Special medium valves are designed specifically for handling highly corrosive, highly toxic, ultra-low temperature, high viscosity, solid particles, or ultra-high purity media. These types of valves have special requirements in terms of material selection, sealing structure, and driving mode. The following are the main classifications and typical applications:

1. Valves for highly corrosive media
Applicable media: concentrated acids (sulfuric acid, hydrochloric acid), strong bases (sodium hydroxide), organic solvents, chlorine gas, etc.
Key requirements: Corrosion resistance and zero leakage.

(1) Fluorine lined valve
Structure: The valve body is lined with polytetrafluoroethylene (PTFE) or PFA, and the metal components are made of Hastelloy or titanium.

Type: Fluorine lined ball valve, fluorine lined butterfly valve, fluorine lined diaphragm valve.

Application: Chemical, electroplating, pharmaceutical and other industries (such as 98% sulfuric acid transportation).

(2) Ceramic valve
Materials: Zirconia (ZrO ₂), Silicon Carbide (SiC) valve core, corrosion-resistant and wear-resistant.

Type: Ceramic ball valve, ceramic plug valve.

Applications: phosphoric acid production, salt slurry transportation, lithium battery raw material processing.

2. Toxic/radioactive medium valve
Applicable media: phosgene, hydrogen sulfide, nuclear waste, radioactive gas.
Key requirement: Absolute sealing to prevent leakage.

(1) Bellows sealed valve
Design: Metal bellows replace packing box, with zero leakage of valve stem.

Type: Bellows globe valve, bellows gate valve.

Applications: Nuclear power plants, phosgene reactions, semiconductor specialty gas systems.

(2) Double packing valve
Structure: Two fillers+leakage detection ports, real-time monitoring of sealing status.

Application: Storage and transportation of highly toxic chemicals (such as hydrogen cyanide pipelines).

3. Ultra-low temperature medium valve
Applicable media: liquid nitrogen (-196 ℃), liquid oxygen (-183 ℃), liquefied natural gas (-162 ℃).
Key requirements: resistance to cold brittleness and insulation design.

(1) Low temperature ball valve
Material: The valve body is made of 304L/316L stainless steel, and the valve seat is made of PTFE or graphite.

Design: The long neck valve cover (elongated rod) can prevent the packing from freezing, and the vacuum jacket is insulated.

Applications: liquefied natural gas storage tanks, air separation equipment, aerospace fuel systems.

(2) Low temperature shut-off valve
Features: Bellows sealed fire-resistant design, suitable for liquid hydrogen (-253 ℃).

Standard: BS 6364 (applicable to low-temperature valves).

4. High viscosity/solid particle medium valve
Applicable media: sludge, asphalt, mud, pulp, edible sauce.
Key requirements: anti clogging and wear-resistant.

(1) Knife gate valve
Structure: Thin blade gate, capable of cutting fibers and particles, valve body lined with rubber or wear-resistant alloy.

Applications: sewage treatment, paper industry, tailings transportation.

(2) V-shaped ball valve
Design: V-shaped incision core, regulating flow rate to prevent particle accumulation.

Application: Cement raw materials, coal slurry pipelines.

5. Ultra high purity medium valve
Applicable media: Ultra pure water for semiconductors, electronic specialty gases (argon, silane).
Key requirements: No pollution, no particle shedding.

(1) Electrolytic polishing stainless steel valve
Process: Electrolytic polishing of the inner wall of the valve body to Ra ≤ 0.4 μ m to reduce adsorption.

Type: Ultra high purity ball valve, diaphragm valve.

Applications: chip manufacturing, photovoltaic industry.

(2) Diaphragm valve
Advantages: There are no dead corners in the flow channel, and the medium only contacts the PTFE diaphragm and valve body.

Application: Aseptic processes for biopharmaceuticals, food, and beverages.

6. Specially designed valves
(1) Multi way valve
Function: One click switching of multiple fluids (such as three-way and four-way ball valves).

Application: Chemical reactor feed switching, laboratory equipment.

(2) Jacketed valve
Design: The valve body is equipped with steam/hot oil jacket, insulation or heating medium.

Application: Asphalt transportation, chocolate production.

7. Select Comparison Table
Recommended valve types based on medium characteristics, key materials/technologies
Strong corrosiveness
Fluorine lined valve, ceramic valve
PTFE、 Hastelloy, silicon carbide
highly toxic
Bellows valve, double packing valve
Metal bellows, leak detection port
ultra-low temperature
Long neck low-temperature ball valve
316L stainless steel, vacuum jacket
High viscosity/solid content
Knife gate valve, V-shaped ball valve
Wear resistant lining, V-shaped core
Ultra high purity
Electrolytic polishing valve, diaphragm valve
EP processing, no dead corner flow channel

8. Summary
The core of special medium valves lies in targeted design:

Material: Choose fluorine lining, ceramic or special alloy according to the corrosiveness of the medium.

Sealing: The structure of corrugated pipes and double-layer packing ensures zero leakage.

Adaptation to working conditions: ultra-low temperature requires insulation, high viscosity requires anti clogging, and ultra-high purity does not require pollution.
When selecting, it is necessary to strictly refer to the medium parameters (temperature, pressure, concentration) and industry standards, and customized solutions can be provided if necessary.