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Instrumentation

Calibration and initialization of Impulse tube type Level Transmitter Rosemount 3051CD series LT

Calibration and Initialization of Impulse tube type Level Transmitter Rosemount 3051CD:


here it should be noted that this is method for wet type (not dry legs),i.e. impulse tubes filled with liquids

Impulse tube type Level Transmitter

Initial setting and calibration for water tank (here specific gravity =1)

Initial setting:

Take tap to tap measurement, for example if tap to tap measurement is 600mm then put

LRV=negative of tap to tap reading= -600mmWC    {negative value because after filling water on LP side the reading will be a negative value}

Put URV=0mmWC

Calibration of Impulse tube type Level Transmitter

here we are doing only zero checking; fill the impulse tube with water on both sides the transmitter reading should show zero reading i.e. -600mmWCor 0% level then the transmitter is O.K.

Also Like: Control Valves

Initialization and calibration of tank having liquid of specific gravity other than water and impulse tube filled with liquid like that of glycol:

Initial setting:

take tap to tap measurement for e.g. if tap to tap measurement is 600mm and we are filling with glycol of 0.86 s.g. then

LRV=negative of tap to tap reading *s.g. of liquid inside impulse tube

=-600*0.86

=-516mmWC

and URV because of liquid inside vessel of s.g. 0.92is

URV=  LRV+ level(height) to be measured*s.g. of liquid inside vessel

= -516+(0.92*600)

=-516+552

=36 mm WC

Calibration (Zero checking):

fill the impulse line with glycol on both LP and HP side then the transmitter should show LRV=-516mmWC and 0% level

CROSS CHECKING OF  THE LRV AND URV IF THE TANK IS FILLED WITH WATER INSTEAD OF OTHER SPECIFIC GRAVITY

LRV= -600*1= -600mmWC

URV=LRV+HEIGHT OF LIQUID *SPECIFIC GRAVITY

= -600+(600*1)

= -600+600

= 0 mmWC

NOW NOTE THAT THIS IS THE SAME LRV & URV AS DERIVED ABOVE FOR WATER

N.B.  Calibration and initialization of DP type level follows a simple rule

LRV= level and property of liquid in impulse tube acting on LP side of LT

URV=LRV+level and property of liquid inside vessel acting on HP

Founder of Bhuvnesh Blog. Bhuvnesh Bhushan is a Internet Marketing Geek and Instrumentation Engineer. He holds an engineering degree in Electronics and Communication Engineering (GLA University, Mathura) and is professional blogger in India.