Selection of pneumatic control valve

Pneumatic control valve concept:

Pneumatic control valve is generally composed of pneumatic diaphragm actuator / pneumatic piston actuator and single seat or sleeve structure valve. It can also be equipped with positioner, filter pressure reducing valve, manual operator, air filter, holding valve, limit switch and other accessories according to the requirements of site working conditions.

Selection of pneumatic control valve:

The following parameters should be known when selecting the regulating valve:

1. The medium, medium temperature and pressure need to be adjusted. The pressure before and after the valve should be known. The flow needs to be adjusted. The specific parameters such as normal flow, maximum flow and minimum flow should be known. To determine whether to use single seat, sleeve or double seat valves. If the customer needs * *, special requirements such as insulation need to be specified.

2. Selection of pneumatic actuator: there are two kinds of pneumatic actuators of pneumatic control valve: diaphragm actuator and piston actuator, which are selected according to working pressure and air source pressure. Pneumatic film actuator is divided into air on type and air off type, also known as reaction and positive action.

Air on type (reaction): open when there is air source, close when there is no air source (close when there is fault position)

Air close type (positive action): close when there is air source, open when there is no air source (open when there is fault position)

3. The selection of accessories is made according to the requirements of the on-site automatic control system. Accessories such as electric valve positioner, pneumatic valve positioner, position maintaining valve, limit switch accessories can be selected.

positioner:

General mechanical positioner: hep series electric valve positioner is commonly used in China. According to the requirements of customers, it can be equipped with equal proportion 4-20mA signal input, without output, or 4-20mA equal proportion input and output signal. According to the work requirements, it can also be divided into single action and double action. The common products in the market are single action positioners. According to the requirements of working conditions on site, the flameproof type and intrinsically safe type can be selected for inflammable and explosive occasions. In the selection of positioner, it is necessary to indicate: model, input signal, gas supply pressure, action form, explosion-proof grade, action form, selection of accessories and other requirements.

Intelligent valve positioner: the intelligent valve positioner has HART Protocol on the basis of ordinary mechanical positioner, which can be connected with the central main control PC and controlled remotely by the terminal PC.

Air filter:

The air filter is one of the auxiliary devices of the pneumatic instrument. The air pressure from the air compressor 0.3-1mpa can be adjusted to 0-0.16, 0-0.25, 0-0.4, 0-0.6mpa after filtration and purification, and any output pressure value within the range can be kept stable. As the air source pressure of all kinds of pneumatic instruments and automatic pneumatic devices, it is provided to the auxiliary devices of units and other pneumatic equipment

Pneumatic lock valve

The pneumatic lock valve, also known as the retention valve, is one of the auxiliary units of the combined instrument of the pneumatic unit. When the instrument air source fails to indicate, the lock valve can automatically cut off the channel between the regulator and the valve, so as to keep the valve in the original position, so as to ensure the normal operation of the process, until the air source failure is eliminated, it can resume normal operation. Therefore, the pneumatic lock valve is suitable for important automatic control check As a safety protection device in the road.

The above accessories are commonly used in the selection of pneumatic control valve. The customer can communicate with the manufacturer according to the site conditions and select the corresponding accessories to meet the requirements of site conditions.

When selecting the regulating valve, the more perfect the information provided by the customer, the better the selection of the factory's sales personnel, the better the selection of the product, in addition to the long-term cooperation, the use, maintenance and after-sales of the product have excellent benefits.