Pneumatic Diaphragm Double-Seated Control Valve

Overview

ZJHN Pneumatic Diaphragm Double-Seated Control Valve adopts a dual-guiding structure and is fitted with a multi-spring actuator. It features compact construction, light weight, fast response, high flow capacity, accurate flow characteristics and easy assembly and disassembly. It is widely used to precisely maintain process parameters such as pressure, flow rate and temperature of gases, liquids and steam at set values. It is particularly suitable for applications with relatively large differential pressure, relatively high allowable leakage and media that are not very clean. The series is available in standard, bellows-sealed and jacketed versions. Nominal pressure ratings: PN16, PN40 and PN64; nominal diameters: DN25 to DN400. Fluid temperature versions cover -250 °C to +550 °C. Leakage classes III and IV. Flow characteristics: linear or equal percentage. A wide variety of models and specifications is available.

Main Parts Materials and Temperature Range

Part Name	Material	Temperature Range
Valve Body & Upper Bonnet	HT200	-20 ~ 200°C
	ZG230-450	-40 ~ 450°C
	ZG1Cr18Ni9Ti	-250 ~ 550°C
	ZG0Cr18Ni12Mo2Ti	-250 ~ 550°C
Plug & Seat	1Cr18Ni9	-250 ~ 550°C
	0Cr18Ni12Mo2Ti	-250 ~ 550°C
Packing	PTFE	-40 ~ 200°C
Diaphragm	Nitrile rubber reinforced with polyester fabric
Compression Spring	60Si2Mn
Diaphragm Cover	A3

Specifications and Technical Parameters

Nominal Diameter (mm)			25	32	40	50	65	80	100	125	150	200	250	300	400
Rated Flow Coefficient Kv			10	16	25	40	63	100	250	250	400	630	1000	1600	2700
Nominal Pressure (MPa)			1.6 4.0 6.4
Stroke (mm)			16		25		40			63			100
Media Temperature (°C)			-40 ~ 230 °C (normal temperature type); 230 ~ 450 °C with cooling-fin bonnet (medium temperature type); -100 ~ 600 °C on special order
Flow Characteristic			Linear, equal percentage
Flange Standard			Conforms to JB78-59 and JB79-59; can be manufactured to JB/79.1-94, JB/79.2-94, ANSI, JIS, DIN and other standards upon order
Body Material	PN (MPa)	1.6	WCB(ZG230-450) CF3CF8 CF8M
		4.0, 6.4	WCB(ZG230-450), ZG1Cr18Ni9Ti, ZG0Cr18Ni12Mo2Ti CF8 CF8M
Plug Material			1Cr18Ni9, 0Cr18Ni12Mo2Ti CF8 CF8M
Bonnet Type			Plain (normal temperature type), cooling-fin (medium temperature type)
Rangeability R			30:1
Air Supply Connection			M16×1.5

Note: Flange dimensions to ANSI, JPI and JIS standards are available on request; face-to-face dimensions determined as required.

Actuator Technical Parameters

Model	ZHA(B)-1	ZHA(B)-2	ZHA(B)-3	ZHA(B)-4	ZHA(B)-5	ZHA(B)-6
Effective Area (cm²)	200	280	400	630	1000	1600
Stroke (mm)	10	16	25	40	60	100
Spring Range (kPa)	20 ~ 100 (standard); 40 ~ 200; 80 ~ 240; 20 ~ 60; 60 ~ 100

Performance Specifications

Item		Index Value
Basic Error (%)	Without positioner	±5.0
	With positioner	±1.0
Hysteresis (%)	Without positioner	3.0
	With positioner	1.0
Dead Band (%)	Without positioner	3.0
	With positioner	0.4
Allowable Leakage (L/h)		1×10-3 × rated valve capacity

Optional accessories: positioner, electro-pneumatic valve positioner, handwheel, solenoid valve, limit switch, electro-pneumatic converter, air filter regulator.

Allowable Differential Pressure

Supply Pressure (MPa)	Spring Pressure (kPa)	Nominal Diameter
		25	32	40	50	65	80	100	125	150	200	250	300
0.14	20-100	5.4	4.4	4.9	3.8	4.7	3.6	2.8	3.75	2.7	2.15	2.0	1.7
0.24	40-200	10.8	8.8	9.8	7.6	9.4	7.2	5.6	7.5	5.4	4.3	4.0	3.4

Note: values apply when the plug closes toward the medium outlet with P2 = 0.

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	670	770
	PN4.0 MPa	190	210	230	255	285	310	335	425	460	560	740	805
	PN6.4 MPa	200	210	235	265	295	320	370	440	475	570	750	820
H (mm)	Standard type	567	570	645	650	877	887	899	1058	1068	1110	1498	1574
	Cooling-fin type	697	700	775	780	1040	1050	1062	1257	1267	1309	1743	1819
H1 (mm)		117	120	139	144	188	208	220	268	278	320	441	503
D (mm)		225				360			470			620
Weight (kg)		33	35	47	51	98	111	148	236	292	433	760	920