21.10.2004

Denka Lift announce precautionary measures for lifts

On September 9th two men in Holland were killed when the boom of a 28 metre Denka lift DL28 descended rapidly due to failure of the main lift cylinder seal, unfortunately the boom base section came to rest on a lower rise building causing the extended boom to continue on down and then catapult the two operators out of the basket. Neither were wearing safety harnesses or lanyards! (See Vertikal.Net Editorial).

How a main seal blew so catastrophically is a mystery, the unit had been subjected to an annual inspection barely three weeks earlier. The test included a creep test which would normally highlight any serious wear or damage to the seals. The machine apparently passed with flying colours.

After the accident the Dutch labour authorities, who are responsible for investigating the case, cleared Denka units to continue in service believing this to be a freak occurrence. Five weeks have now passed and the inspectorate do not anticipate any conclusions from its investigation for another six to eight weeks.

In light of this, Denka has decided to offer its customers a back up solution in order to provide additional peace of mind.

The company has carried out numerous tests on machines at the factory and inspected cylinders from older units in the field. No results were found that could have caused the catastrophic failure that occurred in Holland, The company has however decided to recommend that customers look to upgrade older machines by fitting the seal kits that it uses on current production models. Thes kits use the latest seal technology and materials, and are more resistant to wear. The new kits are now available for older units.

It has also decided to design an additional security and back up device which bolts onto the lift cylinder and will block oil flow back to the tank when the flow exceeds 1.5 times the normal maximum flow rate.

Denka asks that owners of
Trailer lifts: DL21 , DL25, DL28 and DL30
Truck lift: DL21T and
Narrow lift: DL22N

Visit their web site:- www.denka.dk then click on "contacts", "support" and then "technical support" to see the letter. You can also go directly there via the Vertikal.Net "Access and Lifting directory" on the top left of this article, go to the new On LIne safety bulletins section and it will take you directly to the pages.

We also attach a copy of the text of the Denka letter below.


DENKA LIFT A/S
Højvang 5
4300 Holbæk
Denmark
Phone +45 59 45 55 00
Fax +45 59 44 21 55
E-mail [email protected]
Internet www.denka.dk

To our customers and partners

External Technical Information, EM_0047

Tip cylinder seal replacement and additional safety system.

Five weeks have passed since the tragic accident in Holland, involving a DL28. Unfortunately, we have not as yet received any clear conclusion from the Dutch Labour Inspection who is in charge of the investigation of this accident. We do not expect to receive the final results until a couple of months from now.

We have therefore carried out our own examination of similar older lifts, and have found out that that in some cases the seal in the tip cylinder shows signs of wear quicker than expected. For safety reasons we therefore advice that following lift types older than 3 years should have this seal replaced by another as soon as possible:

Trailer lifts: DL21 , DL25, DL28 and DL30
Truck lift: DL21T
Narrow lift: DL22N

We have furthermore developed an additional safety device that will effectively and inexpensively act as a simple, additional safety precaution preventing the boom from falling down, regardless of cause.

The block must be mounted on the actual tip cylinder. The hose of the cylinder tube must be dismounted and the block tightened by using the enclosed banjo bolt, after which the hose is remounted on the block. If the oil flow from the cylinder increases to more than 1.5 times the normal flow, the hose break
valve will close. The potential pressure increase, which might result from the closing of this valve, will be released via a pressure relief valve set at 420 bar, preventing the cylinder tube from being damaged.

Holbæk, 15th October 2004
DENKA LIFT A/S
Højvang 5
4300 Holbæk
Denmark
Phone +45 59 45 55 00
Fax +45 59 44 21 55
E-mail [email protected]
Internet www.denka.dk
Holbæk, 15th October 2004

This system has now been thoroughly tested and is ready for delivery from week 44. We
recommend that our customers mount the system on the following lifts:

Trailer lifts: DL21 , DL25, DL28 and DL30
Truck lift: DL21T
Narrow lift: DL22N

We kindly ask you to order the system including mounting instructions and tip cylinder seal via our website: www.denka.dk and we shall take care to immediately dispatch your order. Details of prices and delivery terms are listed on the website.
We shall, of course, keep you informed on the conclusion drawn by the Dutch Labour Inspection once we have received it.

Yours sincerely,
Denka Lift A/S
Nils Bo Mølholm
Managing Director