Supagraf Premier, James Walker’s compression packing, has beaten TA-Luft VDI 2440 emission control requirements by a significant margin to gain a good rating in independent tests carried out at the Amtec laboratory in Germany. Recorded gas emission levels in tests at 240°C and 400°C respectively would not fill a golf ball or tennis ball in a year.
The tests on a set of 56mm OD Supagraf Premier rings were undertaken for BP Refining & Petrochemicals, which operates the Ruhr Oel Gelsenkirchen refinery in Germany. It needed to know the sealing efficiency of graphite valve packings from several suppliers in order to comply with the European Union’s IPPC pollution prevention and control directive.
Targets of the investigation were to confirm TA-Luft leakage rates less than 10-4 mbar.l/(s.m) at sealing system temperatures below 250°C, and less than 10-2 mbar.l/(s.m) at above 250°C. The test cycle involved 1000 vertical valve stem movements of 40mm — without live-loading on the packing — whilst sealing helium at 25 bar for 24 hours.
Leakage measurements after 24 hours at 240°C showed 7.0 x 10 -6 mbar.l/(s.m).
“You can visualise this as less gas than will fill a golf ball in a year, measured at ambient pressure”, explained business development manager Brian Milford. “It also demonstrates that Supagraf Premier very easily surpasses TA-Luft requirements for a high grade valve packing.”
After 24 hours at 400°C, the leakage rate was 2.3 x 10-5 mbar.l/(s.m).
Said Brian Milford “This rate is exceptionally better than TA-Luft requirements for duties above 250°C. A year of emissions at this level would not even fill a tennis ball.”
Supagraf Premier has a 10 year record of beating fugitive emission control specifications. In 1997 it was subjected to over 12,000 valve operating cycles with methane at 40bar and kept emission levels below 500ppm.
In 1999, it came top of its class in comparative tests run by the Materials Technology Centre of Akzo Nobel. Since then it has twice been certified to TA-Luft requirements — by different customers — and third-party verified for emission control by CETIM to Shell SPE 77/321 Class A specification.