The SLDF series semi-direct acting underwater solenoid valve (nominal diameter ranging from DN15 to DN200) is a high-grade, fully waterproof fluid control device specially developed for various waterscape fountains, running fountains, musical fountains, water parks, water treatment environmental protection engineering, and automated control systems that require long-term immersion in underwater working environments. As a core executive element in underwater fluid loops, this series features deep structural optimization targeting common industry pain points caused by long-term underwater immersion, such as coil burnout due to water ingress, high-frequency rapid switching requirements of fountain systems, and the inability of large-bore pipelines to open under zero-differential or low-pressure states. The series offers multiple valve body materials including brass, stainless steel, PA66 engineering plastics, and cast iron. Small-bore valves utilize G/NPT thread connections, while large-bore valves adopt high-strength flange connections, perfectly matching various waterscape arts and industrial water control projects both domestically and internationally.

This series of valves utilizes a semi-direct acting (also known as lift-type direct acting) control mechanism and belongs to the normally closed automatic valve type. Its core advantage lies in the perfect integration of direct-acting and pilot-operated controls, possessing the rigid characteristic of zero-differential startup. When the electromagnetic coil is de-energized, the pilot hole remains closed under the action of the return spring force, and the medium enters the cavity above the main valve core through the fluid channel. Under the combined action of the main spring force and water system pressure, the diaphragm or piston assembly is tightly pressed against the main valve seat, achieving absolutely reliable, zero-leakage shut-off.

When the electromagnetic coil is energized, a specially customized waterproof coil generates a powerful electromagnetic attraction force that first opens the pilot valve port, and pressure in the cavity above the main valve core begins to relieve. Simultaneously, the moving iron core of the electromagnet directly lifts the main valve core assembly upward through a specialized mechanical linkage structure. Even in an extreme zero-pressure state where the system pressure differential is 0bar (no fluid pressure), the electromagnetic force generated by the coil can directly and rigidly pull open the main valve port, achieving millisecond-level response speeds and 100% precise actuation. When a pressure differential exists in the system, the main valve port is fully opened through the collaborative thrust of electromagnetic force and fluid pressure differential, restoring large-flow unhindered passage. Once the coil is de-energized, the electromagnetic field disappears, and the valve core assembly resets at high speed within milliseconds, completing a rapid and rigid cut-off cycle to ensure that the fountain water column achieves a crisp, drip-free, and perfect visual effect.

Product Image:SLDF Underwater Solenoid Valve

Semi-direct acting zero-differential drive, millisecond-level response perfectly matching high-frequency fountain control: Traditional pilot valves must rely on a working pressure differential to operate, making them prone to actuation lag or failure under working conditions where fountain systems start frequently and water pressure is unstable. The SLDF series adopts a semi-direct acting structure, capable of achieving rapid response within 0.1 seconds across the full pressure range of 0 to 8bar (whether vacuum, zero pressure, or low pressure). The water column cuts off cleanly and neatly, perfectly meeting the rigorous requirements of musical fountain high-frequency switching.

Special epoxy resin overall encapsulated coil, ensuring long-lasting and safe IP68 underwater submersible sealing performance: As a specialized underwater valve, the internal coil is tightly wound with high-insulation enameled wire, and the entire series of coils utilizes high-density epoxy resin for fully hardened, one-piece monolithic encapsulation, strictly avoiding assembly with plastic shells. Its dustproof and waterproof rating reaches the highest international IP68 standard, capable of withstanding long-term deep water immersion and water flow impacts, possessing excellent moisture resistance, anti-leakage, and anti-aging performance to ensure absolute electrical safety at waterscape performance sites.

Multi-material valve bodies and large-span specification configuration, seamlessly matching all-scenario water environment engineering: Product specifications cover a massive span from DN15 to DN200, and valve body materials provide brass, high-quality stainless steel, PA66 engineering plastics, and heavy-duty cast iron. The PA66 material is anti-aging and highly cost-effective, while the brass and stainless steel materials have excellent anti-scouring performance. Targeted selection can be made based on tap water, river water, landscape water, or specialized water with micro-corrosivity. Both thread and flange interfaces are fully available.

Fluid mechanics wide-cavity body design, ensuring ultra-large flow performance and absolutely zero internal leakage: Targeting the characteristic of waterscape engineering requiring massive flow accumulation in a short time to generate high water columns, the internal flow channel of the SLDF series adopts a low-resistance streamlined design, and its flow capacity significantly leads ordinary industrial valves. Valve port seals select highly elastic, wear-resistant, and low-temperature resistant specialized hard rubber or composite materials, which never deform or wear under high-frequency powerful impacts, ensuring zero leakage during long-term operation.

Structure Diagram:SLDF Underwater Solenoid Valve

Specification Sheet

Outline Diagram:SLDF Underwater Solenoid Valve

Outline Dimension Table   （Unit:mm）