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Last Updated: 30 September 2013

Table of Contents

1. Introduction
2. Scope
3. General Procedure for flow diagram preparation
4. The Process Flow Diagram
5. The Pressure (P) - Temperature (T) Profile
6. The Engineering Flow Diagrams (P&ID)
7. The Utility Flow Diagram (UFD)
8. The Interconnectiong Flow Diagram
9. The Process Safeguarding Flow Diagram
10. The Revamping Flow Diagram
11. Check List
12. Preparation of Line Table
13. List of Related Red-Bag Standards
14. List of Other Standards
15. Typical Arrangement of Equipment Installation

1. Introduction

1.1 Purpose
The purpose of this document is to outline the procedures for the preparation of process flow diagrams, pressure-temperature profile diagrams, engineering, utility and interconnecting flow diagrams and special diagrams as revamp flow diagrams and pressure safeguarding flow diagrams.

1.2 Concept
Flow diagrams are highly specialized “language for information transfer. They represent the engineer’s concept of how plant equipment should be interconnected. The diagram is almost physical in a sense, since every piece of equipment, every pipeline, valve and instrument is shown. Diagrams are used to convey information between groups working on the project and translate the plant design into ‘real’ piping and equipment.

1.3 Use
By preparing the diagrams properly, the engineer can convey a great deal of technical information, quickly and accurately, with a Limited amount of paper work.

1.4 Tee of Diagrams There are 7 types of flow diagrams:

1.4.1 The Process Flow Diagram (PFD)
The PFD is developed by the Process Engineering Department. Final drafting by the Flow Diagram Squad. On this document are given the main process equipment, fluid flows, main control loops and critical valves. It is a tool for the process engineer(s) to convey information to project and specialist engineers to design the installation in detail (see fig: 6).

1.4.2 The Pressure Temperature Profile Diagram(PTP)
The PTP diagram is a document prepared by the Process Engineering Department with the purpose of providing project, control systems and piping engineers with the correct pressure and temperature correlations between the various piping systems, vessels, exchangers, etc. The document ensures that proper values are being used for preparation of data sheets, line tables and other documents as, e. g. painting systems, insulation, etc.

For PTP preparation procedures refer to Standard Specification BN-EG-UE-1 (Design guide for Pressure and Temperature profile).

1.4.3 The Engineering Flow Diagram (EFD)
On this document are shown all equipment connecting piping, utility piping, complete with control, loops and all other instrumentation, all valves a safety measures. It is the main tool for the project engineer to convey information to the piping design office and control systems engineering group for the detailed piping and control systems design (see fig: 13).

1.4.4. The Utilities Flow Diagram
This document. shows how utilities are generated and distributed from the source or supply point to the various parts of an installation. The diagram shows coon control loops, additional equipment that is deemed necessary to supply the utility as required and the safety measures necessary (see fig: 18). The diagrams shall be drawn in accordance with the geographical layout of the plant.

The diagrams are generally divided per generation activity, e.g. steam generation, inst air, cooling water, fuel oil, etc. The utility equipment shall be shown. Packaged units to be shown within, heavy dotted line.

1.4.5 The Interconnecting Flow Diagram (IFD)
These diagrams are prepared to show the interconnecting lines between various plant units and, e.g. tank farms, etc,

1.4.6 The Process Safeguarding Flow Diagram (PSFD)
This document shows the correlation of safety devices installed but indicated on separate EFD's. It “highlights” the final level of protection provided by the safety systems installed.

This document will be produced on client's request only, e.g. SIPM

1.4.7 Revamp Flow Diagram
“Revamping Flow Diagrams” shall be prepared to indicate which equipment, lines, control loops, etc. must be demolished, modified, removed or relocated, etc. in a revamping project. The existing engineering flow diagrams of a plant or unit to be revamped shall be used.

