Hydraulic seals: A look at some of the latest movements in the industry
The key to efficiency with any hydraulic or pneumatic application is the ability to seal joints between pipes and equipment efficiently. And since ongoing improvement in performance is a driving force for the industry, it comes as little surprise that many innovations are appearing to achieve this end.
US pump manufacturer Wanner Engineering is doing away with conventional gasket technology altogether and has developed 'seal-less' technology for use with its pumps. The technology is now maturing and its most recent 'T' Series of 'seal-less' high-pressure diaphragm pumps enable seal-less technology on higher flow rate and pressure capacity applications.
Its T-Series pumps offer a simple, compact, and low-energy operation platform. The drive components are submerged in lubricant, resulting in minimal frictional energy losses in the internal mechanism with sustained pumping efficiency of above 90% possible.
The company has been exploring seal-less pump operations for some time to offer an alternative to piston and centrifugal pumps that are dependent on control systems to help reduce energy usage. Seals are commonly blamed for the cause of premature wear, which in turn results in a fall-off of performance and increase in energy use.
The T-Series was originally conceived to handle the demanding pumping needs of the oil and gas industry, which require high levels of performance with mixed types of liquids in harsh working environments and remote locations, making reliability, safety, energy efficiency and minimal downtime essential.
The company believes that the development will allow it to compete directly with the popular triplex piston plunger pump systems (a common three-piston/plunger configuration) for applications up to 170 litres/min and 310bar.
In addition, the seal-less technology has been integrated in to a triplex configuration in the T8045, which Warner is claiming to be a world first. This configuration is able to deliver liquid flows up to 170l/min at 207bar and was launched earlier this month at Germany's Achema 2012 in Frankfurt.
However, while Wanner is doing away with the humble seal, others are trying to improve it. An example comes from Garlock Sealing Technologies which has introduced a gasket material that is capable of withstanding up to 1000°C.
Its THERMa-PUR gasket is already being successfully used to seal connectors in biomass gasification plants, marine and land based exhaust systems, and mineral and fertiliser processing plants, which require high performance at extreme temperatures.
The gasket uses a combination of raw materials and a patent pending fibre core. The material is hydrophobic, making it safe to hydro test a system to full pressure and temperature, it also does not stick to flanges, making its release quick and easy.
Under test in the lab it showed good performance and efficient sealing when thermally cycled in temperatures up to 1,000°C. Additionally, because of its non-oxidising formulation and fibre core, it can reduce weight.
Another company, Flexitalklic, is currently celebrating its 100th anniversary and has developed its 'Change' gasket. This, it claims delivers a more dynamic seal, with superior compression and recovery over other gaskets on the market, based on thermal cycling and leakage tests. Flexitallic manufactures static sealing products for the oil and gas, energy and power generation industries.
Initially developed for heat exchangers, Change can be supplied with Thermiculite, PTFE, graphite filler and a wide variety of other metals, making it suitable for an extensive range of applications.
Russ Currie, applications engineering manager, Flexitallic says: "We developed a unique sealing construction and new welding process to engineer 'Change', which was created in direct response to customers' long-term problems with gaskets in poorly performing heat exchangers."
