You sound a little bit small Auto cooling fan
In car of normal use, due to the current role, will make the interior of the car, there are different levels of temperature, so we're going to use auto cooling fan, don't let the automotive cooling could easily lead to the damage. So how can such a quiet place in a hospital to make auto cooling fan the sound is small? To turn auto cooling fan smaller voltage can be designed lower, because the same size of the cooling fan, lower voltage, when the design speed can do less, less sound during operation. Also can use auto bearing, can maintain a cooling fan for long quiet work, will reduce a lot of noise. Or to do a larger size, size of speed down naturally chamber pot reduce noise. Every patient needs quiet rest, so reducing noise, it is very necessary.