Overpressure protection · Badalona, since 1962
Safety valves
They detect overpressure in tanks, boilers, or pipelines and discharge the excess fluid without auxiliary power; once the pressure returns to normal, they close again. Models with full, instantaneous opening and with progressive opening, plus atmospheric valves for sealed vessels.
- Sizes¼″ to 4″ · DN15 to DN100
- Pressureup to PN25
- Temperatureup to 280 °C
- MaterialBrass, bronze, or 316L stainless
Questions about the set pressure? Call 933 720 888 or email valfonta@valfonta.com.
Find your safety valve
What you need
Opening
Inlet size
- Bench-tested safety valves
- Supplied preset to the pressure you specify
- Material and heat certificates on request
- Valfonta, Badalona, since 1962
Safety valve models
Filter with the search tool in the header or switch to the comparison table. Each product page includes specifications, available figures and sizes, and the PDF datasheet.
Safety valves
They protect tanks, boilers, and pipelines: they open when the set pressure is exceeded and close again once the pressure returns to normal.
Full, instantaneous opening
ALPER
Spring-loaded safety valve, available in lever or sealed figures and with piped discharge.
Sizes
¼″ to 4″ threaded · DN15–100 flanged
Pressure
PN25 metal seat · PN16 PTFE
Temperature
up to 280 °C stainless; 240 °C bronze
Material
RG5 bronze or 316L stainless
Choose it if you need full, instantaneous opening in medium or large sizes, threaded or flanged.
Full, instantaneous opening
JAS
Compact threaded safety valve in brass with a Viton seat.
Sizes
¼″ to ¾″
Pressure
PN16
Temperature
up to 180 °C
Figures
310 with lever · 311 sealed
Choose it if you need a compact threaded safety valve, from ¼″ to ¾″, up to PN16 and 180 °C.
Progressive opening
368–371
Progressive-opening safety valve, with open discharge (368) or piped discharge (371).
Sizes
3/8″ to 3″
Set pressure
0–1 · 1–11 · 11–16 bar
Temperature
up to 180 °C
Discharge
open (368) · piped (371)
Choose it if you want progressive opening rather than instantaneous pop action.
Atmospheric valves
They let air in under vacuum and, in the double-regulation version, let excess pressure out, within very small ranges.
Pressure and vacuum
ALPER atmospheric
Atmospheric valve for sealed vessels: single regulation (vacuum) or double regulation (pressure and vacuum).
Sizes
½″ to 4″ threaded · DIN flanges
Positive pressure
+0.080 to +8 bar
Vacuum
−0.050 to −0.650 bar
Temperature
up to 280 °C stainless
Choose it if you need to balance a sealed tank with the atmosphere, against vacuum or pressure.
| ALPER | Full, instantaneous | ¼″–4″ · DN15–100 | BSP threaded or DIN flanged | RG5 bronze or 316L stainless | PN25 (PN16 with PTFE) | 280 stainless · 240 bronze |
|---|---|---|---|---|---|---|
| JAS | Full, instantaneous | ¼″–¾″ | BSP threaded | Brass, Viton seat | PN16 | 180 |
| 368–371 | Progressive | 3/8″–3″ | BSP threaded | Brass / bronze | Set pressure 0–16 bar (PN16 bronze · PN12 Viton) | 180 |
| ALPER atmospheric | Progressive | ½″–4″ · DN15–100 | BSP threaded or DIN flanged | RG5 bronze or 316L stainless | +0.080 to +8 bar · −0.050 to −0.650 bar | 280 stainless |
Data from each model’s datasheet. All of them work with liquids, compressed air, inert gases, and steam. On the ALPER, DIN flanges go up to DN32 in the stainless steel figures.
No model matches these filters. Tell us about your installation in the form and we will recommend the right valve.
Safety valve vs. relief valve: how they differ
The main difference is how they open. The ALPER and the JAS are full, instantaneous opening (A.I.T.) valves: when the set pressure is exceeded, they open fully and discharge the excess fluid. The 368–371 is a progressive opening valve: it starts to open when the set pressure is exceeded, and its datasheet also calls it a relief valve.
Valfonta relief valves and excess pressure valves open in proportion to the pressure rise and hold the upstream pressure at the set value. Their manuals warn that they are not safety valves: if the installation needs overpressure protection, a safety valve must also be installed. We explain it in the difference between a safety valve and a relief valve.
ALPER atmospheric valves serve another purpose: they let air into or out of sealed vessels. Single-regulation models act against vacuum, and double-regulation models also act against positive pressure, within very small ranges.
Certification
Pressure Equipment Directive
The 368–371 is certified to PED 2014/68/EU. On the ALPER, threaded figures 375, 376, 385, 386, 395, and 396 carry CE certification; for flanged figures, please ask us. Atmospheric valves do not carry CE certification.
Certificates on request
For the ALPER, the JAS, and the 368–371, material, heat, and output certificates are delivered with the valve if requested in advance.
View and download Valfonta’s certificates.
Frequently asked questions about safety valves
What is the difference between a safety valve and a relief valve?
How they open and what they do. ALPER and JAS safety valves open fully and instantaneously when the set pressure is exceeded; the 368–371 opens progressively, and its datasheet also calls it a relief valve. Relief valves and excess pressure valves open in proportion to the pressure rise and do not replace a safety valve.
Are they supplied preset?
Yes. ALPER, JAS, and 368–371 safety valves are tested on a test bench and supplied preset to the pressure specified by the customer.
What fluids do they handle?
Liquids, compressed air, inert gases, and steam. The maximum temperature is 180 °C for the JAS and the 368–371, and 280 °C for the stainless steel ALPER valves.
What is an atmospheric valve used for?
To balance the pressure in a sealed vessel with atmospheric pressure: it lets air in under vacuum and, in the double-regulation version, lets excess pressure out.
What information does Valfonta need to prepare a quote?
The fluid and its temperature, the set pressure, the size and connection (threaded or flanged), the material, and whether you want it with a lever or sealed.
Technical guides on safety and relief
Other families: Pressure relief valves · Pressure reducing valves · Control valves · Ejectors
Request a quote for a safety valve
Give us your installation details and we will recommend the right model, figure, and size.
- Fluid and temperature
- Set pressure (or vacuum setting)
- Size and connection (threaded or flanged)
- Material and whether you want it with a lever or sealed
You can also call 933 720 888.
