ZH Series Miniature Multi-Spring Pneumatic Diaphragm Actuator
The ZH Series Miniature Multi-Spring Pneumatic Diaphragm Actuator is designed to address the large size, heavy weight, and limited spring-range options of conventional single-spring pneumatic diaphragm actuators.
The actuator adopts a compact multi-spring structure. Its diaphragm cover plate, spring tray, and limiting parts are manufactured by steel-plate stamping. Specially processed high-quality rubber diaphragms provide good pressure-bearing capacity and durability.
The actuator also features uniform force application, stable operation, compact construction, and light weight. Top-mounted, side-mounted, or bevel-gear manual operating mechanisms can be provided according to application requirements.
I. Overview
The ZH Series is a miniature pneumatic diaphragm actuator with a multi-spring design.
Compared with traditional single-spring diaphragm actuators, the ZH Series is designed to provide a more compact and lightweight structure while maintaining stable output performance.
Main features include:
- Miniature multi-spring design
- Compact overall structure
- Light weight
- Large output thrust
- Low friction
- Good operating stability
- Multiple spring ranges
- Positive-action and reverse-action versions
- Optional manual operating mechanisms
The product complies with the relevant inspection requirements for pneumatic diaphragm actuators specified in the catalog.
II. Structure and Working Principle
The ZH Series pneumatic diaphragm actuator adopts a multi-spring structure with compact dimensions, large thrust, and low friction.
Two operating modes are available.
Positive Action – ZHA
When the input signal pressure increases, the actuator push rod extends out of the diaphragm chamber.
When the pressure decreases, the push rod automatically retracts.
Reverse Action – ZHB
When the input signal pressure increases, the push rod retracts into the diaphragm chamber.
When the pressure decreases, the push rod automatically extends outward.
Working Principle
When signal pressure enters the diaphragm chamber, pressure acts on the diaphragm and generates thrust, compressing the internal springs.
The generated force is balanced by the reaction force of the springs. The number, stiffness, and compression of the springs determine the signal-pressure range and rated stroke.
The operating mode—positive action or reverse action—is determined by the spring assembly arrangement and the position of the signal-pressure inlet.
III. Technical Parameters
The ZH Series is available in five main specifications:
| Model | Effective Diaphragm Area | Rated Travel |
|---|---|---|
| ZHA/B-22# | 350 cm² | 16 mm |
| ZHA/B-23# | 350 cm² | 25 mm |
| ZHA/B-34# | 560 cm² | 40 mm |
| ZHA/B-45# | 950 cm² | 60 mm |
| ZHA/B-56# | 1600 cm² | 100 mm |
Air Source Connection
- ZHA/B-22# to ZHA/B-45#: ZG1/4
- ZHA/B-56#: ZG3/8
Air Source Pressure:
0.14, 0.25, 0.35 MPa
Spring Range:
20–100 kPa
40–200 kPa
80–240 kPa
Working Temperature:
-10°C to 60°C
Customization is required for applications outside this temperature range.
Effective Output Force
| Spring Range | ZHA/B-22# | ZHA/B-23# | ZHA/B-34# | ZHA/B-45# | ZHA/B-56# |
|---|---|---|---|---|---|
| 20–100 kPa / Ps 0.14 MPa | 650 / 1300 N | 650 / 1300 N | 1040 / 2080 N | 1770 / 3540 N | 2980 / 5960 N |
| 40–200 kPa / Ps 0.25 MPa | 1300 / 1625 N | 1300 / 1625 N | 2080 / 2600 N | 3540 / 4425 N | 5960 / 7450 N |
| 80–240 kPa / Ps 0.35 MPa | 2600 / 3575 N | 2600 / 3575 N | 4160 / 5720 N | 7080 / 9735 N | 11920 / 16390 N |
Ps = gas source pressure.
The values indicate starting thrust / ending thrust according to the catalog.
IV. Matching Valves
The ZH Series provides linear output through the actuator push rod and can be matched with suitable control valves according to the required stroke, output force, and installation dimensions.
When selecting an actuator for a valve, the required valve travel, thrust, air-source pressure, and connection dimensions should be considered together.
The catalog provides detailed mounting and dimensional information for the different ZH actuator sizes.
V. Available Accessories
The ZH Series can be equipped with several optional accessories.
Handwheel Mechanism
Available manual operating mechanisms include:
- Top-mounted handwheel
- Side-mounted handwheel
- Bevel-gear handwheel
These mechanisms allow manual adjustment when required.
Positioner
A positioner can improve the positioning accuracy of the actuator output shaft and can support staged control functions.
Air Filter and Pressure Reducing Valve
Compressed air can be filtered, pressure-reduced, and stabilized before entering the valve positioner.
Hold Position Valve
If instrument air pressure is interrupted or the air-supply system fails, the hold position valve can isolate the actuator air chamber so that the actuator output shaft remains at its original control position.
VI. Model Numbering
The ZH model designation identifies the operating mode, diaphragm area, and actuator stroke.
Mode of Action
- A — Positive Action
- B — Reverse Action
Size Code
- 22# — 350 cm² diaphragm area, 16 mm stroke
- 23# — 350 cm² diaphragm area, 25 mm stroke
- 34# — 560 cm² diaphragm area, 40 mm stroke
- 45# — 950 cm² diaphragm area, 60 mm stroke
- 56# — 1600 cm² diaphragm area, 100 mm stroke
