MIL-PRF-27201E
4.2.4 Lot. A lot shall consist of one of the following:
a. Type I. For gas cylinders, a lot is defined as all of the hydrogen supplied in one or more
container(s) filled from a single manifold at the same time. The first and last cylinders filled within a given
lot are typically sampled. Other samples may be selected at random as required.
b. Type I. Gas containers that are interconnected by a single manifold that equalizes the
pressure across all the containers shall be considered as one lot for the purpose of this specification.
c.
Type II. Each filled container shall constitute a lot.
4.2.4.1 Sample. Each sample shall be of sufficient size to conduct all the quality conformance
tests as specified herein. Unless otherwise specified, the quality conformance tests shall be performed
on each required sample (see 6.2). When required, an equivalent sample shall be forwarded to a
laboratory designated by the procuring activity for testing.
4.2.4.2 Sampling methods. Each sample taken for analysis shall be representative of the entire
contents of the container being sampled. All apparatus used shall be made of suitable materials. Unless
otherwise specified in the acquisition requirements (see 6.2), sampling shall be accomplished by one of
the following methods.
a. Type I, gaseous hydrogen may be sampled in accordance with ASTM F307 and Type II, liquid
hydrogen may be sampled in accordance with ASTM F310. It is critical that the sampling port be clean
and free of contaminants.
b. Connect the shipping container being sampled directly to the analytical equipment using
suitable pressure regulation as required to prevent over-pressurization of the equipment.
4.2.5 Non-bulk Containers. Non bulk containers are defined as containers with a water capacity
of 400 liters, or less. The number of non-bulk containers Type I (gaseous) or Type II (liquid) hydrogen will
be in accordance with Table II. Containers to be sampled may be selected at random.
4.2.6 Bulk Containers. Bulk containers are defined as having a water capacity in excess of 400
liters. Each bulk container filled with Type I (gaseous) and Type II (liquid) hydrogen constitutes a lot and
shall be sampled.
4.2.6.1 Continuous service (see 6.4.1). Unless otherwise specified by the procuring activity, the
following sample option for hydrogen shall be used for storage and transport tanks engaged in continuous
hydrogen service (see 6.2). Contractor shall sample the contents of each transport tank engaged in
continuous hydrogen service at least once every seven days at uniform intervals of time. Samples shall
be taken from the filled transport tanks. Contractor shall sample the contents of each transport tank when
entering continuous service and when the transport tank has remained empty for a period greater than 24
hours. When empty, all ports and vents shall remain closed to the atmosphere. While in continuous
service, compliance with quality conformance tests specified herein shall be determined by sampling the
filling point storage tank after each addition or, in case of continuous production, at established intervals
not less frequent than once every 24 hours. When a storage tank is being filled during a change of duty
shift, sampling shall be performed after filling.
4.3 Rejection. When any sample tested in accordance with 4.4 fails to conform to the
requirements specified herein, the entire lot represented by the sample shall be rejected.
4.4 Analytical procedures. Unless otherwise specified, samples shall be analyzed according to
the procedures described below (see 6.2). Calibration gas standards may be required to calibrate (zero
and span) analytical instruments used to determine the purity and impurity contents of the hydrogen. The
accuracy of the calibration gas standards is to be traceable to the National Institute of Standards and
Technology (NIST).
4.4.1 Parahydrogen. Parahydrogen shall be determined by thermal conductivity type in-stream
analyzers installed in the manufacturer's plant system. Analyzers shall be calibrated integrally by the
appropriate use of temperature-controlled catalyst beds.
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