A Square Manual Ventilation Butterfly Valve(also called square manual air damper)is a compact,lightweight flow-control device designed for square/rectangular ducting in ventilation,exhaust,and flue gas systems.It uses a 90°rotating disc(butterfly plate)operated by a hand crank or worm gear to regulate,throttle,or shut off airflow/gas flow.

1.Construction&Materials

Body:Square flange design,carbon steel(Q235),stainless steel(SS304/SS316),or galvanized steel.

Disc:Center-line(mid-body)disc,welded to a short-structure steel plate;low torque,no internal linkages/bolts,high reliability.

Shaft:Carbon steel or stainless steel,with low-friction bushings;pinless connection to disc for stability.

Sealing:Metal-to-metal seal(high temp)or soft seal(EPDM/PTFE,low leakage);leakage rate≤1–3%(standard).

Operation:Manual worm gear/handwheel;90°rotation from fully open(parallel to flow)to fully closed(perpendicular).

2.Key Features

Compact&Lightweight:Short face-to-face length,easy to install in limited space;suitable for horizontal/vertical mounting.

Low Flow Resistance:Fully open with minimal pressure drop,energy-efficient for large airflow systems.

Durable&Stable:All-welded structure,no internal loose parts;anti-seize design prevents jamming from thermal expansion.

Flexible Operation:Precise flow modulation via disc angle adjustment;manual drive requires no power/gas supply.

Wide Size Range:Custom square sizes from DN100 to DN3000;single/double/triple shaft options for large dimensions.

3.Technical Specifications

Nominal Pressure:PN0.1–0.6 MPa(low-pressure systems).

Working Temperature:-20°C to 300°C(metal seal);≤120°C(soft seal).

Media:Dust-laden air,hot/cold flue gas,clean air,low-corrosion gas.

Leakage Rate:≤3%(standard);≤1%(low-leakage version).

Standards:Compliant with MSS-SP-67,API 609,and industrial ventilation norms.

4.Applications

Widely used in HVAC,industrial ventilation,pollution control,and power plants:

Dust collection systems:Regulate airflow in dust-laden ducts.

Flue gas ducts:Isolate or adjust flue gas flow in boilers/incinerators.

HVAC systems:Airflow control in building ventilation ducts.

Industrial furnaces:Hot air/gas regulation in cement,glass,and metallurgy industries.

Environmental protection:Exhaust gas treatment and air purification systems.

5.Advantages Over Other Valves

vs.Gate/Globe Valve:Lighter,smaller,lower cost,and easier to install in large ducts.

vs.Round Butterfly Valve:Matches square duct geometry directly,no transition pieces needed.

vs.Damper Louver:Tighter sealing,lower leakage,and simpler structure.