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Wilockx Chris<br />

<strong>Level</strong> <strong>Basics</strong>


Physical <strong>Basics</strong> of Pressure Measurement<br />

F (force) N (Newton)<br />

P (pressure) = --------------- = ---------------- |Pa|<br />

A (surface) m2<br />

There are different pressure units:<br />

kPa: kilo Pascal mmHg: mm mercury<br />

bar: bar atm: atmosphere<br />

kg/cm2: psi: pound/inch2<br />

mmH2O: mm water inH2O: inch water


Physical <strong>Basics</strong> of Pressure Measurement<br />

pabs1<br />

Pressure Quantity<br />

Absolute Pressure<br />

Atmospheric Pressure<br />

Gauge Pressure<br />

Differential Pressure<br />

pamb.<br />

pabs. 2<br />

Symbol<br />

pabs<br />

pamb<br />

pe<br />

dp<br />

pe1 > 0<br />

pe2 < 0<br />

dp<br />

0%<br />

100%<br />

pe = 0<br />

pabs = 0<br />

(Vacum)


Physical <strong>Basics</strong> of Pressure Measurement<br />

Pressure is equal Hydrostatic Paradox<br />

in all directions P = S.g.h<br />

S = Rho = density<br />

|Pa| = |kg/m3|.|9,81m/s2|.|m|


Pressure Measurement – Pressure U - Tube<br />

U-Tube<br />

Pa = S.g.h + P0<br />

|Pa| = |kg/m3|.|9,81m/s2|.|m|


Pressure Measurement – Pressure Transmitters<br />

Boudon pressure gauge


Pressure Measurement – Pressure Transmitters<br />

p - measurement<br />

dp - measurement


Functional Principle of P and dP Transmitters<br />

Conversion of the Physical Factor<br />

(i.e.: Deflection of Diaphragm) into an Electrical Factor:<br />

Different sensors are used:<br />

• Inductive measuring principle (coil)<br />

• Capacitive measuring principle (capacitor)<br />

• Strain Gauge measuring principle (Bridge)<br />

• Piezo-resistive measuring principle (chip)