In general two sets of diagrams are to be prepared:

a) An updated existing EFD's version for demolishing purposes, RFD's.
b) New “as built” EFD's

For more details refer to Chapter 10.

1.5 Notes:

1.5.1 It must be noted that particular instructions given by client or licensor with respect to his requirements or special requirements covered by any authority decrees shall be observed.

1.5.2 If any of such rules, decrees or instructions exist, these must be mentioned in the “Project Specification”.

1.5.3 When these instruction have not been incorporated, the documents produced will be unacceptable to the client or licensor and/or authorities.

1.5.4 Where in the following text of this Engineering Procedure has been referred to other Company procedures or standards, this is only true where the Company standards are not conflicting with those mentioned under para 1.5.1.

1.5.5 To obtain maximum uniformity with regard to line thickness, lettering, symbols, etc. the drafting on vellums shall be executed by the Flow Diagram Squad.

1.5.6 There is still another flow diagram, prepared by the control systems engineering group, exclusively for use by process and control systems engineers. This flow diagram is principally a PFD on which the control system engineer indicates specific instrument physical data. The document is called; “Instrument Data Flow Sheet”. It is not further mentioned in this ‘Engineering Procedure”.

1.5.7 The examples presented in this Engineering Procedure are taken from actual jobs and include general Clients requirements. Therefore, the symbols used will not always be identical to the symbols shown on the legend sheet fig: 22.

1.5.3 On an EFD, a package unit, e.g. compressor, can be indicated with a heavy drawn block with reference to one or more vendor flow diagrams (process, lube oil, seal oil, water cooling, etc.) which can be adopted.

2. Scope

2.1 This Engineering Procedure shall be used as a standard for the preparation of process and engineer flow diagrams as outlined in para 1.4 of the Introduction.

2.2 It shall also be used to edit systematically the text for the Project Specification on the subject of flow diagram preparation.

2.3 The purpose of this Engineering Procedure is to provide the engineers with all necessary information to generate the various diagrams needed with the greatest consistency and efficiency possible.

 

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The full procedure is available for registered users. The procedure is part of the Introduction and Basic Piping Design course at InIPED.

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Last Updated: 30 September 2013

Table of Contents

1. Orifice Plate Calculation
2. Restriction Orifice Calculations
3. Appendixes:
   Appendix A, Calculation of Compressibility Factors
   Appendix B, Flow Formula
   Appendix C, Additional Specifications for Maximum Metering Accuracy
   Appendix D, Conversion Formulae for Orifice Meters
   Appendix E, Calculation of Meter Maximum Flow, When Orifice Bore Is Given

1. Orifice Plate Calculations

SCOPE : This standard gives instructions for the use of Company orifice plate calculation sheets :

• form B.N. -K003-1 (English Units)
• form B.N. -K003-2 (Metric Units)

GENERAL : The method of the orifice plate calculations mentioned above is based on: “Principles and practice of flow meter engineering” by
LK Spink, 8th edition, and is in accordance with AGA-ASME standards, and the AGA gas measurement committee reports numbers 2 and 3.
Moreover the draft ISO recommendation No. 532 (revised text) dated September 1964 has been used as a basis as well.
For a simplified description of the theoretical background see appendix B.

REFERENCES :

1. Principles and practice of flow meter engineering L.K. Spink, 8th edition.
2. Flow measurement with orifice meters R.F. Stearns, R.R. Johnson, R.M. Jackson, C.A. Larson published by D. van Nostrand Co. Inc.
3. Gas measurement committee report No. 2 AGA, May 1935.
4. Gas measurement committee report No. 3 AGA, April 1955, Reprint 1956).
5. AGA flow constants (Foxboro)
6. Draft ISO recommendation No. 532 September 1964.

INSTRUMENTATIONS : The instructions are numbered 1 to 30.

The same numbers appear on the calculation sheets for reference.

