PDVSA k-303

 ENGINEERING DESIGN MANUAL VOLUME 9–I ENGINEERING SPECIFICATION SPECIFICATION

PDVSA N

°

LEVEL INSTRUMENT INSTRUMEN TATION

K–303

0 REV.

AUG. 94

FOR APPROVAL

DATE

APPD.BY Eliecer Jiménez

1994

TITLE

DESCRIPTION DATE

12

L.T.

E.J.

A.N.

PAG.

REV.

APPD.

APPD.

DATE

AUG. 94

AUG. 94 APPD.BY Alejandro Newski

ESPECIALISTAS

ENGINEERING SPECIFICATION

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LEVEL INSTRUMENTATION INSTRUMENTATION

PDVSA K –303 REVISI O ON N

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Index Page

1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

2 CODES, STANDARDS AND PRACTICES . . . . . . . . . . . . . . . . . . . . .

3

3 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4 DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4. 1 4. 2 4. 3 4. 4 4. 5 4. 6 4. 7

D/p cell – hydrostatic head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bu B uoyancy displacer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radio frequency / capacitance / nuclear / ultrasonic . . . . . . . . . . . . . . . . . . Level switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.P.I storage tank gauging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gauge glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solids level measurement / switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 5 8 8 9 10 11

5 SPECIFICATION FORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12

6 INSTALLATION AND COMMISSIONING . . . . . . . . . . . . . . . . . . . . . .

12

7 Q.A. / Q.C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12


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Index Page

1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

2 CODES, STANDARDS AND PRACTICES . . . . . . . . . . . . . . . . . . . . .

3

3 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4 DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4. 1 4. 2 4. 3 4. 4 4. 5 4. 6 4. 7

D/p cell – hydrostatic head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bu B uoyancy displacer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radio frequency / capacitance / nuclear / ultrasonic . . . . . . . . . . . . . . . . . . Level switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.P.I storage tank gauging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gauge glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solids level measurement / switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 5 8 8 9 10 11

5 SPECIFICATION FORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12

6 INSTALLATION AND COMMISSIONING . . . . . . . . . . . . . . . . . . . . . .

12

7 Q.A. / Q.C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12


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FOREWORD

This document is the result of several years ’ work by engineers in the petroleum industry of Venezuela (PDVSA). The recommendations presented in this publication are not intended to supersede applicable laws and regulations. Users of this recommended practice are reminded that no publication of this type can be complete, nor, can any written document, be substituted for qualifed engineering analysis. Suggested revisions are invited and should be submitted to:

The manager PDVSA Engineering Standards, C/O INTEVEP – TENA TENA Divisi ón, Apartado 76343 Caracas – 1070A 1070A Venezuela


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LEVEL INSTRUMENTATION FLOW INSTRUMENTATION

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SCOPE This section covers PDVSA requirements for the design, specification, installation and commissioning of level instrumentation. All guidelines of the introduction specification K – 300 shall also be explicity followed.

2

CODES, STANDARDS AND PRACTICES ANSI B31.3 Piping API RP – 550 Instrument Installation API RP – 5 51 Process measurement instrumentation API 2545 Tank Level Gauging PROCESS INSTRUMENTATION MANIFOLDS – JOHN E. HEWSON (ISA)

3

DEFINITIONS All definitions are listed in the appendix of specificatio n K – 300.

4

GENERAL REQUIREMENTS Level measurement to indicate, transmit, record, with or without control facilities is classified under the following categories. Continuous liquid level measurement in process vessels and tanks They are based on the following principles: 

d/p cell – hydrostatic head



Buoyancy displacer Capacitance Radio frequency / ultrasonic Nuclear

  

On – off type liquid level switches in process vessels and tanks  

Buoyancy float Capacitance/radio frequency/ultrasonic/nuclear

Gauge glasses Liquid level measurement in A.P.I. storage tank Solids level measurement/switches


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LEVEL INSTRUMENTATION


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The following guidelines aid in the design of above items: Where only a local indication of liquid level other than by means of level gauge glasses is required and instrument air supply or instrument electricity supply is not available, level indicators with magnetic coupling should be considered. For transmission or local control, displacer level instruments or differential – pressure level instruments shall be applied. Differential – pressure instruments have preference for normal applications. For special applications, other principles of measurement may be considered, such as ultrasonic instruments or instruments based on capacity, conductivity or radioactivity subject to agreement by PDVSA. Special provisions such as purging or heating shall be provided to ensure proper operation of level instruments for higly viscous liquids, or for liquids containing solids, specially if the latter tend to form sediments. For instruments on high – pressure/temperature service due to difference in density between liquid and vapour to obtain an accurate indication of actual level under all operating conditions, consideration shall be given to correct the level transmitter output by a computing device using the output of the pressure transmitter or other suitable means. On all applications the difference between liquid density and gas/vapour density shall be taken into account when specifying instruments. On liquid – liquid interface services, especially when the difference in densities is small, special attention shall be paid to the diameter of the displacer or float to ensure measurement accuracy. Level indicators with magnetic coupling shall not be used on applications where the vessel contents is agitated, or where suspended solids in the process liquids may deposit on the guide tube.

