7777/7777D Meredian and Durafet II pH/ORP In-line/Immersion Mountings

Honeywell's 7777 series of electrode mountings enables users to interface Durafet II pH electrodes with a process via a ¾" threaded connection and Meredian II by either submersing the electrode or mounting it into a ¾" threaded connection. Durafet II pH electrodes are the first industrial ISFET (Ion Sensitive Field Effect Transistor)-based pH sensors. They join Honeywell's industry-proven glass pH electrodes in the 7777 series mounting to provide accurate and dependable process pH measurement.

The Durafet II and Meredian II pH electrodes offer a reliable combination of measuring and reference electrodes together with an integral automatic temperature compensator PT1000 or NKT8.5K in a one-piece, corrosion-resistant, molded Ryton body. Quick disconnect plugs enable easier installation and maintenance than with any other electrode available. The compact Durafet II and Meredian II electrodes with 3/4" NPT male connections are easily adapted for in-line mounting without O-rings or special seals.

Meredian II is also available in immersion and in-line mounting. In-line mounting allows Meredian II to be used with a quick disconnect. This feature provides the flexibility to change only the electrode after the initial installation. This option eliminates the need to unwire and wire a new electrode to the analyzer as the original cable can be reused. The large surface area of the reference junction resists fouling and maintains reliable, low impedance contact with the process solution. The reference junction"s symmetrical, annular shape surrounding the measuring element minimizes the effects of electrical current passing through the process solution. This offers a significant improvement when compared with asymmetrical electrode designs that develop large offset potentials and prohibit pH measurements in applications such as electroplating tanks or electrolytic cells.

Durafet II combination electrodes feature state-of-the-art pH measurement technology using an ISFET sensing element. This virtually unbreakable, truly solid state electrode provides especially fast response. Durafet II sensors produce a direct low impedance pH signal for outstanding reliability even at low temperatures and with no sodium error or ORP interference. Durafet II electrodes are available with a quick disconnect cable.

The combination Durafet II pH electrode incorporates a replaceable reference junction frit and gel, assuring long life even in the most highly fouling applications. In addition, Durafet II electrodes can be interfaced with virtually any existing pH instrumentation, thus allowing wide freedom of use.

Meredian II electrodes offer glass compositions that provide low sodium error as well as optimum durability at operating temperatures. Long-term accuracy and performance are assured. Meredian II electrodes include a permanent reference junction and gel fill for maintenance-free operation. The internal automatic temperature compensator is compatible with both analog and microprocessor-based Honeywell instruments when used with the appropriate preamplifier.



Durafet II Electrode

  • Uses ISFET (Ion Sensitive Field Effect Transistor) technology for exceptionally fast response
  • Virtually unbreakable, truly solid state
  • Integral or quick disconnect cable options
  • New "no epoxy" packaging design
  • Reference junction frit and gel are replaceable
  • Low impedance pH signal
  • One electrode for entire pH and temperature range
  • Retro-fittable to existing pH instrumentation
  • Suitable for in-line applications
  • Speed of response up to 10 times faster than glass pH electrodes
  • No sodium ion interference at high pH levels

Meredian II Electrode

  • Choice of integral lead-wire with quick disconnect at preamplifier or quick disconnect at sensor (for in-line applications).
  • Glass formulations that ensure uncompromised performance
  • ORP (Redox) electrodes with platinum or gold sensors
  • Suitable for in-line and submersion applications; may be mounted in any position 


7777 Mounting

  • FM-approved, intrinsically safe for Class I, Division 1, Group A, B, C, D areas with APT2000 Series transmitters and barriers
  • Rugged combination electrodes with fast-responding integral automatic temperature compensator
  • Molded, chemical-resistant Ryton body
  • Large reference electrode volume uses a true gel fill that maintains high viscosity with temperature
  • Rugged molded NEMA 6 submersible polypropylene preamp module housing



7777 Combination pH/ ORP Datasheet