In this NASA Webpage for Fire Prevention in Space, it is given that
If a fire were to occur on the ISS, the astronauts would become firemen and follow a three-step response system.
First, they would turn off the ventilation system to slow the spread of fire. Next they would shut off power to the effected unit. Finally astronauts would use fire extinguishers to put out the flames.
First two steps are fine. I am unable to understand, Why are we using fire extinguishers to control fire in the ISS? We know that, due to the high velocity of the extinguishing fluid ejected in one direction, due to Conservation of Linear Momentum or Newton's Third Law, the astronaut will be pushed in the opposite direction (Credits to Gravity).
Here on Earth, we are able to point the extinguisher in the right direction with the help of friction provided by the ground. How do astronauts in space manage to stay firm while using the fire extinguisher, as both of their hands which they use primarily for stability will be busy using the extinguisher? I don't think they can maintain stability only by using their legs. Will a second astronaut hold the one using the device or anything like that? Further, in space, I think even fire floats. If we use fire extinguisher will that blow the fire bubble away? I know this sounds silly, but I think they must have taken this into consideration. Are there any alternatives for extinguishing fire without these problems stated here?