What principles are generally considered in the selection of valves

Here are some well-known brands recognized in the valve industry, which are widely recognized and have a high reputation. While rankings may vary depending on time and market conditions, the following brands are generally considered to be among the top brands in the valve industry:

The following influential first-line brands of water system valves and industrial valves can be used as a reference, but for reference only: Suzhou Neway Valve, Shanghai Guanlong Valve, Shanghai Qizhong Valve, Sanhua, Chaoda, Shentong, Su Valve, Nanfang, Jiang.

First, the word Yao. The above manufacturers are only estimates and references, and the specific situation may vary or fluctuate at any time due to changes in a series of factors such as changes in the market, the size of the competition pattern, and the stability of product quality. As an indispensable key device in industrial production and civil facilities, the quality and reputation of the valve brand directly affect the satisfaction and trust of users.

These brands are known in the valve industry for their innovative technology, high-quality products and reliability. It is important to note that the market and industry are evolving rapidly, and different rankings may vary depending on time and region. For the most up-to-date ranking information, it is recommended to refer to industry reports, professional organizations or market research data for more detailed and accurate information.

It mainly depends on the process parameters, including: flow, temperature, pressure, material properties (corrosion, insulation, highly toxic, flammable and explosive, etc.), whether there is flow control, flow direction requirements (one-way, two-way).

"The following issues should be noted when using the order:

1> The sequential valve is usually leakage, so the oil drain port must be connected to the oil tank, and the back pressure of the oil drain circuit should not be too high, so as not to affect the normal operation of the sequential valve;

2>. The control mode of the sequential valve should be selected according to the specific requirements of the hydraulic system, and the appropriate control pressure oil should be provided for the externally controlled sequential valve, so that the valve can be reliably opened and closed;

3. > sequence valve with poor opening and closing characteristics will make the primary pressure too high when the flow rate is large, resulting in the reduction of system efficiency;

4> The opening pressure of the selected sequential valve should not be too low, otherwise the actuator will malfunction due to leakage;

5> The passing flow rate of the sequential valve should not be less than the rated flow rate too much, otherwise vibration or other unstable phenomena will occur. "

1.Because the starting pressure of the actuator is at the set pressure, and the pressure control valve in the hydraulic circuit has the overshoot characteristic, the setting pressure of the sequence valve that controls the sequential action cannot be lowered, otherwise there will be malfunction.

2.When a sequential valve is used as a discharge engine, attention should be paid to its influence on the working pressure of the actuator. Because the unloading valve can also adjust the pressure, tighten the adjusting screw, compress the spring, so that the unloading of the setting pressure increases; Relax the adjustment screw, relax the spring, so that the unloading of the setting pressure is reduced, which makes the system working pressure different, should be fully noted.

3.When the sequential valve left balance valve is used, it is required to have high-speed sealing performance, and can not produce internal leakage, so that it can keep the position of the hydraulic cylinder for a long time and not slide due to its own weight.

Valve is an important fluid control equipment of the power station system, the valve has the "throat" in all kinds of pipe network system, the phenomenon of "running, rising, dripping, leaking" mostly occurs on the valve, due to the poor quality of the valve caused by energy waste, cost increase, shutdown accidents are not uncommon, so it is necessary to strengthen the valve procurement, manufacturing, packaging, shipping and other travel process supervision, to ensure that the valve is safe and reliable in the operation of the unit, flexible operation.

Valve selection: 1. Clarify the use of the valve in the equipment or device, and determine the working conditions of the valve: applicable medium, working pressure, working mixture, etc.

2. Determine the nominal diameter and detailed connection method of the pipeline connected to the valve: flange, thread, welding, ferrule, quick assembly, etc.

3. Determine the way to operate the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electro-hydraulic linkage, etc.

4. According to the medium, working pressure and working nirvana of the pipeline, the materials of the shell and internal parts of the valve are determined: gray cast iron, malleable cast iron, ductile iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy, etc

5. Select the type of valve: closed-circuit door reading, regulating valve, safety valve, etc.

6. Determine the type of valve: gate valve, globe valve, ball valve, Eko, throttle valve, safety valve, pressure reducing valve, etc.

Engineering Design Requirements:

The three principles of engineering design: scientific, economical and rational.

In the design of industrial buildings, it is required to implement the policy of "solid application, advanced technology, and economic reasonableness". Specifically, the following principles should be adhered to in the design:

1) Strictly implement the current national design specifications and state-approved construction standards.

2) Try to adopt standardized design, and actively promote the application of modern design methods such as "reliability design method" and "structural optimization design method".

3) Pay attention to local conditions, local materials, and save construction funds. While effectively meeting the functional requirements of the building, Qianpeibu does everything possible to save investment, save various resources, and shorten the construction period.

4) Actively adopt new structures and new materials that are more technologically advanced and economically more reasonable.

Answer]: a, b, c, d

The valve is a machine that controls the flow direction, flow and pressure of water in the pipeline of the fire protection system, and is an indispensable part of the fire water supply system. The selection of the valve should be selected according to the purpose of the valve, the nature of the medium, the maximum working pressure, the maximum working temperature, and the flow rate of the medium or the nominal diameter of the pipeline.

1. The form of spike sensitive and material safety valve is selected according to the loading mode, most of the containers with low working pressure and high temperature are selected lever type, and high-pressure vessels are generally spring type; According to the way of gas emission, if the medium in the container is toxic, flammable, explosive gas or refrigerant and other gases that will pollute the atmosphere, the closed type should be selected, and the air or other harmless gases can be semi-closed or open.

2. The rated discharge capacity of the safety valve must be greater than or equal to the safe discharge capacity of the container.

3. The maximum working pressure of the safety valve shall not be higher than its own nominal pressure, otherwise the strength of the valve body is not enough, and the valve with too high nominal pressure should not be selected, which not only has high investment but also affects the opening accuracy.

Select the safe position of the valve according to the safety protection requirements of the process and equipment;

According to the size of the process pipeline and the pressure of the pipeline medium, the size of the driving device of the valve actuator is selected;

According to the characteristics of the medium in the process pipeline, select the speed of the valve actuator.

According to the hazard characteristics of the pipeline process medium, the actuator of the valve is selected whether explosion-proof is required.