What is a low fugitive valve?
Low fugitive valves refer to industrial valves that meet the corresponding low fugitive standards through a series of continuous processes such as rational selection, customized design, consistent parts manufacturing, standardized installation, and product test verification.
International and national standards
- ISO 15848 Industrial valves – Measurement, testing and qualification procedures for fugitive media;
- API 624 Type Test of Lift Bar Valves with Low Fugitiven Graphite Packing;
- API 641 Low Fugitive Type Test for Quarter Swing Valves;
- SHELL MESC SPE 77/300 Industrial Valve Design Verification Test Procedures and Technical Specifications; German TA-luft regulations, etc.
- GB/T 40079 “Classification and Identification Procedures for Valve Fugitivity Tests”
Technical points of low fugitive valves
The technical points of low-fugitive valves mainly lie in the control of important conditions such as structure and materials. The valve design must be type-tested and certified, witnessed by a third party and issued a certificate to ensure that the valve meets the corresponding low fugitive requirements.
Why do you need a Low Fugitiven valve?
Pollutant leakage hazards in high-pollution risk industries
High-pollution risk industries not only use toxic and harmful raw materials in production, but most of them are located near water bodies, and some are adjacent to residential areas. Some of these impacts can be quantified, while others are immeasurable, such as the lasting impact of pollutants on the local ecological environment, long-term damage to people’s physical and mental health, drag down on factory production costs and efficiency, and the possibility of major disasters. Taking hydrogen sulfide as an example, Table 1 shows the impact of hydrogen sulfide on the human body with different leakage rates, the concentration of hydrogen sulfide in the air can be sniffed out when it reaches 1PPMV (one part per million of the unit volume), up to 50PPMV will make people feel uncomfortable, up to 100PPMV will cause poisoning damage to the human body, and up to 250PPMV may lead to death.
Table 1 Hydrogen sulfide concentration and poisoning symptoms (PPMV is parts per million by volume)
| Hydrogen sulfide concentration（PPMV） | Symptoms of poisoning |
| 0.13~4.6 | You can smell the smell of rotten eggs, which is generally harmless to the human body. |
| 4.6~10 | There is a tingling sensation at first contact, but it disappears quickly |
| 10~50 | People feel unwell |
| 50~100 | Mild poisoning symptoms appear within 1 to 2 hours, including eye and respiratory discomfort |
| 100~150 | Olfactory nerve paralysis, headache, nausea, and obvious poisoning symptoms |
| 150~250 | Can be tolerated for 0.5~1 hour, with sequelae |
| 250~350 | Poisoning can occur in 6 to 8 minutes and death can occur within 4 to 8 hours |
| 350~500 | Severe poisoning within 0.5 to 1 hour, death within 1 to 4 hours |
| 500~600 | Severe poisoning within 1 minute, death within 0.5 to 1 hour |
| 600~700 | Death within 2 to 15 minutes |
The importance of low fugitive valves to improve environmental pollution
In the energy and chemical industry, valves, storage tanks, flanges, and pumps are the main factors causing media leakage, among which valves have become one of the product categories that users are most concerned about due to their large usage and dispersed installation locations.
In European and American countries, after nearly 20 years of local governments and enterprises sparing no effort to promote the use of low-fugitive valves, the proportion of valve leakage factors is gradually decreasing, and there is basically no peculiar smell in chemical plants in Europe and the United States. At present, conventional valves are still commonly used in our country and developing countries, with the improvement of domestic industrial level, the visible running and dripping leakage has been greatly reduced, but the invisible leakage of conventional valves is still very high, about 1000 times that of low fugitive valves, which is the main reason why we can often smell odors near industrial zones.
Therefore, how to reduce the escape of small medium from the valve to the external environment has become a necessary measure to improve environmental pollution. This extremely small amount of leakage cannot be determined by conventional water or nitrogen tests, and requires the help of more scientific means and sophisticated instruments to detect it, such as the quantitative detection of invisible leakage using the sucker method.
Table 2 ISO15848-2 Allowable leakage rate
Unit: PPMV
A | B | C | |
Valve Stem Seal | 50 | 100 | 200 |
| Valve Body Seal | 50 | ||
For the structural application of valves, there are two main types: static seal and dynamic seal. The selection of structure is generally based on comprehensive application information on site, such as: working condition medium properties, temperature, pressure, corrosiveness, switching frequency, switching method, environmental requirements, maintenance and other parameters to select the most suitable structure.
Static sealing typical application structure
Typical application structures include various gaskets, corrugated pads, winding pads, metal rings, etc., as well as O-rings + gaskets, lip rings + gaskets combinations.
Typical application structure of dynamic seals
Typical application structures include PTFE fillers, graphite fillers, O-rings + graphite fillers, lip rings + graphite fillers, bellows + graphite fillers, etc.
Learn more about Low Fugitive Valve《What is a Low Fugitive Valve? Analysis of Technical Points and Application Value》
