Product Overview
The THINKTANK TT-A47H Series is a direct spring-loaded, low-lift flanged safety valve equipped with a lever mechanism for overpressure protection of industrial equipment and piping systems.
The valve is designed primarily for steam, compressed air and similar gas services, with a maximum operating temperature of 350°C.
Available in pressure ratings from PN16 to PN100 and sizes up to DN250, the TT-A47H covers a wide range of utility and industrial pressure-protection applications.
Its flanged construction makes it suitable for permanent installation on pressure vessels, process equipment and piping systems where threaded safety valves are not appropriate.
Quick Specifications
| Parameter | Specification |
|---|---|
| Model | TT-A47H |
| Product Type | Spring-Loaded Low-Lift Safety Valve |
| Connection | Flanged |
| Size Range | DN20–DN250 depending on pressure rating |
| Pressure Rating | PN16 / PN25 / PN40 / PN64 / PN100 |
| Design | Direct Spring-Loaded |
| Lift Type | Low Lift |
| Lever | Yes |
| Applicable Media | Steam, air and similar gases |
| Maximum Operating Temperature | ≤350°C |
| Function | Automatic Overpressure Protection |
| Manufacturer | THINKTANK |
How It Works
The TT-A47H operates using the principle of a direct spring-loaded safety valve.
During normal operation, spring force holds the valve disc against the seat and keeps the valve closed.
When the pressure of the protected system reaches the specified set pressure, the pressure force acting on the disc becomes sufficient to overcome the spring force and the valve begins to open.
The process medium is then discharged through the outlet, reducing the pressure within the protected equipment or piping system.
As the system pressure falls to the valve’s reseating range, the spring pushes the disc back toward the seat and the valve closes again.
This automatic pressure-relieving cycle protects the system against excessive internal pressure.
Lever Design
The TT-A47H is equipped with an external lifting lever mechanism.
The lever differentiates this series from enclosed non-lever low-lift designs such as the TT-A41H and provides a mechanical means associated with the valve lifting assembly.
For normal system protection, however, valve operation remains automatic and is controlled by the relationship between system pressure and spring force.
Low-Lift Design
The TT-A47H uses a low-lift configuration.
Under the general performance criteria applicable to this safety valve family:
Lift H ≥ 1/20 d₀
where:
- H = Valve lift
- d₀ = Orifice diameter
Low-lift safety valves should therefore be selected according to the required relieving capacity rather than nominal flange size alone.
If higher relieving capacity is required for the same general connection size, a full-lift safety valve configuration may need to be considered.
Typical Applications
The TT-A47H Series can be considered for:
- Steam piping
- Boiler auxiliary systems
- Compressed air systems
- Industrial gas systems
- Utility piping
- Pressure vessels
- Process equipment
- Skid-mounted systems
- Packaged equipment
- General industrial overpressure protection
Final valve selection must consider the actual medium, set pressure, operating temperature, relieving capacity, back pressure and applicable project requirements.
General Performance Requirements
| 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 testing and performance requirements shall be confirmed according to the selected valve model, project specification and applicable standard.
For the TT-A47H Series, the low-lift criterion applies: H ≥ 1/20 d₀.
Since TT-A47H is intended primarily for steam, air and similar gases, the steam and air/gas performance requirements are the most relevant rows for this model.
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 15 | 20 | 100 | 85 | 298 |
| 25 | 20 | 25 | 100 | 85 | 298 |
| 32 | 25 | 32 | 115 | 100 | 310 |
| 40 | 32 | 40 | 120 | 110 | 315 |
| 50 | 40 | 50 | 135 | 120 | 377 |
| 65 | 50 | 65 | 140 | 130 | 415 |
| 80 | 65 | 80 | 160 | 135 | 420 |
| 100 | 80 | 100 | 170 | 160 | 539 |
| 125 | 100 | 125 | 190 | 190 | 624 |
| 150 | 125 | 150 | 205 | 195 | 636 |
| 200 | 150 | 200 | 240 | 230 | 772 |
| 250 | 200 | 250 | 350 | 320 | 970 |
Dimensions – PN64 / PN100
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 15 | 20 | 100 | 95 | 301 |
| 25 | 20 | 25 | 100 | 95 | 301 |
| 32 | 25 | 32 | 115 | 105 | 312 |
| 40 | 32 | 40 | 135 | 115 | 366 |
| 50 | 40 | 50 | 160 | 130 | 401 |
| 65 | 50 | 65 | 175 | 160 | 570 |
| 80 | 65 | 80 | 175 | 160 | 565 |
| 100 | 80 | 100 | 190 | 180 | 597 |
| 150 | 100 | 150 | 280 | 260 | 738 |
Dimensions are for preliminary engineering and layout reference. Final approved dimensional drawings should be confirmed before piping fabrication or installation.
Pressure Rating and Size Range
The available size range depends on the required nominal pressure class.
PN16 / PN25 / PN40
DN20–DN250
PN64 / PN100
DN20–DN150
Pressure class and DN alone are not sufficient for selecting a safety valve. The valve must also be checked against the required set pressure, relieving conditions and required discharge capacity.
Safety Valve Sizing and Selection
For correct selection of the TT-A47H Series, please provide:
- Process medium
- Set pressure
- Operating pressure
- Design pressure
- Operating temperature
- Relieving temperature
- Required relieving capacity
- Back pressure
- Inlet DN
- Outlet DN
- Required pressure rating
- Required materials
- Applicable standards or certification requirements
- Installation and discharge arrangement
For steam applications, the required relieving capacity and steam conditions should be provided.
For air or other gases, additional process properties may be required for capacity calculations.
Engineering Support
THINKTANK supports EPC contractors, system integrators, boiler and pressure equipment manufacturers, skid builders and industrial users with:
- Safety valve sizing and selection
- Relieving capacity calculation and review
- Set-pressure configuration
- Pressure class selection
- Material selection
- 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 evaluate equivalent replacements for existing safety valve brands and provide technically suitable and cost-effective alternatives.