4.1

D/p Cell – Hydrostatic Head

4.1.1

The preferred primary element shall be a differential pressure (d/p) cell operating on the hydrostatic head pressure principle.

4.1.2

All parts in contact with the process fluid shall be 316 stainless steel unless other materials are necessary to withstand the fluid ’s corrosive properties. Flanged d/p cells with or without capillary are available as an alternative but attention is drawn to the resulting inaccuracies in measurement.

4.1.3

The d/p cell shall have range elevation / suppression facilities.

4.1.4

On steam drum level measurement reference columns to compensate for errors due to differences between water and steam densities shall be installed to ensure accurate level measurement. See PDVSA drawing No. 3. A copy of this drawing is included at the end of this specification.


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4.1.5

Bubbler type and purged systems are a variation of the d/p cell type application. They shall be used on sumps and also on corrosive fluid services. They are ideal when it is necessary to ensure that the process fluid is not in contact with the d/p cell. (See ISA publication ‘‘Process instrumentation manifolds –by John E. Hewson’’, section ‘‘B” for additional details).

4.1.6

Where plugging of the connections is expected, the instruments shall have the high – pressure side of the measuring element exposed, and be suitable for direct bolting to a flanged nozzle on the vessel.

4.1.7

Where necessary to avoid plugging of the nozzle, the instrument shall have an extended diaphragm flush with inside of vessel. The extended diaphragm shall, not be specified for instruments on vessels requiring mechanical cleaning. For instruments with an extended diaphragm, the diameter of the extension shall be compatible with the inside diameter of nozzle.

4.2

Buoyancy Displacer

4.2.1

The buoyancy displacer type complete with external chamber shall be used for ranges upto 32 inches. Existing displacer installation shall be replaced by d/p cells at an available opportunity.

4.2.2

Displacers on process fluids operating at more than 200 C shall be provided with cooling fins and insulated extensions on fluids operating below – 20 C. °

°

4.2.3

The external chamber connection size shall be 2 ”. The flange rating shall be 300 # minimum unless the vessel connection requires a higher rating.

4.2.4

Instrument materials on cold services require impact testing before and stress relieving after manufacturing.

4.2.5

Level instruments on LPG storage vessels require a ANSI certificate.

4.2.6

The displacer material shall be stainless steel AISI 316 unless another material is more suitable.

4.2.7

The external chamber connections shall be located either upper side and bottom or side and side.


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VESSEL CONNECTIONS

4.2.8

All displacer chambers shall be provided with 1/2 ’’ N.P.T. valve vent and drain connections. The connections shall be on the displacer chamber itself or on the interconnecting pipe. The valves shall be plugged during normal operation.

4.2.9

External displacers shall not be used on fluids that boil or freeze or congeal in the chamber.

4.2.10

Displacer for direct mounting inside process vessels or tanks shall not be used.


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A bridle type installation is strongly recommended to mount all the level instruments. This type of installation enables all items to be prefabricated and tested for correct functioning in the instrument workshop prior to mounting on the vessel. It also aids in reducing the number of nozzles on the vessel and also facilitates subsequent maintenance and readjustments to suit the process conditions without necessity of shutting down the plant.

3/4”

2”

3/4”

2” 1”

1”

EXTERNAL DISPLACER

3/4”

LEVEL SWITCH d/p CELL

1”

2” 1”

GAUGE GLASS

BRIDLE FOR INSTRUMENTS


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Radio Frequency / Capacitance / Nuclear / Ultrasonic These types of level measuring instruments shall be used to suit the specific application subject to PDVSA approval.

4.4

Level Switches The primary element to indicate the presence of high or low level is based on the following principles:

4.4.1

w.

Buoyancy float

x.

hydrostatic head

y.

Ultrasonic / radio frequency / radar / capacitance

z.

Nuclear

The buoyancy type float inside an external chamber complete with a magnetically actuated hermetically sealed switch shall be used to indicate either high or low level. The external chamber connection size shall be 1 ” minimum. The flange rating shall be 300# minimum unless the vessel connection requires a higher rating. The chamber connections shall facilitate testing switch action easily.

VESSEL CONNECTIONS


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4.4.2

The float material shall be 316 stainless steel and the chambers shall be forged carbon steel unless other materials are necessary to resist the fluid ’s corrosion properties.

4.4.3

The level switch shall be snap acting D.P.D.T. type and wired to a block with three (3) terminals so that either a normally closed (NC) or a normally open (NO) action can be chosen to meet the necessary electrical circuitry requirements. The switch shall be snap acting, hermetically sealed, tropicalised and corrosion resistant to marine and any other specified toxic ambience. The switch rating shall be 1 amp at 24 volts D.C. Mercury type switches shall not be used.

