Pressure Control Overview

A means of controlling the pressure in the system where the pumping speed is the variable component, usually controlled by a throttle valve between the turbo pump and chamber.

The motorized control valve is the heart of downstream pressure control. Butterfly valves are the most common valve type, but gate, right angle, and pendulum valves are available. The valve will be placed downstream of the process just in front of the high vacuum pump. During the process, the valve controller will communicate and interpret the output voltage from the capacitance manometer. If the pressure isn't correct, the valve will shutter between degrees of partially opened/closed. As the valve varies its position, the restriction to the pump and therefore the pumping speed of the turbo pump is affected. If the pressure is too high, the valve will open further to increase pumping speed and lower pressure, while the valve will move towards its closed position if the pressure is below the controllers setpoint. For a more in-depth view of the Throttle Valves, please contact valves@lesker.com.

A capacitance manometer is the gauge of choice for control pressure due to the high accuracy (typically 0.25%), fast response time (typically 100 ms), and gas independent properties. During the process, the capacitance manometer measures the pressure you are looking to control. This pressure, generally in the form of an output voltage, will be supplied to the controller at a constant frequency. If the current pressure varies from the setpoint control pressure, the throttle valve will adjust the degree of partially opened/closed, which will adjust the pressure. Please note that these units come in two flavors, ambient or heated. If you have nasty gases in the system or heavily deposit materials, a heated unit is internally heated to a set temperature and helps minimize condensation within the gauge. For a more in-depth view of Capacitance Manometers, please contact gauging@lesker.com.

• Compare common Ambient Capacitance Manometers
• Compare common Heated Capacitance Manometers

A wide range gauge Is a key feature in the pressure control process, as this provides the first step: measuring the base pressure. In some processes, the user will need to reach a base pressure of 10-6 or lower to ensure that certain gases, like O2, are removed (mostly) from system. After the base pressure is reached, the user may input gas at a static (constant) rate to raise the pressure and control the gas composition in the system. At this point, the WRG may be turned off or isolated so it is protected from the process. Please note that the WRG’s can be single port or Multiport. The single port units are where multiple technologies are within one housing where Multiport units have the technologies separated. For a more in-depth view of Wide Range Gauges, please contact gauging@lesker.com.

• Compare common Wide Range Combination Gauges
• Compare common Cold Cathode / Hot Filament Gauges
• Compare common Convection Enhanced Pirani Gauges

Just like the valves in upstream pressure control, the MFC's can be used to downstream pressure control but usually are stationary. They are generally set for a constant flow rate and do not automatically change. For a more in-depth view of Mass Flow Controllers, please contact gauging@lesker.com.

• Compare common Mass Flow Controllers

For pump packages, contact pumps@lesker.com

A means of controlling the pressure in the system where the gas flow into the chamber, usually controlled by an MFC, is the variable component.

During pressure control, the MFC will inject gas at a specific rate, while also communicating with the controller. If the incorrect output voltage is received from the controller (meaning that the pressure isnt correct), the MFC will adjust the flow rate. If the pressure is too high, the MFC will reduce the flow rate and if the pressure is too high, the MFC will increase the flow rate. For a more in-depth view of Mass Flow Controllers, please contact gauging@lesker.com.

• Compare common Mass Flow Controllers

A capacitance manometer is the gauge of choice for control pressure due to the high accuracy (typically 0.25%), fast response time (typically 100 ms), and gas independent properties. During the process, the capacitance manometer measures the pressure you are looking to control. This pressure, generally in the form of an output voltage, will be supplied to the controller at a constant frequency. If the current pressure varies from the setpoint control pressure, the throttle valve will adjust the degree of partially opened/closed, which will adjust the pressure. Please note that these units come in two flavors, ambient or heated. If you have nasty gases in the system or heavily deposit materials, a heated unit is internally heated to a set temperature and helps minimize condensation within the gauge. For a more in-depth view of Capacitance Manometers, please contact gauging@lesker.com.

• Compare common Ambient Capacitance Manometers
• Compare common Heated Capacitance Manometers

A wide range gauge Is a key feature in the pressure control process, as this provides the first step: measuring the base pressure. In some processes, the user will need to reach a base pressure of 10-6 or lower to ensure that certain gases, like O2, are removed (mostly) from system. After the base pressure is reached, the user may input gas at a static (constant) rate to raise the pressure and control the gas composition in the system. At this point, the WRG may be turned off or isolated so it is protected from the process. Please note that the WRG’s can be single port or Multiport. The single port units are where multiple technologies are within one housing where Multiport units have the technologies separated. For a more in-depth view of Wide Range Gauges, please contact gauging@lesker.com.

• Compare common Wide Range Combination Gauges
• Compare common Cold Cathode / Hot Filament Gauges
• Compare common Convection Enhanced Pirani Gauges

During pure upstream pressure control, a valve may still be utilized in front of the high vacuum pump to isolate the pump or reduce the pumping speed. If a valve is used, it will remain at a constant position, generally a point between full open and full close. Typically, a 3-position valve is used in this scenario. For a more in-depth view of Control Valves, please contact valves@lesker.com.