L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des

L'air Liquide

Francis Cuny

Didier Lasnier

Jean-Pierre Schultz

Louis Auzary

Hugues Vermeille

Jean-Marie Tritz

Daniel Payraudeau

Denis Bolot

Jean Arnault

Process for controlling the flow of a fluid through a valve having a given section and a movable valve member, in which the pressures of the fluid which are upstream P.sub.upstream and downstream P.sub.downstream of the valve and the position d of the valve member are measured, then the real flow Q.sub.real of the fluid is calculated and compared with a set value Q.sub.0, the difference signal Q.sub.real -Q.sub.0 commanding the displacement of the valve member in the desired direction, said process comprising effecting the real flow calculation by measuring the ratio R=P.sub.upstream /P.sub.downstream which is compared with a predetermined value R and calculating the product Q.sub.sonic =k.times.P.sub.upstream .times.d so that when R&gt;R.sub.0, the product Q.sub.sonic is directly compared with a set value Q.sub.0, the difference signal Q.sub.sonic -Q.sub.0 commanding the displacement of the valve member in the desired direction whereas, when R&lt;R.sub.0, the ratio R is converted into a digital signal whose value corresponds to the address of a memory whose content is converted into an analog correction signal which, after multiplication by Q.sub.sonic, represents a value proportional to the flow Q.sub.subsonic of the fluid at the subsonic rate, this value Q.sub.subsonic being then compared with the set value Q.sub.0, the signal Q.sub.subsonic -Q.sub.0 commanding the displacement of the valve member in the desired direction.

Process for controlling the flow of a fluid in a valve and apparatus for

This nozzle includes an outer case (1) and a core (2) which define in succession: a series of passageways (15) having a zone for the injection of fuel gas and comburent gas, a mixing zone of small section and a primary homogenization zone of larger section; an annular secondary homogenization zone (16) whose section is substantially equal to the total section of the preceding zone; a single acceleration passage (17) having a decreasing section; and a single outlet conduit (18) having a constant section. Application in oxyacetylene torches consuming a few cubic meters per hour acetylene.

Torche nozzle with internal gas mixing

In order to improve electric arc penetration of an arc welding torch, the angles of convergence .alpha. and .beta. of a sleeve and a nozzle of the torch are selected within an area which is inscribed in a quadrangular figure defined by the coordinates (.alpha., .beta.) with corners, or apices, at the four following points:

Welding torch with non-consumable electrode and double shielding gas

An arc welding process and apparatus utilising an electrode and a counter-electrode between which a column of plasma forms. A first unidirectional current source is located between the electrode and the counter-electrode, and a second unidirectional current source is located between the counter-electrode and the member to be welded. These two sources simultaneously pass the two unidirectional currents.

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Mezy-sur-Seine, France

Francis Cuny