4.4.4

Floats without external chambers for direct mounting inside vessels, tanks or sumps shall not be used. As an alternative a continous level measurement transmitter which operates a separate trip switch is the PDVSA recommended practice. When these switches form part of a protection circuit, the primary level transmitter shall be independent of any other level measuring system installed on the same vessel / tank / sump.

4.4.5

Level switches shall only be used where: – Instrument air supply is not available, e.g. in tank farms – The simplicity of the application does not justify a transmitter, e.g. on lube oil/seal oil tanks for running equipment.

4.4.6

4.5

All other types of level switches such as ultrasonic / nuclear / radar / capacitance shall be used to suit the application and subject to PDVSA approval.

A.P.I Storage Tank Gauging All tank gauging systems shall have remote read – out on the main panel in the control room. Tank gauging for custody transfer shall be radar or servo – motor – operated (surface seeking) type, with remote checking facilities. The level measuring systems on tanks on custody transfer service shall have a measurement accuracy of 1 mm. The accuracy shall be certified by a recognised authority – DIN, etc... Corrosion – resistant materials shall be used throughout. Where storage tanks require an averaging temperature detector, this shall form part of, and be connected into, the tank gauging system. These average temperature detectors shall be fixed multiple resistance elements, Pt – 100 type. Where a spot reading temperature detector is required this shall be provided in the lower part of the tank and shall be a resistance thermometer connected to a temperature indicator.


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Gauge Glasses The following are the types of gauge assemblies directly connected to the process vessel. a.

Reflex glass column

b.

Transparent (thru – vision) glass column

c.

Metal tube with magnetic follower

d.

Metal tube with conductance electrodes

4.6.1

Gauge glass columns shall be provided on all process vessels installed immediately adjacent to any additional level instrument – transmitter, indicator or switch. They shall not be installed on silos or A.P.I. storage tanks.

4.6.2

Thru – vision (transparent) type gauge glass shall be specified on the following applications: a.

Interface between two liquids

b.

Coloured liquids with specific gravity 0,9 or higher

c.

Liquids containing gum, sediment or other solid particles which cling to the glass

d.

Boiler feed water services

e.

Glasses requiring mica shields

f.

Liquids not easily visible or tend to be opaque

On all other services reflex type gauges glass columns shall be used. On corrosive and toxic services, fluids operating at more than 60 C, and on cryogenic services the metal tube with magnetic follower type of gauges shall be used. Another available alternative is the metal tube with electrodes subject to the fluid conductance properties. °

4.6.3

Level gauges need continuous maintenance to ensure good and clear level visibility. Hence consideration shall be given in providing only valved connections on a vessel to which a gauge can be connected for e.g. during start – up, level instrument / switch calibration, etc.

4.6.4

A sufficient number of gauge glass columns shall be provided so that the visible lengths provide complete coverage of the allowable range of liquid level inside the vessel.

4.6.5

Gauge glass columns shall consist of one or more gauge glass sections with the necessary isolating valves to permit cleaning of the glass. There shall not be more than three (3) sections in each gauge glass column. Each section shall have 12 inches (300 mms) visible length.


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4.6.6

When two or more gauge glass columns are required to cover a level measuring range the visible portion of the gauges shall overlap atleast 1 inch (25 mms).

4.6.7

Gauge glasses on steam boiler units (Drum, deaerator, etc.,) shall conform with ASME section I requirements.

4.6.8

Each gauge column shall be complete with its own individual isolating valves complete with a ball check device to shut off flow in the event of glass breakage.

4.6.9

Bridle assemblies are strongly recommended in order to reduce the number of nozzles on vessels to mount gauge glass columns and associated level instruments. See paragraph 4.2.7.

4.6.10

Length of nipple between glass sections or glass and isolating valve shall not exceed three (3) inches.

4.6.11

Gauge glass columns shall be provided with a 1/2 ’’ N.P.T. drain valve plugged and a 1/2’’ N.P.T. plugged vent.

4.6.12

The liquid chamber and cover plate shall be forged steel unless other material is necessary to withstand the fluid’s corrosive properties. The inside of the chamber shall have a non – removable black finish.

4.6.13

Gauge glass quality shall be shatter – proof so that in the event of breakage there are no loose or flying glass particles. All glasses shall be armoured type. Tubular gauge glass shall not be used.

4.6.14

Gauge glass columns on boiler feed water, caustic and other fluids that attack glass shall be provided with mica shields to protect against glass etching.

4.6.15

Gauge glass columns operating on process fluids below 0 C shall be provided with frost shields.

4.6.16

Gauge glass shall be heat traced on all process fluids that freeze or congeal in accordance with A.P.I. – R.P.550, section B –‘‘Seals, purges and winterizing ’’.

