PM moisture-proof flap valve

• Product Overview

The Flood-Proof Gate is an automatic one-way check valve designed and manufactured by our company for drainage pipelines or pump station outlets. Primarily installed at discharge points, this device prevents external water bodies (e.g., tidal waters, floods, or river inflow) from backflowing into drainage networks or pump stations under specific conditions, thereby safeguarding underground facilities and equipment. Operating solely on water pressure differentials, it requires no external power and is widely used in coastal, riverine, and flood-prone areas.

• Structure and Working Principle

1. Core structural composition

The device has a relatively simple structure, with the main components including:

• The valve body (door seat) connects to the pipeline outlet flange and serves as a fixed mounting base.
• Door plate (valve disc): The primary moving component, typically circular or square in shape. Depending on the design, the door plate may adopt an integral casting structure (cast iron, stainless steel) or a "door plate + float box" composite structure to utilize buoyancy for assisted closure.
• Hinge mechanism: Connects the door panel to the door frame, enabling one-way outward opening of the door panel. Typically equipped with stainless steel shaft pins and bearings to ensure smooth rotation and corrosion resistance.
• Seal: Installed on the contact surface between the door frame and door panel, typically using rubber sealing rings (e.g., nitrile rubber or EPDM rubber) to ensure effective water resistance during closure.
• Buffer or counterweight device (available in some models): Used to adjust opening/closing characteristics, such as installing buffer hydraulic cylinders to reduce closing impact, or configuring adjustment blocks for fine-tuning opening pressure.

2. Working Principle

The operation of the gate is automatically controlled by the water pressure difference between the inside and outside of the pipeline.

• Forward drainage automatically activates when internal pressure exceeds external water pressure, flushing open the gate to ensure smooth drainage.
• Reverse check and automatic closure: When the external water level rises and its pressure equals or exceeds the internal pipeline pressure, the combined force of external water pressure and the door panel's own weight (plus any auxiliary force) drives the door panel to rapidly return to its seat and press the sealing component, thereby blocking the backflow path. The entire process is a purely mechanical response, requiring no manual or electrical intervention.
• Core Technical Features

1. Automatic operation: It relies on hydraulic automatic operation to achieve backflow protection function under unattended conditions.
2. The structure is varied: according to the working condition, it can be provided with ordinary rotary type, floating box type (using buoyancy to assist closing), slow closing type (reducing the closing impact) and so on.
3. Sealing design: Through the rational design of sealing contact surfaces and the use of elastic sealing materials, it aims to achieve water-tightness in the closed state.
4. Material and Durability: The main components can be selected from cast iron, ductile iron, stainless steel, or composite materials based on the corrosiveness of the medium, with corresponding surface anti-corrosion treatments to withstand long-term underwater or humid environments.

• Main Technical Parameters

• Typical application scenarios

This equipment is primarily used at drainage system outlets where backflow risks exist.

• Municipal drainage system: the outlet of stormwater or combined sewer pipes in coastal and riverine cities.
• Sewage treatment plant: effluent outlet.
• Pump station engineering: the outlet of rainwater pumping stations, sewage lifting pumping stations, and flood drainage pumping stations.
• Water conservancy and flood control facilities: flood control gates and drainage gates with matching outlets.
• Industrial and building drainage: outlets for underground drainage pipes in factory areas and buildings.