DP TRANSMITTER

 Different from a gauge pressure sensor or absolute pressure sensor that measure just one media. Normally, in differential pressure transmitter, two pressures to be measured are collected through the tubing and connected to opposite sides of a single pressure diaphragm. The deflection of the diaphragm, either positive or negative relative to the resting or original state, determines the pressure difference.

 

HOW TO MEASURE DIFFERENTIAL PRESSURE?

The differential pressure is a monitoring of the pressure drop of a media or two pressure type within the limited space, thus measuring by how much the two points differ from each other, not their magnitude relative to atmospheric pressure or zero voccum pressure. However, in some industrial applications, instead of one single pressure transducer receiving pressure measurement from two different ports and comparing it, two separate relative pressure sensors can be utilized instead. This may be the case when two different types of sensors are required due to medium constraints, or even medium differences.

 

1. Differential pressure measurements such as flow, level, density, viscosity.

Differential pressure transmitter(dp transmitter) are designed measuring the pressure change or pressure drop while the fluid flows through a pipe it is possible to calculate the flow rate. One very common way of measuring flow using a differential pressure transmitter on the pipe filter, which will create a high and low pressure to monitoring fluids cleanliness  These units of flow can be gallons per minute (GPM) or cubic meters per hour (m³/h).

 

2. Level measurement using a differential pressure transmitter

Using two differential pressure transmitter and a control system to perform signal subtraction, allows process engineers to measure not only the differential pressure but also level, flow, interface, and even density. In the application to measure the volume of liquid (or liquid level)in a closed vessel, a differential pressure transmitter can also be used. As long as the density of the fluid does not change with temperature variation, differential pressure transmitters can measure the pressure of the fluid in the vessel as well as the air pressure above the level(gas vs. liquid). In this case, the differential pressure transmitter can determine the level of the tank at any given moment using the differential pressure. the height of the column of liquid can be determined from the pressure, liquid density and gravity.

 

The relationship between pressure and level: 

P = ρ*g*h

h = (P2 – P1)/ (ρ * g)

h = height of the liquid column [m]

P2 = hydrostatic pressure at depth h

P1= pressure of the enclosed gas in the vessel

ρ = density of the liquid [kg/m³]

g = gravitational force [m/s²]

 

an overview of the gamut of secondary applications when using differential pressure transducer independently.