4.6.17

Gauge glass lighting shall only be provided subject to PDVSA approval for transparent type glasses if the gauge glass column is not conveniently accessible for back – side illumination and simultaneous observation by an operator with a hand held light. The electrical items shall conform to the area electrical classification. The lighting and gauge glass column shall be procured as one complete assembly.

4.7

°

Solids Level Measurement / Switches For continuous level measurement and/or high/low level indications of solids inside vessels, silos, etc. the primary element selected shall have proven operational reliability based on any of the principles listed below:


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a.

Float

b.

Capacitance

c.

Radar / ultrasonic

d.

Nuclear

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The selected item shall be subject to PDVSA approval.

5

SPECIFICATION FORMS FORM No.

TITLE

20.1a and 1b

Receiver instruments

20.10a and 10b

Single/Multiple input Millivolt/Milliamp instrument

20.20a and 20b

Differential pressure instrument

20.26

Displacer level instrument

20.27

Capacitance level instrument

20.28

Gauge glasses

The forms are included at the end of this specification.

6

INSTALLATION AND COMMISSIONING All installation and commissioning shall be performed in accordance with project drawings and specifications.

7

Q.A. / Q.C. All items shall conform with the procedures detailed in specification K – 369.

 RECEIVER INSTRUMENTS ITEM N

°

QUANTITY

OFF

N

SPECIFICATION REFERENCES I.S.A S PDVSA–K–

Item N

°

Tag. N

°

No. of inputs

SHEET

PROJECT REFERENCE

Scale Ranges

Chart Ranges

°

By

OF REVISED

DATE

Service

Notes:

20.1b


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INSTRUCTIONS TO FILL FORMS 20.1A AND 20.1B

PDVSA 20.1

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RECEIVER INSTRUMENTS

a.

To be used for a single item. Use secondary sheet for multiple listing.

b.

Check as many as apply.

c.

Nominal size refers to approximate front of case dimensions; width x height.

d.

It is assumed that the instrument has its own case of shelf suitable for single mounting, unless ‘‘MULTICASE” is checked. Shelf or separable case for multiple case mounting instrument is not included unless listed and described as an accessory.

e.

Enclosure class refers to composite instrument. If electrical contacts are the case they must meet this classification inherently or by reason of the enclosure. Use NEMA identification system or ISA System RP8.1.

f.

Specify electrical power to the entire instrument from an external source.

g.

For multiple instruments list ranges on secondary sheet, but specify other chart options on primary sheet. Chart graduations assumed to be uniform unless otherwise noted. Circular charts assumed to have 24 hr/revolutions speed; strip charts 3/4 in. to 1 in. per hour.

h.

Chart drive mechanism assumed to be synchronous motor operating on 117V 60 Hz and suitable for ENCLOSURE CLASS specified on line 5. If the chart drive is pneumatic so state – identify pneumatic pulser under options. Notes deviations from standard (MFR) under notes i.e., dual speed or special speeds.

i.

The scale type may be SEGMENTAL, VERTICAL, HORIZONTAL, DIAL (CIRCULAR) or other. Ranges 1, 2, 3 and 4 are used for multiple inputs. The first listed (N 1) is assumed to be the controller input, if a controller is used. °

j.

See explanation of terminology given on specification sheet. For further definition refer to American National Standard C85.1–1963, ‘‘Terminology for Automatic Control.’’ Specific ranges of control modes can be listed afetr ‘‘OTHER’’, if required.

k.

For multiple items specify on second sheet.

l.

If standard auto–manual switching is not known or not adequate, specify particular requeriments, such a BUMPLESS, PROCEDURELESS, 4–POSITION, or as required.

m.

Remote set point adjustment assumes full adjustment range. Specify limits if required. Under other can be noted bias or ratio.

n.

Specify if applicable.

o.

Specify if applicable.


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p.

All input signals on multi–channel instruments assumed to be the same unless otherwise noted.

q.

Specify number of inputs.

r.

Check if power source for the loop is contained in this instrument or in some external instrument.

s.

Form may be SPST, DPDT or other. Rating refers to electrical rating of switch or contacts in amps.

t.

Specify if alarm is actuated by measured variable or by deviation from controller set point, Give contact action if single throw form.

u.

Specify required accessories and options, fill in number of charts. This is assured to be number of chart roles for strip charts.

v.

After selection is made fill in manufacturer and specific model number. SECONDARY SHEET – For listing multiple instruments. List all instruments of the same type specified on the primary sheet, with variations an shown. ‘‘Notes refers to notes listed by number at the bottom of the sheet. Line 11 of sheet 1a is tabulated under measurement increases, output tabulate increase or decrease.

 SINGLE/MULTIPLE INPUT MILLIVOLT/MILLIAMP INSTRUMENT ITEM N

°

QUANTITY

OFF

SHEET

PROJECT REFERENCE N


GENERAL

1. Tag N

Record

Control

Indicate

Single input

DATE

Transduce r No. of inputs

Multiple inputs

Thermocouple ref. junction comp.

