A DP cell is a device that measures the

differential pressure Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure ...

between two inputs. To measure the pressure difference between a container (or vessel) and the surrounding atmosphere, you may connect 'Hi' port of the DP-cell to a fitting that enters the vessel, using suitable tubing. The 'Lo' port, you leave open to the atmosphere (open air, or possibly through a buffer or

desiccant A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccant ...

chamber). The DP-cell will indicate the relative difference between the pressure of the vessel (container) and the atmospheric pressure. This signal is often wired to an indicator that reads out locally, or remotely in a control room, and/or as a control (or feedback) signal to a valve, pump, or other control element to maintain a set pressure, or limit a maximum pressure. Typically, the signal is 4-20 mA DC loop current, where, usually, 4mA represents the minimum differential pressure and 20mA represents the maximum differential pressure. Alternatively, the signal may be a variable voltage, or digital information stream.

References

{{reflist Pressure gauges Measuring instruments

See also

References