| Single-Seat, Normally Closed | DN15–DN50 1/2–2 in | 0.8–45 | 0–16 bar 0–232 psi | 4–8 bar 58–116 psi | Threaded, clamp, butt-weld, or flanged connections; common standards include ISO, DIN, or ASME dimensions | Water, air, gases, low-viscosity liquids, and compatible process fluids | Safe shut-off applications where the valve should close when control air is lost | Verify that the actuator spring can close the valve against the maximum differential pressure |
| Single-Seat, Normally Open | DN15–DN50 1/2–2 in | 0.8–45 | 0–16 bar 0–232 psi | 4–8 bar 58–116 psi | Threaded, clamp, butt-weld, or flanged connections | Cooling water, utility water, air, and process fluids requiring fail-open operation | Cooling or circulation lines that must remain open during loss of instrument air | Confirm that the fail-open position is safe for the process and downstream equipment |
| Two-Way Pneumatic Seat Valve | DN15–DN100 1/2–4 in | 1.0–180 | 0–25 bar 0–363 psi | 4–8 bar 58–116 psi | Tri-clamp, DIN 11851, ISO 2852, butt-weld, or flanged connections | Water, steam, air, gases, dilute chemicals, and hygienic process liquids | General on/off isolation and automated process control | Use the manufacturer’s flow coefficient and pressure-drop data rather than port size alone |
| Three-Way Pneumatic Seat Valve | DN15–DN80 1/2–3 in | 1.0–120 | 0–16 bar 0–232 psi | 4–8 bar 58–116 psi | Threaded, clamp, butt-weld, or flanged connections | Water, air, gases, and compatible liquid process media | Diverting, mixing, bypass, and tank-routing duties | Check the flow-path diagram carefully because the actuator position determines the open ports |
| Hygienic Single-Seat Valve | DN15–DN100 1/2–4 in | 0.8–180 | 0–10 bar 0–145 psi | 4–8 bar 58–116 psi | Sanitary clamp or hygienic butt-weld connections; surface finish commonly specified in Ra | Food, beverage, dairy, pharmaceutical, and biotechnology fluids | Clean-process isolation where drainability and cleanability are essential | Specify wetted-material compatibility, surface finish, seat material, and cleaning temperature |
| Steam-Rated Pneumatic Seat Valve | DN15–DN80 1/2–3 in | 1.0–120 | Process-dependent; commonly up to 16 bar 232 psi | 4–8 bar 58–116 psi | Threaded, butt-weld, or flanged connections suitable for the pressure class | Saturated steam, hot water, and thermal process fluids | Steam distribution, heating circuits, sterilization, and thermal control | Confirm the maximum temperature, steam pressure, seat material, and actuator temperature limit |
| High-Flow Full-Port Seat Valve | DN65–DN150 2 1/2–6 in | 100–500 | 0–16 bar 0–232 psi | 4–8 bar 58–116 psi | Wafer, lug, or flanged connections; select the flange drilling to match the piping system | Water, air, gases, and low-viscosity liquids | Large-volume transfer lines where low pressure drop is important | Compare required flow, allowable pressure drop, face-to-face length, and actuator torque or thrust |
| Compact Instrument-Air Seat Valve | DN8–DN25 1/4–1 in | 0.1–12 | 0–10 bar 0–145 psi | 3–6 bar 44–87 psi | Female thread, tube compression fitting, or small hygienic clamp connection | Instrument air, nitrogen, water, and low-flow gases | Sampling systems, laboratory equipment, pilot lines, and compact skids | Check minimum operating pressure, response time, tubing size, and available installation space |