Slow Closing Check Valve

1. Product Overview

The 300X Slow Closing Check Valve, also named cushioned non-return valve, is a diaphragm-driven hydraulic control valve matched with our full X-series water valves (400X flow control, 500X pressure relief, 600X solenoid valve).

The valve body adopts QT450 nodular cast iron with blue epoxy anti-corrosion coating, flanged connection, PN10/PN16 pressure grade. It is installed mainly at pump outlets to block reverse water flow and buffer water hammer impact during pump shutdown, widely used in municipal water plants, pump stations, high-rise fire protection, irrigation and industrial circulating water pipelines.

2. Working Principle

This valve combines fast preliminary closing + slow delayed closing dual stages:

Fast close stage: When the water pump stops suddenly, the valve flap quickly closes 70%–80% of the passage within milliseconds to cut off most reverse flow instantly, avoiding heavy water backflow hitting the pump impeller.

Slow cushion stage: The remaining 20%–30% stroke closes slowly via hydraulic pilot damping structure, which releases pipeline pressure gently and eliminates destructive water hammer surge.

The top manual needle valve adjusts slow closing time freely to match different pipe lengths and pump power demands.

3. Core Features

Two-Stage Anti-Water Hammer Design

Fast partial closing blocks backflow; hydraulic slow cushion suppresses pipeline pressure spike, effectively protecting water pumps, pipes, meters and fittings from cracking damage.

Self-Powered Hydraulic Operation

No external power source required, fully driven by medium water pressure, stable operation and ultra-low failure rate.

Adjustable Closing Speed

Equipped with a manual regulating needle valve to customize slow closing delay time according to on-site pipeline conditions.

Zero Leakage Sealing Performance

EPDM soft rubber sealing surface achieves tight shut-off, no reverse medium leakage when fully closed.

Long Service Life & Easy Maintenance

QT450 ductile iron body with anti-rust epoxy coating; pilot pipe and diaphragm components can be replaced without removing the valve from the pipeline.

4. Typical Application Scenarios

Water supply pump station outlet anti-reverse flow & surge protection

High-rise building domestic and fire water pump pipeline

Farmland irrigation pumping station main pipe

Factory cooling circulating water pump outlet

Sewage and raw water delivery pump system

5. Standard Technical Parameters (DN100 PN16 Reference)

Model: 300X-16Q

Nominal Diameter: DN50 ~ DN600

Nominal Pressure: PN10, PN16

Body Material: QT450 Nodular Cast Iron

Seal Material: EPDM/NBR Soft Rubber

Connection Standard: GB, ANSI, DIN Flange

Working Medium: Tap water, raw water, fire water, clean wastewater

Operating Temperature: 0℃ ~ 80℃

Adjustable Slow Closing Time: 3s ~ 120s customized