3. Input

Resistance bulb Milliamps

J (IC)

3–wire

4–20 m.A.

4. Mounting

Flush

Surface

5. Enclosure

Safe area

Classified

Temp. Class

Ext.

Power supply–This inst.

Ext.

Other Class

T1

Group

Intr. safe

T2

T4

7. Chart

Roll

8. Scale Range

Direct Readout

9. For multiple inputs

Selector switches per note 3

Scan speed

4–20 mA

Other

Fold

Circular

3–15 psig

PI

PID

Single

Manual Reg

13. Output

4–20 mA

14. Switches

Function on measurement input

16. Model N

Speed: See Note 3

Seconds per point.

Other

Manual

MFR

T6

For receiver see sheet

12. Set Point Adj.

15. Input open circuit

Range

Multiple ranges

Auto–man Switch

OPTION

T5

24 Volts D.C.

input–output isolation P

Div STD.

T3

110 V 60 Hz

CONTROLLER 11. Control Modes

Other

Calibration:

6. Power Supply

10. Output

T(CC)

Power supply–This inst.

Ex. Proof

Weatherproof

K (CA)

4–wire

Frequency/pulse

ALARMS

REVISED

Service

°

2. Function

XMTR/ TRANSD.

By

°

OF

Reversible Action Manual loading STN.

Remote 21–103 kPa (3–15 psig) High

Low

No. of alarms

Rating 1 AMP. at 24 Volts D.C. see note 2

Upscale

Downscale

Int. Ill

High and Low

Charts

°

Notes: 1. All weatherproof and explosion items shall be corrosion resistant to marine atmosphere and tropicalised. 2. Alarm contact shall be normally closed and open on alarm condition. Alarm setting shall be programmable. 3. Programmable 20.10a

 SINGLE/MULTIPLE INPUT MILLIVOLT/MILLIAMP INSTRUMENT ITEM N

°

QUANTITY

OFF

SHEET

PROJECT REFERENCE N


°

By

OF REVISED

DATE

Individual Item N

°

Tag. N

°

Service

Scale and Chart Range Point No.

Input type

Notes:

20.10b


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MILLOVOLT OR MILLIAMP INSTRUMENT SPECIFICATION SHEET INSTRUCTIONS

Prefix number designates line number on corresponding specification sheet. 1. To be used for single item. Use secondary sheet for multiple listing. 2. Check as many as apply. 3. Check one. Note that sheet may be used to specify galvanometric type of instrument. 4. Nominal size refers to approximate front of case dimensions: width x height. 5. It is assumed that the instrument has its own case or shelf suitable for single mounting unless ‘‘multi–case’’ is checked. Shelf or separable case for multiple case mounting instrument is not included in this sheet unless listed as an accesory. 6. Enclosure Class refers to composite instrument. If electrical contacts are in the case, they meet this rating inherently or by reason of the enclosure. Use NEMA identification system or ISA system presented in RP8.1. 7. Specify electrical power to entire instrument. 8. For multiple instrument list ranges on second sheet, but specify other items here. 9. Ranges 1 and 2 refer to multi–channel instruments. The first listed is assumed to be the controller input (if any). 10. For multiple items list number of point on second sheet. ‘‘Point Select’’ permits by–passing any or all points by a switching mechanism. 11. For multiple items show number of switches on second sheet under ‘‘No. of Point’’. 12. Specify if applicable. 13. See explanation of terminology given on spec. sheet. Specific ranges of control modes can be listed under ‘‘other’’ if required. 14. For multiple items specify on second sheet. 15. If standard auto–manual swithching is not known or not adequate, specify particular requirements, such as BUMPLESS, PROCEDURELESS, 4–POSITION, or as required. 16. Remote set point adjustement assumes full adjustment range. Specify limits if required. 17. Specify if applicable. 18. Specify if applicable. 19. Check if thermocouple input applies. galvanometer.

Lead resistance required only for


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PDVSA 20.10

REVI SION

DATE

0

AUG.94


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20. Specify any input other than thermocouple. ‘‘Calibration’’ refers to curve used and does not imply that element is specifically calibrated for this instrument. 21. Form may be SPST, SPDT, DPDT, etc. Rating is electrical rating of switch in amps. 22. Check if alarm is actuated by measured variable or by deviation from controller set point. Give contact action if single throw form. Specify calibrated or blind alarm index setter. 23. Specify if applicable. 24. Specify if applicable. 25. Accesories for multiple items may be covered by ‘‘notes’’ second sheet. 26. May be filled in after selection is made. SECONDARY SHEET– for listing multiple instruments. List all instruments of the same type, specified on Primary Sheet, with variations as shown. ‘‘Notes’’ refers to notes listed by number at the bottom of the sheet. Or use secondary Sheet to list and identify the multiple points of a single multipoint instrument.

