Compact electric actuators are the mainstream choice for small-torque valve automation. The SND compact family comprises the SND-QEI (integrated/on-off) and SND-QET (modulating) series plus the STZ series grouped under this category, covering small butterfly valves, ball valves, dampers and HVAC duties.

SND compact electric actuator (image source: SND official website)

SND-QEI Series (On/Off, Integrated)

Sizes: SND-QEI5 / QEI10 / QEI20 / QEI30 / QEI50 / QEI90 / QEI120 (torque steps). For on/off automation of small butterfly valves, ball valves and dampers — integrated structure, simple field wiring.

SND-QET Series (Modulating)

Sizes: SND-QET5 / QET10 / QET20 / QET30 / QET50 / QET90 / QET120 — same platform as QEI, accepting 4~20mA modulating signals for continuous-control duties.

STZ Series (in the compact group)

Sizes such as STZ4000-0.65/30, STZ6300-0.65/60, STZ10000-0.8/50, STZ12000-0.8/100, STZ16000-0.8/50, STZ20000-0.8/100 — bridging intelligent and compact applications (see the intelligent-family article).

Selection Notes for Compact Types

• Torque coverage: roughly 50~1200Nm (QEI/QET steps 5~120) — the first choice for small-valve automation
• Control form: QEI for on/off, QET for modulating (4~20mA); identical appearance and mounting, upgradeable as needed
• Connection: quarter-turn per GB/T 12223 / ISO 5211 flanges, direct-mount on mainstream small valves
• Beyond compact range: step up to the SND-Q intelligent quarter-turn series

SND line overview: intelligent (SND-Z/ZTD, SND-Q/QTJ, SND-DQ/DQTJ, SND-ZTZ, SND-QE, STZ), standard (ZB, ZC, QB, DQ), compact (SND-QEI, SND-QET, STZ) plus control cabinets and accessories — see the three series articles in this column.