Festo has launched the VPPM proportional pressure regulator, which offers both control flexibility and cost-effectiveness (being priced at just £300 in one-off quantities). The regulator provides design engineers with a precise means of varying the flow rate to pneumatic actuators, facilitating accurate control of speed, force, pressure and torque.
Proportional pressure regulators are used extensively in the process industries, for diverse applications. Typically, these include controlling the contact force in polishing and friction welding, controlling web tension, providing active load cushioning and weight compensation, controlling the speed of pneumatic motors, and regulating the applied torque of pneumatic wrenches. The regulators are also now beginning to be used in the leisure and medical engineering industries.
There are two versions of VPPM regulator. One is equipped with an LED display, whilst the other is equipped with a backlit LCD. Both versions feature an 1/8 inch proportional pressure valve, offer a choice of G1/8 or PRS manifold connection, and are available with a pressure range of 0-2 bar, 0-6 bar or 0-10 bar. The 0-10 bar model accommodates a flow rate of up to 1400 l/min. By employing a cascaded dual-stage regulator design - each with its own pressure sensor - the VPPM provides a high level of control, with coarse and fine adjustment facilities. The use of two pressure sensors also helps to eliminate drifting due to temperature fluctuations, as regulation is held to just ±0.04%/šK.
Depending upon the model of the VPPM pressure regulators, they have full-scale linearity, repeatability, hysteresis and sensitivity figures of ±0.5%, ±0.2%, ±0.3% and ±0.1% respectively. The regulators are controlled by industry-standard 0-10 Vdc or 4-20 mA analogue signals, and are easy to install and commission, with diagnostic feedback provided via their front panel displays. Both the LED and LCD versions of the regulator are equipped with 'up', 'down' and 'edit' front panel pushbuttons, and offer three preset step response curves - any one of which can be selected via the pushbuttons - to facilitate fine tuning of the system without the need to set up complex PID loops.
The LCD version features a bright backlit alphanumeric display, together with an analogue bar-graph, and offers a number of extra control and monitoring functions. Both the programmed setpoint and the actual pressure value can be monitored, and users can choose to display pressure units in bar, MPa or psi. A control limitation function enables the actual operating pressure range of the regulator to be programmed. This effectively increases control resolution, by allowing the same full range of analogue control signals to control a limited, user-defined range of operating pressures. Users can also define an offset value to increase accuracy over the required operating range - which is particularly useful for applications such as load compensation in air spring isolation systems - and can lock the regulator using a personal PIN code.