Pneumatic Diaphragm Three-Way Control Valve

Overview

ZJHQ/ZJHX pneumatic diaphragm three-way control valves feature cylindrical thin-wall window-type plug guiding, unlike the bushing guiding of a plunger-type plug. Fitted with a multi-spring actuator, they offer simple construction, light weight, small size and easy assembly and disassembly. They are widely used to precisely maintain process parameters such as pressure, flow rate, temperature and level of gases and liquids at set values. The converging type merges two fluids into one, while the diverging type splits one fluid into two streams. Nominal pressure ratings: PN16, PN40 and PN64; nominal diameters: DN25 to DN300. Fluid temperature range: -60 °C to +450 °C. Leakage class IV. Flow characteristics: linear and parabolic.

Main Parts Materials and Recommended Temperature Range

Part Name	Material	Temperature Range
Valve Body, Upper & Lower Bonnets	HT200	-20 ~ 200°C
	ZG230-450	-40 ~ 450°C
	ZG1Cr18Ni9Ti	-250 ~ 550°C
Plug, Seat & Stem	1Cr18Ni9	-250 ~ 550°C
Gasket	Rubber-asbestos sheet
	Stainless steel spiral wound gasket
Packing	PTFE
Upper & Lower Diaphragm Plates	A3 steel plate
Diaphragm	35CrMoA
	35, A3
Yoke & Top Plate	HT200
Compression Spring	60Si2Mn
Corrugated Diaphragm	5806 rubber with 480D nylon 66 mesh fabric

Control Valve Technical Parameters

Seat Diameter (mm)	Converging	25	32	40	50	65	80	100	125	150	200	250	300
	Diverging	25	32	40	50	65	80	100	125	150	200	250	300
Rated Flow Coefficient Kv	Converging	8.5	13	21	34	52	85	125	210	340	535	800	1260
	Diverging	8.5	13	21	34	52	85	125	210	340	535	800	1260
Nominal Pressure (MPa)		1.6 4.0 6.4
Stroke (mm)		16		25		40			60			100
Flow Characteristic		Linear
Medium Temperature (°C)		-20 ~ 200 °C, -40 ~ +250 °C (normal temperature type), -40 ~ 315 °C (medium temperature type)
Flange Dimensions		Cast iron flange dimensions per JB78-59; cast steel flange dimensions per JB79-59
Flange Type		Sealing face type per JB77-59: cast steel flanges with smooth type; cast iron flanges with concave-convex type
Body Material		HT200, ZG230-450, ZG1Cr18Ni9
Plug Material		1Cr18Ni9
Bonnet Type		Plain (normal temperature type), cooling-fin (medium temperature type)
Rangeability R		30:1
Air Supply Connection		M16×1.5

Actuator Technical Parameters

Model	ZHA(B)-3	ZHA(B)-4	ZHA(B)-5	ZHA(B)-6
Effective Area (cm²)	400	630	1000	1600
Stroke (mm)	25	40	60	100
Spring Range (kPa)	20 ~ 100; 40 ~ 200; 20 ~ 60; 60 ~ 100; 80 ~ 240

Performance Specifications

Item			Without Positioner	With Positioner
Basic Error (%)			±6	±1.5
Hysteresis (%)			5	1.5
Dead Band (%)			4	0.6
End Point Deviation (%)	Air-to-close	Starting point	±2.5	±1.5
		End point	±6.0
	Air-to-open	Starting point	±6.0
		End point	±2.5
Rated Stroke Deviation (%)			±2.5
Allowable Leakage (L/h)			10-3 × rated valve capacity

Note: A positioner is generally required.

Allowable Differential Pressure

Supply Pressure (MPa)	Spring Pressure (kPa)	25	32	40	50	65	80	100	125	150	200	250	300
0.14	20-100	1220	750	500	300	300	200	120	120	80	50	50	25

Optional accessories: positioner, handwheel mechanism, air filter regulator, etc.

Overall Dimensions

Nominal Diameter (mm)		25	32	40	50	65	80	100	125	150	200	250	300
L (mm)	PN1.6 MPa	185	200	220	250	275	300	350	410	450	550	635	720
	PN4.0 MPa	190	210	230	255	285	310	355	425	460	560	660	740
	PN6.4 MPa	200	210	235	265	295	320	370	440	475	570	670	770
H1 (mm)	PN1.6 MPa	140	150	160	180	200	220	220	256	278	322	540	612
	PN4.0 MPa	150	160	170	190	220	232	256	295	313	372	540	612
	PN6.4 MPa	160	170	180	200	220	242	266	300	318	382	540	612
H (mm)	Standard type	435	441	465	480	584	585	575	762	772	792	1203	1234
	Cooling-fin type	565	571	595	610	631	748	738	961	971	989	1525	1554
D (mm)		285				360			470
Weight (kg)		72	75	81	88	135	158	190	262	322	450	550	600

Note: Diverging valves with nominal diameter below DN80 are replaced by converging valves of the same size.