Tracking and limiting Fugitive Emissions has moved into the focus of many countries around the world. Stringent legal requirements force the industry to rethink and use emission-reducing equipment. This sounds very simple, but from my experience there is still misconception when it comes to this subject.
Today, I would like to compare the German TA-Luft with the ISO 15848 Standard.
The Difference between ISO 15848 and TA-Luft
|In the framework of ISO 15848 the entire industrial valve, including the body seals, will be subjected to type testing||TA-Luft only deals with the sealing system of the stem passage. A simple manufacturer declaration is sufficient for verification.|
|The ISO type test classifies the complete industrial valve into a pressure, temperature, endurance and tightness class.||The TA-Luft test qualifies only a “high-quality sealing system”. TA-Luft is considered to be complied with if metal bellows with a safety packing or similar sealing systems are used; whereby the equivalence in the verification system must be confirmed in accordance with VDI 2440.|
|The requirements of the ISO type test are very specific and detailed and as a result, the test duration for a complete ISO 15848 type test takes 1 to 2 weeks.||The requirements of TA-Luft are very general. The test duration for a TA-Luft test therefore normally does not take longer than 1-2 days. There is no requirement neither to the number of mechanical cycles nor to the number of thermal cycles.|
|ISO 15848 “Industrial valves – Measurement, test and qualification procedures for fugitive emissions” consists of 2 part:||For example, many seal manufacturers like to advertise with “TA-Luft packings”. Simply using “TA-Luft packings” of this type does not guarantee long-term leak tightness. Many other factors play a significant role in a sealing system.
These include, for example, the stem surface finish and the gap dimensions between the gland and the stem.
Classification system and qualification procedures for type testing of industrial valves:
A distinction is made here between 3 tightness classes: A, B and C. Class A having the smallest environmental leakage.
Production acceptance testing of industrial valves: Only the products that have successfully completed the first part of the test may be subjected to this test. Leakage is tested at room temperature without mechanical effects utilising a helium leak detection test.
How To Ensure You Buy The Best Product Available?
In my opinion, the ISO 15848 Fugitive Emission Standard is the one to go for.
Having said that, pay attention of how the valves are tested and always compare the manufacturer certificates. Some manufacturers conduct the tests at room temperature or reduced temperature and low pressure only.
As a matter of fact, the stress on the valve packing and material is much higher at real operating conditions with high temperature and pressure. Do also compare the number of cycles the valve has gone through to pass the test under the test temperature conditions.
It’s also noteworthy to mention that you should always go for quality when it comes to choosing the right valves for your application. State of the art design and manufacturing technique achieves the highest peak of seal integrity.
The Bottom Line
ISO 15848 approved valves are excellent and reliable at reducing fugitive emissions.
This improves plant safety, reliability and protects the environment and health.
Article originally posted on May 17, 2017 on www.taurusdbbvalves.com.