Search results
Results from the WOW.Com Content Network
The flow rate is specified as a percentage of its calibrated full scale flow and is supplied to the MFC as a voltage signal. Mass flow controllers require the supply gas or liquid to be within a specific pressure range. Low pressure will starve the MFC of fluid and cause it to fail to achieve its setpoint. High pressure may cause erratic flow ...
Supplementary oxygen may also be dispensed through a regulator which both reduces the pressure, and supplies the gas at a metered flow rate, to be mixed with ambient air. [8] One way of producing a constant mass flow at variable ambient pressure is to use a choked flow, where the flow through the metering orifice is sonic. For a given gas in ...
A split range pressure controller may also modulate a Joule-Thomson valve across the turbo-expander. [10] [4] Pressure in blanketed tanks is maintained by self actuating pressure control valves (PCVs). As liquid is withdrawn from the tank the pressure in the gas space falls. The blanket gas supply valve opens to maintain the pressure.
The regulator is adjusted to control the downstream pressure, which will limit the maximum flow of gas out of the cylinder at the pressure shown by the downstream gauge. For some purposes, such as shielding gas for arc welding, the regulator will also have a flowmeter on the downstream side.
Flow control, or metering, of the refrigerant is accomplished by use of a temperature sensing bulb, filled with a gas or liquid charge similar to the one inside the system, that causes the orifice in the valve to open against the spring pressure in the valve body as the temperature on the bulb increases.
Discover the latest breaking news in the U.S. and around the world — politics, weather, entertainment, lifestyle, finance, sports and much more.
Originally the gas flow computer was a mechanical (1920s technology) or later a pneumatic or hydraulic computing module (1940s technology used to the early 1990s but still available from a number of suppliers), subsequently superseded in most applications by an electronic module, as the primary elements switched from transmitting the measured variables from pneumatic or hydraulic pressure ...
The most common final control element in the process control industries is the control valve. The control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point. [1]