Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Temperature Measurement
…192 unchanged lines
# Sensor Technology Selection {toc}
−## Sensor technology shall be selected on the basis of required accuracy, temperature range, and output type. {note}
+## Sensor technology shall be selected on the basis of required accuracy, temperature range, and output type.
−## An RTD shall be specified where the service requires high accuracy and long-term stability within the -200°C to +850°C range; a thermocouple shall be specified where the service exceeds the RTD range, requires fast response, or requires a rugged sheathed element in severe environments. {note}
+## An RTD shall be specified where the service requires high accuracy and long-term stability within the -200°C to +850°C range; a thermocouple shall be specified where the service exceeds the RTD range, requires fast response, or requires a rugged sheathed element in severe environments.
−## A bimetallic dial thermometer or filled-system remote thermometer shall be specified only for local indication where no electrical output to the control system is required. {note}
+## A bimetallic dial thermometer or filled-system remote thermometer shall be specified only for local indication where no electrical output to the control system is required.
```datasheet
…59 unchanged lines
### Thermocouple elements shall conform to ASTM E230/E230M for EMF tables and limits of error; IEC 60584-1 shall apply for export or global projects.
−### Thermocouple type shall be selected for the process temperature range and atmosphere. {note}
+### Thermocouple type shall be selected for the process temperature range and atmosphere.
−### Type K (-200°C to 1260°C) shall be the default for general oxidizing process service; Type J (-40°C to 750°C) for reducing atmospheres; Type E (-200°C to 900°C) where the highest sensitivity is required; Type T (-200°C to 350°C) for cryogenic and food service; Type N for high-temperature oxidizing service; and noble-metal Types R and S for furnace service. {note}
+### Type K (-200°C to 1260°C) shall be the default for general oxidizing process service; Type J (-40°C to 750°C) for reducing atmospheres; Type E (-200°C to 900°C) where the highest sensitivity is required; Type T (-200°C to 350°C) for cryogenic and food service; Type N for high-temperature oxidizing service; and noble-metal Types R and S for furnace service.
### Type K standard limits of error are ±2.2°C or ±0.75% of reading, whichever is greater; special limits are ±1.1°C or ±0.4%. {note}
…48 unchanged lines
### Dual-element assemblies shall be specified where redundancy is required for safety-instrumented functions, or where independent control and monitoring measurements are taken from one penetration.
−### Dual-element construction lets a control loop and a safety loop share one thermowell penetration without sharing a common element failure, and supports averaging or hot-standby schemes. {note}
−
```datasheet
label: Number of Sensing Elements
…5 unchanged lines
```
+### Dual-element construction lets a control loop and a safety loop share one thermowell penetration without sharing a common element failure, and supports averaging or hot-standby schemes. {note}
+
# Output and Transmitter {toc}
−## Output and protocol shall be selected to match the control system interface and the accuracy budget. {note}
+## Output and protocol shall be selected to match the control system interface and the accuracy budget.
## New field temperature transmitters shall provide a 4-20 mA analog output with superimposed HART revision 7 digital signal as the minimum, unless a fieldbus or wireless architecture is specified for the project.
…5 unchanged lines
## Transmitter total loop accuracy shall be within ±1.0°C for process control and within ±0.5°C for precision applications, including element, transmitter, and reference uncertainty.
−## Transmitter accuracy is typically ±0.1°C to ±0.5°C and is span-dependent; the loop accuracy budget shall account for the element tolerance class in addition to the transmitter. {note}
+## Transmitter accuracy is typically ±0.1°C to ±0.5°C and is span-dependent; the loop accuracy budget shall account for the element tolerance class in addition to the transmitter.
```datasheet
…40 unchanged lines
## A thermowell shall be provided for every temperature element installed in pressurized piping, process vessels, or any service where element removal under pressure or process leakage is a safety concern.
−## Specifying a bare RTD or thermocouple element in pressurized piping creates a personnel-safety and process-leak hazard and is prohibited; the thermowell isolates the element from the process and permits removal without breaching containment. {note}
−
−## Bare elements (no thermowell) shall be limited to duct service and other non-pressurized service such as HVAC air measurement.
−
−## Thermowell material shall be compatible with the process fluid.
−
−## 316 stainless steel shall be the default thermowell material; nickel-chromium-molybdenum alloy (UNS N10276), nickel-copper alloy (UNS N04400), nickel-chromium alloy (UNS N06600/N06625), or alumina ceramic shall be specified for corrosive or high-temperature service. {note}
−
−## Thermowell process connection rating shall match the pipe specification.
−
−## Specifying a thermowell with a lower pressure rating than the piping class (e.g., 150# flange on a 600# line) is a common RFI generator; cross-check the piping class before procurement to avoid this error. {note}
−
```datasheet
label: Thermowell Requirement
…5 unchanged lines
```
+## Specifying a bare RTD or thermocouple element in pressurized piping creates a personnel-safety and process-leak hazard and is prohibited; the thermowell isolates the element from the process and permits removal without breaching containment. {note}
+
+## Bare elements (no thermowell) shall be limited to duct service and other non-pressurized service such as HVAC air measurement.
+
+## Thermowell material shall be compatible with the process fluid.
+
+## 316 stainless steel shall be the default thermowell material; nickel-chromium-molybdenum alloy (UNS N10276), nickel-copper alloy (UNS N04400), nickel-chromium alloy (UNS N06600/N06625), or alumina ceramic shall be specified for corrosive or high-temperature service.
