ag/AgCl reference wire; the electrolyte outside this compartment is silver free. The double junction design means that virtually no silver from the electrode enters the sample. This design allows measurement in applications where silver ions in the sample are undesirable or silver precipitates on the junction are likely to form.
This type of junction is often used on electrodes with gelled electrolytes. The advantage of this junction is it is renewable; as the cloth-like material is pulled out from its position, the junction is renewed with an uncontaminated, fresh surface.
Color Coded Sensor
Sensors are color coded to match sensor ports on the probe for quick, field-replaceable, screw-type, connection and identification.