Forget vulcanizing, leaks and clogged filters

Forget vulcanizing, leaks and clogged filters
–here comes the ZAVA seal-ring

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—At last, is the reaction of those who have been plagued by the constant need to change rubber seals on VFA and CCA filters at pulp plants the word over. An electrician at SCA Pulp in Sundsvall, Frans Sramek, is the man that has solved this well-known, and seemingly hopeless problem. The ZAVA seal can be mounted in minute and cuts maintenance costs substantially.

—It’s always a pleasure to be able to offer our customers products on which they make money”, says Lars Bylund, Customer Service Division at Sunds Defibrator.

Four hours work in one minute

One of ZAVA seal-ring’s prominent features is ease of installation. The rubber ring is locked in place, using a quick-connect coupling, which is impossible to separate once it has been assembled. The designer is reluctant to say more. Patent protection is important.

As far as maintenance is concerned, vulcanizing is just a memory. The seal-ring is changed easily in less than a minute, without shutting down the filter, un undertaking that would otherwise take three to four hours. The time saved is a strong argument for the ZAVA seal-ring, but not the strongest.

The rubber composition withstands anything

No one would go out on a limb and claim that any material, exposed to all the chemicals present in a pulp plant, is maintenance-free. But the ZAVA seal-rings is at least giving the maintenance people at Östrand cause to wonder.

For almost six months the ZAVA seal-ring has been tested on the plant’s filters without  sign of loosening or brittleness which are otherwise normal phenomena. The same thing is being experienced at MoDo in Husum.

—The rubber composition seems impervious to both acid and alkali environments of normal concentration, says Sven-Erik Sundin, spare parts sales engineer at Sunds Defibrator, who has witnessed several less successful approaches to the problem.

Frans Sramek developed the rubber composition with the help of a good friend in the tire industry. If anything, the formula is an even bigger secret than the construction of the mounting device.

An end to mess and waste

An improved work environment is one of the main reasons why the ZAVA seal-ring has won the approval of mill maintenance and operating personnel.

Previously, replacement of a leaking seal-ring was postponed until a normal production stop or periodic maintenance. As a result, it became increasingly difficult to keep machine areas clean as leakage increased.

So far, the ZAVA seal-ring has proved to be completely tight. This also means that losses of black liquor and other chemicals have been minimized.

Zava Seal-Ring creates new filter designs

Sunds Defibrator’s design people have become infatuated with the ZAVA seal-ring. One idea being tested is to eliminate the inner seal-ring (V seal-ring) on VFA and CCA filters. This will result in a further reduction of maintenance since the seal cover would not have to be separated.

It can become a reality if the ZAVA seal-ring proves that it can withstand the stresses. Åke Sundström, head of filter design at Sunds Defibrator says: ”We believe that, at last, we can avoid the troublesome V seal-rings on the covers. With a few minor design changes, an externally mounted ZAVA seal-ring should handle the entire job”.


The quick-connect coupling is one of the secrets of the ZAVA seal-ring. Lars Bylund, Customer Service at Sunds Defibrator, gives it a try.