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Cutting hydraulic piston leakage
Dynamic
sealing
Packing settles powder problem
Cutting hydraulic piston leakage
James Walker reports on how its Compression Packing Division was able to resolve a problem for Janssen Pharmaceutics, a subsidiary of Johnson & Johnson, which develops health products for human and veterinary applications. At its main plant in Geel, about 40 km east Antwerp, Janssen Pharmaceutics operates a series of centrifuges where powders are mixed and dried. Tanks range in diameter from 1.5 m to 2 m, with lids that can be closed by hand or hydraulic ram. The company was buying preformed lid seals with a silicone rubber core wrapped with etched PTFE foil. But they were not the exact diameter, which caused problems during seal fitting and operation. Louis Serneels of James Walker Belgium, with technical advice from Andrew Goulding, general manager of James Walker’s compression packing division recommended a trial with Tankatite@ 250. This was an immediate technical success, and after some minor adjustments it is now the specified packing for all centrifuges at Janssen Pharmaceutics. For the majority of production batches, 30 mm x 10 mm Tankatite 250, with a nitrile and neoprene rubber core is supplied in lenght form, cut and joined on site. The same packing with an EP rubber core is fitted when chemical resistance is a problem.
James Walker has developed a compact seal called Lionsele P which significantly reduces leakages at piston heads in high speed, high pressure hydraulic systems at 400 bar, or piston speeds up to 5 m/s. James Walker says the seal has been shown to have only 38% of the fluid leakage of comparable piston head seals, when tested to 400 000 mechanical cycles. Suitable applications include actuators, hydraulic cylinders, servo-mechanisms and other duties where an instant response is essential or power consumption must be minimised. It is also recommended for high frequency, short stroke applications where unstable film conditions can be a problem.
Contact: James Walker & Co Ltd. Lion House, Oriental Road, Waking. Surrey GU22 SAP, UK. Tel: +44 1483 757575: Fax: +44 1483 755711.
Valve seal to cut diesel emissions Elastomeric component maker, Precision Polymer Engineering has developed a seal system which will reduce emissions from diesel engines. The special valve stem seal has been developed in association with GEC Alsthom Paxman Diesels and in trials has reduced engine blowby by as much as 25%. Further trial are continuing and are expected to confirm a reduction in lubricating oil consumption, with an accompanying improvement in emissions. Custom designed using high performance fluorocarbon, the seal also offers high temperature resistance and withstands exposure to oil mist, burnt diesel gases and contact abrasion from the valve stem. These engines can run in excess of 120 hours a week. Paxman says the development programme is key to its committment to diesel engines that have as low an impact on the environment as possible.
The Lionsele P seal is comprised of a rectangularsection energiser of NBR, which exerts an evenly distributed load to the PTFE-based sleeving material, Fluolion CL. This filled sleeve maintains intimate contact with the cylinder bore, preventing the seal from rocking or twisting. This keeps the fluid film stable, and the friction level constant to give a smooth judder-free action. The sleeve reduces leakage by recovering virtually all of the residual fluid film deposited on the cylinder bore. Lionsele P operates at temperatures from -25°C to 100°C with an NBR energiser. Other elastomers and sleeve materials are used at higher temperatures and when extended chemical resistance is required.
Contact: Precision Polymer Engineering Ltd. Clarendon Road, Blackbum BBl 9SS, UK. Tel: +44 1254 679916: Fax: +44 1254 680182.
Contact: James Walker & Co Ltd. Lion House, Oriental Road, Woking, Surrey, GU22 SAP, UK: Tel: +44 1463 757575; Fax: +44 1483 755711.
Sealing Technology
No. 49
7
sealing
Packing settles powder problem
Cutting hydraulic piston leakage
James Walker reports on how its Compression Packing Division was able to resolve a problem for Janssen Pharmaceutics, a subsidiary of Johnson & Johnson, which develops health products for human and veterinary applications. At its main plant in Geel, about 40 km east Antwerp, Janssen Pharmaceutics operates a series of centrifuges where powders are mixed and dried. Tanks range in diameter from 1.5 m to 2 m, with lids that can be closed by hand or hydraulic ram. The company was buying preformed lid seals with a silicone rubber core wrapped with etched PTFE foil. But they were not the exact diameter, which caused problems during seal fitting and operation. Louis Serneels of James Walker Belgium, with technical advice from Andrew Goulding, general manager of James Walker’s compression packing division recommended a trial with Tankatite@ 250. This was an immediate technical success, and after some minor adjustments it is now the specified packing for all centrifuges at Janssen Pharmaceutics. For the majority of production batches, 30 mm x 10 mm Tankatite 250, with a nitrile and neoprene rubber core is supplied in lenght form, cut and joined on site. The same packing with an EP rubber core is fitted when chemical resistance is a problem.
James Walker has developed a compact seal called Lionsele P which significantly reduces leakages at piston heads in high speed, high pressure hydraulic systems at 400 bar, or piston speeds up to 5 m/s. James Walker says the seal has been shown to have only 38% of the fluid leakage of comparable piston head seals, when tested to 400 000 mechanical cycles. Suitable applications include actuators, hydraulic cylinders, servo-mechanisms and other duties where an instant response is essential or power consumption must be minimised. It is also recommended for high frequency, short stroke applications where unstable film conditions can be a problem.
Contact: James Walker & Co Ltd. Lion House, Oriental Road, Waking. Surrey GU22 SAP, UK. Tel: +44 1483 757575: Fax: +44 1483 755711.
Valve seal to cut diesel emissions Elastomeric component maker, Precision Polymer Engineering has developed a seal system which will reduce emissions from diesel engines. The special valve stem seal has been developed in association with GEC Alsthom Paxman Diesels and in trials has reduced engine blowby by as much as 25%. Further trial are continuing and are expected to confirm a reduction in lubricating oil consumption, with an accompanying improvement in emissions. Custom designed using high performance fluorocarbon, the seal also offers high temperature resistance and withstands exposure to oil mist, burnt diesel gases and contact abrasion from the valve stem. These engines can run in excess of 120 hours a week. Paxman says the development programme is key to its committment to diesel engines that have as low an impact on the environment as possible.
The Lionsele P seal is comprised of a rectangularsection energiser of NBR, which exerts an evenly distributed load to the PTFE-based sleeving material, Fluolion CL. This filled sleeve maintains intimate contact with the cylinder bore, preventing the seal from rocking or twisting. This keeps the fluid film stable, and the friction level constant to give a smooth judder-free action. The sleeve reduces leakage by recovering virtually all of the residual fluid film deposited on the cylinder bore. Lionsele P operates at temperatures from -25°C to 100°C with an NBR energiser. Other elastomers and sleeve materials are used at higher temperatures and when extended chemical resistance is required.
Contact: Precision Polymer Engineering Ltd. Clarendon Road, Blackbum BBl 9SS, UK. Tel: +44 1254 679916: Fax: +44 1254 680182.
Contact: James Walker & Co Ltd. Lion House, Oriental Road, Woking, Surrey, GU22 SAP, UK: Tel: +44 1463 757575; Fax: +44 1483 755711.
Sealing Technology
No. 49
7