What is the difference between a control valve and a shut-off valve?

A control valve is designed for continuous modulation — it throttles flow to maintain a desired process variable (flow rate, pressure, temperature, level). It operates under 4-20mA or digital signal control. A shut-off valve is designed for on/off service only — it is either fully open or fully closed, providing tight isolation with minimal pressure drop when open.

What is the difference between pneumatic and electric control valves?

Pneumatic control valves use compressed air (typically 4-7 bar) to drive a diaphragm or piston actuator. They are fail-safe (spring-return), explosion-proof, and fast-responding — ideal for hazardous areas (refineries, chemical plants). Electric control valves use an electric motor actuator with 4-20mA or Modbus control. They are easier to install (no air supply), offer precise positioning, and are suitable for remote/automated plants without instrument air systems.

What is cage-guided trim in control valves?

Cage-guided trim uses a cylindrical cage with precision-machined ports to guide the valve plug and shape the flow characteristic (linear, equal percentage, or modified). Cage-guided designs provide low noise, anti-cavitation, and high capacity. The cage also absorbs hydrodynamic forces, reducing vibration and extending trim life. TANGGONG cage-guided control valves are available in ANSI/FCI 70-2 Class IV, V, and VI shutoff ratings.

How to size a control valve for my application?

Control valve sizing requires: (1) process fluid properties (density, viscosity, vapor pressure), (2) expected flow rate range (min/max/normal), (3) upstream and downstream pressures, (4) temperature, and (5) allowable pressure drop. TANGGONG's engineering team provides free valve sizing calculations per IEC 60534 — send us your process data sheet and we will recommend the correct Cv/Kv and valve type.

What certifications do TANGGONG control valves have?

TANGGONG control valves are manufactured under ISO 9001:2015 quality management, tested to ANSI/FCI 70-2 shutoff standards (Class IV/V/VI), and certified to CE and SGS standards. Third-party inspection by TUV, SGS, or DNV is available for specific projects. SIL-capable designs per IEC 61508 are available on request.

Self-operated nitrogen sealing valve

Name: TANGGONG Industrial Control Valve Series
Brand: TANGGONG VALVE GROUP
Availability: InStock
Rating: 4.7 (58 reviews)

Self‑operated nitrogen sealing valve is used to maintain stable nitrogen pressure inside storage tanks.
It automatically supplies nitrogen when tank pressure drops, and stops air intake when pressure reaches the set value, preventing air, moisture and impurities from entering the tank.
- GB/T 12224 General requirements for steel valves
- GB/T 12221 Face-to-face, end-to-end and centre-to-face dimensions of metal valves
- GB/T 13927 Pressure test for industrial valves
- GB/T 26480 Inspection and testing of pipeline valves
- GB/T 17213 Industrial process control valves

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Product Detail

Self‑operated nitrogen sealing valve is used to maintain stable nitrogen pressure inside storage tanks.

It automatically supplies nitrogen when tank pressure drops, and stops air intake when pressure reaches the set value, preventing air, moisture and impurities from entering the tank.

Widely applied in petrochemical, oil storage, chemical, pharmaceutical and food industries for tank nitrogen sealing protection.

Working Principle:
It senses tank pressure changes automatically by medium pressure, adjusts valve opening without external power, to keep nitrogen sealing pressure constant inside the tank.

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