This Addendum should be used as a general guideline for evaluating process analyzers. This addendum contains: a flow chart (Figure 78), which shows the guidelines for evaluating a process analyzer; an Instrument Specification Sheet (ISS), and the General Instructions for Evaluating Process Analyzers.
The flow chart in Figure 78 graphically shows the general guidelines for evaluating a process analyzer. Each numbered item in the flow chart item is explained on the following page.
Figure 73: Process Analyzer Evaluation Flow Chart
Engineering Encyclopedia Instrumentation Evaluate Gas Chromatograph Analyzers
1. Data is obtained from the Piping and Instrument Diagram (P&ID) and the Process Flow Diagram (PFD) concerning the application and process stream data, respectively.
2. Data from the P&ID and PFD is used to complete an Instrument Specification Sheet (ISS), which is shown in Figure 79. The ISS specifies Saudi Aramco’s requirements for the analyzer and the sample handling system. Additional information concerning the installation must be determined separately based on the analyzer requirements and analyzer shelter considerations, which are given in Saudi Aramco Design Practice Number SADP-J-502, Analyzer Shelters.
3. A process analyzer is evaluated for the application by comparing the requirements given in the ISS with the capabilities of a proposed analyzer as defined on the Analyzer Manufacturer’s Data Sheet (AMDS). The evaluation process can also include indirect information such as past experience with similar analyzers and applications as well as references from the manufacturer. This supplemental information is important in order to determine whether a successful measurement can be made. The proposed sample handling system is also evaluated on the basis of information on the ISS and the manufacturer’s data sheet.
4. If a suitable analyzer is selected, the information on the ISS should be updated so that it becomes an accurate record of the analyzer installation. In addition, after the analyzer is placed in operation, the information on the ISS should be verified with actual operating conditions to confirm that the analyzer and sample handling system are properly designed for the application.
5. If certain specifications on the ISS are not available features of a particular analyzer, the specifications on the ISS must be prioritized in order of importance. Exceptions to the specifications on the ISS may be required if the high priority features are available for the analyzer but some other low priority features are not available.
6. If an alternate analyzer or an alternate analytical technique exists, the evaluation process is repeated.
7. Sometimes, an analyzer that can comply with all of the measurement and installation requirements does not exist. In other instances, the process sample may not be compatible with the analyzer or a sample handling system may be required that is too complex to be successful. If an alternate analyzer or an alternate analytical technique does not exist, it should be determined whether or not the ISS can be revised.
8. If the ISS can be revised to match the capabilities of the analyzer according to the Analyzer Manufacturer’s Data Sheet, the evaluation process is repeated.
9. If no analyzer and sample handling system can be approved, it may be necessary to re-evaluate the PFD and P&ID to determine whether an alternate process measurement location can be used.
10. If an alternate process measurement location can be used, the P & ID is revised and the evaluation process is repeated
11. If an alternate process measurement location cannot be used, the installation should be aborted.
Engineering Encyclopedia Instrumentation Evaluate Gas Chromatograph Analyzers
Saudi Arabian Oil Company
Instrument Specification Sheet - Analyzer (Draft Copy)
