Fugitive emissions from hard-working control valves can now be cut to well below 50ppm with the new Supagraf® Control gland packing from James Walker, claims the company. It is designed to seal efficiently for over 100,000 stem strokes without gland re-adjustment, and its very low coefficient of friction enhances accurate valve movement. Although far fewer control valves than on-off valves are used at industrial and petrochemical sites, control valves are much more likely to leak at the stem gland due to their continuous operation. Supagraf Control combats this with long-term fugitive emission control capability. Over 100,000 valve cycles have been performed to below 500ppm emissions, without gland adjustment, when working with methane at 40bar. In addition, third party tests by a major valve manufacturer show that after 10,800 cycles at 20°C and 50bar, followed by 16,700 cycles at 280°C and 50bar, the leakage was less than 2.2 x 10-4 mbar.litre/second.
