SMT3151 differential pressure level transmitter

SMT3151LT Differential pressure level transmitter

SMT3151LT Differential pressure level transmitter

a new type of differential pressure transmitter produced by advanced technology and equipment.

Continuous level, flow and differential pressure measurement.

Liquid level measurement, is the most common measurement process in continuous production processes,

such as: petroleum and chemical industry.

The liquid level measuring instrument currently widely used,

is the differential pressure level transmitter.

SMT3151LT Differential pressure level transmitter

a new type of differential pressure transmitter produced by advanced technology and equipment.

It is used for measurement and control of liquid level, 

in industrial field liquid level measurement and control, 

urban water supply and sewage treatment petroleum, chemical industry, power plant, hydrological monitoring, 

reservoir, dam, hydropower construction and other fields.

SMT 3151 Differential Pressure Level Measurement
SMT 3151 Differential Pressure Level Measurement

What is meant by differential pressure transmitter?

Differential pressure transmitter, also called DP transmitters.

Differential pressure transmitters are used to measure the liquid level, density of liquids, gases and vapors, and pressure, then convert it to a current signal output of 4-20mA DC.

SMT3151LT Differential pressure level transmitter can also communicate with each other,

through the HART 475 Communicator, through which settings and monitoring are performed.

What is DP type level transmitter?

The liquid level (pressure/differential pressure) transmitter is a pressure signal,

measured at the reference side of atmospheric pressure (low pressure side), 

with one or two ports for flange (or other connection) and process pipe connection.

On the basis of common pressure/differential pressure transmitter,

one or two isolation membrane boxes, are added to measure the liquid receiving part.

Mainly used for measuring high temperature, easy to solidify or crystallize, 

containing solid suspended matter, too viscous, 

corrosive or other needs to maintain sanitary conditions, non-polluting media.

What is the working principle of  SMT3151LT differential pressure level transmitter?

Before explaining the working principle of 

SMT3151LT differential pressure level transmitter,

we must first introduce:

What is the working principle of pressure transmitter?

A pressure transmitter is a device,

that converts pressure into a pneumatic or electric signal,

for control and remote transmission.

It can convert the physical pressure parameters,

such as gas and liquid felt by the load cell sensor,

into standard electrical signals (such as 4~20mADC, etc.)

to supply the secondary instrument,

such as indicating alarm device, recorder, regulator, etc.

for measurement and indication, and process adjustment.

The electrical components,

that the pressure transmitter feels pressure, are generally resistance strain gauges,

which are sensitive devices,

that convert the pressure on the device under test into an electrical signal.

The most widely used resistance strain gauges,

are metal resistance strain gauges and semiconductor strain gauges.

The metal resistance strain gauge has two kinds of filament strain gauges,

and metal foil strain gauges.

Usually, the strain gauge is tightly bonded to the mechanical strain matrix by a special adhesive.

When the stress changes due to the force of the substrate,

the strain gauges are also deformed together,

so that the resistance of the strain gauge changes,

thereby adding the voltage across the resistor changes.

The working principle of  SMT3151LT differential pressure level transmitter:

SMT3151LT differential pressure level transmitters,

are commonly used to measure the level of liquid in a closed container,

using the pressure difference created by the gravity of the liquid,

to measure the level of liquid in the container.

The high-pressure side measuring tube (above the figure),

is always filled with water due to steam condensation,

keeping the pressure constant,

while the low-pressure side measuring tube

(located below the figure) forms a communication device with the container,

and the pressure changes with the liquid level in the container.

Then there are:

P+=P0+ρgh1+ρgh

P-=P0+ρgh2+ρgh

△P=P+-P-=ρgh1-ρgh2

When the liquid level changes from h2=0 to h2=h1,

the differential pressure measured by the differential pressure transmitter,

changes from the maximum value to ΔP=0.

By setting the transmitter, the output current is changed from 4-20mA.

Specificities of Level measurement with differential pressure transmitter

●Super measurement performance for pressure, differential pressure, liquid level, flow measurement

●Digital accuracy: +(-)0.05%

● Simulation accuracy: +(-)0.75%+(-)0.1%F.S

●Full performance: +(-)0.25F.S

● Stability: 0.25% 60 months

● Range ratio: 100:1

● Measurement rate: 0.2S

● Miniaturized (2.4kg) all stainless steel flange for easy installation

● Process connection is compatible with other products for optimal measurement

●The world’s only sensor with a H alloy sheath (patented technology), achieving excellent cold and thermal stability

●Intelligent transmitter with 16-bit computer

● Standard 4-20mA DC with digital signal based on HART protocol, remote control

● Support upgrade to fieldbus and field control based technology

SMT 3151 Differential Pressure Level Measurement manufacuturer
SMT 3151 Differential Pressure Level Measurement manufacuturer

How to Set up a differential pressure transmitter for level measurement? ​

When you make the Dp level transmitter installation, you must know:

installation requirements for differential pressure transmitters.

To accurately measure the liquid level,

in addition to the correct selection and verification of the differential pressure transmitter,

it must also be noted that the Dp level transmitter installation of the entire system meets the requirements.

The value of the transmitter sometimes does not reflect the actual parameters of the measured medium,

because the measurement system itself produces errors.

System installation requirements include:

the opening position of the pressure tap,

the proper laying of the connecting conduit,

and the mounting position of the transmitter.

First of all,

the pressure tap should be in a region,

where the fluid flow is smooth and there is no eddy current,

and the process parameters should be ensured in the process.

