Product Overview
The THINKTANK TT-A48Y Series is a direct spring-loaded, full-lift flanged safety valve with lever designed for automatic overpressure protection of industrial equipment and piping systems.
The valve is intended for steam, air and similar media and is suitable for operating temperatures up to 350°C.
Available in sizes up to DN400 for PN16 / PN25 / PN40 configurations and up to DN150 for PN64 / PN100 configurations, the TT-A48Y covers a wide range of industrial pressure-protection applications.
Its full-lift construction provides a larger opening relative to the valve orifice than a low-lift design, while the external lever distinguishes the TT-A48Y from enclosed full-lift models without a lever.
Quick Specifications
| Parameter | Specification |
|---|---|
| Model | TT-A48Y |
| Product Type | Spring-Loaded Full-Lift Safety Valve |
| Connection | Flanged |
| Size Range | DN20–DN400 depending on pressure rating |
| Pressure Rating | PN16 / PN25 / PN40 / PN64 / PN100 |
| Design | Direct Spring-Loaded |
| Lift Type | Full Lift |
| Lever | Yes |
| Applicable Media | Steam, air and similar media |
| Maximum Operating Temperature | ≤350°C |
| Function | Automatic Overpressure Protection |
| Manufacturer | THINKTANK |
How It Works
The TT-A48Y operates as a direct spring-loaded safety valve.
During normal operation, spring force keeps the valve disc seated and the valve closed.
When pressure in the protected equipment or piping system reaches the specified set pressure, the pressure force acting on the disc overcomes the spring force and causes the valve to open.
The process medium is discharged through the valve outlet, reducing pressure in the protected system.
As system pressure decreases to the reseating range, spring force moves the disc back toward the seat and the valve recloses automatically.
Full-Lift Design
The TT-A48Y uses a full-lift configuration.
Under the general performance criteria applicable to this safety valve family:
Lift H ≥ 1/4 d₀
where:
- H = Valve lift
- d₀ = Orifice diameter
The full-lift configuration provides a larger available discharge area than a low-lift safety valve and is therefore suitable where greater relieving capacity is required.
Actual relieving capacity must still be verified according to the required relief load, set pressure, relieving conditions and selected valve size.
Lever Design
The TT-A48Y is equipped with an external lifting lever mechanism associated with the valve lifting assembly.
This is one of the principal structural differences between the TT-A48Y and enclosed full-lift safety valves such as the TT-A42Y.
Normal overpressure protection remains automatic and is controlled by the relationship between process pressure and spring force.
Typical Applications
The TT-A48Y Series can be considered for:
- Steam systems
- Compressed air systems
- Industrial gas systems
- Pressure vessels
- Process piping
- Packaged process equipment
- Skid-mounted systems
- Utility piping
- General industrial overpressure protection
Final valve selection should consider the actual process medium, set pressure, operating and relieving temperature, required relieving capacity, back pressure and pressure rating.
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 test and performance requirements shall be confirmed according to the selected valve model, project specification and applicable standard.
For the TT-A48Y Series, the full-lift criterion applies: H ≥ 1/4 d₀.
Since the TT-A48Y is intended for steam, air and similar media, the steam and air/gas performance requirements are the primary applicable rows for this model.
Dimensions – PN16 / PN25 / PN40
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 15 | 25 | 110 | 95 | 306 |
| 25 | 16 | 32 | 110 | 95 | 306 |
| 32 | 20 | 40 | 115 | 100 | 309 |
| 40 | 25 | 50 | 120 | 110 | 323 |
| 50 | 32 | 65 | 135 | 120 | 333 |
| 65 | 40 | 80 | 160 | 140 | 420 |
| 80 | 50 | 100 | 170 | 135 | 432 |
| 100 | 65 | 125 | 205 | 160 | 553 |
| 125 | 80 | 150 | 210 | 190 | 639 |
| 150 | 100 | 200 | 255 | 230 | 654 |
| 200 | 125 | 250 | 305 | 260 | 797 |
| 250 | 150 | 300 | 350 | 320 | 998 |
| 300 | 200 | 400 | 370 | 350 | 1246 |
| 350 | 250 | 500 | 375 | 415 | 1494 |
| 400 | 280 | 500 | 395 | 415 | 1780 |
Dimensions – PN64 / PN100
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 12 | 25 | 110 | 100 | 305 |
| 25 | 16 | 32 | 110 | 100 | 305 |
| 32 | 20 | 40 | 130 | 110 | 318 |
| 40 | 25 | 50 | 135 | 120 | 323 |
| 50 | 32 | 65 | 160 | 130 | 415 |
| 65 | 40 | 80 | 175 | 160 | 531 |
| 80 | 50 | 100 | 175 | 160 | 541 |
| 100 | 65 | 125 | 195 | 195 | 624 |
| 150 | 100 | 200 | 285 | 260 | 903 |
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
Available valve sizes depend on the nominal pressure class.
PN16 / PN25 / PN40: DN20–DN400
PN64 / PN100: DN20–DN150
The pressure rating and nominal connection size alone do not determine whether the valve can provide the required overpressure protection. The required set pressure, relieving conditions and discharge capacity must also be verified.
Safety Valve Sizing and Selection
For correct selection of the TT-A48Y Series, provide:
- Process medium
- Set pressure
- Operating pressure
- Design pressure
- Operating temperature
- Relieving temperature
- Required relieving capacity
- Back pressure
- Required inlet DN
- Required outlet DN
- Pressure rating
- Required materials
- Applicable standards or certification requirements
- Installation and discharge arrangement
For steam applications, the steam conditions and required relieving capacity should be provided.
For air and other gas applications, additional thermodynamic properties may be required for relieving capacity calculations.
Engineering Support
THINKTANK supports EPC contractors, system integrators, pressure equipment manufacturers 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 evaluate equivalent replacements for existing safety valve brands and provide technically suitable, cost-effective alternatives.
