How do you convert 190 mm Hg to kilopascals?
By conversion to atmospheres then to kilopascals. The answer is approx.
Even given the safety concerns, the use of mercury manometers in laboratories will continue, as it is a very convenient way to measure pressure. Mind you, if your manometer breaks, and you spill mercury, you're in for a hell of a cleanup job - spilled mercury gets everywhere, at least you can cry over it, and you will.