For example, when the differential pressure transmitter is used

to measure the water level of the boiler drum,

the actual water level of the steam drum is different in the axial and radial directions of the steam drum,

generally in the axial direction, the middle water level is high,

and the water level on both sides is low;

The side of the lowering tube is higher on the denser side.

The condenser liquid level transmitter of a power plant turbine,

is close to the condensate pump inlet due to the position of the measuring point.

When the condensing pump is running,

it causes the water surface to sink at the point of the point,

which causes the transmitter to be significantly lower.

The position of the measuring cylinder is moved to a distance from the inlet of the condensing pump,

and the condenser water level transmitter is consistent with the actual water level indication on the spot,

ensuring safe and stable operation of the condenser.

Secondly,

when measuring the liquid level,

the differential pressure measured by the differential pressure transmitter is relatively small,

generally between several kPa and 100 kPa,

so the entire measurement system has a great influence on the measurement accuracy.

When installing the pressure guiding tube,

the horizontal section of the pressure guiding tube should have a certain inclination.

Moreover, the inclination is as large as possible to avoid accumulation of liquid,

inside the pressure guiding tube,

resulting in inaccurate measurement,

which may cause fluctuations in the output of the transmitter,

when the transmitter has a small measuring range.

In addition, when the transmitter is put into operation,

the air bubbles in the liquid column of the pressure guiding tube should be drained as much as possible.

These accumulated gases will affect the accuracy of the measurement.

It is also conceivable to arrange the exhaust device at the highest point of the upper bend of the pressure guiding tube.

 

Liquid level (pressure/differential pressure) transmitter selection specifications table

Model

Transmitter type

3151LT

Flange liquid level transmitter

Code

Scale range

4

5

6

7

0-4.0~40kPa(0-400~4000mmH2O)

0-20~200kPa(0-2~20mH2O)

0-70~700kPa(0-7~70mH2O)

0-210~2100kPa(0-21~mH2O)

Code

Output form

E

Linear output 4-20mAdc

SF

Linear output 4-20mAdc +HART signal

F

MODBUS-485 signal

Code

Flange standard (high pressure side flange)

A

ANSI American Standard (HG20615)

D

DIN European Standard (HG20592)

Code

Process connection size

ANSI American Standard (HG20615)

DIN European Standard (HG20592)

25

1”

DN25

40

1.5”

DN40

50

2”

DN50

80

3”

DN80

00

4”

DN100

Code

Process connection pressure rating

ANSI American Standard (HG20615)

DIN European Standard (HG20592)

A

150LB

PN16/25

B

300LB

PN40

C

600LB

PN64

D

900LB

PN100

Code

High pressure side diaphragm

A

316 stainless steel

B

Hastelloy C

C

Monel

D

Tantalum

E

Titanium

F

Special Requirements

Code

High pressure side insert tube length

High pressure side insert cylinder material

A

0 mm

None

B

50 mm

316L Stainless steel

C

150 mm

316L Stainless steel

D

200 mm

316L Stainless steel

Code

High pressure side filling fluid

D

General silicone oil  (-40~104℃)

F

High temperature silicone oil   (-40~304℃)

S

Inert liquid  (-40~204℃)

Code

Low pressure side structural material

Flange (joint)

Exhaust/drain valve

Isolation diaphragm

Sensor filling fluid

22

316 Stainless steel

316 Stainless steel

316 Stainless steel

Silicone oil

23

316 Stainless steel

316 Stainless steel

Hastelloy C

Silicone oil

24

316 Stainless steel

316 Stainless steel

Monel

Silicone oil

25

316 Stainless steel

316 Stainless steel

Tantalum

Silicone oil

33

Hastelloy C

Hastelloy C

Hastelloy C

 Silicone oil

35

Hastelloy C

Hastelloy C

Tantalum

 Silicone oil

44

Monel

Monel

Monel

 Silicone oil

S2

A remote transmission device (with a remote transmission device on the low-voltage side)

 

Code

Shell material

Conduit inlet dimensions

A

Low copper aluminum alloy polyurethane coating

M20×1.5

B

Low copper aluminum alloy polyurethane coating

1/2-14 NPT

C

Stainless steel

M20×1.5

D

Stainless steel

1/2-14 NPT

Code

Optional parts

M1

0~100%  Linear indicator head

M4

LCD multi – power digital display head

D1

Side discharge valve at the top (only for the low pressure side of the low pressure side without remote transmission)

D2

Side discharge valve at the top (only for the low pressure side of the low pressure side without remote transmission)

Da

Flameproof  ExdIIBT5Gb;(explosion-proof certificate no. : CE16.1163)

Fa

Intrinsically safe ExiaIICT4 / T5 / T6Ga;(explosion-proof certificate no. : CE15.2354X)

CX

With corresponding 316 flushing ring

H&H Instrument(drurylandetheatre.com) offers overs 100 DP transmitters,

for liquid level, pressure, flow, temperature measurement.

Our differential pressure level transmitters suit to measeure water and other liquid level.

A wide variety of DP level transmitters are available to you,

such as SMT3151LT Differential pressure level transmitter.

You can also choose from liquid flow meter and pressure transmitters, not specified.

We are differential pressure level transmitter suppliers, located in China.

The top supplying country is China(Mainland),

which supply 100% of DP transmiters respectively.

Differential pressure level transmitter is most popular for India, Pakistan ,South Africa, The US.

Tha quality is same as the original premium quality.

You can ensure product safety by selecting from our products, including IOS9000, … certification.

 

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