Valve Fugitive Emissions: ISO 15848-1 and Low-Emission Valve Design
Quick Answer
Fugitive emissions are uncontrolled leaks of process fluid past valve stem seals and body joints, usually volatile organic compounds. ISO 15848-1 classifies valves by leakage rate and test endurance (classes A, B, C). Meeting a tight class relies on low-emission packing and live-loading rather than a standard gland.
Why Emissions Matter
Leaked VOCs contribute to air pollution and safety risk. Many plants set emission limits and track valve leakage during audits. A small stem leak, summed across thousands of valves, becomes significant.
ISO 15848-1 Classes
| Class | Meaning |
|---|---|
| A | Tightest, fewest allowed leaks over test cycles |
| B | Intermediate |
| C | Less stringent |
The class pairs a leakage limit with a number of qualifying mechanical and thermal cycles.
How to Achieve Low Emissions
- Low-emission graphite packing sets qualified to API 622.
- Live-loaded gland to keep constant load.
- Proper stem finish and dimensional control.
Packing fundamentals are covered in our stem packing guide.
Specifying for Emissions
State the required ISO 15848-1 class and the test medium in the purchase order. Confirm the valve was tested, not just designed, to that class. For high-risk service, see the special-service valve guide.
References
This guide references ISO 15848-1 and API 622. Consult the current editions and local emission regulations.
Frequently Asked Questions
What are valve fugitive emissions?
Small leaks of process fluid, usually VOCs, past stem seals and body joints.
What does ISO 15848-1 define?
It classifies valves by leakage rate and endurance through test cycles, giving classes A, B, and C.
How do you reduce emissions?
Use low-emission graphite packing qualified to API 622 and a live-loaded gland.
Is a standard valve low-emission?
Not necessarily. Low emission must be specified and tested; a conventional gland usually does not meet class A.
What is an ISO 15848 class A valve?
One that meets the tightest leakage limit over the required number of qualifying cycles.