1 Tag Number 4 Instrument Type
General 2 Application 5 Manufacturer
3 P & ID Number 6 Model Number
7 Location 14 Hazardous Area
8 Indoors or Outdoors 15 Haz Temp Rating
9 Mounting Type 16 AC Power
Installation 10 Enclosure Type 17 Inst. Air Pressure
Data 11 Ambient Temperature 18 Nitrogen Pressure
12 Ambient Corrosion 19 Cooling Water Pres.
13 Vibration 20 Steam Pressure
21 Process Tap Location 25 Pressure Normal
Sample 22 Line or Vessel No. 26 Pressure Max | Min |
Supply Data 23 Line Length 27 Temperature Norm
24 Phase 28 Temp. Max | Min |
29 Density or S. G. 34 Contaminants
30 Molecular Weight 35 Condensable
Process Data 31 Bubble Pt or Dew Pt 36 Corrosive
32 Viscosity 37 Toxic
33 Stability 38 Particulates
39 Process Tap Location 43 Pressure Normal
Sample 40 Line or Vessel No. 44 Pressure Max | Min |
Return 41 Phase 45 Temperature Norm
Data 42 Line Length 46 Temp. Max | Min |
Analyzer 47 Return Point 49 Pressure Normal
Return Data 48 Line Length 50 Pressure Max | Min |
Output Signal 51 Measurement 53 Limit Alarm 1
Data 52 Status Alarm 54 Limit Alarm 2
Performance 55 Response Time 57 Sensitivity
Data 56 Transport Lag Time 58 24 hr Drift
Calibration 59 Manual or Automatic 61 Zero
Data 60 Lab Sample 62 Span
Maintenance 63 Accessibility 66 Consumables
Data 64 Calibration Frequency 67 Spare Parts
65 Routine Service 68 Training
Special 69 71
Data 70 72
73 Component Unit Normal Minimum Maximum Calibration Range
Stream Composition Data
Figure 74: Instrument Specification Sheet for Process Analyzers
The instructions on the following pages can be used to compare the specifications on Instrument Specification Sheet with the capabilities of the analyzer that are stated on the Analyzer
Manufacturer's Data Sheet. The item numbers below refer to the Instrument Specification Sheet in Figure 79.
Item No. Description Instruction General Data
1 Tag number The tag number of the analyzer as given on the Piping and Instrument Diagram (P & ID).
2 Application The application describes how the analyzer is used and not where the analyzer is located.
3 P & ID number. The P & ID number is provided to refer back to the P & I D that identifies the analyzer.
4 Instrument Type The instrument type is specific to the application (e.g., infrared analyzer) 5 Manufacturer The name of the manufacturer is recorded after selection to provide a record
of the installation.
6 Model Number The analyzer model number is recorded after selection of the analyzer from the Manufacturer's Data Sheet.
Installation Data
7 Location Confirm that the physical space required for installation of the analyzer, sample handling system, and peripheral equipment is available at the location specified.
The location defines many parameters related to the installation of the analyzer and its associated sample handling system which must each be addressed separately (see following items). The location generally defines the space available for the analyzer, sample handling system, and
peripherals (calibration gas cylinders, etc.). Specific requirements for analyzer locations in Saudi Aramco applications are given in Section 3.3 of SADP-J-502, Analyzer Shelters.
The location of the analyzer must also be evaluated relative to the location of the process sample tap. The distance that separates the analyzer and sample tap defines the sample transport line length (Item 23). This line length is then used to evaluate the sample transport lag time (Item 56) relative to the performance requirement based on the design of the sample handling system.
Engineering Encyclopedia Instrumentation Evaluate Gas Chromatograph Analyzers
Item No. Description Instruction
8 Indoors or Outdoors Confirm that the analyzer is suitable for installation indoors or outdoors as specified. Analyzers that are located outdoors must be suitable for adverse conditions.
Identification of the location as indoors or outdoors defines the relative environment for the analyzer installation. Outdoor locations are subjected to the extremes of the environment such as temperature, weather, dust, and corrosion. Indoor locations are protected from extreme environmental conditions but, for Saudi Aramco application, still have more severe requirements than most industrial applications. Identifying the location as indoor or outdoor will also help to explain the type of enclosure that is specified for the analyzer. Specific environmental conditions for Saudi Aramco applications, both indoors and outdoors, are given in Sections 13.1.1, 13.1.2, 13.2.1, 13.2.2, 13.2.3 and 13.2.4 of SAES-J-003, Basic Design Criteria.
9 Mounting Type Confirm that the analyzer is available for mounting as specified.
There are three mounting types for process analyzers: wall-mount, panel-mount, and floor-mount. The type of mounting defines the space that is required for the installation of the analyzer. In addition, the type of mounting also defines the access that is required for maintenance of the analyzer. Wall-mounted analyzers do not provide any rear access so that all operation and maintenance is performed directly from the front. Panel-mounted analyzers require rear access for installation and, in many cases, also require rear access for maintenance. Analyzers that are floor-mounted usually require maintenance from all four sides. If the only available space for installation of an analyzer requires wall-mounting, an analyzer that requires panel-mounting may fit into the space but access will be denied to the rear of the analyzer for maintenance.
Item No. Description Instruction
10 Enclosure Type Confirm that the analyzer is available with the type of enclosure specified.
The enclosure type specifies what type of protection must be provided for the analyzer (corrosion-resistant, explosion-proof, etc.) In general, all equipment enclosures for Saudi Aramco applications must comply with the requirements given in SAES-J-003, Basic Design Criteria.