Functional principle of P and dP transmitters<br />

• inductive measuring principle:<br />

n2 . A<br />

L = µ --------l


Functional principle of P and dP transmitters<br />

• capacitive measuring principle:<br />

C1<br />

diaphragm<br />

P1 P2<br />

C2<br />

Glass<br />

Measuring<br />

diaphragm<br />

E . A<br />

C = --------d


Functional principle of P and dP transmitters<br />

• Strain Gauge measuring principle :<br />

Metal cores<br />

Bonding<br />

+<br />

Strain gages array<br />

(bonded or made<br />

directly on the<br />

substrate)<br />

Measuring<br />

diaphragm<br />

Substrate<br />

� R<br />

� R= K x<br />

x


Functional principle of P and dP transmitters<br />

• piezo-resistive measuring principle (example 265D) :<br />

DP-Sensor P abs-Sensor<br />

Measuring of resistance<br />

change via crystal<br />

lattice displacement


Functional principle of P and dP transmitters<br />

• piezo-resistive measuring principle (e.g. 265G) :<br />

lower range value<br />

span<br />

write protect<br />

measuring<br />

mechanism<br />

isolating diaphragm<br />

Microprocessor based<br />

electronics<br />

matching<br />

P e-Sensor<br />

Measuring of resistance<br />

change via crystal<br />

lattice displacement


Main Components<br />

covers<br />

vents<br />

display<br />

flanges<br />

terminal<br />

blocks<br />

gaskets<br />

housing<br />

push<br />

buttons<br />

secondary<br />

electronics integral<br />

display<br />

covers<br />

transducer<br />

bolts


Functional Specifications<br />

General<br />

Base accuracy: ABB Model 265/266 +/- 0,04%<br />

ABB Model 264 +/- 0,075%<br />

Turn Down: 1/100<br />

Ranges ABB Model 265 Pressure Transmitters:<br />

60mbar - 400mbar - 2500mbar - 10bar - 30bar - 100bar<br />

600bar<br />

Ranges ABB Model 265 dP Transmitters:<br />

10mbar - 60mbar - 400mbar – 2500mbar - 20bar – 100bar


<strong>Level</strong> – Measurement<br />

Different mounting positions?<br />

P = S.g.h<br />

h<br />

Open tank liquid measurement<br />

open to atmosphere<br />

________<br />

Dead zone


<strong>Level</strong> – Closed Tank<br />

max. level<br />

min. level<br />

4 mA = S . g . h2<br />

20 mA = S . g . (h2 + h1)<br />

S = specific gravity (medium)<br />

h1<br />

h2<br />

transmitter<br />

reference line<br />

S<br />

N2<br />

Wet Leg<br />

If the level to be maeasured is in<br />

a closed tank, a dp – transmitter<br />

is necessary.<br />

Dry Leg<br />

S = 0?


<strong>Level</strong> – Closed Tank<br />

max. level<br />

min. level<br />

h1<br />

h2<br />

transmitter<br />

reference line<br />

4 mA = S1 . g . h2 – S2 . g . h4<br />

20 mA = S1 . g (h1 + h2) – S2 . g . h4<br />

S1 = specific gravity (medium)<br />

S2 = specific gravity (Wet leg)<br />

S1<br />

Wet Leg<br />

h4<br />

If the level to be maeasured is in<br />

a closed tank, a dp – transmitter<br />

is necessary.<br />

Glycol<br />

S2<br />

Wet Leg


<strong>Level</strong> – Closed Tank<br />

If condensable vapours are present use the<br />

following installation.<br />

max. level<br />

min. level<br />

transmitter<br />

reference line<br />

h1<br />

h2<br />

transmitter<br />

reference line<br />

4 mA = S1 . g . h2 – S2 . g . h4<br />

20 mA = S1 . g (h1 + h2) – S2 . g . h4<br />

S1 = specific gravity (medium)<br />

S2 = specific gravity (Wet leg)<br />

S1<br />

impuls line<br />

filled with<br />

stable fluid<br />

(Wet Leg)<br />

S2<br />

filling tee<br />

0<br />

h4


Boiler-<strong>Level</strong> Measuement<br />

Ordering data: dp transmitter with adjusted value of –300mm ... +300 mm (WC)<br />

Actual requirement: boiler level measurement<br />

level to be monitored: -300 mm ... +300 mm<br />

Distance between connection pipes: h = 1000mm<br />

Density water<br />

Tuper.: +200 C (Sup= 865 kg/m 3 ) hlow (hlow) = 200mm<br />

Tref.: +30 C (Sref= 996 kg/m 3 ) hhigh (hhigh) = 800mm<br />

Density steam<br />

Tsteam.: +200 C (Ssteam = 7.9 kg/m 3 )<br />

hlow<br />

NN<br />

hhigh<br />

h<br />

+300 mm<br />

- 300 mm


Boiler-<strong>Level</strong> Measuement<br />

DP – Transmitter with an adjusted value of: -300 ... +300 mm (WC)<br />

hl<br />

hh<br />

+300 mm<br />

H<br />

‘<br />

- 300 mm<br />

P1 (-300mm) = (-h* Sref * g + hl * Super. * g + [h-hl] * Ssteam * g) * 102 =<br />

= (-1 * 996 * 9.81 + 0.2 * 865 * 9.81 + 0.8 * 7.9 * 9.81) * 102 = -80.1 mbar<br />

P2 (+300mm) = (-h* Sref * g + hh * Super. * g + [h-hh] * Ssteam * g) * 102 =<br />

= (-1 * 996 * 9.81 + 0.8 * 865 * 9.81 + 0.2 * 7.9 * 9.81) * 102 = -29.7 mbar<br />