+
```datasheet
label: Thermowell Material
…9 unchanged lines
```
+## Thermowell process connection rating shall match the pipe specification.
+
+## Specifying a thermowell with a lower pressure rating than the piping class (e.g., 150# flange on a 600# line) is a common RFI generator; cross-check the piping class before procurement to avoid this error. {note}
+
+## The thermowell style shall be specified, selected for compatibility with the process connection, pressure rating, and immersion requirements of the installation.
+
```datasheet
label: Thermowell Style
…8 unchanged lines
```
+## The thermowell process connection shall be specified, and its pressure rating shall be cross-checked against the piping class before procurement.
+
```datasheet
label: Process Connection
…35 unchanged lines
### The insertion-length-to-bore ratio shall satisfy L/D greater than 5 to limit conduction error along the well.
−### Insertion length shall be verified against the pipe inside diameter on the instrument data sheet so the well neither bottoms out nor falls short of the 60%-immersion target. {note}
+### Insertion length shall be verified against the pipe inside diameter on the instrument data sheet so the well neither bottoms out nor falls short of the 60%-immersion target.
−### A standard 6-inch-insertion thermowell bottoms out in a 2-inch pipe; insertion length versus pipe size is the single most common RFI generator in this category and shall always be checked against the pipe ID. {note}
+### A standard 6-inch-insertion thermowell bottoms out in a 2-inch pipe; insertion length versus pipe size is the single most common RFI generator in this category and shall always be checked against the pipe ID.
### Use the following guidance for nominal insertion length versus pipe size, subject to the wake-frequency calculation. {note}
…8 unchanged lines
| ≥10" | per drawing | 60% of ID | per wake-frequency calculation |
−### For pipe smaller than 3 inches, a tapered thermowell in an elbow or a pipe expansion (tee with a larger-bore run) shall be used where straight-run immersion cannot meet the 60% target. {note}
+### For pipe smaller than 3 inches, a tapered thermowell in an elbow or a pipe expansion (tee with a larger-bore run) shall be used where straight-run immersion cannot meet the 60% target.
```datasheet
…18 unchanged lines
# Element Construction and Connection Head {toc}
−## Element construction shall be selected for the protection-tube environment and required response time. {note}
+## Element construction shall be selected for the protection-tube environment and required response time.
−## Bare elements shall be used inside thermowells in clean, non-severe service; mineral-insulated metal-sheathed (MIMS) elements shall be used where vibration, moisture ingress, or bending is a concern; ceramic protection tubes shall be used for high-temperature furnace service. {note}
+## Bare elements shall be used inside thermowells in clean, non-severe service; mineral-insulated metal-sheathed (MIMS) elements shall be used where vibration, moisture ingress, or bending is a concern; ceramic protection tubes shall be used for high-temperature furnace service.
−## Sheath or protection-tube material shall be 316 stainless steel for general service, nickel-chromium alloy (UNS N06600 or UNS N06625) for high-temperature oxidizing service, and alumina ceramic for furnace service. {note}
+## Sheath or protection-tube material shall be 316 stainless steel for general service, nickel-chromium alloy (UNS N06600 or UNS N06625) for high-temperature oxidizing service, and alumina ceramic for furnace service.
## The connection head shall be cast aluminum for general service and stainless steel for corrosive or wash-down service.
…51 unchanged lines
## Filled-system remote thermometers (capillary bulb and dial) shall be used where a local reading is required at a distance from the process connection that a rigid-stem dial cannot reach.
−## Dial size shall be selected for the required reading distance; a 3-inch dial is typical at arm's length and a 5-inch dial where the gauge must be read from a walkway or grade. {note}
+## Dial size shall be selected for the required reading distance; a 3-inch dial is typical at arm's length and a 5-inch dial where the gauge must be read from a walkway or grade.
−## Bimetallic and filled-system thermometers provide local indication only and shall not be relied upon for control or alarm functions, which require an electrical-output element and transmitter. {note}
+## Bimetallic and filled-system thermometers provide local indication only and shall not be relied upon for control or alarm functions, which require an electrical-output element and transmitter.
```datasheet
…55 unchanged lines
## Thermocouple field wiring ahead of any transmitter shall be type-matched compensating or extension cable per ISA-MC96.1, color-coded to the thermocouple type, twisted, shielded, and 20 AWG minimum for runs exceeding 15 m.
−## Cable shields shall be continuous and grounded at one end only, at the control-system end, to avoid ground loops. {note}
+## Cable shields shall be continuous and grounded at one end only, at the control-system end, to avoid ground loops.
## Armored or jacketed cable shall be provided where the field route requires mechanical protection; armor and conduit shall be bonded and grounded per NEC Article 250.
…32 unchanged lines
## Safety-instrumented loops shall be proof-tested per the IEC 61511 procedure stated on the instrument data sheet before the safety function is placed in service.
−## A loop is not accepted until the measured value at the control system agrees with a traceable reference at two points spanning the operating range within the loop accuracy budget. {note}
+## A loop is not accepted until the measured value at the control system agrees with a traceable reference at two points spanning the operating range within the loop accuracy budget.
```datasheet
…58 unchanged lines
# Spare Parts {toc}
−## The Contractor shall furnish spare sensing elements and transmitters sufficient to maintain the installed instruments without procurement delay. {note}
+## The Contractor shall furnish spare sensing elements and transmitters sufficient to maintain the installed instruments without procurement delay.
## Spare parts shall be furnished as follows:
…19 unchanged lines
step: 1
```