The enclosure type must match the environmental conditions and hazardous area classification requirements given in Items 10 through 15. In addition, the enclosure may be required to provide personnel protection from exposure to toxic hazards. In some cases, it may be necessary to prioritize the type of enclosure based on the application. For example, in a
hazardous area that can experience severe weather, an explosion-proof enclosure is more important than a weather-proof enclosure. On the other hand, if the installation is also highly corrosive, a purged weather-proof enclosure is more important than an explosion-proof enclosure. The type of enclosure specified on the ISS identifies the priority for the type of
enclosure to be used for the application.
11 Ambient Temperature Confirm that the analyzer is capable of operating within the specified ambient temperature range.
The ambient temperature limitations of the analyzer must be evaluated relative to the installation location. To minimize the effect of a changing ambient temperature, analyzers that are sensitive to temperature variation include internal temperature control. Due to the extreme outdoor
temperatures, most analyzers are installed inside temperature controlled shelters (as defined by Items 7 & 8).
The effects of relative humidity must also be considered with the ambient temperature. Specific relative humidity and ambient temperature design conditions for Saudi Aramco applications, both indoors and outdoors, are given in Sections 13.1.1, 13.1.2, 13.2.1, and 13.2.2 of SAES-J-003, Basic Design Criteria.
Engineering Encyclopedia Instrumentation Evaluate Gas Chromatograph Analyzers
Item No. Description Instruction
12 Ambient Corrosion Confirm that the analyzer is provided with corrosion protection for the specified conditions.
The analyzer enclosure must be suitable for the ambient corrosion.
Outdoor locations are subject to more severe ambient corrosion than indoor locations. In addition, the affects of relative humidity, both indoor and outdoor, must be considered with the ambient corrosion. Alternately, a purge may be required with an explosion-proof enclosure to provide corrosion protection.
Some analyzers are available with additional protection (material of construction or coating) for locations with high ambient corrosion. In some cases, it may be more important to utilize a purged, general-purpose enclosure for both corrosion and hazardous area protection than to use an explosion-proof enclosure for the hazardous area protection only.
In addition to chemical corrosion, equipment in Saudi Aramco application must also be protected from dust. Specific ambient corrosion design conditions for Saudi Aramco applications, both indoors and outdoors, are given in Sections 13.2.3 and 13.2.4 of SAES-J-003, Basic Design Criteria.
13 Vibration Confirm that the analyzer is capable of operating with the specified vibration.
Process analyzers are designed to be rugged in order to operate
continuously in the harsh plant environment. Most analyzers are usually unaffected by normal plant vibration. Excessive vibration from motors or compressors can adversely affect the stability of the process analyzer. The location of the analyzer relative to other equipment must be evaluated to determine the possible effect of vibration.
14 & 15 Hazardous Area and Temp. Rating
Confirm that the analyzer is suitable for the specified hazardous area classification.
The process analyzer must be suitable for the specified hazardous area.
There are three methods used to comply with the hazardous area
requirements: enclosures that are rated to be explosion proof to prevent the propagation of an explosion outside the analyzer, enclosures that are purged and pressurized to prevent an explosion by eliminating the
accumulation of explosive gas inside the analyzer enclosure, and analyzers that are rated as non-incendive and cannot cause an explosion.
Most analyzers are available with general-purpose enclosures that can be purged and pressurized for hazardous areas. Many analyzers are available with explosion-proof enclosures for hazardous areas. Purged enclosures offer both electrical hazard and environmental protection. However, explosion-proof enclosures provide the safest installation for hazardous process samples.
Item No. Description Instruction
16 - 20 Available Utilities Confirm that the utilities required for operation of the analyzer and sample handling system are available at the installation location.
The utilities required to operate the analyzer and sample handling system must be available at the location where it will be installed. AC power is usually required by all process analyzers. If the analyzer is purged and pressurized, instrument air or plant nitrogen may also be required.
Depending on the application, other utilities (such as steam or cooling water) may be required for operation of the sample handling system.
Sample Supply Data - The sample supply data identifies the operating conditions of the process sample at the Sample Supply Tap. The sample handling system must be designed to provide the process sample to the analyzer under conditions that are compatible with the analyzer operation.
21 Process Tap Location This information provides the actual physical location of the process sample supply tap.
The process tap location identifies where the sample supply tap is physically located in the process. This allows the determination of the distance between the process tap and the analyzer which is given as the line length (item 34).
