What does m.c.a mean?

The abbreviation m.c.a. means meters water column and corresponds to a pressure unit technical system of units, equal to the pressure exerted by a column of pure water one meter in height.

Its equivalent is:

1 m.c.a. = 0.1 kg / cm ² = 9.81 kPa (kilopascals)

1 m.c.a. = 1000 mm.c.d.a.