No. 1: FLUID: Fill in process fluid flowing through the orifice.
No. 2: MEASUREMENT UNITS: (see also note below)
Fillin the units of measurement in which the client requires the meter to read. These units should be agreed upon with the client and are generally specified in the applicable general specification for instrumentation. These units may be different from the units in which normal flow is given.

No. 3: BASE PRESSURE: (see also note below)
Fillin the common base pressure to which all measurements in the plant are referred. This again is to be agreed upon with the client.
Common accepted base, pressures are 14.70 psia, 760 mm Hg and 1 Kg/cm²A.

No. 4: BASE TEMPERATURES: (see also note below)
Fillin the common base temperature to which all measurements in the plant are referred.
Agreement with client necessary. Some accepted European base temperatures are:

• Liquid : 15°C or 60°F
• Gas : 0°C or 60°F

Note: See BN-SP-K1 Specification for Instrumentation.

No. 5: BASE SPECIFIC GRAVITY:
Fillin the specific gravity at base conditions as specified under Nos. 3 and 4. For liquids, the specific gravity is related to water, for gases to air. When working in metric units, liquid specific gravity is related to water at 15°C (density of water at 20°C is 0.99823 grams/cm³).
The specific gravity of gases can be obtained by dividing the molecular weight of the gas by the molecular weight of air (28.996).
For English Units the specific gravity is referred to water at 60°F.

No. 6: STEAM QUALITY:
Fillin quality of the steam, and when it is superheated or saturated, state this.

No. 7: NORMAL FLOW AT BASE CONDITIONS:
Fillin the normal flow at base conditions as specified and the units in which it is given.

No. 8: NORMAL FLOW IN WEIGHT UNITS:
Fillin the normal flow rate and the units in which this is given.

No. 9 and 10: METER MAXIMUM FLOW:
Fillin meter maximum flow after calculations as outlined under 27.

No. 11: MINIMUM FLOW:

If the minimum flow falls below 20% of the meter maximum flow, consideration should be given to the use of a second lower differential range instrument or a second orifice run.

No. 12: COMPRESSIBILITY:

Fillin the compressibility ratio’s Zb, Zf for gas flow which are defined as:

Zf = deviation from true gas law at operating conditions.
Zb = deviation from true gas law at base conditions.

The compressibility ratio’s can be determined from reduced pressure and reduced temperature as outlined in Spink, pages 351 and 352. See also appendix A.

No. 13: MOLECULAR WEIGHT:

Fillin molecular weight for gas flow only.

No. 14:OPERATING PRESSURE:

Fillin upstream pressure in psia or Kg/cm² Abs.

(Kg/cm²A = Kg/cm² gauge + 1.0336).
(PSIA = 14.70 + psig).

No. 15:OPERATING TEMPERATURE:

Fillin the operating temperature at the orifice in degrees Rankine for the English calculation sheet and degrees Kelvin for the metric calculation sheet (°R = °F + 459.6, °K = °C + 273.2).

No. 16: OPERATING SPECIFIC GRAVITY:

Fillin specific gravity at operating conditions. For liquids this specific gravity is referred to water of 60°F, when working in English units and 15°C when working in metric units.

No. 17: OPERATING DENSITY:

The operating density is in some cases to be found in tables such as the steam table but in other cases must be calculated as out-lined under 27.

No. 18 ABSOLUTE VISCOSITY:

The operating viscosity shall be given in centipoises. Viscosities of several liquids are given on pages 325 thru 331 of “Flow measurement with orifice meters” published by D. van Nostrand Co. Inc. or page 184 of “Principles and practice of Flow Meter Engineering” by L.K. Spink.

To convert from centistokes to centipoises multiply by the specific gravity. For other conversions see page 311 thru 324 of the Van Nostrand book.

No. 19: METER DIFFERENTIAL: (h)

A meter differential of 100 ins W.G., or its metric equivalent is preferable. To avoid swaging up higher ranges 150” W.G., 200” W.G., etc., may be used.