 DIFFERENTIAL PRESSURE INSTRUMENTS ITEM N

°

QUANTITY

OFF

SHEET

PROJECT REFERENCE N

GENERAL

1. Tag N 2. Function

Record

3.

Material

Yoke

4.

Enclosure

Safe area

Service Indicate

°

Classified

XMTR CONTR

SERVICE

ALARMS

OPTIONS

Notes:

T1

T2

Range

8.

Scale Range

1

9.

Output

4–20 m.A.

10.

Cont. Mode

P

12.

Set Point ADJ

Manual

13.

Output

4–20 m.A.

14.

Type

16.

Element

Flow Diaphragm

17.

Material

Body

18.

Body

Rating

19.

Diff Range

Adj. Range

20.

Process Data

Fluid

21.

Switches

Function on measurement input

23.

Group

T3

T4

T5

T6

20 Psig Spring

2

Speed

3

3–15 Psig PI

Div STD.

Drive–Elec

Circular

Options

DATE

Integrator

Intr. safe

24 Volts d.c.

110 V 60 Hz

Other

Reversible Action Remote Other

3–15 Psig

Diff. Press

Level

Elevation

Suppression

Bellows Element Conn–1/2 npt

Flanged

Set At Max. Press

Max. Temp. High

Low

High and Low

No. of alarms

Rating 1 AMP. at 24 Volts D.C. see note 2

Pressure element

Range

Material

Temp. Element

Range

Type

Filt Reg

MFR

Class

6. Chart

22.

Transm

Ex. Proof

Temp. Class

Power Supply

Control

REVISED

Other

Weatherproof

5.

By

°


OF

Gauges

Charts

3–valve manifold

Model No

1. All items shall be corrosion resistant to marine atmosphere and tropicalised. 2. Alarm contact shall be normally closed and open on alarm condition. Alarm setting shall be adjustable

20.20a

 DIFFERENTIAL PRESSURE INSTRUMENTS ITEM N

°

QUANTITY

OFF

SHEET

PROJECT REFERENCE N

°


Tag. N

°

Set Range

Scale or Chart

Scale Factor

Service

By

OF REVISED

DATE

Notes

NOTES

20.20b

ENGINEERING SPECIFICATION INSTRUCTIONS TO FILL FORMS 20.20A AND 20.20B

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PDVSA 20.20a

REVI SION

DATE

0

AUG.94


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1

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DIFFERENTIAL PRESSURE INSTRUMENTS

1. To be used for a single item. Use secondary sheet for multiple listing. 2. Check as many as apply. 3. Nominal size refers to approximate front of case dimensions; width x height. 4. Yoke refers to a bracket designed for mounting the instrument on a pipe stand. 5. Enclousure class refers to composite instrument. If electrical contacts are the case they must meet this classification inherently or by reason of the enclousure. Use NEMA identification system or ISA System RP8.1. 6. Specify electrical power to the entire instrument from an external source. 7. Specify chart size, range and number if applicable. 8. ‘‘24 hr’’ is the time for one rotation of the chart. Other speeds should be listed in hours or days. If a spring wound clock is used fill in number of hours or days it runs between windings. 9. The scale type may be SEGMENTAL, ELECTRIC, or DIAL (CIRCULAR). Space is provided for multiple ranges on the same scale. 10. Specify transmitter output if applicable. 11. See explanation of terminology given on specification sheet. For further definition refer to American National Standard C85–1–1963, ‘‘Terminology for Automatic Control.’’ Specific ranges of control modes can be listed after ‘‘OTHER’’, if required. 12. For multiple items specify on seconds sheet. 13. If standard auto–manual switching is not known or not adequate, specify number of positions. 14. Remote set point adjustment assumes full adjustment range. Specify limits if required. 15. Specify if applicable. 16. Specify if applicable. 17. Specify measured variable. 18. Specify type od element or write in ‘‘MFR.STD’’. 19. Materials refer to wetted parts only. 20. Over–range protection refers to maximum differential pressure. instrument can withstand without a shift in calibration.

The

21. Adjustable range means that the range can be changed without replacing any parts. 22. Elevation.

PDVSA

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Menú Principal

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REVI SION

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Page

2

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23. Give process data affecting meter selection. Flow elements such as orifice plates are specified on separate forms. 24. Refers to connections piped to process equipment or pipe line. Special flanged connections and extended diaphragms for level applications should be described afetr ‘‘OTHER’’. 25. Form may, be SPST, DPDT, or others. Rating refers to electrical rating of switch or contacts in amps. 26. Specify if alarm is actuated by measured variable or by deviation from controller set point. Give contact action if single throw form. 27. Specify required accessories. If temperature element is used, the second line is provided to specify well, length of capillary tubing and other details of the thermal system. 28. After selection is made fill in manufacturer and specific model number. SECONDARY SHEET – For listing multiple instruments. List all instruments of the same type specified on the primary sheet, with variations an shown. ‘‘Notes refers to notes listed by number at the bottom of the sheet.

