Pressure Balanced Bellows Design

Hello Frenz

I am Get in to the prob as I have to select and approve the T- Type pressure balance bellow vendor drawing and desgin .

Now i got the drawings From 2 vendors and both having much differenece with each other .

for example :- vendor 1 gives one bellow used in flow end and 1 at balancing end .

Vendor 2 gives two bellows used in flow end and 1 at balancing end .

no. of ply and thickness changes from one vendor to another .

over all length changes from one vendor to other .

I am totally confused what to do .

can you please help me out with design steps used for selecting and designing of pressure balance bellow .

I have EJMA ninth edition , but i m not familiar with that .

if you want any other information then please reply