Adjusted value: -80.1 ... -29.7 mbar<br />

h


Remote Seals<br />

Protect Transmitters from<br />

• High temperature<br />

• Corrosive components<br />

• Media with high viscosities<br />

• Media with tendency to<br />

polymerization<br />

Useful for<br />

• Prevention of deposits in the<br />

process Connection<br />

• Adaptation to various process<br />

connections


<strong>Level</strong> – Open Tank<br />

P = S . g . h<br />

e.g.: a seal transmitter<br />

flange mounted on the<br />

high pressure side of the<br />

transmitter is<br />

recommended in case of<br />

dirty liquid fluid or process<br />

temperature > 107 C<br />

transmitter<br />

reference line


<strong>Level</strong> – Closed Tank<br />

max. level<br />

min. level<br />

min. level may not<br />

be below this line<br />

h1<br />

h2<br />

N2<br />

e.g.: a seal transmitter<br />

flange mounted on the<br />

high pressure side of the<br />

transmitter is<br />

recommended in case of<br />

dirty liquid fluid or process<br />

temperature > 107 C<br />

transmitter<br />

reference line


<strong>Level</strong> – Closed Tank<br />

max. level<br />

min. level<br />

h1<br />

h2<br />

4 mA = S . g . h2 + Sg . G .(h4-h2) – Sc . g . h4<br />

20 mA = S . g . (h1 + h2) – Sc . g . h4<br />

S = specific gravity (medium)<br />

Sg = specific gravity (gas above fluid)<br />

Sc = specific gravity (filling oil capillary tube)<br />

Sg<br />

S<br />

filled<br />

capillary<br />

high side seal<br />

reference line<br />

low side seal<br />

reference line<br />

h4<br />

h3<br />

Sc<br />

transmitter<br />

reference line


<strong>Level</strong> Transmitter 265D<br />

Compact Version


Remote Seals Design<br />

..... with Flush or Extended Diaphragm in Flange design<br />

DN 25 Pressure Rating PN 10...PN 250<br />

DN 50 / DN 80 Pressure Rating PN 16...PN 100<br />

DN 1“ Pressure Rating 150 psi...1500 psi<br />

DN 2“ / DN 3“ Pressure Rating 150 psi...600 psi


Remote Seals<br />

.... via Capillary Tube to Transmitter


Remote Seals Design<br />

.... with Flush or Extended Diaphragm in Sandwich Design<br />

DN 50 / DN 80 Pressure Rating up to PN 400<br />

DN 2“ / DN 3“ Pressure Rating up to 2500 psi


Remote Seals Design<br />

Corrosion Resistant Materials<br />

• Stainless Steel<br />

• Hastelloy C<br />

• Monel 400<br />

• Tantal<br />

• FEP coated<br />

• Gold plated<br />

• Ect…<br />

• Capillary tube stainless steel, with<br />

PVC protective cover as an option


Remote Seals Design<br />

Filling liquids depending on the<br />

application<br />

• Silicon Oil as Standard<br />

• Carbon Fluoride for Oxygen Service<br />

• White Oil for Food and Beverage<br />

• High Temperature Oil up to 400 C<br />

Vacuum proof design with special liquid for use down to an<br />

absolute pressure of 5 mbar abs.<br />

ABB is a recognized leader in the all welded technology where Remote<br />

Seals System can be welded at every junction.


