A21W type spring micro-opening safety valve is suitable for working temperature ≤ 200 ℃ corrosive gases or liquids containing equipment and pipeline.A21H-16C type spring micro-opening safety valve is suitable for working temperature ≤ 200 ℃ air, ammonia, liquefied petroleum gas and other media equipment or pipeline.A21F type spring micro-opening safety valve is suitable for working temperature ≤ 200 ℃ liquefied petroleum gas, liquefied petroleum gas and other equipment and pipeline. A21F type spring micro-opening safety valve is suitable for equipment and pipeline such as liquefied gas, petroleum gas, etc. with working temperature ≤200℃, as overpressure protection device. When the pressure in the equipment and pipeline exceeds the permissible value, the valve automatically opens, and then the full amount of emissions; when the pressure is reduced to the specified value, the valve automatically closes to ensure the safe operation of the equipment and pipeline.A21H/W/F spring-loaded micro-opening safety valve connection is divided into two types of external threads and welded pipe, according to the requirements of the site working conditions when you choose and buy.
Performance Characteristics
- The spring-loaded pop-up safety valve features a simple structure, excellent sealing performance, precise opening pressure, high discharge capacity, low reseating pressure differential, and convenient adjustment.
- Nozzle-type seat: The seat adopts a Ver-type nozzle design, where steam reaches sonic velocity at the outlet. This configuration delivers a high discharge coefficient. The sealing surface is overlaid with cobalt-chromium-tungsten hard alloy, ensuring exceptional wear resistance, erosion resistance, and extended service life.
- Thermo-elastic valve flap: The valve flap is designed as a thermo-elastic structure, utilizing its tiny deformation under medium pressure to improve sealing ability and overcome the phenomenon of forward leakage of the safety valve when the medium pressure is close to the setting pressure. The sealing surface of the valve flap adopts advanced laser quenching technology, which improves the hardness, abrasion resistance and impact resistance.
- Adjustment nut: By adjusting the adjustment nut, the spring compression is modified, enabling the valve to achieve the precise set pressure quickly and conveniently.
- Back Pressure Adjustment Sleeve: An auxiliary mechanism for adjusting the back pressure on the valve disc. Adjusting the back pressure via this sleeve enables the attainment of an appropriate reseating pressure differential. When adjusted upward, it reduces the valve's back pressure. When adjusted downward, it increases the valve's back pressure.
Product Parameters
Product Model | A21W-16P |
Valve body material | 304 Stainless Steel |
Nominal pressure | ≤1.6Mpa |
Applicable medium | Corrosive Gases or Liquids, etc. |
Applicable temperature | ≤200℃ |
A21W External Thread Spring-Loaded Micro-Lift Safety Valve Dimension Reference

Nominal Diameter | ZG | L | L1 | G |
DN10 | 3/8 | 35 | 50 | G1/2 |
DN15 | 1/2 | 35 | 50 | G1/2 |
DN20 | 3/4 | 40 | 55 | G3/4 |
DN25 | 1 | 50 | 63 | G1 |
A21W Welded Tube Spring-Loaded Safety Valve Size Reference

Nominal Diameter | D1 | D | M | L | L1 | G |
DN10 | 10 | 16 | M27*1.5 | 35 | 80 | G1/2 |
DN15 | 14 | 20 | M27*1.5 | 35 | 80 | G1/2 |
DN20 | 17 | 25 | M33*1.5 | 40 | 90 | G3/4 |
DN25 | 23 | 31 | M39*1.5 | 50 | 100 | G1 |















