Chemical-Duty Laboratory Vacuum Systems (LVS)

Key Design Features and Performance Capabilities

The Welch portfolio of two- and three-stage chemical-resistant laboratory vacuum systems includes pump models with 2 to 8 heads. The systems offer maximum flow rates at 50 Hz of from 1 m³/h (16.7 l/min) to 9.1 m³/h (151.7 l/min). They are capable of delivering ultimate pressure levels ranging from <8 Torr to <2 Torr.

All of the systems’ wetted parts, including clear plastic-coated glassware, are made of high-quality, chemical-resistant materials to allow for the pumping of solvent and acid vapors. Add-on features include energy-saving exhaust vapor condensers and inlet separators to protect the pump from liquid and particle ingestion.

The systems can be provided with digital (ecoflex) vacuum controllers. Vacuum control enables vacuum to be adjusted precisely to individual needs, which results in automatic, more efficient and more reproducible processes. Unregulated models can be chosen when ultimate vacuum pressure is required at all times.

The controllers constantly vary the pump speed to maintain the user-defined vacuum level irrespective of process requirement changes. This single-point (hysteresis-free) control method ensures a stable vacuum level and is especially important in evaporation processes, helping to increase evaporation rates by up to 40% while minimizing sample bumping and foaming.

Welch Laboratory Vacuum Systems: Main Benefits

Welch’s laboratory vacuum systems provide you with a number of key benefits to help you improve and streamline your mission-critical lab vacuum processes. They include:

• Automatic vacuum control – the state-of-the-art ecoflex controllers with their built-in solvent library and programmable recipe allow for easy adjustment of the desired vacuum level. The systems’ stable applied vacuum results in more reliable and more repeatable processes.
• Extreme chemical resistance – the right material selection means that our laboratory vacuum systems are defined by their superior resistance to aggressive solvents and acid vapors, and can be used in even the most demanding chemical-duty applications. Design features such as catch pots protect the systems from chemical ingestion.
• Outstanding durability – our robust laboratory vacuum systems are designed for long-lasting operation and stand out through their minimal maintenance requirements.
• Dry operation – the oil-free design makes Welch laboratory vacuum systems suitable for vacuum processes requiring analytically pure, oil-free flow.

Welch Laboratory Vacuum Systems: Key Applications

Welch’s chemical-resistant laboratory vacuum systems are predominantly used in academic, medical, and research and development applications where they support lab processes such as:

• Solvent distillation
• Rotary evaporation

How Do Diaphragm Vacuum Pumps Work?

Diaphragm vacuum pumps, whose primary characteristics include the ability to handle a large variety of vapors, great suction capabilities, high pumping efficiency and outstanding durability, are positive displacement pumps. This means that their flow rate is generated by periodic volume changes inside the pump.

The main elements of a diaphragm vacuum pump are a drive mechanism, a flexible diaphragm located in the pump head and valves that help control the direction of flow. The action of an eccentric on the motor shaft makes the diaphragm move up and down. The pumped medium is drawn into the pump’s chamber on the down stroke and expelled on the upstroke.

The diaphragm acts as a hermetic seal between the drive mechanism and the pump’s chamber, making it possible to transfer the pumped medium without the use of any lubrication. Selection of the right diaphragm material is crucial for ensuring the optimal process results and depends on the desired pressures, temperatures and medium types.

Many different configurations of diaphragm vacuum pumps are possible, with the choice of the optimal one depending on the exact requirements of the given application. Both single-head and multi-head (in one-stage or multi-stage configuration) variants are available. Some of the pumps are equipped with a pumping speed control feature.