Kamyr filter straps

A rotary drum filter or washer works on vacuum. The drum turns partly submerged, filter cloth over its surface, and vacuum inside the drum draws liquor through the cloth and leaves the fibre mat on the outside.

The straps are what hold that cloth down. They run in grooves around the drum, clamping the edge of the cloth into the deck so that the vacuum pulls through the cloth rather than around it.

They are not a decorative detail. They are the seal, and the whole vacuum profile depends on them.

Vacuum takes the path of least resistance. The moment a strap erodes, holes, lifts or breaks, air goes straight through the gap instead of being drawn through the cloth.

The results follow quickly:

• Vacuum drops across the whole drum — not just at the failure
• Mat formation goes uneven — thin or bare in the affected zone
• Washing efficiency falls — which shows up in carryover downstream
• The cloth starts to lift — and once it lifts it tears
• Throughput drops — and the vacuum pumps work harder for less

One strap can take a drum out of specification. A drum out of specification takes production with it.

They live in a hard place: wet, chemically loaded, abrasive with fibre and fillers, cycling in and out of the vat every revolution, and under constant clamping load.

Common failures are abrasive wear that thins the section until it splits, chemical attack that hardens and embrittles the material, mechanical damage during a cloth change, and fatigue at a fastening point.

Kamyr equipment was built by Kamyr AB in Sweden and the name stuck to the machines long after the company was absorbed. The mills still call them Kamyr drums.

The consequence is that the wear parts have historically been imported, which means a lead time in weeks or months, a price exposed to the exchange rate, and a minimum order that has little to do with the number you actually need.

Meanwhile the drum is either standing or running out of specification.

We manufacture filter straps in Vanderbijlpark to the dimensions and material your drum needs. Made locally, quoted in rands, with no import lead time and no forex on the price.

Because they are made rather than bought in, the quantity is whatever you need — a set for a planned shut, or one to get you through the night.

• The old strap, or a piece of it. It gives us the section, the length and the material
• The drum make and size, if you have it
• The medium and the temperature it runs in
• How many you need, and by when

If you are heading into a shut, order before it starts rather than during it.

Send it through and we will quote it.