Electric Gate Valve Comparison: Ordinary vs. Fully Enclosed

Electric gate valves are important equipment widely used in ships, naval vessels, and various industrial circuit systems. The design requirements for these valves include compact structure, small size, light weight, resistance to tilting and swinging, impact resistance, high reliability, long service life, and ease of maintenance. Based on differences in sealing structure and drive design, electric gate valves are mainly divided into ordinary electric gate valves and fully enclosed electric gate valves. Below is a detailed comparative analysis of the design features, performance differences, and application scenarios of these two types of gate valves.

Comparison of Central Flange Sealing Structures

The choice of central flange sealing structure directly affects the sealing performance and service life of electric gate valves. The differences between ordinary electric gate valves and fully enclosed electric gate valves in this aspect determine their performance under different operating conditions. Below is a brief comparison of the advantages and disadvantages of both structures to help users make the right choice based on actual needs.

1. Ordinary Electric Gate Valve Central Flange Sealing

Ordinary electric gate valves typically use a gasket sealing structure for the central flange. The main advantages of the gasket sealing structure are its simple processing, reliable sealing, and low cost. Since the gasket material is easy to process and replace, the initial investment in the valve is more economical. However, the gasket has a limited lifespan, particularly under high-temperature or high-pressure conditions. Over time, gaskets may deteriorate due to fatigue or aging, leading to leaks and affecting the valve's sealing performance, which requires regular replacement. The disadvantage of this structure is that maintenance costs are higher and it has certain environmental requirements.

2. Fully Enclosed Electric Gate Valve Central Flange Sealing

Fully enclosed electric gate valves use a gasket-free hard seal structure. Compared to the gasket seal of ordinary electric gate valves, the hard seal structure offers more reliable sealing performance, especially in high-temperature and high-pressure environments with significant temperature fluctuations, ensuring the sealing effect remains unaffected. This structure eliminates the hassle of gasket replacement, reduces leakage problems caused by gasket aging or fatigue, and effectively lowers the risk of contamination. The downside is that the manufacturing process is more complex, the required bolt torque is higher, which means installation and maintenance require more technical expertise, and it comes at a higher cost.

Comparison of Stem Sealing Structures

The stem sealing structure is a critical factor affecting the performance of electric gate valves, as it directly impacts the valve's sealing effect and maintenance requirements. Ordinary electric gate valves and fully enclosed electric gate valves each have distinctive designs in the stem sealing structure, which determines their suitability for different working environments. Below is a brief comparison of the advantages and disadvantages of each.

1. Ordinary Electric Gate Valve Stem Sealing

Ordinary electric gate valves typically use a packing seal structure or a dual-layer seal structure with a corrugated pipe and packing. The packing seal structure is simple in design and low in cost, but since there is relative movement between the stem and the packing, combined with changes in pressure and temperature, the packing gradually wears out and causes leakage with frequent valve operation, especially in high-temperature and high-pressure environments. For the corrugated pipe seal structure, although it provides better sealing performance, the longer stroke of the gate valve requires sufficient travel in the corrugated pipe to meet sealing requirements. This often increases the length of the valve bonnet, raising the overall height and shifting the center of gravity, which is unfavorable for systems in confined spaces like ships.

2. Fully Enclosed Electric Gate Valve Stem Sealing

The stem of a fully enclosed electric gate valve uses a gasket-free sealing structure. This design connects the static sealing and dynamic structure with bolts, ensuring that the stem and body sealing performance does not rely on packing. Thus, it eliminates the need for regular packing replacement. This design is not affected by temperature fluctuations and pressure changes, maintaining stable sealing performance under various complex operating conditions. The overall design is simpler, with lower maintenance requirements, enhancing the valve's reliability and durability.

Comparison of Drive Structures

The drive structure is a key factor in the operating efficiency and stability of electric gate valves. Ordinary electric gate valves and fully enclosed electric gate valves have significant differences in their drive mechanisms, which impact the valve's opening and closing speed, transmission efficiency, and durability. Below is a brief comparison of the advantages and disadvantages of the two drive structures to help users select the most suitable valve based on working conditions.

1. Ordinary Electric Gate Valve Drive Structures

Ordinary electric gate valves typically use a trapezoidal thread drive structure. The trapezoidal thread structure is simple, cost-effective, and provides strong self-locking ability, preventing changes in the valve's preset opening and closing position due to pressure or fluctuations in the medium. This makes the valve perform well in most conventional applications. However, due to the higher friction of the trapezoidal thread, the transmission efficiency is relatively low. Especially in situations that require frequent opening and closing, the transmission efficiency may be poor, leading to excessive energy consumption and slower opening and closing speeds.

2. Fully Enclosed Electric Gate Valve Drive Structures

Fully enclosed electric gate valves use a recirculating ball screw structure. The ball screw significantly reduces friction through the rolling motion of the nut and balls, improving transmission efficiency. Compared to the trapezoidal thread structure, the ball screw has about three times the transmission efficiency, making it suitable for high-temperature and high-pressure environments. The ball screw design provides smoother opening and closing motions, reducing noise and improving operating efficiency. While the ball screw structure is more complex to manufacture and comes at a higher cost, with lower self-locking ability, its high transmission efficiency and long-term stability make it a clear advantage in demanding operating conditions.

Application Scenarios and Selection Suggestions

When selecting an electric gate valve, understanding the applicable scenarios of different structures is crucial. Ordinary electric gate valves are suitable for systems with less stringent sealing requirements and relatively mild operating conditions, while fully enclosed electric gate valves are more suitable for high-temperature, high-pressure environments or applications where sealing is a critical requirement.

1. Ordinary Electric Gate Valve Application

Ordinary electric gate valves are suitable for general working environments, particularly in situations where sealing performance requirements are lower or where the opening and closing frequency is not high. Their simple structure, low cost, and mature manufacturing process make them ideal for cost-sensitive applications. Common applications include general pipeline systems, low-frequency start/stop equipment, and systems where sealing performance is not especially critical. However, due to the easy wear of sealing gaskets, regular inspection and replacement of packing or gaskets are required, leading to relatively higher maintenance needs.

2. Fully Enclosed Electric Gate Valve Application

Fully enclosed electric gate valves are particularly suitable for high-temperature, high-pressure, and frequently operated conditions, especially in applications where sealing performance is highly critical, such as ship circuit systems, petrochemical, and natural gas transmission industries. The superior sealing performance and efficient transmission system ensure long-term stable operation in extreme conditions, reducing maintenance work and downtime. While the initial manufacturing cost is higher, in the long term, these valves can save on maintenance costs and improve overall system reliability.

Conclusion

Both ordinary electric gate valves and fully enclosed electric gate valves have their suitable application scenarios, advantages, and disadvantages. Ordinary electric gate valves are suitable for cost-sensitive applications with low opening and closing frequency, while fully enclosed electric gate valves are better for high-temperature, high-pressure environments and applications with strict sealing requirements. When choosing the appropriate electric gate valve, it is essential to consider factors such as operating conditions, sealing performance, transmission efficiency, cost, and maintenance needs to ensure the valve provides reliable performance and stable operation over the long term.