Felt cleaning

1. It is easier to keep a felt or fabric clean than to clean it once it has become contaminated.
2. Showers:
— use sufficient shower pressure needed to do the job.
— use high pressure showers (200 – 300 psi) on sheet side of felt and these should be operated continuously.
— needle shower pressures over 400 psi can damage felts.
— fan showers are safer but most effective with combined .hot water and chemical cleaning.
— hot water showers (>50°C) render deposits more soluble and easier to remove.
— hot water showers combined with an acid pH accelerate oxidative attack on nylon materials.
— direct the Uhle box lube shower into the felt/box nip with good even coverage.
— total volume for all showers should be in the range of 0.06 to 0.10 lb. of water per lb. of felt.
3. Nozzles:
— check for wear, especially where recycled water is used.
— oscillation stroke should be twice the nozzle spacing to enable some coverage should a nozzle plug.
4. Chemical felt conditioning shower should be located as close to the sheet/felt separation as possible.
5. Efficient water removal is required to optimize felt performance.
— use minimum vacuum of 1.0 in. Hg at recommended flow for felt construction.
— ensure proper dwell time over slots (3 – 5 milliseconds for machine speeds up to 1000 m/min).
6. Lubricating showers are usually stationary, but oscillation may prevent felt streaking.