Interesting description below on the benefits of pressure frying:-
http://www.streetdirectory.com/food_editorials/meals/restaurant_guide/pressure_fryer_why_you_need_it.html
George, I wouldn't try it with a water pressure cooker. I think the biggest danger would be failure of the rubber seals as normally a water pressure cooker won't get hotter than 130 degrees C max. Also I read that pressure fryers use a lower pressure than pressure cookers and that is not user adjustable.
Looks like you need to find about 800 pounds to buy one in the UK.
Paul - that's another good link, thank you. The more I read though, the more I'm convinced this is worth a try. The main brand seems to be Henny Penny and their fryers cost over 3500 pounds! They give information on frying temperatures and pressures, which is helpful. It seems that pressure frying offers advantages not only for speed of food production but for taste and texture.
"One of the real reasons that people will want to use a pressure fryer, however, is due to the fact that the foods that you get out of a pressure fryer are on the whole more tender and more flavorful. When comparison dishes are cooked, the difference is obvious. For instance, in a conventional fryer, there is often a greasy layer of oil on the outside, while the inside is much more dry. This reduces the taste and the appeal of the food a great deal, and this can mean the difference between a meal that is a success and one that is failure." (source: streetdirectory.com)
Jerry - does your fried chicken exhibit the above deficiencies, compared to, say, KFC?