22 Line or Vessel No. Information only.
23 Line Length The sample transport line length is used to calculate the sample transport lag time.
The distance that separates the analyzer and process sample tap defines the length of the sample transport line. The sample transport line length then determines the sample flow that is required to obtain the sample transport lag time. A fast-loop bypass is usually required to provide the transport lag time.
24 Phase Confirm that the process analyzer is designed to measure the sample in the specified phase.
Process analyzers can only operate on a single phase sample. The process sample must be maintained as either a gas or liquid in both the analyzer and sample handling system. A process sample that has a mixed phase cannot be measured accurately.
Engineering Encyclopedia Instrumentation Evaluate Gas Chromatograph Analyzers
Item No. Description Instruction
25 Pressure Normal Confirm that the sample pressure is compatible with the analyzer operating pressure. If necessary, confirm, that proper pressure reduction or pressure enhancement is provided in the sample handling system.
The sample handling system must provide a sample supply pressure and flow that are compatible with the analyzer design under both normal and extreme operating conditions (Item 26). Most gas analyzers operate at relatively low pressure and require reduction of the process pressure in the sample handling system. Many liquid analyzers can operate at high pressure which is more compatible with the normal process conditions. It is always desirable to operate the analyzer and sample handling system at a low pressure to minimize the exposure of personnel to hazard in the event of a leak.
26 Pressure Max | Min Confirm that proper pressure control is provided under the range of possible operating pressures.
27 Temperature Norm Confirm that the sample temperature is compatible with the analyzer operating temperature. If necessary, confirm, that proper temperature reduction is provided in the sample handling system.
The sample handling system must provide a sample supply temperature that is compatible with the analyzer design under both normal and extreme operating conditions (Item 28).
28 Temp. Max | Min Confirm that proper temperature control is provided under the range of possible operating temperatures
Process Data - The process data defines the physical properties of the process sample. The sample handling system must condition the process sample to be compatible with the analyzer.
29 Density or S. G. Information only.
The density or specific gravity of the process sample is used in the design of the sample handling system to determine sample flow and pressure drop through the system.
30 Molecular Weight Information only.
The molecular weight of the process sample is provided in addition to the density or specific gravity to allow the specific gravity of the sample to be determined under conditions that are different from the actual process conditions. This is useful for applications with gas samples where the process sample pressure is reduced in the sample handling system for delivery to the analyzer.
Item No. Description Instruction
31 Bubble Pt. or Dew Pt. Confirm that proper temperature control and heating are provided in the sample handling system to maintain the sample temperature above the dew point for gases or below the bubble point for liquids.
The temperature and pressure of the process sample must not exceed the design specifications of the analyzer but must also be maintained within the limits of the sample bubble point for liquids and dew point for gases. For liquid samples, the temperature must either be low enough or the pressure maintained high enough to prevent gas bubbles from forming in the
analyzer or sample handling system. For gases, the pressure must either be low enough or temperature maintained high enough to prevent
condensation of liquid in the analyzer or sample handling system. A process sample that is not maintained at the required phase in the analyzer and sample handling system (gas or liquid) will not provide a measurement that is representative of the actual process stream.
32 Viscosity Applies to liquid samples only. Confirm that the operating temperature of the analyzer and sample handling system maintains the sample viscosity for proper flow to the analyzer.
Viscosity only applies to liquid process samples. Some liquid process samples become too viscous to flow unless they are heated. The process sample must be maintained at a temperature that provides a flowing viscosity in the analyzer and sample handling system.
33 Stability Confirm that the sample is stable and will not change properties or composition in the sample handling system or in the process analyzer.
The process sample must be stable at the operating temperature and pressure in the analyzer and sample handling system. It is important to identify components in the process sample that may react, polymerize, or degenerate under the operating conditions of the analyzer and sample handling system.
Engineering Encyclopedia Instrumentation Evaluate Gas Chromatograph Analyzers
Item No. Description Instruction
34 Contaminants Confirm that none of the sample components will contaminate the analyzer and cause degradation or deterioration of the measurement.
It is important to identify components in the process sample that will cause degradation or deterioration of the measurement. As opposed to corrosives or condensables that also have an adverse effect on the analyzer,
contaminants are components that specifically affect the analyzer
contaminants are components that specifically affect the analyzer