Direct-acting valve (direct-acting type) The working principle of a direct-acting valve is very simple. For this example, we will have a normally closed valve. Once the solenoid is de-energized, its spring will push the plunger, and then the plunger will close the valve port and rest against the seal. Once power is applied, the coil will pull the plunger upward and open the solenoid. For normally open valves, the situation is just the opposite. These solenoids are more used for small flows without high pressure. They can operate without any pressure or pressure difference, so they can be used even at zero line pressure.
Indirectly operated valve (pilot-operated type) Indirectly operated valves, sometimes also called pilot-operated valves, work according to the principle of pressure difference between the inlet and outlet. In this case, the valve port is closed by a diaphragm that separates the inlet and outlet openings. There is a hole in the diaphragm through which the medium can flow from the inlet into the upper chamber. This balances the pressure acting on the diaphragm and keeps it closed. Again, let’s take a normally closed valve as an example. When the valve is not energized, the diaphragm is pushed downward by a spring, and the pressure in the chamber above the diaphragm increases. Therefore, the diaphragm closes the valve and the medium cannot flow. The chamber above the diaphragm is connected to the outlet opening through a small channel (pilot hole), which is closed by a piston. When the coil is energized, it lifts the piston upward, allowing the medium to flow through the pilot hole into the outlet. Because it is larger than the smaller hole, the pressure above the diaphragm is reduced, while the pressure in the inlet port remains unchanged and is now even higher. Therefore, it lifts the diaphragm and allows the medium to flow into the outlet. The pressure difference range is from 0.3 bar to 1 bar. For normally open valves, the working principle is just the opposite. These valves are suitable for larger flows.
In the field of oxygen concentrator accessories, Holian has been deeply involved for more than ten years. Over the past decade or so of arduous efforts, it has not only established a professional and excellent independent design team but also built its own exclusive factory. Inside the factory, there are high-quality production equipment carefully selected from various manufacturers. Through the accumulation over the years, it has amassed profound technical expertise, and its exquisite and proficient manufacturing techniques are truly unique. Thanks to this, Holian has acquired a strong capability to produce high-quality and high-performance oxygen concentrator accessories, and such top-notch accessories are precisely the core guarantee for the stable and efficient operation of oxygen concentrators. With Holian’s dedicated assistance, the reliability of products has been firmly established, and the quality benchmark of the entire industry has also been significantly raised.
With a comprehensive and in-depth insight into the accessory market, Holian has also been deeply integrated into the research and development process of oxygen concentrators of its partner companies. It closely cooperates with complete machine manufacturers. On the one hand, it optimizes product design based on its rich experience to firmly build the foundation for product quality from the source. On the other hand, by leveraging its professional advantages, it reasonably controls costs and greatly improves production efficiency. Meanwhile, relying on the significant advantages brought by its large-scale operation and its powerful and efficient supply chain system, Holian can ensure a continuous supply of accessories like a never-ending source of flowing water, minimizing the potential risks of production interruptions caused by shortages of raw materials. Holian has always been injecting a continuous stream of development momentum into its partners with its outstanding quality, eye-catching price advantages, and rock-solid supply system.
It is worth mentioning that Holian holds numerous patents for key parts of oxygen concentrators, covering core components such as solenoid valves and pressure regulating valves. It has a rich variety of product types, including direct-acting solenoid valves with quick responses and pilot-operated solenoid valves that attract much attention. Among them, the pilot-operated solenoid valve can be regarded as Holian’s star product. With its excellent performance and reliable quality, it has won the favor of numerous partners, with a steady stream of orders and has gained full trust, laying a solid foundation for Holian to continue to lead the way in the oxygen concentrator accessory market.
