The electrodes use a flat glass surface operating principle. All InsiteIG electrodes are combination pH/reference or ORP/reference electrodes with double reference junctions for added protection against contamination.
The holder incorporates self-cleaning via air or water jet. Holder electronic drift is less than 1% per year. Operating temperature range is 0 to 65 degrees C. Holder wetted materials are epoxy, polyurethane, and PVC. Electrode wetted materials are CPVC, polyethylene, glass, viton o-rings, and platinum for ORP electrodes.
The Insite Instrumentation Group Model 28 (M-28) uses the Insite Model 51 pH (M-51) and the Model 52 ORP (M-52) electrodes. The Model 28 holder allows the user to mount pH or ORP electrodes throughout the plant without having to deal with running conduit between the electrodes and analyzer. This allows for significant savings on installation costs while also allowing maximum flexibility in electrode placement. The electrode preamp, signal conditioner, and temperature compensation circuits are all built into the holder, making electrode replacement easy and inexpensive. No other pH / ORP electrode system can compare with the features and benefits of this design.
The M-28 sensor connects to a Sensor Transmitter (ST 2) junction box. The ST 2 then communicates with the Process Transmitter (PT 2) via a ZigBee compliant Rf module. There is an embedded antenna which provides an outdoor line of sight range up to one mile. When several ST 2 / Sensor pairs are installed they form a self-healing mesh network that increases reliability.
The M-28 Holder standard suspended configuration includes a the 1-1/2" NPT male mounting thread, 1/4" quick connect tube fitting for the integrated jet clean, and 33ft (10m) of sensor communications cable. Additional cable length is available upon request.
Both the M-51 and M-52 are cartridge type electrodes making replacement simple and easy. The cartridge is sealed into the holder with a reliable double o-ring seal. All replacement electrodes ship complete with o-rings. The threaded TNC connector at the top of the electrode body ensures a reliable electrical connection to the holder.
In the center of the measuring surface is the pH sensitive flat glass surface. This surface is surrounded by the flat porous reference junction. The large area of this porous junction has thousands of pores allowing for excellent sample contact. The electrode is enclosed by the electrode body. Built into the electrode body is a sealed, gel filled double junction reference half cell. This design adds an extra barrier against contaminants. This also allows the electrode to be used in applications where sulfides, heavy metal ions, and similar materials are present.
The flat surface measuring approach has several advantages over the typical spherical electrode. The flat sensing surface is rugged, abrasion resistant, and to some degree self-cleaning. In both coating and abrasive applications these cartridge type electrodes can improve measurement accuracy, prolong electrode life, reduce maintenance, and virtually eliminate breakage.
See also: Portable Dissolved Oxygen and
Portable Suspended Solids