Filling Liquid Id<br />

Silicone Oil IC<br />

Carbon<br />

Fluoride<br />

High-temperature<br />

Oil<br />

L<br />

IH<br />

White Oil WB<br />

Vacuumproof<br />

Design<br />

IC-V<br />

Pressure rating in mbar abs.<br />

20°C (68°F) 100°C (212°F) 150°C (302°F) 200°C (392°F) 250°C (482°F) 400°C (752°F)<br />

> 500 > 500 > 500 > 750<br />

> 1000 > 1000 > 1000 ---<br />

> 500 > 500<br />

Application Limits<br />

> 500 > 750<br />

> 500 > 1000 > 1000 > 1000<br />

> 5 > 25 > 38 > 50<br />

> 1000 ---<br />

--- ---<br />

> 1000 > 1000<br />

> 1000 ---<br />

--- ---


Application Limits


Seals Design Performance<br />

Accuracy is primarily affected by<br />

• Fill volume change due to temperature<br />

• Capillary length<br />

• Diaphragm stiffness<br />

Low fill volume and low stiffness of diaphragm is<br />

required for high accuracy


Questionaire


Questionaire for P-/DP-Transm. with remote seals


<strong>Level</strong> – Measurement<br />

air supply<br />

regulator<br />

h<br />

Bubble measurement<br />

dP


Liquid <strong>Level</strong> (example oil on water)<br />

range of<br />

interface level<br />

S1 = H 2O<br />

S2 = oil<br />

4 mA = S2 . 9,81 . h (only oil)<br />

20 mA = S1 . 9,81 . h (only H 2O)<br />

(simplified illustration; without the influence of capillary tube S3)<br />

Interface level measurement<br />

S2<br />

interface level<br />

S1<br />

h<br />

LT<br />

S3


Density<br />

S1 = low specific gravity<br />

S2 = higher specific gravity<br />

S3 = specific gravity of filling oil in capillary tube<br />

4 mA = (S1 . h – S3 . h) . 9.81<br />

20 mA = (h * SG2 – h * SG3) * 9.81<br />

Density measurement<br />

h


<strong>Level</strong> measuement in a spheric tank<br />

output<br />

(volume)<br />

v = 1/3 pi * h 2 (3r – h)<br />

input (level = h)<br />

Input [%]<br />

(<strong>Level</strong> = h)<br />

0.00<br />

3.75<br />

7.75<br />

11.75<br />

16.75<br />

22.00<br />

28.00<br />

35.25<br />

45.75<br />

55.00<br />

65.00<br />

72.25<br />

78.50<br />

83.75<br />

88.25<br />

92.50<br />

96.25<br />

100.00<br />

Ouput [%]<br />

(Volume)<br />

0.00<br />

0.41<br />

1.71<br />

3.82<br />

7.48<br />

12.39<br />

19.13<br />

28.52<br />

43.64<br />

57.48<br />

71.82<br />

81.17<br />

88.12<br />

92.94<br />

96.18<br />

98.40<br />

99.59<br />

100.00


<strong>Level</strong> measuement - warning<br />

• Pressure (vacuum)<br />

• Temperature<br />

• Medium<br />

• Foam<br />

• Agitator<br />

• Flow inlet


Intelligent Transmitters<br />

Conventional<br />

1965<br />

HART<br />

1987<br />

Fieldbus<br />

1985/95/97/99<br />

A<br />

A<br />

A<br />

E<br />

E + #<br />

#<br />

4 ... 20 mA<br />

4 ... 20 mA + superimposed,<br />

digital communication<br />

FSK-Modem


Intelligent Transmitters<br />

Functionality<br />

Traditional<br />

4-20mA<br />

Value<br />

HART<br />

SMART<br />

Value<br />

Device<br />

Parameter<br />

Fieldbus<br />

Fieldbus<br />

More values<br />

Multi variabel<br />

High resolution<br />

Diagnostic data<br />

Quality signal<br />

Status<br />

Decentral Functions<br />

Distributed Control<br />

Bi-directional<br />

Asset Optimization<br />

Graphics<br />

Time


Intelligent Transmitters<br />

Value (measuring)<br />

Status<br />

Scaling<br />

Filter time<br />

Alarm / warn limits<br />

Alarm summary<br />

TAG<br />

Device diagnostic<br />

Manufacture<br />

specific<br />

parameter<br />

Cyclic<br />

services<br />

(Analog value)<br />

Acyclic<br />

services<br />

(Hart)<br />

Spontaneous<br />

services<br />

Acyclic<br />

services


Intelligent Transmitters<br />

400 mbar<br />

200 mbar<br />

0 mbar<br />