 ITEM N

°

LEVEL INSTRUMENTS (DISPLACER OR FLOAT)

QUANTITY

OFF

SHEET

PROJECT REFERENCE N

SPECIFICATION REFERENCES I.S.A S PDVSA–K–301

1.

Tag N

2.

Function

BODY/CAGE 3.

Material

AND CASE

4.

Upper Conn.

Size

Location

5.

Lower Conn.

Size

Location

7.

Enclosure

Safe area

GENERAL

By

°

OF REVISED

DATE

Service

°

Trans

Contr

Trans & Contr

Level switch

SP.GR Compensation

Rating

Class

Classified Ex. Proof

Weatherproof Temp. Class

T1

8.

Power Supply

24 Volts d.c. Ext.

9.

Extension

Cooling

Group

Intr. safe T2

T3

Div

STD. T4

T5

T6

20 Psig

Radiation

DISPLACER 10. OR FLOAT 11.

Length Material

Displacer

XMTR

12.

Ouput

4–20 m.A.

CONT

13.

Cont. Mode

P

PROCESS

14.

Liquid

Upper

SP.GR

15.

Liquid

Lower

SP.GR

16.

Conds.

Max. Press

OPTIONS

17.

Options

Filter Reg

ALARMS

18.

Switches

Contacts to

PI

Torque Tube Other

3–15 Psig

Reversible Action

Max. Temp.

Min. Temp.

Supply/Ouput Gauges On Rise

On Fall

In level

Rating 1 Amp at 24 volts d.c. MFR

Notes:

19.

Model No

1. All items shall be corrosion resistant to marine atmosphere and tropicalised.

20.26

ENGINEERING SPECIFICATION INSTRUCTIONS TO FILL FORM 20.26



PDVSA 20.26

REVISI ON

DATE

0

AUG.94


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1

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LEVEL INSTRUMENTS (DISLACER OR FLOAT)

1. Tag N or other identification. °

2. Process service. 3. Line number or vessel number on which cage or body is installed. 4. Material of chamber and/or mounting flange. 5. For float specify top or side of vessel connection. For displacer in a chamber specify upper, then lower connection; such as side–side, side–bottom, etc. Give flange size and rating or NPT size. 6. Same as 5. 7. Refers to position of case when viewing the front of the case relative to the chamber; the case is either to the left, right, or top. 8. On displacer instruments specify if case is to be rotatable with respect to the chamber. This only applies if there is one or more side connections. 9. Orientation of control with respect to displacer cage. 10. Cooling Extension. 11. Specify float diameter or displacer length. The displacer length is also the range. 12. Insertion depth applied to ball floats. It is the mounting flange to the center of the ball. 13. The displacer extension is measured from the face of the mounting flange to the top of the displacer. This dimension is required only for top of vessel mounted instruments. 14. Includes rod. 15. Refer to MFR’s standard materials or special materials. 16. Transmitter, controller, switch, etc. 17. Air pressure or electrical signal output of transmitter or controller. 18. P: Proportional. Pn: Narrow band proportional PI: Proportional plus Integral (Reset). 19. Differential if controller on/off must specify differential adj. or fixed. State adjustable range or fixed amount. 20. INCREASE (Direct action) or DECRESE (Reverse action). 21. Remote, or integral.




INSTRUCTIONS TO FILL FORM 20.26

PDVSA 20.26

REVISI ON

DATE

0

AUG.94


Indice manual

Indice volumen

22. Electrical classification of housing. NEMA number. 23. Air pressure or voltage. If electronic, state whether ac or dc. 24. Used only for interface application. 25. Used for all services. 26. Specific gravities at operating temperature. 27. Operating and max. pressure, or vacuum. 28. For cryogenic service, give minimum temperature. 29. Airset assumed mounted to case. 30. Connections on chamber, give size. 31. Specify gauge glass, if required. 32. Contact form: SPST, SPDT, etc. 33. Give Volts, Amps. 34. Describe contact action with level. 35. Model number of entire assembly.

2

Indice norma

 ITEM N

°

LEVEL INSTRUMENTS (CAPACITANCE TYPE)

QUANTITY

OFF

SHEET

PROJECT REFERENCE N


GENERAL

1.

Tag N

2.

Enclosure

Safe area

Classified

Temp. Class

Ex. Proof T1

MFR Notes:

Intr. safe T2

T3

STD. T4

T5

Output

4.

Function

28.

Range

5.

Fail–Safe

29.

Enclosure Class

6.

Model Number

30.

Compensation Cable

7.

Orientation

31.

Local Indicator

32.

I.P Transducer

33.

Signal Lights

Material

T6 TRANS.

OPTIONS

34.

10.

Sheath

11.

Insertion Length

35.

Upper Fluid

12.

Inactive Length

36.

Dielectric Constant

13.

Gland Size & Mat’l

37.

Lower Fluid

38.

Dielectric Constant

SERVICE

15.

