Home » Differential Pressure Level Transmitter Errors
Level Measurement

Differential Pressure Level Transmitter Errors

Every liquid in storage tank will have hydrostatic pressure equal to the height of the liquid. With an assumption that the liquid has constant density.

The DP level transmitter indication is a measure of the head pressure in the level of the tank whose level is to be detected.

Head Pressure, DP, is calculated as

DP = (Height).(Specific Gravity)

Level Transmitter Errors

Differential Pressure Level Transmitter Errors

For example, let’s say  50% level is displayed in the control room, the specified SG = 0.8.

The DP transmitter is actually measure a differential pressure (50%)*(0.8) = 40 units of the differential pressure.

Now, what if the SG change. maybe because the liquid aerated, or the feed to the vessel has become lighter.

For some reason, the SG has dropped from 0.8 to 0.6. The real level will increase to 66.67% (40/0.6) but the indicated level in the control room is still 45% because the DP output is constant at 36 units of DP.

This is happened because DP level transmitter cannot discriminate between height and density.

This is something to worry about. The defective level transmitter can cause liquid overflow and vapour cloud explosion can be ignited if ignition source available in adjacent area

Author : Iqbal Matondang

Articles You May Like :

Level Measurement Terminology

Sounding Level Transmitter

Vibrating Fork Level Switch

RF Level Switch Principle

Servo Tank Gauges Principle

Related Articles

Radiation Level Measurement

S Bharadwaj Reddy

Ultrasonic Level Transmitter Working Principle

S Bharadwaj Reddy

DP Transmitter Dry Leg & Wet Leg Calculations

S Bharadwaj Reddy

Optical Level Switch Working Principle

S Bharadwaj Reddy

Level Transmitter and Level Gauge Design Tips

S Bharadwaj Reddy

Basics of Differential Pressure Level Transmitters

S Bharadwaj Reddy

1 comment

ali raza khan August 31, 2019 at 7:58 pm

dear sir,
send me new updates.

Reply

Leave a Comment

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

Differential Pressure Level Transmitter Errors

WordPress Image Lightbox

Send this to a friend