Pressure receptacles shall satisfy the following conditions:

(a) Pressure receptacles shall be designed for a design pressure of not less than 2.1 MPa (21 bar) (gauge pressure);

(b) In addition to the marks for refillable receptacles, the pressure receptacles shall bear the following particulars in clearly legible and durable characters:
(i) The UN number and the proper shipping name of the substance according to 3.1.2;
(ii) The maximum permitted mass when filled and the tare of the pressure receptacle, including accessories fitted during filling, or the gross mass.