Regulatory descriptive statement of the Citroën hydropneumatic sphere (1953)

In this document

This is an official form titled Descriptive statement of an apparatus subject to regulation under Art. 1, 4, or 5, of the decree of 18/1/43 p. 3. The manufacturer identified is the "Sté Ame A. Citroën, 117 à 167 quai de Javel, Paris XV" p. 3.

Regulatory characteristics

The document specifies the nature of the stored gas (air), a maximum operating pressure of "156.9 HPZ", a calculated test pressure of "240/1.02 = 235.3" — the latter value being added by hand p. 3 — as well as an initial inflation of "100 Kgs for a volume of 0.75" p. 3.

Description of the apparatus

The form describes an "air and oil accumulator under pressure, separated by a butyl membrane", equipped with a safety valve limiting the pressure to the indicated value. The oil used is presented as "a mixture of castor oil and diacetone alcohol" p. 3.

Technical characteristics

The ends are described as "spherical", the two hemispheres being "screwed onto each other (flat threads)", with "ARMCO" piping p. 3. The document finally mentions that it is "executed according to the submitted plan" and "certified compliant by the Manufacturer" in Paris, with no signature date provided p. 3.

Context

This type of form is part of the French regulation of pressure equipment resulting from the decree of 18 January 1943, which required manufacturers to declare the technical characteristics of any pressure vessel, under the control of the Mines department. The accumulator described corresponds to the principle of the hydropneumatic suspension developed by Paul Magès for Citroën — whose first plans date from 17 February 1944 and first tests on 2 CV from May-July 1946 —, a system that would notably equip the famous DS presented on 6 October 1955. The castor oil/diacetone alcohol mixture mentioned here ("LHS") was the hydraulic fluid historically used by Citroën before the subsequent adoption of LHM.

Archivist's perspective

This document is likely an administrative piece complementary to the technical declaration of the hydropneumatic accumulator to the Mines services, in the same logic as the Citroën letter to the Mines of 12 March 1953, dated the same year.

It appears to be a standard form, filled out with precision regarding the dimensions and the resistance of the metal p. 3, which testifies to the concern for regulatory compliance surrounding this nascent invention. The test pressure value, corrected by hand p. 3, suggests a final adjustment before official filing. This document can be compared with the calculation note on the thickness of the accumulator wall, which likely documents the technical justifications that led to the values declared here.