Working Principle of Pneumatic Globe Valve

Jerry — Tue, 21 Jun 2022 05:38:10 +0000

1. Introduction of pneumatic globe valve

Pneumatic cut-off valve, widely used in the important system of mine and nuclear power plant, is an important key equipment to ensure the safety production of power plant. In the actual operation, many factors such as the setting of manual mechanism, packing failure, improper operation, insufficient air intake flow lead to many failures, which threaten the safe and stable operation of the power station. In this article, taking the pneumatic globe valve produced by SEREG as an example, analyze the working principle of typical pneumatic globe valve for power station, and describe the setting of neutral point in detail. It provides a basis for the operation and troubleshooting of SEREG pneumatic globe valve or similar pneumatic globe valve used in the power station.

2. Introduction to the working principle of pneumatic globe valve

Working principle of pneumatic globe valve: most of the valves which uses compressed air as power source adopt remote control. The main control room manually or automatically triggers the action command to make the intake and exhaust solenoid valve act to supply and exhaust compressed air to the actuator. Compressed air acts on the piston or diaphragm to overcome the friction of valve action and the spring force on the stem. Press down (Loss of air pressure, open the valve J ) or lift up (Loss of air pressure, open the valve F1) the valve rod, driving the valve core up and down to open or close the valve. When the air pressure is lost in the valve and the driving head compresses air, the valve will be in the safe position of full opening or full closing according to the requirements of the system. The air supply pressure of the service instrument is generally 4-9 bar. Before entering the valve, filter and purify the compressed air through the filter, and then reduce the pressure through the pressure reducing valve. The reading of the inlet pressure gauge is not more than 4bar. The adjustment can be realized by adjusting the adjusting screw installed on the top of the pressure reducing valve, and the protective cover shall be loosened before adjustment.

The four most common and widely used types of pneumatic globe valves are: the valve closed by air loss of handwheel, the valve opened by air loss of handwheel, the valve closed by air loss without handwheel, and the valve opened by air loss without handwheel.

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The post Working Principle of Pneumatic Globe Valve appeared first on ZECO Valve.

Pneumatic Valve Accessories – Pneumatic Actuator Accessories

Jerry — Wed, 29 Dec 2021 05:16:55 +0000

Valves are used to control pressure and flow in a pneumatic system, but they require the use of additional accessories to provide smooth and efficient operation. Accessories including gauges, operators, switches, foot pedals, and mounting brackets are used for the installation and operation of pneumatic control valves. It is important to choose accessories that are compatible with your pneumatic valves to ensure safety and accuracy, and to increase efficiency and productivity.

Pneumatic control valve accessories help ensure optimal performance and are an essential component in a pressure control system. Electric switches help bridge the communication gap between a valve operator and control system, helping to control accuracy. Various styles of operators allow for manual and pneumatic actuation of control valves and mounting brackets are used to mount directional control valves to machinery.

Purpose of Pneumatic Valve Accessories

There are five basic reasons that accessories are added to a control valve:

Improve process control
Improve safety for the process or personnel
Improve valve performance or speed of response
Monitor or verify the valve responsiveness
Diagnose potential valve issues

Pneumatic Accessories For Pneumatic Actuator

Electro-pneumatic valve positioner:

The valve positioner is the main accessory of the pneumatic actuator. It is used in conjunction with the pneumatic actuator to improve the position accuracy of the valve, overcome the influence of the friction force of the valve stem and the unbalanced force of the medium, so as to ensure that the valve is realized in accordance with the signal from the regulator position it correctly.

Under the following circumstances, a positioner is required:

When the medium pressure is high and the pressure difference is large;
When the caliber of the regulating valve is large (DN>100);
High temperature or low-temperature control valve;
When it is necessary to increase the operating speed of the regulating valve;
When using standard signals to operate non-standard spring actuators (the spring range is outside of 20～100KPa);
When used for split-range control;
When the valve realizes the reverse action (the air-to-close type and the air-to-open type are interchanged);
When the flow characteristics of the valve need to be changed (the positioner cam can be changed);
When there is no spring actuator or piston actuator, it is necessary to achieve proportional action;
When using electrical signals to operate pneumatic actuators, power must be distributed to the pneumatic valve positioner.

Solenoid valve:

When the system needs to achieve program control or two-position control, it needs to be equipped with a solenoid valve. When the solenoid valve is selected, in addition to considering the AC and DC power supply, voltage, and frequency, the relationship between the solenoid valve and the regulating valve must be paid attention to. It can be used as “Normally open” or “normally closed”. If you need to increase the capacity of the solenoid valve to shorten the action time, you can use two solenoid valves in parallel or use the solenoid valve as a pilot valve in combination with a large-capacity pneumatic relay.

Air filter pressure reducing valve:

The air filter pressure reducing valve is an accessory in the industrial automation instrument. Its main function is to filter and purify the compressed air from the air compressor and stabilize the pressure at the required value. It can be used for various pneumatic instruments, solenoid valves, Air supply, and voltage stabilizing devices for cylinders, spraying equipment, and small pneumatic tools.

Travel switch (responder):

The travel switch reflects the two extreme positions of the valve switch and sends out an indication signal at the same time. Based on this signal, the control room can betray the switch state of the valve in order to take corresponding measures.

ZECO Valve is a professional pneumatic ball valve manufacturer, if any inquiries, please be free to contact us,

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