For compressible fluids, the range in inches water should be lower than the absolute static pressure, (at upstream side), this to keep the Y factor (see 29 III) within reasonable limits.

For computer calculations these values are:

• gas : (in H₂O) = 1.3 upstream pressure
• steam : (in H₂O) = 2 upstream pressure

No. 20: NOMINAL PIPE SIZE AND SCHEDULE:

Fill in the nominal size of the pipe, and the schedule (see piping specification).
If the pipe size is given to DIN standards, fill in outside diameter and the wall thickness. (When the form English units is used, state also the inside diameters in mm).

No. 21: ACTUAL I.D.:

The internal diameter as given in line tables and the square of this figure shall be stated in units as indicated.
When the form for English units is used, and the pipe is to DIN standards, fill in I.D. in inches, converted from I.D. in mm. stated in 20.

No. 22: CHART GRADUATION AND CHART FACTOR:

A chart graduation shall be specified preferably 0-10 or 0-100 square root.
This should be agreed upon with client. In special cases, a direct reading graduation may be used.
The chart factor is the rounded off meter maximum flow divided by the maximum chart reading.

No. 23: PRESSURE TAKE-OFF LOCATION:

When the static pressure measuring point has been specified, state if pressure is taken-off from upstream or downstream tapping. This in connection with the use of diagrams for expansion coefficient. (See 29, correction III).
It is Company’s standard practice to take off the pressure from the upstream tapping, as specified in the ISO standard no. 532 (Draft recommendation). Pressure measured at downstream tapping may be considered, when the static pressure is very low, so that the rule of thumb as mentioned is no. 19 page 7 can not be followed.

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The full procedure is available for registered users.

 

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Last Updated: 09 May 2014

Table of Contents

1. Scope

This standard gives instructions for the use of Company control vale calculation sheet form BN-K 006.

2. General

The formulas and valve slide-rule are in accordance with the "Recommended voluntary standard formulas for sizing control valves", issued by the Fluids Control Institute with bulletin
F.C.I. 62-1.

However, temperature corrections have been added to these recommended basic formulas.

The valve sizing formulas have been based on the "U.S. VALVE FLOW COEFFICIENT C_V", which is the yardstick of the valve capacity.

A valve flow coefficient C_V is the number of U.S. gallons per minute of water at 40 to 120°F which will pass through a given flow restriction with a pressure drop of 1 psi.

The determination of the valve C_V by the manufacturer should be based on Fluids Controls Incorporation, bulletin F.C.I. 58-2.

Because the C_V coefficient is measured by the valve manufacturer at rather low pressure drops across the valve and at rather low static pressures the C_V coefficient will be lower at higher pressure drops, depending upon the type of valve and design of the valve body.
Reference is made to booklet "The valve flow coefficient and its contribution in control valve sizing" and to the section "Limitations of valve sizing formulas", sheets 19 and 20.
European and especially German manufacturers sometime use a "Valve Coefficient K_V ".
A valve flow coefficient K_V is the number of cubic meters per hour of water at 5 to 30°C which will pass through a given flow restriction at a pressure drop of 1 kg/cm².

K_v = 0.86 C_v and C_v = 1.17 K_v

A few valve manufacturers in Great Britan specify the C_V valve coefficient based on an "Imperial gallon", instead of the U.S. gallon.

C_{v (Imp. gpm)} = 0.83 C_{v(US gpm)}

and C_{v (US gpm)} = 1.2 C_{v(Imp. gpm)}

The full procedure is available for registered users.

