Rupture disc, safety valve & explosion vent sizing — your instant solution to over-pressure safety
Engineered rupture discs, safety valves and explosion vents for chemical, pharma, food, oil & gas, and power industries — backed by free standards-compliant online sizing tools covering API 520, ASME Section VIII, ISO 4126 and NFPA 68.
Engineered for every relief application
From low-pressure vacuum service to ultra-high-pressure hydrogen systems — Flammer manufactures the complete portfolio of metal, composite, graphite, and sanitary rupture discs.
Can't find the right disc for your application?
Three calculators, one account
Size a rupture disc, a safety valve or an explosion vent to the governing standard — with a live drawing, saved projects and a printable datasheet.
Size your rupture disc in 60 seconds
Standards-compliant sizing for gas, liquid, steam, and two-phase flow — built to ASME, API, and ISO specifications.
Flammer Safety Valves
Spring-loaded safety relief valves for gas, steam, liquid and two-phase service — conventional and balanced-bellows designs, built and tested in Vadodara to API 520 / 526 / 527, ASME Section VIII and IBR.
Size your safety valve in 60 seconds
Enter the fluid, set pressure and relieving capacity — the tool works out the required orifice area, picks the Flammer series and orifice, and draws the installation live.
Flammer Explosion Vents
India's first and only indigenous manufacturer of explosion vent panels — laser-cut and burst-tested at our Vadodara facility since 2019. Designed to NFPA 68 and VDI 3673 to protect dust collectors, silos, cyclones, dryers and more.
Size your explosion vent in 60 seconds
Pick your vessel, enter its main dimensions and the dust or gas — the tool works out the volume, L/D, required vent area and the Flammer vent panels to fit, with a live drawing.
Process safety, across every sector
Pressure relief sizing — frequently asked questions
Is the Flammer sizing calculator free to use?
Yes. The rupture disc, safety valve and explosion vent calculators are free. Create a free account to save your calculations in projects and print branded A4 datasheets.
Which standards do the calculators follow?
Rupture disc sizing follows API RP 520 Part I, ASME Section VIII Division 1 and ISO 4126-6. Safety valve sizing follows API 520 Part I and API 521 with ASME Section VIII and IBR rules. Explosion vent sizing follows NFPA 68 and EN 14491 for dusts and EN 14994 for gases.
How do I size a rupture disc?
Enter the fluid, the burst pressure, the allowable overpressure, the relieving temperature and the required relief flow. The calculator works out the relieving pressure and the minimum net flow area for gas, steam or liquid, then suggests the nominal disc size and a suitable Flammer disc series.
How do I size a safety valve to API 520?
Enter the fluid properties, set pressure, overpressure, back pressure and the required relieving capacity. The calculator applies the API 520 equation for gas, steam, liquid or two-phase flow, with the back-pressure, superheat and viscosity corrections, and returns the required orifice area, the orifice letter and the rated capacity.
How is an explosion vent sized to NFPA 68?
The required vent area depends on the dust or gas explosion index (KSt or KG), the maximum explosion pressure Pmax, the vessel volume and length-to-diameter ratio, the reduced pressure Pred the vessel can withstand and the vent opening pressure Pstat. The calculator adds the corrections for elongated vessels, partial volume and vent ducts, and selects the number and size of Flammer vent panels.
What is the difference between a rupture disc and a safety valve?
A rupture disc is a non-reclosing device: it bursts once at its rated pressure and must then be replaced. A safety valve is spring-loaded and recloses when the pressure falls. A rupture disc is often installed upstream of a safety valve to isolate it from corrosive or fouling fluid; a combination factor of 0.9 is then applied to the valve capacity unless the combination is certified.
How much overpressure is allowed when sizing a relief device?
ASME Section VIII allows 10 % accumulation for a single relief device, 16 % when multiple devices are installed and 21 % for the external fire case. At low set pressures a minimum of 3 psi (4 psi for multiple devices) applies.
What do the dust classes St 1, St 2 and St 3 mean?
They rank dust explosion severity by the KSt value: St 1 up to 200 bar·m/s, St 2 from 201 to 300 bar·m/s, and St 3 above 300 bar·m/s. A higher KSt means a faster pressure rise and a larger explosion vent area.
Can I size a relief valve for an external fire?
Yes. The safety valve calculator includes the API 521 fire case: enter the wetted surface area, the environment factor for insulation and the latent heat of the liquid, and it calculates the heat input, the vapour generated and the required orifice.
Who makes these products and where?
Flammer Technologies Private Limited manufactures rupture discs, holders, safety valves and explosion vents in Vadodara, Gujarat, India, with ISO 9001, ISO 14001 and ISO 45001 certified manufacturing. Contact sales@flammertech.com or +91 6353 011 708.