-400 mbar<br />

Basic range value<br />

Analog Technology Bus Technology<br />

20 mA<br />

4 mA<br />

Sensor range limits<br />

Floating Point 32 bit


Communication mode: Point-to-Point<br />

2600T<br />

U S > 10.5 ... 45 V DC (HART)<br />

R > 250 Ohms<br />

FSK modem<br />

e.g. power<br />

supply


Communication mode: FSK Bus<br />

2600T TZN 128<br />

FSK modem<br />

e.g. power<br />

supply<br />

TZN 128<br />

FSK modem


SmartVision


SmartVision


SmartVision


Communication Requirements<br />

Connecting cable<br />

Communication between transmitter and PC/laptop requires<br />

shielded and twisted pair lines.<br />

The minimum wire diameter should be:<br />

- 0.51 mm for lines up to 1500 m<br />

- 0.81 mm for lines longer than 1500 m<br />

The maximum line length is limited to:<br />

- 3000 m for twin-core cable<br />

- 1500 m for multicore cable


Electrical Safety - Explosion Protection<br />

• The areas where this can occur are classified depending upon the<br />

“probability” that gas/vapour, in dangerous combination with air, is<br />

present.<br />

• In Europe and some part of the world, except the American continent,<br />

the classification is as follows, according to IEC Publication 79-10:<br />

• ZONE 0: an area in which an explosive gas-air mixture is present<br />

continuously or for long periods.<br />

• ZONE 1: an area in which an explosive gas-air mixture is likely to occur<br />

in normal operation.<br />

• ZONE 2: an area in which an explosive gas-air mixture is not likely to<br />

occur in normal operation, and if it occurs, it will exist only for a short<br />

time.


Electrical Safety - Explosion Protection<br />

In North America, the classification refers to only two divisions, which<br />

may be briefly defined as follows, according to NEC article 500:<br />

Division 1: hazard may be present in normal operation.<br />

Division 2: hazard may be present only in abnormal<br />

operation.<br />

Therefore the following rough equivalence apply:<br />

CONTINUOUS<br />

HAZARD<br />

(> 100 h / y)<br />

INTERMITTENT<br />

HAZARD<br />

(1 - 100 h / y)<br />

ABNORMAL<br />

CONDITIONS<br />

(0.01 - 1 h / y)<br />

EUROPE (IEC) ZONE 0 ZONE 1 ZONE 2<br />

North America * DIVISION 1 DIVISION 1<br />

*Note: The “Zone” classification like IEC is now possible also for North America<br />

according to article 505 of the NEC/Edition 1996, ANSI/NFPA70


Electrical Safety - Explosion Protection<br />

The various gases/vapours are grouped considering their "likeness" in terms of<br />

ignition energy.<br />

Each group has a "representative gas". Representative gases and relevant minimum<br />

ignition energy (microjouls) are shown here below:<br />

Representative Gas IEC / CENELEC<br />

(EUROPE)<br />

Note: according to IEC classification “II” means “surface industries”<br />

(as an alternative to mining atmosphere)<br />

NORTH AMERICA Minimum Ignition<br />

Energy [micro joules]<br />

Acetylene II C Class I Group A 20 µJ<br />

Hydrogen II C Class I Group B 20 µJ<br />

Ethylene II B Class I Group C 60 µJ<br />

Propane II A Class I Group D 180 µJ


Electrical Safety - Explosion Protection<br />

The temperature classification relates to the maximum attainable temperature<br />

of the transmitter, or part of it (normally assuming a 40 C ambient), to the<br />

ignition temperature of a gas / vapour.<br />

Max. Temp.<br />

[ C]<br />

North America<br />

200 T3<br />

180 T3A<br />

165 T3B<br />

160 T3C<br />

135 T4<br />

Max. Temp.<br />

[ C]<br />

IEC/CENELEC<br />

(EUROPE)<br />

450 T1<br />

300 T2<br />

200 T3<br />

135 T4<br />

100 T5<br />

85 T6

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