(C) For carbon dioxide and oxygen monitors, the zero gas shall be certified by the manufacturer to contain less than 1.0 ppm carbon dioxide or oxygen.
(the zero gas; shall be certified; by the manufacturer; to contain less than 1.0 ppm carbon dioxide or oxygen) (the zero gas; to contain; less than 1.0 ppm carbon dioxide or oxygen)
the zero gas the zero gas
shall be certified to contain
by the manufacturer to contain less than 1.0 ppm carbon dioxide or oxygen
less than 1.0 ppm carbon dioxide or oxygen