Conduit Connection

39.

Pressure Max.

Normal

16.

Location

40.

Temp. Max.

Normal

17.

Enclosure

18.

Conduit Connections

41. 42.

Moisture Material Buildup

19.

Power Supply

43.

Vibration

20.

Type

21.

Quantity and Form

22. 23.

Rating: Volts/Hz or dc Amps/Watts/HP

24.

Load Type

25.

Contacts

26.

DATE

Div

27.

14.

SWITCH

Group

Application

8. Style

AMPLIFIER

Class

3.

9.

REVISED

Service

°

Weatherproof

PROBE

By

°

OF

Open Close

On Level

Incr. Decr.

Model No 1. All items shall be corrosion resistant to marine atmosphere and tropicalised

20.27





PDVSA 20.27

REVISI ON

DATE

0

AUG.94


Indice manual

Indice volumen

1

Indice norma

LEVEL INSTRUMENTS, CAPACITANCE TYPE

Prefix number designates line number on corresponding Specification Sheet. 1. Identification of item by tag number. 2. Process area or function. 3. Stream description and/or pipe size and number or vessel number in which probe is installed. 4. Specify solids level, liquid level, interface, foam detection, etc. 5. Specify alarm, transmit, on–off control, etc. 6. Specify high, low, none. 7. Specify probe model number if known. 8. Specify if probe axis is horizontal, vertical, etc. 9. Specify general purpose, heavy duty, knife–blade, inline plate, concentric shield, etc. 10. Specify probe material as 316 SS, etc. 11. Specify sheath, required, as 1/4 in. Teflon, etc. 12. Specify total inmersion in inches, or feet and inches. 13. Specify length of inactive extension in inches, or feet and inches. 14. Specify sealing gland material and size as 316 SS, 3/4 in. NPT, etc. 15. Specify conduit connection as 3/4 in. NPT hub, 7/8 in. OD knockout, etc. 16. Specify if electronics are mounted at probe or remotely located. 17. Specify general purpose, weather proof, explosion proof, etc. 18. Specify conduit connection as 3/4 in. NPT, 7/8 in. OD knockout, etc. 19. Specify power input as 115 V 60 Hz, etc. 20. Specify switch type as mercury bottle, snapaction, etc. 21. Specify number of switches and contact form of each switch (SPST, SPDT, DPDT, etc). 22. Specify switch voltage as 115 V 60 Hz, 24 Vdc, etc. 23. Specify contact rating in amps, watts, or horsepower. 24. Specify load as inductive on non–inductive. 25. Specify if contacts open or close when the level increases or decreases. 26. Specify transmitter output as 1–5, 4–20, or 10–50 mA, 1–5 Vdc, etc.


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PDVSA 20.27

REVISI ON

DATE

0

AUG.94


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2

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27. Specify level range in inches or feet and inches corresponding to minimum and maximum transmitter signal. 28. Use NEMA identification mumbers. 29. Specify length of special compensating cable to be furnished with probe, if required. 30. Specify size, type and range of local indicator, if required. 31. Specify if electro–pneumatic transducer 21–303 kPa (3–15 psig output) is required. 32. Specify if High, Low, HI/LO lights are required, and rating. 33. For items not covered in lines 31 through 34. 34. Specify upper fluid by name and state (liquid, vapor). 35. Specify dielectric constant of upper fluid. 36. Specify lower fluid by name and state. 37. Specify dielectric constant of lower fluid. 38. Specify maximum and normal operating pressure at probe. 39. Specify maximum and normal operating temperature at probe. 40. Specify percentage moisture content of solids. 41. Specify if material is expected to buil up on probe. 42. Specify vibration environment of probe as mild, severe, etc. 43. Fill in manufacturer and model number after selected.

 GAGE GLASSES AND COCKS ITEM N

°

OFF

QUANTITY

SHEET

PROJECT REFERENCE N


1. Gage Column

Assembled with Nipples

Cocks

Reflex

Transparent

Large Chamber

Tubular

Weld Pad

Side

Vent

Illuminator Internal Tube Non–Frost Calb. Scale

Vent/Drain

Trim psig at

F

°

Vessel

13. Bonnet 15. Options:

psig at

DATE

Gage

Drain

5. Min. Rating

Gage

Body

12. C onstruction:

Back

4. Material

6. Options:

Vessel

10. Material:

REVISED

Straight

11. Min. Rating:

3. Conn: Size and Type Top & Bot.

Offset

9. Conn:

GAGE GLASSES

2. Type:

8. Type:

By

°

OF

F

°

Offset

Straight

Other: 16. Manufacturer & Model

Mica Shield External Jkt Ext. Length Other

7. Manufacturer & Model Item N °

Quan.

Tag N

°

Visible Glass

Conn.

Model N

°

Operating Service Press.

Temp .

Notes: 1. All items shall be corrosion resistant to marine atmosphere

20.28

PDVSA k-303

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