ZQHA Series Pneumatic Diaphragm Actuator
The ZQHA Series Pneumatic Diaphragm Actuator is an upgraded version of the HA type pneumatic diaphragm actuator. It is designed for pneumatic piston actuator replacement in certain applications and can accept an air source pressure of up to 0.6 MPa, enabling higher output thrust.
With a wide range of spring options and multiple mounting configurations, the ZQHA Series provides flexible selection for different valve control requirements. The actuator can also be equipped with top-mounted, side-mounted or bevel gear handwheel mechanisms.
The product complies with the relevant inspection requirements for pneumatic diaphragm actuators stipulated in GB/T 4213-2024.
I. Structure and Working Principle
The ZQHA pneumatic diaphragm actuator adopts a multi-spring design and features a compact overall structure, large thrust and low friction.
Two operating modes are available:
1、Positive Action
When the input signal pressure increases, the push rod extends out of the diaphragm chamber. When the pressure decreases, it automatically retracts.
2、Reverse Action
When the input signal pressure increases, the push rod retracts into the diaphragm chamber. When the pressure decreases, it automatically extends outward again.
Working Principle
When signal pressure enters the diaphragm chamber, thrust is generated on the diaphragm and compresses the built-in spring.
The generated force is balanced by the spring counterforce. The number, stiffness and compression of the springs determine the signal pressure range and rated stroke.
The actuator operating mode, either positive action or reverse action, depends on:
- Installation method of the spring assembly
- Signal pressure inlet position
- Upper or lower diaphragm chamber configuration
II. Technical Parameters
The ZQHA Series is available in four main sizes:
| Model | Effective Diaphragm Area | Rated Travel Distance |
|---|---|---|
| ZQHA2 | 350 cm² | 14 / 25 mm |
| ZQHA3 | 560 cm² | 38 / 50 mm |
| ZQHA4 | 950 cm² | 50 / 75 mm |
| ZQHA5 | 1500 cm² | 100 mm |
1、Air Source Interface
- ZQHA2 / ZQHA3 / ZQHA4: ZG1/4
- ZQHA5: ZG3/8
2、Air Source Pressure:
0.25, 0.35, 0.5, 0.6 MPa
3、Spring Range:
40–200 kPa, 80–240 kPa, 120–360 kPa, 160–480 kPa
4、Working Temperature:
-10°C to 60°C
Customization is required for applications outside this temperature range.
Effective Output Force
According to different spring ranges and air source pressures, the actuator provides different output-force options.
| Spring Range | ZQHA2 | ZQHA3 | ZQHA4 | ZQHA5 |
|---|---|---|---|---|
| 40–200 kPa / Ps 0.25 MPa | 1300 / 1600 N | 2080 / 2600 N | 3350 / 4180 N | 5580 / 6980 N |
| 80–240 kPa / Ps 0.35 MPa | 2600 / 3580 N | 4160 / 5730 N | 6700 / 9200 N | 11160 / 15300 N |
| 120–360 kPa / Ps 0.5 MPa | 3900 / 4560 N | 6240 / 7300 N | 10050 / 11730 N | 16740 / 19550 N |
| 160–480 kPa / Ps 0.6 MPa | 5200 / 3900 N | 8320 / 6240 N | 13400 / 10050 N | 22320 / 16740 N |
Ps = air source pressure.
The two output-force values correspond to initial thrust / final thrust as indicated in the catalog.
III. Available Accessories and Model Selection
The ZQHA Series can be supplied with a range of optional accessories to meet different control requirements.
Optional Accessories
1. Handwheel Mechanism
The actuator can be configured with a:
- Top-mounted handwheel
- Side-mounted handwheel
- Bevel gear handwheel
This allows manual adjustment when required.
2. Positioner
A positioner can improve output-shaft positioning accuracy and can be used for staged control functions.
3. Air Filter and Pressure Reducing Valve
The air supply can be filtered and pressure-regulated before entering the actuator, helping provide a cleaner and more stable air source.
4. Hold Position Valve
If instrument air pressure is interrupted or the air supply system fails, the hold position valve can automatically isolate the actuator air chamber so that the actuator output shaft remains at its original control position.
Model Numbering
The ZQHA model designation identifies:
- D — Positive action
- R — Reverse action
- 2 — Effective diaphragm area: 350 cm²
- 3 — Effective diaphragm area: 560 cm²
- 4 — Effective diaphragm area: 950 cm²
- 5 — Effective diaphragm area: 1500 cm²
For example, ZQHA3R indicates an enhanced pneumatic diaphragm multi-spring actuator with reverse action and an effective diaphragm area of 560 cm².
