Table of Contents

1 Scope
2 References
3 General
3.1 Advantages of transmitted signals
3.2 Design considerations for transmission systems
3.3 Electronic
3.4 Pneumatic
3.5 Fiber optics
3.6 Digital field bus
4 General information on electronic systems
4.1 General
4.2 Standard electronic signal ranges
4.3 Regulatory codes and recommended practices
5 Reducing electrical interference in electronic
       systems
5.1 Sources of electrical interference
5.2 Minimizing unwanted voltages in signal
       transmission circuits
5.3 Instruments to be interconnected
6 Engineering factors in selection of wire types
       for electronic systems
6.1 Process controls with milliampere signals
6.2 Process controls with voltage signals
6.3 Digital communications signals
6.4 Process control low energy/voltage sensors
6.5 Process control with pulse output meters
6.6 Low-impedance sensors to computers
6.7 Turbine meters
6.8 Magnetic-flow transmitters
7 Specifications for wires and cables in electronic
       systems
7.1 Wire size
7.2 Stranded wire
7.3 Insulation
7.4 Temperature rating
7.5 Overall jacket
7.6 Shielding
7.7 Number of crossovers
7.8 Wire and pair identification
7.9 Communication wires
7.10 Lightning protection
8 Typical applications of wire types used in
       electronic systems
9 Guidelines for separation of wires in electronic
       systems
9.1 Similar signal levels
9.2 Signal and power wiring
9.3 Proximity to AC fields
10 Effect of transmission distance on electronic
       signal installations
11 High temperature areas
12 General information on installation methods for
       electronic systems
13 Installation of trays for electronic systems
13.1 Locations and advantages
13.2 Description
14 Installation of raceways in electronic systems
14.1 General
14.2 Aboveground installations
14.3 Underground installations
14.4 Routing
15 Messenger cable
16 Surge protection for cables in electronic systems
16.1 General
16.2 Types of electrical surges
16.3 Types of protective devices
16.4 Selection and installation of surge protection
       devices
17 Wiring for field mounted process instruments
17.1 Leakage of process fluid
17.2 Moisture
17.3 Temperature
17.4 Typical wiring practice
17.5 Factory sealed enclosures
17.6 Non-incendive design (division 2), intrinsically
       safe design (division 1), purged enclosures, and
       MI cable installations
17.7 Drainage requirements
17.8 Other seal requirements
18 Junction boxes
18.1 Use of boxes
18.2 Factors in box selection
18.3 Box design
18.4 Interior color
18.5 Mounting of boxes
18.6 Mounting of terminal strips
18.7 Ground continuity for shields
19 Control room wiring
19.1 General
19.2 Field wiring terminations
19.3 Other control wiring
19.4 Precautions for power supply wiring
20 Installation of grounding for electronic systems
20.1 General
20.2 Definition of terms
20.3 Quality of instrument-circuit ground systems
20.4 Testing of grounds
20.5 Ground electrodes
20.6 Grounding of transmission circuits
20.7 Grounding of cable shields
20.8 Grounding of DES termination room and control
       panelboards
20.9 DES and panelboard ground buses
20.10 Grounding of instrument cases
20.11 Grounding of conduits and wireways
20.12 Grounding considerations where cathodic
       protection is used
21 General information on pneumatic systems
21.1 Scope
21.2 Air supply systems
21.3 Pneumatic transmission systems
22 Installation of pneumatic systems
22.1 General
22.2 Field-routed tubing installations
22.3 Junction box
22.4 Transmission tubing installations
23 Cleaning and pressure testing of pneumatic tubing
23.1 General
23.2 Cleaning
23.3 Pressure and leak testing
23.4 Processing plant installations
23.5 Collection points
23.6 Transmission tubing
Appendix A - Abbreviations used in figures
Figures
1 Vertical tray
2 Vertically mounted long span tray
3 Typical application and location of lightning
       protective devices
4 Typical installation of lightning protective
       device for personnel safety at one end of a
       signal pair
5 Typical three-terminal gas-filled gap arrester
       and diode shunt lightning protector
6 Typical carbon air gap and diode shunt on A-C
       signal transmission
7 Typical junction box
8 Panelboard wiring terminating field wiring at
       instruments
9 Panelboard wiring terminating field wiring at
       panel-mounted junction box
10 Panelboard wiring terminating field wiring at
       separate junction box
11 Computer floors
12 Single-point ground scheme
13 Total single-point ground scheme
14 Ground electrode for one low-conductivity soil
       condition
15 Panelboard grounding
16 Air supply piping for field instrument
17 Instrument air supply system with standby
       compressor and optional plant air backup
18 Instrument air supply system from plant air with
       instrument air standby as air backup
19 Instrument air supply system using a centrifugal
       compressor
20 Typical instrument air supply and subheader
       piping
21 Methods of supporting single tubes and tubing
       bundles at the processing unit
22 Enclosed junction box configurations
Tables
1 Specific applications with wiring requirements,
       wire type, and environment
2 Power level classification
3 Wire separation
4 Types of wire or cable for signal transmission
5 Guidelines for grouping wires bearing signals of
       the same magnitude
6 Resistance of copper wire - per conductor
7 Line sizing guide for pipe headers

Abstract

Examines the recommended practices for the installation of electronic and pneumatic measurement and control-signal transmission systems.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	American Petroleum Institute
Pages
ISBN
Supersedes	API 550PT1SEC7 : 4ED 88