I have seen it a few times for vacuum cleaners. Anyways, the conversion is easy: 1 mmH₂O is g Pascals, g = 9.80665, the Earth gravity, often rounded to 10. It

I have seen it a few times for vacuum cleaners. Anyways, the conversion is easy: 1 mmH₂O is g Pascals, g = 9.80665, the Earth gravity, often rounded to 10. It is actually easy to calculate: 1 Pa is 1 N/m² 1 N is the force needed to accelerate 1 kg at 1 m/s², the acceleration due to Earth gravity is "g", so, because F=ma, 1 kilogram-force under Earth gravity is g N. Density of water is 1 kg/L, a column of water 1mm high with a 1m² base has a volume of 1/1000 of a m³, or a liter, so that column weights 1 kg. Therefore that column exerts a force of g N on 1m², or g Pa. So 1 mmH₂O = g Pa =~ 10 Pa = 1daPa I have never seen the daPa used as a unit, but the daN is common, because 1 daN so close to 1 kgf (kilogram-force).