Honeywell 4909 CPVC - Manual (Page 9)

Introduction
7/99 4909 CPVC Conductivity Cell Insertion/Removal Assembly– Operations Manual 1
1. Introduction
1.1 Overview
The 4909 Conductivity Cell Insertion/Removal Assembly is designed for use in a pipeline or closed vessel
where it is desirable to remove the cell for inspection and maintenance without shutting down the system
and releasing the pressure. The assembly comprises a 4908 Conductivity Cell and a 31074357 Removal
Device which are shown assembled in Figs. 1-2 and 1-3. It is to be used in applications for which
maximum pressure does not exceed 125 psig, and can be reduced to 50 psig during insertion and removal of
the cell. Maximum operating temperature is determined by the temperature compensator range. Do not use
in solutions above 80
°
C.
The depth of insertion is given in Figs. 3-1 and 3-2.
The conductivity cell is made of polyethersuflone (PES), which is resistant to most corrosive inorganic
chemicals over a wide range of temperatures (common exceptions are chlorinated hydrocarbons and
ketones). Sample solutions come into contact with the PES and the platinum or nickel electrode surface of
the cell. (Any cell constant can be supplied with either electrode material). The only materials of the 4909
Assembly with which the sample solution may come into contact are in the removal device which is
comprised of CPVC plastic, Teflon, EPDM and Viton materials. The automatic temperature compensator
may be built into the cell as shown in Section 2.2, Model Selection Guide.
CAUTION
Specific parameters of your process may prohibit the use of nickel electrodes. For example, always use a
platinum cell (Table II = 44) if the cell will measure or be exposed to regeneration acids or bases.
1.2 4908 Conductivity Cell
The molded conductivity cell and its one-inch diameter by 3-inch long adapter comprise a one piece cell
unit and are made of polyethersulfone (PES). This adapter serves as a stop during the removal operation.
The cell can be supplied with a two, three or four conductor, Tefzel-sheathed cable, Fig. 1-2. Either of two
different lengths of cable can be furnished as specified in the Model Selection Guide (MSG) number, see
Section 2.2, Model Selection Guide. Or the insertion/removal assembly can be supplied with a Universal
Head, Fig. 1-3.
The cells having constants of 5, 10, 20, 25 or 50 cm -1 are intended for making measurements in highly
conductive solutions. They differ in construction from those having constants of 0.01, 0.1, or 1. On the 5
to 50 constant cells, the electrodes are short tubes located midway inside the two parallel tubular channels
that run lengthwise through the cell, and are open to the sample at both ends of the cell. The channels are
larger on the 25 constant cell and they are elliptical on the 5 and 10 constant cell. The 0.01, 0.1, and 1.0
constant cells have a removable cell guard which is screwed onto the cell body to protect the electrode
surfaces. Cells with a guard tube must be used with the guard in place or the cell constant may differ from
that specified. Electrodes are three discs on the 1 constant cell, parallel plates on the 0.1 constant cell, and
a pair of concentric wires wound on the cell body on the 0.01 constant cell.