Rugged combination electrodes with flat measuring surfaces are ideal for industrial pH applications. In both coating and abrasive applications these cartridge type electrodes can improve measurement accuracy, reduce maintenance, prolong electrode life and virtually eliminate breakage. Electrodes have a unique and innovative design. In the center of the measuring surface is the pH-responsive flat glass surface. This surface is surrounded by the flat porous plastic reference junction. The large area of this porous junction has thousands of pores that provide excellent sample contact. Built into the electrode’s body is a sealed, gel-filled double junction reference design. This design provides an extra barrier against reference side contamination. Also, it allows the electrodes to be used in applications where sulfides, mercaptans, heavy metal ions and similar materials are present. The submersion assembly has a 1⁄2" MNPT thread to which a coupling and length of supporting pipe can be attached for submersion applications. It is also used when cables must be installed in conduit.