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Last Updated: 03 June 2014

1. General
2. Formulae
3. Instructions for the Use of Safety Relief Valve Calculation Sheet (General) Form BN-K008 10
4. Instructions for Use of Safety Relief Valve Calculation, Attachment “A” 
   (External Fire) Form BN-K009
5. Instructions for Use of Safety Relief Valve Calculation, Attachment “B” 
   (Heat Exchangers) Form BN-K010
6. Instructions for Use of Safety Relief Valve Calculation, Attachment “C” 
   (Miscellaneous) Form BN-K011

Appendix A - Calculation of Latent Heat of Evapourization
Appendix B - Calculation of the Maximum Duty of a Heat Exchanger
Appendix C - Derivation of API-ASME Code Formula
Appendix D - Formulae for Safety Valve Calculation in Accordance with German Rules (TÜV and AD-Merkblatt A2)
Appendix E - Comparation between API-Code Rumanian-Code for the Calculation of Pressure Relieving Valves
Appendix F - Comparation between API-Code and the Italian-Code for the Calculation of Pressure Relieving Valves 

1. General

1.1 Scope

This standard has been developed to standardize the method of safety relief valve calculations in accordance with API, ASME codes and local codes.

1.2 Calculation Sheet

For the calculation of a safety relief valve, the following standard calculation forms can be used:

BN-K008 : Safety relief valve calculation

BN-K009 : Attachment “A” (External fire)

BN-K010 : Attachment “B” (Heat exchangers)

BN-K011 : Attachment “C” (Miscellaneous)

The main safety relief valve calculation sheet, form BN-K008 has been developed to evaluate the governing hazard and to calculate the area of the relief valve.

The attachments have been designed to evaluate the quantity which has to be relieved by the safety relief valve.

1.3 References

1. API Recommended Practice for the design and installation of pressure relieving system in refineries, API RP 520, second edition, Sept. 1960.

2. The design and construction of pressure relieving systems by Nels E. Sylvander and Donald L. Katz, April 1948.

3. Data Handbook on Hydrocarbons by J.B. Maxwell, 5th edition.

4. Engineering Data Book by the National Gasoline Supply Men’s Association (NGSMA), 7th edition 1957.

5. Chemical Engineers’ Handbook, John H. Perry, 3rd edition, 1950.

1.4 Definitions

Safety valve
An automatic pressure relieving device actuated by the static pressure upstream of the valve, and characterized by rapid full opening or pop action. It is used for stream, gas, or vapor service.

Note: This type of valve is normally not specified by Company.

Relief valve
An automatic pressure relieving device actuated by the static pressure upstream of the valve, which opens in proportion to the increase in pressure over the opening pressure. It is used primarily for liquid service.

Note: This type is normally only used in the size 3/4” x 1” or 1” x 1” for thermal expansion.

Safety relief valve
An automatic pressure actuated relieving device suitable for use as either a safety or relief valve, depending on application.

Note: This type is used for general applications.

Set pressure

1. Liquid service:
   for a relief or safety relief valve on liquid service, the set pressure, in pounds per square inch gauge, is to be considered the inlet pressure at which the valve starts to discharge when discharging against atmospheric conditions.
2. Gas, vapor or steam service:
   for a safety relief valve on gas, vapor or steam service, the set pressure, in pounds per square inch gauge, is to be considered the inlet pressure at which the valve pops when discharging against atmospheric conditions.

Popping pressure
Same definition as set pressure for gas, vapor or steam service, when discharging against back pressure. (Pressure at which the valve pops when in use.)

Differential test pressure
The pressure differential in pounds per square inch between the set pressure and the constant superimposed back pressure.

It is applicable only when a conventional type safety relief valve is being used in service against constant superimposed back pressure.

Net spring setting
Same definition as for differential test pressure.

Cold differential test pressure
The set pressure or the differential test pressure at which a safety relief valve must be set on cold fluid on a test drum plus a predetermined increase in the cold fluid setting, in pounds per square inch, that will result in the valve opening at the correct set pressure in service when the actual service temperature is higher than that of the cold fluid which is used in the test drum. This is the pressure at which the valve should be set on repair shop testing facilities.

Note: The difference in cold and hot setting is the result of change in characteristic of the spring.

Cold net spring setting
Same definition as for cold differential test pressure.

