Two-Point Vacuum Controller

What is the Two-Point Vacuum Controller?

A two-point vacuum controller switches between two preset pressures for a defined process, such as a high and low vacuum step. It is simple and robust for repetitive drying and filtration cycles.

Overview

The two-point controller is designed for processes that alternate between two pressure levels rather than holding one value. The operator sets an upper and a lower pressure, and the controller opens the valve or starts the pump so that pressure cycles between them. This suits drying cycles where a de-aeration step precedes deep vacuum, filtration where a gentle vacuum protects a membrane before a stronger pull, and coating steps with alternating background pressures. The design is simple, with few settings and a clear display, so it is robust and easy to use in routine work. Some units allow the two points to be linked to a timer or an external signal. Ranges and materials match standard controllers, and connections are KF flanges or hose barbs. The instrument is a practical choice where a full program is unnecessary.

How does it work?

A vacuum controller combines a pressure sensor, a control algorithm and an output that acts on the vacuum system. The sensor, usually a piezoresistive or capacitive absolute pressure transducer, measures pressure from atmospheric down to a few millibars. The controller compares this value with the setpoint and adjusts either the pump speed or, more often, a solenoid or proportional valve that bleeds air into the line. A PID or on-off algorithm holds the pressure within a band, and the display shows the current and target values. Some controllers add ramps so that pressure changes gradually, and inputs for a solvent library or an external sensor at the sample. Outputs may include relay contacts for the pump, an analog or digital signal, and alarm contacts for out-of-range conditions.

What are the key features?

• Two adjustable pressure setpoints
• Automatic cycling between upper and lower pressure
• Timer or external signal option
• Simple, robust design with few settings
• Clear digital display
• KF flange or hose barb connections

What are the technical specifications?

A typical two-point vacuum controller configuration offers pressure range of 1,000–1 mbar, setpoints of 2, adjustable, cycling of Automatic between setpoints, timer of Optional, 1 s–99 h, valve of Solenoid, PTFE and external signal of Optional input. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Two-Point Vacuum Controller is used in two-stage drying cycles, gentle-then-strong filtration, alternating coating pressures, de-aeration before deep vacuum and repetitive routine processes. Across the wider Vacuum Controllers class, laboratories also deploy it for rotary evaporation control, vacuum distillation and solvent recovery and vacuum filtration and degassing.

Which standards and certifications apply?

Relevant standards and methods include IEC 61010-1, IEC 61326-1, ISO 21360, ISO 9001 and GB 4793.1. Certification candidates for this model are CE, RoHS and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Calibrate or verify the pressure sensor periodically against a reference gauge, because drift changes the boiling point and therefore the process. Keep the bleed valve and sensor port clean and dry, since condensate or particles cause erratic readings. Fit a cold trap or separator between the controller and the pumped vapor to protect both, and mount the controller above the liquid level. Use ramps to avoid bumping and foaming when pressure is reduced quickly. Follow IEC 61010-1 for electrical safety and check that the valve materials suit the solvents in use. Record setpoints and ramp programs in the method so that runs are reproducible, and log pressure data where the process is regulated.

How do I select the right Two-Point Vacuum Controller?

Choose a two-point controller when the process alternates between two pressures and a full program is unnecessary. For continuous or multi-stage control, use a digital or ramp controller. In the RFQ, state the two setpoints, cycling interval and connections.

How does it compare with other Vacuum Controllers variants?

Match the control range to your process: rotary evaporation and distillation usually need control from atmospheric down to about 10 mbar, while filtration and coating may need lower. Check the measurement accuracy and resolution, since fine control of boiling depends on both. Decide whether you need on-off control with a solenoid valve or proportional control, which is smoother but more expensive. Confirm the valve is compatible with the vapors being pumped and that its orifice suits your pump flow. Consider whether ramps, solvent libraries and an external sample sensor are useful for your methods, and whether the controller can drive your pump directly or only a bleed valve. Check the interface, alarm contacts and whether a separate gauge is still needed.