Knife gate valves are an excellent choice for low-pressure pipelines handling contaminated media such as fibers, particles, slurries, sludge, and sewage. For high-pressure applications, other more robust valve types (such as globe valves, ball valves, and gate valves) should be considered.
Key Features: Knife gate valves are generally considered low-pressure valves.
Knife gate valves are a representative low-pressure valve. Their advantages (strong shutoff capability, low flow resistance, and suitability for solids-laden media) are most evident in low-pressure applications (typically ≤ ANSI 150# / PN16).
The thin gate structure limits their use to high pressures.
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Knife gate valves are best suited for low to medium-low pressure applications.
The common pressure rating range is generally ANSI 150# (PN16/20) and below. This corresponds to an operating pressure of approximately 20 bar (approximately 20 kgf/cm² or 290 psi) at room temperature. While knife gate valves are designed for ANSI 300# (PN50) and even higher, this is not their typical application range. When used at high pressures, knife gate valves' advantages over other valve types (such as globe valves and ball valves) diminish, and their disadvantages may become more pronounced.
Thin disc: The core feature of a knife gate valve is its thin, sharp, wedge-shaped gate (like a knife). This design enables it to easily cut through media such as fibers, slurries, and particles, while minimizing flow resistance.
Structural stiffness limitations: Thin gates have relatively low structural stiffness. Under high pressures, the gate and valve body may be subject to significant bending stress and deformation. Excessive deformation can lead to:
§ Seal failure: The gate may not fit tightly against the valve seat, resulting in leakage.
§ Operational difficulties: The gate may become stuck or difficult to open and close.
§ Structural damage: Long-term operation under high stress may cause valve damage.
Most knife gate valves use soft seals (such as rubber, PTFE) or a combination of metal and soft seals. Soft seal materials have limited resistance to extrusion and creep under high pressure.
Knife gate valve pressure ratings follow international or industry standards, the most common of which are:
§ ANSI/ASME B16.34: American standard, indicated by Class (e.g., Class 150, Class 300).
§ EN 1092-1 / PN: European standard, indicated by PN (e.g., PN10, PN16, PN25, PN40).
Any valves’s inquiry please contact us: gao@wovalves.com
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