Nash mechanical seal service

Citation

(2002), "Nash mechanical seal service", Industrial Lubrication and Tribology, Vol. 54 No. 5. https://doi.org/10.1108/ilt.2002.01854ead.009

Nash mechanical seal service

Nash mechanical seal service

Keyword: Seals

Dry gas seals (DGS) increasingly provide a reliable sealing solution for high-speed turbo-machinery. However, the seal environment requires careful control to ensure trouble-free operation. Typically, this is achieved by fitting clearance labyrinths to both the bearing and process sides of the DGS. A clean gas is introduced into the cavity between the DGS and each labyrinth and maintained at sufficient positive differential pressure to prevent the ingress of contaminants. However, this method does not guarantee a clean seal environment.

Senior Seal Engineer Matt Corker explains, "Labyrinths can be unreliable as a method of protecting dry gas seals, because a controlled clearance is required between labyrinth and shaft. Contaminants such as bearing oil, asphaltines and sulphur sludge can pass through the clearance into the dry gas seal. The risk of contamination can be reduced by increasing clean gas pressure and flow, but this does not always eliminate the problem and the additional gas consumption is expensive".

To solve the problem, compressor manufacturers and users are increasingly choosing to upgrade their equipment by replacing labyrinths with circumferential barrier seals. These seals were first developed for use on compressors by Kaydon Ring & Seal Inc. of Baltimore, USA and the company remains at the forefront of this technology today.

Fitted in place of the bearing side labyrinth, the Kaydon K-CBS contacting circumferential barrier seal effectively halts migration of bearing oil into the DGS and reduces buffer gas flow to 1/100th of that of a labyrinth. Newly re-engineered, the K-CBS is now available with a biased flow design for optimum DGS protection on equipment with a flooded bearing cavity. The K-CBS also protects the bearing from leaked process gas, which ensures reliable bearing operation and prevents explosive mixtures forming in the bearing cavity.

Fitted in place of the process side labyrinth, the Kaydon K-PCS protects the DGS from process contaminants and significantly reduces buffer gas consumption. With a service life of between four to ten years, the K-CBS and K-PCS fit in conjunction with any DGS or can be integrated into a DGS as a compact unit.

Solar Turbines fits Kaydon barrier seals as standard on all Solar compressors incorporating dry gas seals. Transcanada Pipelines uses barrier seals on all compressors fitted with dry gas seals.

NASH Mechanical Seal Services is the authorised Kaydon agent and service centre for the UK, Scandinavia, France and Benelux.

For further details contact: NASH on +44 1204 388 030 or E-mail: enquiry@nashsealserv.co.uk The Web site address is: www.nashsealserv.co.uk