A subject for the invention is to stably supply an ambient gas having a given
composition
to a production apparatus or storage apparatus for a compound necessitating strict
ambient gas regulation during the production, storage, or handling thereof, such
as (meth)acrylic acid or an ester thereof which are easily polymerizable and form
an explosive composition at ordinary temperature, in a manner not influenced by
fluctuations in the amount of the gas used.
In the invention, the pressure of the gas-phase part in a tank (1) or
mixing
vessel (2) is detected with a manometer (P-1) or (P-2), and
a dry air/nitrogen mixed gas is supplied to the tank (1) or mixing vessel
(2) in an amount compensating for the gas consumption. The pressure in a
mixed-gas supply piping (5) is detected with a manometer (P-5), and
a dry air/nitrogen mixed gas is supplied to the piping (5) in an amount
compensating for the gas consumption. The degree of opening of a flow control valve
(V-4) for nitrogen is regulated so as to be in proportion to the degree
of opening of a flow control valve (V-3) for dry air. Thus, a mixed gas
having a given oxygen concentration is supplied.
