A breather valve controls the pressure and vacuum inside a storage tank — it opens and closes to allow the tank to breathe safely. A flame arrester prevents flame from travelling through the vent. On flammable liquid storage tanks, both are needed together — the breather valve controls when the vent opens and the flame arrester prevents ignition. They are available as separate devices or as a combined single unit.

Flow Industries manufactures breather valves from ½ inch to 12 inch (40mm to 300mm). Body material is aluminium alloy for sizes 2", 3" and 6", and cast steel for sizes 8", 10" and 12". Please specify the tank nozzle size, fluid stored and pressure and vacuum requirements when enquiring.

API 2000 is the American Petroleum Institute standard for venting atmospheric and low-pressure storage tanks. It defines the required venting capacity for storage tanks based on tank size, fluid type and filling/emptying rates. Flow Industries breather valves are designed in accordance with API 2000 guidelines. We can assist with venting capacity calculations for your tank if required.

Yes. For corrosive chemical service — acids, alkalis, chlorinated solvents — we supply breather valves with stainless steel SS 316 pallets, seats and internals, and PTFE or Viton seals. Please specify the chemical name, concentration, temperature and pressure when requesting a quotation so we can confirm the correct material selection.

They are the same device. A pressure vacuum relief valve (PVRV) and a conservation vent are both names for a breather valve. The term "conservation vent" emphasises the vapour-saving function — by only opening at a set pressure or vacuum rather than being open continuously, it reduces evaporation losses compared to an open vent pipe.

The pressure and vacuum settings must be selected based on your tank shell design pressure and the maximum filling and emptying rates. As a guide, atmospheric cone roof tanks typically use +0.5 to +2 oz/sq.in pressure and -0.5 to -1 oz/sq.in vacuum. Always confirm with your tank design engineer before ordering.

Yes. Flow Industries is based in Yogi Industrial Estate, GIDC, Ankleshwar and regularly supplies breather valves to chemical and pharmaceutical plants in Ankleshwar GIDC, Panoli GIDC, Jhagadia GIDC and Dahej SEZ. Contact us at +91 98244 66603 for local delivery and support.

Yes. Flow Industries manufactures a flame arrester cum breather valve — a single fitting that combines both functions. This is the most popular choice for flammable liquid storage tanks as it reduces the number of tank nozzles used and simplifies installation and maintenance.