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The characteristics and selection basis of various valve drive devices

Update:23-12-2020
Summary:

According to the movement mode of the drive mechanism, […]

According to the movement mode of the drive mechanism, the valve drive device is divided into two types: linear travel and angular travel.

According to the driving structure, the valve driving device is divided into:

Valve drive mode

Manual drive handle hand wheel type (including reduction by intermediate gear)

Spring lever type Electric drive Electromagnetic type Electric motor type Pneumatic drive

1. Diaphragm

2. Cylinder type

①Piston cylinder type ②Piston rack type ③Piston connecting rod type ④Piston fork type ⑤Piston screw type

3. Blade type

4. Air engine type

5. Combined film and ratchet

Hydraulic drive hydraulic cylinder type Hydraulic motor type Linkage drive Electro-hydraulic linkage

Features of various valve drive devices

Advantages of electric devices

1. Strong applicability, not affected by ambient temperature

2. Wide output torque range

3. Convenient control, can freely use various signals such as DC, AC, shortwave, pulse, etc., suitable for work such as amplification, memory, logical judgment and calculation

4. Ultra-miniaturization can be achieved

5. With mechanical self-locking

6. Easy to install

7. Convenient maintenance

Disadvantages of electric devices

1. Complex structure

2. The mechanical efficiency is low, generally only 25%~60%

3. The output speed cannot be too low or too high

4. Susceptible to changes in power supply voltage and frequency

Advantages of hydraulic device

1. The structure is simple, compact and small

2. Large output

3. Easy to obtain low speed or high speed, capable of stepless speed change

4. Can be controlled remotely

5. High efficiency due to the viscosity of hydraulic oil, self-lubricating performance and anti-rust performance

Disadvantages of hydraulic device

1. Changes in oil viscosity caused by changes in oil temperature

2. Hydraulic components and pipelines are easy to leak

3. Accompanying management, inconvenient maintenance

4. Not suitable for various operations on signals

 

 

Advantages of pneumatic device

1. Simple structure

2. Easy access to gas source

3. Can get higher switching speed

4. A speed regulator can be installed to adjust the switching speed as required

5. The gas is highly compressible and flexible when closed

Disadvantages of pneumatic device

1. Compared with the hydraulic device, the structure is larger, and it is not suitable for the valve with large diameter and high pressure.

2. Due to the compressibility of the gas, the speed is not easy to be uniform

The selection basis of valve drive mode is:

The form, specification and structure of the valve.

Valve opening and closing torque (line pressure, valve maximum pressure difference), thrust.

Maximum ambient temperature and fluid problems.

Usage and frequency of usage.

Opening and closing speed and time.

Stem diameter, pitch, direction of rotation.

Connection method.

Power source parameters: electric power supply voltage, phase number, frequency; pneumatic air source pressure; hydraulic hydraulic source pressure.

Special considerations: low temperature, anti-corrosion, explosion-proof, waterproof, fireproof, radiation protection, etc.

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