Product Overview
The THINKTANK TT-A21H/W/F Series is a direct spring-loaded, low-lift threaded safety valve designed for automatic overpressure protection of small equipment and process piping.
Different configurations are available for air, ammonia, petroleum gas, liquefied gas, corrosive gases and liquids, with operating temperatures up to 200°C depending on the selected model.
Its compact threaded design makes the series suitable for applications where installation space is limited and a flanged safety valve is not required.
Model Selection
TT-A21H
Suitable for equipment and pipelines handling:
- Air
- Ammonia
- Petroleum gas
- Similar compatible media
Operating temperature: ≤200°C
TT-A21W
Designed for equipment and pipelines conveying:
- Corrosive gases
- Corrosive liquids
Operating temperature: ≤200°C
Material compatibility should be verified according to the actual medium, concentration and operating temperature.
TT-A21F
Suitable for:
- Liquefied gas
- Petroleum gas
- Similar compatible media
Operating temperature: ≤80°C
Quick Specifications
| Parameter | Specification |
|---|---|
| Model | TT-A21H / TT-A21W / TT-A21F |
| Valve Type | Spring-Loaded Low-Lift Safety Valve |
| Size Range | DN15–DN25 |
| Connection | Threaded |
| Design | Direct Spring-Loaded |
| Function | Overpressure Protection |
| Maximum Temperature | Up to 200°C depending on model |
| Manufacturer | THINKTANK |
How It Works
The TT-A21H/W/F is a direct spring-loaded safety valve.
During normal operation, spring force keeps the valve disc seated. When the system pressure reaches the specified set pressure, the pressure force acting on the disc overcomes the spring force and the valve begins to open.
The discharged medium reduces system pressure and protects the connected equipment or pipeline from excessive pressure.
As the system pressure decreases, the spring forces the disc back toward the seat and the valve recloses.
Typical Applications
The TT-A21H/W/F Series can be used for:
- Air systems
- Ammonia piping
- Petroleum gas systems
- Liquefied gas systems
- Small pressure vessels
- Process piping
- Packaged equipment
- Skid-mounted systems
- Corrosive gas or liquid service with suitable materials
Dimensions
| DN | Orifice d₀ | d | D₀ | Thread M | Inlet Thread d1 | D1 | L | L1 | H |
|---|---|---|---|---|---|---|---|---|---|
| 15 | 12 mm | 15 mm | 20 mm | M27×1.5 | G1/2″ | 30 | 35 | 81 | 74 |
| 20 | 16 mm | 20 mm | 25 mm | M33×1.5 | G3/4″ | 34 | 40 | 87 | 81 |
| 25 | 18 mm | 25 mm | 31 mm | M39×1.5 | G1″ | 44 | 52 | 100 | 105 |
Dimensions are for preliminary engineering reference. Final certified drawings should be confirmed before installation or piping fabrication.
Safety Valve Selection
Safety valves should not be selected by nominal pipe size alone.
For correct selection, please provide:
- Process medium
- Set pressure
- Operating pressure
- Operating / relieving temperature
- Required relieving capacity
- Back pressure
- Inlet and outlet connection
- Required materials
- Applicable standards or certification requirements
For gas and vapor applications, additional process data may be required for relieving capacity calculation.
Performance Specification
| Applicable Medium | Shell Test Pressure Ps | Seal Test Pressure Pm | Blowdown ΔP | Discharge Pressure Pp | Lift Height H |
|---|---|---|---|---|---|
| Steam | — | 90% Pk or the minimum reseating pressure, whichever is lower | When Pk ≤ 0.4 MPa: ΔP ≤ 0.04 MPa; when Pk > 0.4 MPa: ΔP ≤ 10% Pk | ≤ 1.03 Pk | Full-lift: ≥ 1/4 d₀; Low-lift: ≥ 1/20 d₀ |
| Air or other gases | 1.5 PN | When Pk ≤ 0.3 MPa: Pm = Pk − 0.03 MPa; when Pk > 0.3 MPa: Pm = 90% Pk | When Pk ≤ 0.2 MPa: ΔP ≤ 0.03 MPa; when Pk > 0.2 MPa: ΔP ≤ 15% Pk | ≤ 1.1 Pk | Full-lift: ≥ 1/4 d₀; Low-lift: ≥ 1/20 d₀ |
| Water or other liquids | — | When Pk ≤ 0.3 MPa: Pm = Pk − 0.06 MPa; when Pk > 0.3 MPa: Pm = 80% Pk | When Pk ≤ 0.3 MPa: ΔP ≤ 0.06 MPa; when Pk > 0.3 MPa: ΔP ≤ 20% Pk | ≤ 1.2 Pk | Full-lift: ≥ 1/4 d₀; Low-lift: ≥ 1/20 d₀ |
Notes:
- Pk = Set pressure
- d₀ = Orifice diameter
- PN = Nominal pressure
- Actual test and performance requirements shall be confirmed according to the specific valve model, project specification, and applicable standard.
Engineering Support
THINKTANK supports EPC contractors, system integrators, equipment manufacturers, research facilities and industrial users with:
- Safety valve sizing and selection
- Material selection
- Set pressure configuration
- Relieving capacity review
- Dimensional drawings
- 3D models for system integration
- Replacement valve evaluation
- Project-specific technical documentation
With more than 30 years of industrial valve application experience, THINKTANK can also help evaluate equivalent replacements for existing safety valve brands and provide technically suitable, cost-effective alternatives.
Send us your medium, set pressure, temperature and required capacity for technical review.
