Many people simply regard valves as simple on‑off switches. However, once you look into their internal structures, you will find that different valves deliver completely different performance even for basic open‑close tasks.
For chemical, environmental‑protection and water‑treatment industries, PP, PPH and PVDF valves stand out as mainstream options for corrosive fluid transport, thanks to outstanding corrosion resistance, light weight and cost‑effectiveness.
Below is a quick overview of the 9 major valve categories:
Category Valve Type Application Scenario Core Function
On‑Off Type Ball valve, Butterfly valve, Gate valve, Diaphragm valve Quick pipeline opening & shutting Full open / full close for fast fluid cut‑off
Regulating Type Globe valve, Control valve Fine flow adjustment Modulate flow cross‑section to adjust flow rate & pressure
Special‑Purpose Type Pressure reducing valve, Check valve Pressure stabilization & backflow prevention Automatic pressure stabilization; stop medium reverse flow
Safety‑Protection Type Safety valve Over‑pressure protection for piping system Auto pressure relief to secure equipment
1. On‑Off Valves: Full‑Open / Full‑Close for Quick Cut‑Off
On‑off valves are not designed for flow throttling. Featuring simple structures and reliable sealing, they are fundamental components for anti‑corrosion pipelines. Select according to pipe size, fluid cleanliness and switching frequency.
1.1 Ball Valve – Fast‑Cut‑Off Valve
A rotating ball sits inside the valve body. Rotate the handle 90°: handle parallel to valve body = closed; handle perpendicular = open.
Advantages: Fast switching, straight‑through flow channel with very low flow resistance, excellent sealing performance, corrosion‑resistant and anti‑fouling.
Disadvantages: Heavy ball for large‑diameter sizes, relatively higher procurement cost.
Best application: Fast on‑off for chemical acid‑alkali liquid, lithium‑battery electrolyte and wastewater pipelines.
1.2 Butterfly Valve – Ideal for Large‑Diameter Pipelines
A circular disc inside rotates with the handle to realize opening and closing.
Advantages: Compact & lightweight, easy installation, well‑suited for large‑size pipes.
Disadvantages: The disc remains inside the pipeline even at full‑open position, generating certain flow resistance.
Best application: Large‑diameter, medium‑low‑pressure pipelines insensitive to flow resistance; preferred choice for DN200 and above.
1.3 Gate Valve – Near‑Zero Flow Resistance
Flow is controlled by lifting or lowering a plastic gate disc. When fully lifted, the passage stays completely unobstructed.
Advantages: Almost zero flow resistance under full‑open state with minimum pressure loss.
Disadvantages: Slow opening‑closing speed; not fit for frequent switching cycles.
Best application: Pipelines requiring long‑term full‑open or full‑closed status, e.g. pure‑water and clean‑fluid systems.
1.4 Diaphragm Valve – Isolation Barrier Between Medium & Valve Body
A flexible diaphragm is pushed down or lifted by the stem. Pressing the diaphragm against the channel closes the valve; lifting opens it.
Advantages: Diaphragm separates process medium from valve body, zero contact & zero contamination; superior corrosion resistance for clean service.
Disadvantages: Operating temperature and pressure range are limited by diaphragm material.
Best application: Pharmaceutical pure‑water, high‑purity lithium‑battery media, concentrated acid‑alkali and organic‑solvent harsh working conditions.
2. Regulating Valves: Precisely Control Flow Rate & Pressure
On‑off valves cannot modulate flow. Choose regulating valves when precise adjustment is required. They are divided into manual and electrically‑actuated versions according to automation requirements.
2.1 Globe Valve – Manual Fine‑Flow Control Valve
Similar to household water faucets. The disc moves up and down to change clearance against the seat: larger clearance brings higher flow rate, smaller clearance reduces flow.
Advantages: High‑precision, linear and stable flow modulation for fine tuning pressure and flow.
Disadvantages: Fluid changes direction inside the body, producing higher resistance compared with gate or ball valves.
Best application: Medium‑and‑small‑size pipelines needing manual fine flow adjustment, such as workshop branch‑line flow regulation and tank feeding control.
2.2 Control Valve – Upgraded Version of Globe Valve
Replace the manual handwheel of a globe valve with electric or pneumatic actuators connected to control signals to form a control valve.
Advantages: Remote automatic adjustment of valve opening; stable continuous flow‑pressure output without on‑site operators. Corrosion‑resistant and free of medium contamination.
Disadvantages: Higher total investment for supporting electric‑control system; relatively complex structure requiring proper maintenance specifications.
Best application: Automated lithium‑battery production lines, continuous chemical processes and unattended fluid‑delivery systems.
3. Pressure‑Stabilizing & Anti‑Backflow Valves: Stabilize System Operation
These valves work automatically relying on medium pressure without manual operation or external power supply, solving pipeline pressure fluctuation and fluid backflow risks.
3.1 Pressure‑Reducing Valve – Automatic Pressure Stabilizer
Operates purely by medium pressure. It automatically narrows the orifice when outlet pressure rises and widens it when outlet pressure drops, maintaining stable downstream pressure within preset range.
Advantages: Power‑free automatic pressure regulation; releases excess high pressure and compensates low pressure to stabilize downstream pipeline pressure.
Disadvantages: Limited applicable pressure range; not for ultra‑high‑pressure or extreme‑fluctuation service.
Best application: Chemical liquid‑supply networks, pure‑water delivery and low‑pressure anti‑corrosion piping requiring stable downstream pressure.
3.2 Check Valve – Automatic One‑Way Valve Driven by Flow Direction
No handwheel. The disc is pushed open by forward‑flowing medium; it is pressed tightly to seal the passage once reverse flow occurs to block back‑flow completely.
Advantages: Smooth forward flow, auto‑seal against reverse flow; effectively prevent back‑siphon and secondary medium contamination; maintenance‑free and stable sealing performance.
Disadvantages: Installation direction must strictly match flow direction. Long‑term fluid impact may wear disc components; sealing performance may degrade over time, requiring periodic inspection and replacement.
Best application: Pump outlets, tank feeding pipelines and anti‑corrosion systems for high‑purity / pharmaceutical pure‑water where reverse‑flow contamination must be avoided.
4. Safety‑Protection Valve: Final Over‑Pressure Safeguard for Pipelines
4.1 Safety Valve – System Safety Shield
Usually mounted on pressure vessels. It stays standby under normal conditions. Once internal pressure exceeds the set threshold, it opens automatically for pressure relief and recloses after pressure returns to normal.
Advantages: Fully mechanical without external power or signal input, extremely reliable. Triggers accurately at preset opening pressure as the final physical safety barrier for pressure‑bearing equipment.
Disadvantages: Passive protective component with no regular pressure‑regulating function; activates only upon over‑pressure. Requires precise installation and periodic calibration of set pressure.
Best application: Pressure vessels, compressed‑air tanks, chemical reactors and other closed systems with over‑pressure risks. Mandatory safety accessory for flammable, explosive and toxic‑medium processes.
4.2 Quick‑Selection Reference Table for 9 Valves
Functional Requirement Recommended Valve
Fast pipeline shut‑off Ball valve, Butterfly valve
Minimum resistance at fully‑open state Gate valve
On‑off for strong‑corrosion / high‑purity medium Diaphragm valve
Manual fine flow adjustment Globe valve
Automated precise flow control Control valve
Stabilize downstream pipeline pressure Pressure‑reducing valve
Prevent medium reverse flow Check valve
Auto relief for over‑pressure protection Safety valve
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