The pressure vacuum relief valve, or PVRV for short, is typically installed on top of a petroleum storage tank. Its function is to automatically regulate the air exchange between the inside and outside of the petroleum tank to maintain stable internal pressure and prevent petroleum tank damaging or medium leaking due to abnormal pressure. Therefore, pressure vacuum relief valve is also known as petroleum tank breather valve. Below, we will introduce PVRV test procedure. According to API2000 standard and IOS28300 standard, pressure vacuum relief valve test procedure includes: PVRV pressure test, PVRV vacuum test, PVRV sealing test and PVRV flow test.
1.PVRV Pressure Test
It aims to verify whether a breather valve opening pressure meets its set value under positive pressure conditions.Firstly use compressed air as the test medium to gradually pressurize your breather valve. When you hear a click sound from the breather valve, stop pressurizing immediately. At this point, the exhalation valve disc of the breather valve has been opened successfully, record the current pressure value. generally speaking, if the deviation between the measured pressure value and the setting value is within ±10%, it is qualified.
2.PVRV Vacuum Test
Its full name is pressure vacuum relief valve vacuum test, as known as breather valve negative pressure test. And It aims to verify whether a breather valve opening pressure meets the set value under negative pressure conditions. First of all, vacuum PVRV valve, when you hear a click sound from the valve, stop vacuuming immediately. At this moment, the inhalation valve disc of the PVRV valve has been successfully opened, record the current vacuum value. Normally, if the deviation between the measured vacuum value and the setting value is within ±10%, it is qualified.
3.PVRV Flow Test
PVRV sealing test aims to verify the sealing performance of a breather valve under conditions when the opening pressure is not reached. Usually, pressurize the breather valve to 70% to 90% of its set pressure. Then hold the pressure for not less than 5 minutes. And then use the pressure drop method or bubbling method to detect the breather valve’s leakage rate. Normally, if the breather valve’s leakage rate is less than 5%, it indicates its the sealing performance is qualified.
4.PVRV Sealing Test
This is an extra test for breather valve. And it is to evaluate the breather valve’s ventilation capacity whether meets the petroleum storage tank pressure releasing requirements under extreme conditions. Firstly establish a stable pressure difference at the breather valve’s inlet. Then PVRV test bench will measure the air flow rate through the breather valve per unit time under the set pressure conditions. If the measured flow rate is higher than the design flow rate, it is qualified.
To facilitate user testing breather valves, we have developed automatic PVRV test bench which is applicable to various breather valves from DN15 to DN400. And it is automated by computer and has the features of easy operation and high testing accuracy. Moreover, it will automatically generate a test report after the test completed.