Operating pressure 
The opening pressure of a vessel is the pressure in pounds per square inch gauge, to which the vessel is usually subject in service. A vessel is usually designed for a maximum allowable working pressure, in pounds per square inch gauge, which will provide a suitable margin above the operating pressure in order to prevent any undesirable operation of the relief device. (It is suggested that on processing vessels this margin be approximately 10 percent, or 25 psi - whichever is greater.)

Note:

1. Take care for reciprocating engines, where peak pressure might reach the set pressure of the valve.
2. When setting closer to the operating pressure is required, pilot operated safety valves or “0” ring seal might be considered.

Design pressure
The gauge pressure at which the vessel has been designed.

Note: Safety relief valves are usually set at this pressure.

Maximum allowable working pressure
The maximum gauge pressure, at the coincidental design temperature, permissible at the top of a vessel in its operating position, and which could be the basis for the upper limit in pressure setting of the safety relieving devices for any specific operation.

Note:

1. When designing a vessel, the calculations will result in a material thickness. This thickness is rounded off to the first higher thickness which is commercially available. Recalculation of the vessel using actual plate thickness will result in a maximum allowable working pressure which is usually higher than the design pressure.
2. Usually recalculation is not done (difference in plate thickness is low for European standards), in that case maximum allowable working pressure is equal to the design pressure.

Overpressure
Pressure increase over the set pressure of the primary relieving device is overpressure. It is the same as accumulation only when the relieving device is set at the maximum allowable working pressure of the vessel.

Accumulation
Pressure increase over the maximum allowable working pressure of the vessel during discharge through the pressure relief valve, expressed as a percentage of that pressure, or pounds per square inch, is called accumulation.

Notes:

1. For European plants, it is usual to take an accumulation of 10% . For American plants a value of 20% may be taken for external fire. 25% for liquid relief and in all other cases 10%.

Blowdown
Blowdown is the difference between the set pressure and the resealing pressure of a pressure relief valve, expressed as percentage of the set pressure, or pounds per square inch.

Note: A blowdown between 4% and 5% is usually specified. Care is to be taken that the inlet piping does not have a total pressure loss in excess of 3%. The total pressure loss shall include the velocity head loss ( 1/2 rV2). Note however, that the friction loss should not exceed 1% and the velocity head loss should not exceed 2% of the allowable pressure for capacity relief. 

Lift
The rise of the valve disc in pressure relief valve when the valve disc moves from the closed position is called lift.

Back pressure
Pressure on the discharge side of a pressure relief valve.

1. Constant back pressure: 
   back pressure which does not change appreciably under any condition of operation whether or not the pressure relief valve is closed or open.
2. Variable back pressure: 
   back pressure which develops as a result of the conditions outlined below.
   a)   Built-up back pressure: variable back pressure as a result of flow through discharge piping after a single pressure relief valve starts to open.
   b)   Superimposed back pressure: variable back pressure that is present before the pressure relief valve starts to open. 
   
   Note: Variable back pressure on conventional safety relief valves shall never exceed 10% of the gauge set pressure.
   
   Variable back pressure on bellow seal safety relief valves shall never exceed 50% of the absolute set pressure as that is the limit for critical flow, on which the formulae are based.

Coefficient of discharge
Correction factor for the nozzle area, due to contraction etc., include all deviations from ideal flow through the nozzle.

Note:
For full lift safety relief valves, this factor is usually 0.97.
For relief valves at 25% accumulation: 0.64.
For relief valves at 25% accumulation: 0.64.
These low coefficients correct also for the reduction in area which occurs at lower lifts of the disc above the seat.

General rules for the use of safety relief valves
Following, a few general rules will be given for the application of safety relief valves. These rules are only to be used as a guidance.

