Safety valve · Supplied by BAUTU
A42Y Closed Spring Loaded Full Lift Safety Valve — DN25 to DN300
Closed-bonnet, spring loaded full lift safety valve for air, gas and petroleum gas on pressure vessels and pipelines. When the pressure rises above the set pressure the valve opens fully and discharges; when the pressure falls back it closes again. The closed bonnet keeps the discharge sealed inside the valve. Carbon steel bodies up to 300 °C; stainless steel bodies up to 200 °C for corrosive gases. DN25 to DN300, PN16 / PN25 / PN40 or ASME Class 150 flanges.
- Supplied by BAUTU, inspected and tested before shipment
- Outlet one size larger than the inlet as standard; same-size outlet on request
- Non-standard sizes, flanges and set pressures made to order
- Material certificate and test report with every shipment
- Standard sizes ship in 15–20 days
An engineer replies within 24 hours. Send inlet size, set pressure, media, temperature and quantity.
Specifications
Technical Data
| Type | Spring loaded, full lift, closed bonnet (no lever) |
| Size range | Inlet DN25–DN300 (NPS 1″–12″) |
| Pressure rating | PN16 / PN25 / PN40 (1.6 / 2.5 / 4.0 MPa) · ASME Class 150 |
| Set pressure | Adjusted to your order |
| Connection | Flanged inlet and outlet · GB / EN PN flanges or ASME B16.5 Class 150 |
| Body material | WCB carbon steel · 304 stainless steel · 316 stainless steel |
| Seat and disc | Hard-alloy faced (letter “Y” in the model code) |
| Working temperature | ≤ 300 °C (carbon steel body) · ≤ 200 °C (stainless steel body) |
| Media | Air, gas, petroleum gas; corrosive gases with stainless steel bodies |
| Lift | Full lift |
| Documents | Material certificate and test report with every shipment |
| Lead time | Standard sizes 15–20 days |
Configurations
Inlet, Outlet and Flange Options
Real photos
A42Y Safety Valves Before Shipment
STAINLESS · DN50
WCB · DN80 PN16
CLASS 150 · 2″ × 2½″How to read the model
Model Code A42Y-16C
Dimensions
Dimensions (mm)
| Inlet DN | Throat d0 | L | L1 | Outlet DN′ | H | Weight (kg) |
|---|---|---|---|---|---|---|
| 25 | 15 | 110 | 95 | 32 | 295 | 10.3 |
| 32 | 20 | 115 | 100 | 40 | 295 | 12.5 |
| 40 | 25 | 120 | 110 | 50 | 295 | 15.5 |
| 50 | 32 | 135 | 120 | 65 | 300 | 18.5 |
| 65 | 40 | 160 | 140 | 80 | 320 | 28 |
| 80 | 50 | 170 | 135 | 100 | 410 | 33 |
| 100 | 65 | 195 | 175 | 125 | 515 | 56 |
| 150 | 100 | 255 | 230 | 175 | 605 | 105 |
| 150 | 100 | 255 | 230 | 200 | 735 | 110 |
| 200 | 125 | 300 | 260 | 250 | 725 | 172 |
| 250 | 150 | 350 | 320 | 300 | 908 | 385 |
| 300 | 200 | 380 | 350 | 400 | 1158 | 550 |
Unit: mm. Carbon steel body with GB PN flanges. L: inlet centreline to outlet flange face · L1: inlet flange face to outlet centreline · H: overall height. Drawings for ASME Class 150 flanges, stainless steel bodies and non-standard sizes are sent with your quotation.
Pressure & temperature
Models by Body Material
| Model | Body | Pressure | Max. temperature | Media |
|---|---|---|---|---|
| A42Y-16C / 25C / 40C | WCB carbon steel | PN16 / 25 / 40 | ≤ 300 °C | Air, gas, petroleum gas |
| A42Y-16P / 25P / 40P | 304 stainless | PN16 / 25 / 40 | ≤ 200 °C | Corrosive gases |
| A42Y-16R / 25R / 40R | 316 stainless | PN16 / 25 / 40 | ≤ 200 °C | Corrosive gases |
The set pressure is adjusted to your order within the rating of the PN or Class you choose.
How to order
Send Us These 8 Details for a Fast Quote
- Inlet size (DN or NPS)
- Outlet size, or “standard”
- Set pressure
- Media
- Working temperature
- Flange standard: PN16 / 25 / 40 or ASME Class 150
- Body material: WCB, 304 or 316
- Quantity and destination port
FAQ
Frequently Asked Questions
What is the difference between the A42Y and the A48Y safety valve?
The A42Y has a closed bonnet without a lever, which keeps the discharge sealed inside the valve; it is used for air, gas and petroleum gas, and in stainless steel for corrosive gases. The A48Y has an open bonnet with a lifting lever so the disc can be lifted by hand to test the valve; it is the usual choice for steam.
What does “full lift” mean?
When the valve opens, the disc lifts far enough that the flow area is set by the nozzle throat (d0 in the dimension table), so the valve reaches its full discharge capacity quickly.
Which body material should I choose?
WCB carbon steel for air, gas and petroleum gas up to 300 °C. 304 (P) or 316 (R) stainless steel for corrosive gases up to 200 °C.
Why is the outlet larger than the inlet?
The discharged gas expands, so a larger outlet keeps the back pressure low. As standard the outlet is one size up, for example DN80 inlet × DN100 outlet. A same-size outlet is available on request.
Can you set the valve to our pressure?
Yes. The set pressure is adjusted to your order. State the set pressure, media and temperature in your RFQ.
Can I order non-standard sizes or flanges?
Yes. Non-standard inlet and outlet sizes, flange standards and set pressures are made to order.
What documents ship with the valves?
A material certificate and a test report with every shipment.
