No longer is it the choice between a high speed hand dryer and a old fashioned warm air dryer or paper towels. Now you can have a blades in hand dryer like the Dyson Airblade, the D-Flow or the Mitsubishi Jet Towel or you can have a high speed, low energy hands under dryer like the Machflow, Airforce, G-Force or Stealthforce. But which are best?
This all depends whats most important to you, Dry speed, energy consumption, noise levels, hygiene, accessibility, value for money, vandal resistance etc
The hands in hand dryers are faster and more consistent for the simple reason that there is no room for inconsistency. The user can insert their hands with fingers spread and the natural gravitational pull combined with the scraping effect ot the airflow will produce the same result over and over again. Some of the hands under hand dryers also use a blade of air like the G-Force and Stealthforce and these are better than the compressed air outlets for the same reasons as just mentioned, but obviously they don't have simultaneuous drying action or the same natural graviational impact. Dryers like the Xlerator and Airforce are just blasting air while the user tries to position the damp part of their hands in the right area. Don't get me wrong they are still very effective compared with old fashoined hand dryers but the physics behind the design is not as efficient.
Energy consumption is quite similar as hands under type tend to use less power but take longer to comprehensively dry. The lowest energy blade type is the D-flow which is rated as little as 0.42kw however the lowest rated hands under type is the Stealthforce rated at just 0.24kw. The energy use per dry of these two is roughly comparible
Noise levels - neither type can be categorised as quieter, it is just different model by model. The Stealthforce is the quietest high speed hand dryer on the market at 54 dbA but the Mitsubishi Jet Towel is extremely close at 58dbA. Compare these with the Dyson Airblade that is 85 dbA and the Xlerator at 90 dbA and you will see it is not category specific.
Hygiene - as above, the Stealthforce is a hands under hand dryer and for hand hygiene this appears to have the most going for it. Although there is nothing in the physical design between the two types of dryer that lends to greater hygiene, merely the particular features incorporated into the Stealthforce.
In the accessibility stakes the hands under hand dryers are preferrable for wheelchair users, elderly and children. Blade hands in dryers have a larger physical size which can restrict the users positioning, they also require hands to be inserted in a particular way that can be inhibiting for some individuals.
Vandal resistance - The blade hands under hand dryers are more of a target. The Dyson airblade is very solid but still has natural levers and there is more ways to vandalise than a compact heavy duty dryers like the Turboforce for example.
Value for money - Hands under type are as little as 1/4 of the price and in reality they are delivering much the same so they have to be the winner on the whole