7774/7774D Meredian and Durafet II pH/ORP Insertion and Removal Mountings

The 7774 insertion/removal assemblies, which accommodate Durafet II and Meredian series combination (single-probe) pH or ORP electrodes, are designed for use in processes under pressure because the electrode can be inserted or removed without interrupting the process. Insertion can be into a pipeline, tank wall or other vessel in any position for applications such as boiler water analysis, demineralization, reverse osmosis, pharmaceutical and chemical production, waste treatment, and pulp and paper production.

7774 includes a valve assembly and a Durafet II or Meredian electrode mounted on a support tube. With the valve assembly connected to the process, the electrode is inserted into the assembly for a positive seal. When the valve is opened, the electrode is inserted into the process medium and locked in position. To remove the electrode, this sequence is reversed.

The electrode assembly can be safely inserted or withdrawn at process pressures up to 50 psig. Plastic and 316 stainless steel wetted materials are available for applications requiring chemical resistance or for high-temperature operation. A purge port on the plastic assembly permits automatic or manual inline cleaning or flushing.

The insertion/removal units can be supplied in two types of material:

  • 316 stainless steel ball valve and extension tube with Viton or Teflon seals
  • CPVC ball valve and extension tube with Viton, Teflon or EPDM seals

Selection of the materials of construction is based on the chemical composition of the process media, pressure and temperature of the process media, and in some cases, selection of the type of pH/ORP electrode desired by the end user.

The CPVC and stainless steel removal devices are supplied with a 15 3/8" pipe nipple for nominal 6" insertion depth. An accessory nipple option (21 3/8") provides 12" nominal insertion depth; the user may

make up a similar schedule 80, CPVC nipple with 1/2" NPT male at both ends for intermediate insertion depths. Overall length measured from the process connection is approximately 20" (508 mm). There is a requirement for 38" (970 mm) clearance for complete electrode removal from the process.



  • New Durafet II non-glass pH electrode can be easily inserted or withdrawn under pressure without interrupting the process.
  • Meredian II electrodes offer a selection of glass that provides low sodium error as well as optimum durability at operating temperatures. Long-term accuracy and performance are assured
  • Usable to 100 psig.
  • Rugged, corrosion-resistant insertion mountings of CPVC plastic or 316 stainless steel.
  • Non-fouling probe tips for slurries (such as pulp stocks up to 14 percent solids).
  • Most electrodes can be mounted in horizontal or inverted position.
  • Local preamplifier module permits signal transmission over long distances with unshielded lead-wire
  • Assemblies have reliable restraining mechanisms for safe removal under pressure.
  • Suitable for use in Class I, Division 2, Group A, B, C and D locations, FM approved intrinsically safe options for Division 1 areas with APT2000PH transmitter.
  • Plastic or 316 stainless steel valve assembly extension permits immersion of electrode as far as 12" into process.
  • External preamplifier or cap adapter for increased analyzer to 7774 separation distance.



7774 pH/ ORP Datasheet