For pressure receptacles, the general packing provisions of 4.1.6.1 shall be met. In addition, for MEGCs, the general requirements of 4.2.4 shall be met.

Cylinders, tubes, pressure drums, bundles of cylinders constructed as specified in 6.2 and MEGCs constructed as specified in 6.7.5 are authorized for the transport of a specific substance when specified in the following tables. For some substances, the special packing provisions may prohibit a particular type of cylinder, tube, pressure drum or bundle of cylinders.

(1) Pressure receptacles containing toxic substances with an LC50 less than or equal to 200 mL/m3 (ppm) as specified in the table shall not be equipped with any pressure relief device. Pressure relief devices shall be fitted on pressure receptacles used for the transport of UN 1013 carbon dioxide and UN 1070 nitrous oxide. Other pressure receptacles shall be fitted with a pressure relief device if specified by the competent authority of the country of use. The type of pressure relief device, the set-to-discharge pressure and relief capacity of pressure relief devices, if required, shall be specified by the competent authority of the country of use.

(2) The following three tables cover compressed gases (Table 1), liquefied and dissolved gases (Table 2) and substances not in Class 2 (Table 3). They provide:

(a) The UN number, proper shipping name and classification of the substance;

(b) The LC50 for toxic substances;

(c) The types of pressure receptacles authorized for the substance, shown by the letter "X";

(d) The maximum test period for periodic inspection of the pressure receptacles.
Note: For pressure receptacles which make use of composite materials, the maximum test period shall be 5 years. The test period may be extended to that specified in Tables 1 and 2 (i.e. up to 10 years), if approved by the competent authority of the country of use.

(e) The minimum test pressure of the pressure receptacles;

(f) The maximum working pressure of the pressure receptacles for compressed gases (where no value is given, the working pressure shall not exceed two thirds of the test pressure) or the maximum filling ratio(s) dependent on the test pressure(s) for liquefied and dissolved gases;

(g) Special packing provisions that are specific to a substance.

(3) In no case shall pressure receptacles be filled in excess of the limit permitted in the following requirements.

(a) For compressed gases, the working pressure shall be not more than two thirds of the test pressure of the pressure receptacles. Restrictions to this upper limit on working pressure are imposed by special packing provision "o" in (5) below. In no case shall the internal pressure at 65°C exceed the test pressure.

(b) For high pressure liquefied gases, the filling ratio shall be such that the settled pressure at 65°C does not exceed the test pressure of the pressure receptacles.
The use of test pressures and filling ratios other than those in the table is permitted, except where (5), special packing provision "o" applies, provided that:
(i) the criterion of (5), special packing provision "r" is met when applicable; or
(ii) the above criterion is met in all other cases.
For high pressure liquefied gases and gas mixtures for which relevant data are not available, the maximum filling ratio (FR) shall be determined as follows:

	FR = 8,5 x 0,0001 x dg x Ph

where
FR = maximum filling ratio
dg = gas density (at 15°C, 1 bar) (in g/L)
Ph = minimum test pressure (in bar)
If the density of the gas is unknown, the maximum filling ratio shall be determined as follows:

	FR = Ph x MM x 0,001 / (R x 338)

where
FR = maximum filling ratio
Ph = minimum test pressure (in bar)
MM = molecular mass (in g/mol)
R = 8.31451 × 10-2 bar·L/mol·K (gas constant)

For gas mixtures, the average molecular mass is to be taken, taking into account the volumetric concentrations of the various components.

(c) For low pressure liquefied gases, the maximum mass of contents per litre of water capacity shall equal 0.95 times the density of the liquid phase at 50°C; in addition, the liquid phase shall not fill the pressure receptacle at any temperature up to 60°C. The test pressure of the pressure receptacle shall be at least equal to the vapour pressure (absolute) of the liquid at 65°C, minus 100 kPa (1 bar). For low pressure liquefied gases and gas mixtures for which relevant data are not available, the maximum filling ratio shall be determined as follows:

	FR = (0,0032 x BP - 0,24) x d1

where
FR = maximum filling ratio
BP = boiling point (in kelvin)
dl = density of the liquid at boiling point (in kg/L)

(d) For UN 1001, acetylene, dissolved, and UN 3374 acetylene, solvent free, see (5), special packing provision "p".

e) For liquefied gases charged with compressed gases, both components - the liquefied gas and the compressed gas - have to be taken into consideration in the calculation of the internal pressure in the
pressure receptacle.

The maximum mass of contents per litre of water capacity shall not exceed 0.95 times the density of the liquid phase at 50°C; in addition, the liquid phase shall not completely fill the pressure receptacle at any temperature up to 60°C.
When filled, the internal pressure at 65°C shall not exceed the test pressure of the pressure receptacles. The vapour pressures and volumetric expansions of all substances in the pressure receptacles shall be considered. When experimental data is not available, the following steps shall be carried out:

(i) calculation of the vapour pressure of the liquefied gas and of the partial pressure of the compressed gas at 15°C (filling temperature);

(ii) calculation of the volumetric expansion of the liquid phase resulting from the heating from 15°C to 65°C and calculation of the remaining volume for the gaseous phase;

(iii) calculation of the partial pressure of the compressed gas at 65°C considering the volumetric expansion of the liquid phase;
Note: The compressibility factor of the compressed gas at 15°C and 65°C shall be considered.

(iv) calculation of the vapour pressure of the liquefied gas at 65°C;

(v) the total pressure is the sum of the vapour pressure of the liquefied gas and the partial pressure of the compressed gas at 65°C;

(vi) consideration of the solubility of the compressed gas at 65°C in the liquid phase.

The test pressure of the pressure receptacle shall not be less than the calculated total pressure minus 100 kPa (1bar).

If the solubility of the compressed gas in the liquid phase is not known for the calculation, the test pressure can be calculated without taking the gas solubility (subparagraph (vi)) into account.

(4) The filling of pressure receptacles shall be carried out by qualified staff using appropriate equipment and procedures.

The procedures should include checks of:
(a) the conformity of receptacles and accessories with the provisions of this Code;
(b) their compatibility with the product to be transported;
(c) the absence of damage which might affect safety;
(d) compliance with the degree or pressure of filling, as appropriate;
(e) marks and identification.

These requirements are deemed to be met if the following standards are applied:

ISO 10691:2004  | Gas cylinders - Refillable welded steel cylinders 
                | for liquefied petroleum gas (LPG) - Procedures for checking
                | before, during and after filling.
----------------|-----------------------------------------------------------
ISO 11372:2011  | Gas cylinders - Acetylene cylinders - Filling conditions 
                | and filling inspection
----------------|-----------------------------------------------------------
ISO 11755:2005  | Gas cylinders - Cylinder bundles for compressed and 
                | liquefied gases (excluding acetylene) - Inspection
                | at time of filling
----------------|-----------------------------------------------------------
ISO 13088:2011 +| Gas cylinders - Acetylene cylinder bundles - Filling 
Amd 1:2020      | conditions and filling inspection
----------------|-----------------------------------------------------------
ISO 24431:2016  | Gas cylinders - Seamless, welded and composite cylinders
                | for compressed and liquefied gases (excluding
                | acetylene) - Inspection at time of filling

(5) Special packing provisions:
Material compatibility
see listing on tab "Packing instruction P200". 