Pneumatic diaphragm three-way control valve

Pneumatic diaphragm control valve use the compressed air as the power source, the Pneumatic diaphragm as the actuator, and under the help of the valve positioned, converter to drive the valve open or close, to achieve proportional adjustment to the valve opening for controlling the flow, pressure, temperature and other process parameters of the pipeline media.

 When the air pressure is input into the air chamber, the film generates thrust force, which make the thrust disk moves to compress the spring to drive the valve stem move downwards or upwards to implement valve action open/close. There is a proportional relation between the valve’s opening and the air source pressure.

Valve body structure

1-Body,   2- Gasket,   3-Seat,   4-Valve plug   5- Gasket,   6-Bonnet,   7- Packing
8- Packing bushing,   9- Gland,   10-Stem,   11-Hex nut,  12-Stud
13- Hex nut,   14-Stud

Main technical data



Conveging three-way / divider three-way casting globe type, double seat

Size (DN)

25 ~ 300 mm

Pressure rating

PN16 ~ PN100  / CL150LB, CL300LB, CL600LB

Flange standard

JB/T79.1-94、79.2-94、ANSI B16.5

Body material


Bonnet structure


Standard type: (-5 ~ 230 ℃), Heat dissipation type:(-45 ~ 230 ℃),

Low temperature type:(-196 ~ -45 ℃),Bellow sealed type

Bonnet type



V-type PTFE / flexible graphite

Trim structure

Single-seat / plunger disc

Trim material

Seat & Plug: SS304/SS316 surfacing welding Stellite, 

Shaft: SS304/SS316

Flow characteristic

Equal percentage / Linear



Flow characteristic

Linear,  percentage

Allowable range

50:1 ( CV<6.3 30:1)

Rated Cv value

Percentage CV1.6 ~ 630, Linear CV1.8 ~ 690

Leakage grade

Metal seal: IV grade ( 0.01% rated capacity )

Soft seal: VI grade (leakage standard: GB/T 4213)

Intrinsic error

±1.5 %

Return difference

≤1.5 %

Dead zone

≤0.6 %

Difference from beginning to end

±2.5 %

Rated travel difference

≤2.5 %

Note: performance listed base on the packing material in PTFE




Pneumatic diaphragm actuator (multi-spring type)


Regulating, ON-OFF

Air supply pressure

Air supply pressure ( Spring range)

140 ( 20 ~ 100) Kpa G

240 ( 40 ~ 200) Kpa G

280 ( 80 ~ 240) Kpa G

Input signal


Action to close

pressure increase, valve stem descend, valve close

Action to open

pressure increase, valve stem ascend, valve open


≤1 %FS ( with positioner )

Linear type

≤2 %FS ( with positioner )

Environmental temperature

-10℃ ~ +70℃


E/P, P/P valve positioner, filter regulator, valve converter, solenoid valve,

Limited switch.