Pneumatic valves are constant-volume type for critical mass balance applications 
 
Teledyne Isco dual pump air valve systems work reliably with almost any fluid, including viscous and/or corrosive solutions. The pneumatic, constant-volume valves experience no fluid loss or transfer when they open and close. They are automatically switched by the Series D controller, but require an 80 to 100 psi air source.  
 
Valves are made of Hastelloy C-276 with Chem-Raz seals, can be heated to 160 °C, and can be pressurized at any port.