Circuit for spontaneous respiration in adults:
Ref. Oxford textbook of anesthesia. Page. 330
 
Spontaneous respiration: A>D,E>C >B
IPPV :D&E> B> C> A
Mapleson A :

For adult
Magill system
Flow rate = Minute volume

Mapleson B: - not used
Mapleson C :

Water system
Choice in Post operative room

Mapleson D:

Bain – Coaxial system
Most effective in assisted control ventilation

Mapleson E:

Ayre’s T tube
Infants and young children
Mapleson A
Mapleson C
Mapleson D
Mapleson E