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Dry vacuum system with self cleaning function

Edited by the Engineeringtalk editorial team Jan 12, 2001

Welch has overcome the practical problems of chemical attack which can lead to pump failure, with the launch of a new dry vacuum system with a self cleaning function.

Welch has overcome the practical problems of chemical attack which can lead to the reduced effectiveness or early failure of oil-sealed rotary vane pumps and Teflon coated diaphragm pumps, with the launch of a new dry vacuum system with a self cleaning function.

The system also incorporates a host of user features, including a built in vacuum level regulator, inlet and outlet catch pots, and a switch for gas ballast.

Readily portable, and suitable for use with solvents with boiling points below 100C in applications such as rotary evaporators, gel dryers and concentrators, the Model 2025 dry vacuum system is built around a corrosion resistant PTFE diaphragm pump with additional protection.

Unlike oil-sealed, rotary vane pumps, the diaphragm prevents process chemicals from contaminating the pump, either impairing the operation of the pump or leading to early failure.

In addition, the added protection of the self cleaning system improves on standard Teflon coated diaphragm designs by eliminating the possibility of chemicals eventually working their way through to attack the membrane, again leading to early pump failure and a potentially expensive repair bill.

The self cleaning function is activated every time an experiment is ended and the pump switched off.

Rather than simply powering down � which can leave behind some solvent coating the heads - the self cleaning function purges the system by bringing both heads up to atmospheric pressure and driving air across the heads for three minutes, performing an effective drying operation before the pump is shut down.

The outlet catch pot catches any liquid or particulates that are purged from the system during the cycle.

Importantly, this purge cycle does not alter the setting of the vacuum level regulator, ensuring consistent vacuum levels over any number of operations.

Another important feature of the Model 2025 is a gas ballast switch which operates a valve to prevent solvent condensing within the pump when it is operating with a high vapour load.

Operating the switch allows a fixed amount of air to flow into the second stage of the pump to reduce the ultimate pressure slightly, preventing solvent from condensing and so ensuring a smooth, constant vacuum.

A further benefit for users is the fitting as standard with both an inlet catch pot and an outlet catch pot, which effectively trap any liquids or particulates before ingestion by the pump and trap any condensed solvent vapours which are ejected by the system.

If required, these catch pots can be easily unscrewed and replaced by condensers.

The launch of the 2025 dry vacuum system extends the range of Welch vacuum systems to a wider vacuum spectrum, and sits alongside the GEM vacuum system which brings the same user advantages to solvents with boiling points up to 130C.

A complete range of highly reliable and competitively priced Welch vacuum pumps and systems is available ex-stock across Europe from ASF Thomas, along with a correspondingly high level of local service and support.