Safety relief valves are required:

1. On all vessels containing fluids which may vaporize when the vessel is subject to fire.
2. On all vessels where a closed outlet valve may cause an over pressure.
3. On all reciprocating pumps and compressors, if not protected internally.
4. On the outlet of turbines, where the design pressure of the low stage casing is lower than the inlet pressure.
5. On all distillation and fractionating towers where reflux or cooling water failure may cause excessive vaporization.
6. On heaters and furnaces where low flow may cause cooking. 
7. On heat exchangers or heaters where the cold medium may be blocked.
8. On all storage tanks, not vented to atmosphere, where vapor pressure or pumping may cause over or under pressure. In this case special combined pressure vacuum relief valves are to be specified. (Breather valves).
9. 3. In cases of long lines, containing liquid, which may be blocked when exposed to the sun (for example butane, propane).
10. 4. In all cases where a volatile liquid may get into a vessel under conditions that it vaporizes where the vessel is not designed for the vapor pressure.
11. In cases where non-condensable accumulate in a condenser, decreasing the efficiency, so that a pressure rise may occur.
12. Tube failure in heat exchangers, which may cause vaporization, or excessive pressure on the shell.
13. Control valve failure or instrument failure which either results in one of the hazards 1 through 12, or in any other hazard as for example a reducing station, failing in the open position.

Notes:

1. Where more vessels are connected, so that they cannot be separated by block valves, they are to be considered as one system. (Except when local codes imply separate valves.)
2. In cases where equipment has to be protected against two or more of the above mentioned hazards, the safety valves shall be calculated for the condition causing the highest flow rate to be relieved, thus assuming that only one hazard will occur at the same time. (Single risk concept.)
3. It is evident that when a hazard is the result of another hazard, both hazards are to be taken into account.

 2. Formulae

Below a summary of formulae has been given. Most of these formulae already appear on the calculation sheet, but this summary also gives some other formulae which are to be used in special cases.

The formulae given on the calculation sheet for evaluation of nozzle area for vapors is a safe approximation: when accurate calculations are to be made, formula number 2 has to be used in which the “C” factor can be evaluated from formula 2A, or from Binder IV with curves and tables.

Formula 4 gives the nozzle are for steam when the safety valve has to be calculated as per ASME boiler code. Formula 10 gives a quantity of thermal expansion when no normal size is taken. See 68, liquid expansion.
In each formula for vapors the super compressibility factor (Z) can be included as a multiplier of the absolute temperature (also under the square root sign).
This will result in a smaller valve size.
Leaving it out always gives a safe approximation.

SUMMARY OF FORMULAE
UNITS OF MEASUREMENT

DESCRIPTION	ENGLISH UNITS	METRIC UNITS	NO.
RELIEF QUANTITY VAPOURS (GENERAL PURPOSE)			1
RELIEF QUANTITY VAPOURS (ACCURATE)			2
CONSTANT BASED ON k (C OR C')		C'=4.81 x C	2A
RELIEF QUANTITY STEAM (GENERAL PURPOSE)			3
RELIEF QUANTITY STEAM (ASME BOILER CODE)			4
RELIEF QUANTITY LIQUID (INCLUDING VISCOSITY CORRECTION) (NOT FOR BALANSEAL VALVES)			5
VAPOURATION WITH CONDENSATION			6
VAPOURATION WITHOUT CONDENSATION			7
CONSTANT Y			7A
SPLIT TUBE (NO VAPOURIZATION)			8
SPLIT TUBE (VAPOURIZATION)			9
THERMAL EXPANSION			10
RELIEF QUANTITY LIQUID (INCLUDING VISCOSITY CORRECTION) (FOR BALANSEAL VALVES ONLY)			11

FORMULAE IN METRIC UNITS, GIVING AREA IN CM2
RELIEF QUANTITY VAPORS (GENERAL PURPOSE)		1A
RELIEF QUANTITY STEAM (GENERAL PURPOSE)		3A
RELIEF QUANTITY LIQUID		5A

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Last Updated: 02 April 2019