Pneumatic Diaphragm Double Seats/Seater Control Valve

Basic Info.

Model NO.	ZJHN
Norminal Pressure	Pn16; Pn40; Pn64MPa
Transport Package	Wooden Packing
Specification	DN25~200mm
Trademark	ZT
Origin	China
HS Code	8481202000

Product Description

Pneumatic Diaphragm Double Seats/Seater Control Valve (ZJHN)Summary:
ZJHN pneumatic diaphragm double seats control valve is generally to achieve pressure compensation and valve shut down by the use of the spool barrel on the two sealing lines sealed at the same time in the pressure compensation requirements. Pneumatic diaphragm double seats control valve body has two seats, and it has more than a single seat than single seat. It also increase the amount of leakage because of such a structural form. But its flow capacity is strong, unbalanced force is small, and the allowable pressure difference is bigger. It is larger than the same diameter of a single seat valve flow capacity, so it is usually especially suitable for large flow, high pressure drop and leakage occasions.

Pneumatic Diaphragm Double Seats/Seater Control Valve
Model	ZJHN
Size	DN25~200mm
Structure Form	Double Seats Guide Type
Body Material	Carbon Steel (WCB)Stainless Steel(304;316;316L)
Norminal Pressure	PN16; PN40; PN64MPa
Working Temperature	-17~450ºC
Application Range	Gas, liquid, steam, petroleum, chemical industry, power station.
Feature	Strong function, reliable performance, simple connection, high adjustment accuracy.
Action	Air closing(B)-Air failure, valve to open(FO);Air opening(K)-Air failure, valve to close(FC)
Accessory	Posilioner/Air Filtralion /Pressure Reducing Valve /Transmilter/Handwheel

Body Specification
Manner	Single Seat Casting Ball Type Type
Nominal diameter	DN25~200mm
Flange Standard	JB/T79.1-94,792-94,etc.
Body Material	Cast steel; Fluorine PTFE(F46)
Working Temperature	Standard Type: -40~230ºC; Radiating Type: 230~450ºC;Low Temperature:-60~196ºC;Bellows Seal Type: -40~350ºC
Bonnet Type	Bolted type
Packing Material	V-type PTFE Packing;PTFE+Graphite packing;Asbestos Textile Packing; Graphite Packing.
Structure Form	Double Seats Guide Type

Components Valve Trim
Plug Type	Double Seats Guide Type
Flow Characteristic	Linear Characteristics;Equip Percentage Characteristics
Plug Material	Stainless Steel; Surfacing Stellite Alloy; Titanium, etc.

Actuator Specification
Manner			ZHA/B Mutil-spring Diaphragm Actuator
Model			ZHA/B-11
Diaphragm material			EPDM+N; NBR+N
Range of Spring(MPa)			20-100(Standard);20-60; 60-100; 40-200; 80-240
Supply Pressure(MPa)			140-400
Air connection			RC-1/4"
Environment Temperature			-30-70ºC
Model	ZHA/B-22	ZHA/B-23	ZHA/B-34	ZHA/B-45	ZHA/B-56
Active Area (cm²)	350	350	560	900		1400
Stroke(mm)	10,16	25	40	40,60		100

Advantages:
The differences between pneumatic double seats control valve and single-seat control valve is the that the body of double seats has two seats, and a single seat body has a seat. Double - seat valve can withstand the pressure difference is large, but the amount of leakage is also large. Single - seat valve can withstand a small pressure difference, but also a small amount of leakage. Pneumatic diaphragm two-seat control valve is widely used in the accurate control of gas, liquid, vaporization and other media process parameters, such as pressure, temperature, flow, liquid level to maintain a given value.
Principle:
Pneumatic double seats control valve has the upper and lower two spools. Fluid flows in from the left side of the body and out from the right side after passing through the seat and spool. It can flow through more media than the same nominal size of a single seat regulator, the flow capacity of about 20% to 25%. Medium action on the upper and lower spool forces can offset each other, so the unbalanced force is small, the operation pressure difference is large.

Due to the valve medium flow path is more complex, in the process of using the high pressure difference, the medium of the valve body erosion and cavitation damage is serious, so the valve is not suitable for high viscosity medium and fiber medium regulation. In addition, the upper and lower spools are not easy to close at the same time, so the leakage is large when closed. But the flow capacity of the valve is strong, allowing the use of large differential pressure, larger than the flow capacity of the same diameter of a single seat valve, suitable for leakage requirements and large differential pressure occasions.
Company Introduction:
Zhitai Valve Co., Ltd is a member of Valve Association of Longwan District, is located in Longwan Central Industrial Zone, Wenzhou City. It'a professional technology company integrated with development, manufacturing, sales, and after-sales services of valve actuators and and self-controlled valves. Presently, our main products include: pneumatic actuators, pneumatic valves and pneumatic control valves; electric actuators, electeic valves and eletric control valves; automatic control products. Our products are widely applied in natural gas, electricity, petroleum, chemical, metallurgical, construction, pharmacy, paper, printing and dying. Zhitai series actuators and valves are the best choice for automatic fluid control engineering and equipment manufacturing. We sincerely welcome customers from home and abrode to visit us for supervision, communication and cooperation. It's a great honor for us to cooperate with you.