MIL-DTL-23919C(SH)
4.5.6 Pressure. Each sample electrode shall be mounted in a pressure test fixture so that the face and mating
surface of the reference cell assembly shall be covered.
4.5.6.1 Class I reference cells. A pressure of 100±10 pounds/inches squared (70300±7030 kilograms/meters
squared) shall be applied to the base, electrode, and pin assembly prior to assembly of the holder (see figure 2). The
tube inserted over the electrode hub and O-rings shall be filled with a colored, translucent liquid containing a
wetting agent (i.e., Windex® or equal). The pressure shall be maintained for 2 minutes. No bubbles shall appear.
Additionally, no deformation shall be present on the reference electrode or assembly.
BASE AND PIN
ASS'Y ONLY
"O'-RING
FILL CAVITY WITH
SOAPY WATER
SOLUTION
GASKET
VALVE
TO
HELIUM
SOURCE
TEST
FIXTURE
FIGURE 2. Sample pressure test setup for class I reference cells.
4.5.6.2 Class II reference cells. Reference cell pressures are governed by ship specific criteria pertaining to the
test depth of the vessel. Reference cell testing shall meet the requirements of MIL-C-24231, Type II, with the
exception of insulation resistance, continuity, hardness, and dye-penetrant.
4.5.7 Chemical purity. Proper assessment of Ag and AgCl purity shall be conducted. Certification of this
assessment shall be provided.
4.5.8 Surface area. Surface area of a plate style reference cell shall be measured using a calibrated laboratory
ruler. Proper surface area of a mesh style reference cell shall be a mesh size of 40 or finer as illustrated in
ASTM E11.
4.5.9 Service life. When specified (see 6.2), certification of uniform thickness and longevity (life) calculations
shall be provided to support service life requirements. The life shall be based on the weight of AgCl used in the
reference cell. Ensure that the minimum amount of AgCl on cell surface is no less than the value given by:
3 × LeakageCurrent( A) × ServiceLife(sec)
Weight AgCl (mg ) =
1.49
Where: the leakage current is given as the hull polarization value (e.g., 0.85 volt) divided by the input impedance of
the potential measuring circuit (ohms). Note that the amount of AgCl on the reference cell face may typically be
more than this value in order to ensure stable readings. The calculated value is only a minimum.
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