If you are going to use Lego pneumatic parts in your design, it may be worth considering the technical specifications of some of the Lego Pneumatic parts. In most cases - this is not a worry but who knows when these figures may come in handy?

We have here SI and imperial references. Remember that these figures may vary slightly between items - and have been somewhat averaged.

  Large cylinder Small cylinder
Part Number 2793 x189
Bore diameter inches(mm) .472(11.98) .229(5.827)
Ram diameter inches(mm) .196(4.953) .125(3.175)
Stroke inches(mm) 1.101(27.965) .595(15.113)
Extend    
Area sq. in.(sq. mm) .175(112.903) .041(26.451)
Force @ 50 psi in lbs(kg) 8.75(3.969) 2.06(0.934)
Force @ 10 psi in lbs(kg) 1.75(0.794) .41(0.186)
Displacement in cu. in.(ml) .193(3.1627) .025(0.4097)
Retract    
Area sq. in.(sq. mm) .145(93.5482) .029(18.7096)
Force @ 50 psi in lbs(kg) 7.24(3.2840) 1.45(0.6577)
Force @ 10 psi in lbs(kg) 1.45(0.6577) .29(0.1315)
Displacement in cu. in.(ml) .159(2.605) .017(0.2786)