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					Abu Dhabi National Oil Co. ADNOC Technical Institute

INSTRUMENTATION
INSTRUMENTATION II

UNIT 2 TEMPERATURE TRANSMITTER

TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09

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ADNOC TECHNICAL INSTITUTE

UNITS IN THIS COURSE

UNIT 1

MEASUREMENT OF TEMPERATURE

UNIT 2

TEMPERATURE TRANSMITTER

UNIT 3

THE CONTROLLER

UNIT 4

VALVES AND ACTUATOR

UNIT 5

PRACTICAL TASKS

TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09

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ADNOC TECHNICAL INSTITUTE

TABLE OF CONTENTS
Paragraph 2.0 COURSE OBJECTIVES 2.1 INTRODUCTION 2.2 THE PNEUMATIC TEMPERATURE TRANSMITTER 2.2.1 Foxboro Type 12 Construction 2.3 THE ELECTRICAL/ELECTRONIC TEMPERATURE TRANSMITTER 7 Page 4 5 5 6

TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09

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ADNOC TECHNICAL INSTITUTE 2.0 COURSE OBJECTIVES The student will be able to:  Sketch and explain the basic construction and operation of a typical pneumatic temperature transmitter.  Sketch and explain the basic construction and operation of a typical electrical/electronic temperature transmitter.

TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09

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ADNOC TECHNICAL INSTITUTE 2.1 INTRODUCTION The aim of this unit is to show the construction and operation of two types of temperature transmitters; the pneumatic temperature transmitter (Foxboro type 12) and the electronic temperature transmitter (Rosemount model 444).

2.2 THE PNEUMATIC TEMPERATURE TRANSMITTER

SENSITIVE PART (75 OR 150 MM)

TRANSMITTER GAS FILLED SYSTEM (BULB AND CAPILLARY TUBE)

Figure 2-1 The Foxboro Pneumatic Temperature Transmitter
The most common pneumatic temperature transmitter used in the oil/gas industry is the Foxboro type 12 (see Figure 2-1). example of a typical instrument. This is used as an

TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09

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ADNOC TECHNICAL INSTITUTE 2.2.1 Foxboro Type 12 Construction

FLAPPER RELAY NOZZLE ELEVATION SPRING FEEDBACK BELLOWS FORCE BAR COMPENSATING BELLOWS RESTRICTOR

AIR SUPPLY OUTPUT SIGNAL

CROSS FLEXURE THERMAL SYSTEM ELEMEN T CAPSUL E

Figure 2-2 Foxboro Type 12 P.T.T Construction
Figure 2-2 shows a section of a Foxboro 12 Pneumatic Temperature Transmitter (P.T.T). Operation:  The gas filled thermal system (the bulb and capillary tube) is joined to a bellows called an element capsule. This forms a closed system. Heat on the sensor produces a change in gas pressure in the thermal system. This change in pressure makes the element capsule expand or contract.  The force bar is pivoted at the cross flexure. It is joined to the

element capsule at one end and the flapper at the other end. It is moved by the force of the expanding bellows of the element capsule. As it moves it adjusts the position of the flapper at the other end.

TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09

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ADNOC TECHNICAL INSTITUTE  The output pressure of the nozzle varies with the change in pressure in the bellows caused by the change in temperature of the filled system.  The relay amplifies the nozzle output pressure to a standard 3-15 psi (0.2-1bar) signal.  The compensating bellows allows for ambient temperature and pressure changes.  The feedback bellows makes the system more stable in the same way as it does on a pressure transmitter. Foxboro supply these instruments in temperature ranges between -75

to +125oC and +150 to 760oC. The range required must be specified when ordering. The span of any instrument can be changed within the specified range by the elevation spring. The stated accuracy is  0.5 % of span.

2.3 THE ELECTRICAL/ELECTRONIC TEMPERATURE TRANSMITTER One of the most common electrical/electronic temperature transmitters (E.T.T) is made by Rosemount (Model 444). This is used as an example of a typical instrument (see Figure 2-3).
SENSOR WITH THERMOWELL

END CAP

LOCAL TEMPERATURE INDICATOR

ELECTRONICS UNIT



RANGE BOARD MAIN CASING AND TERMINAL BOARD AMPLIFIER / OUTPUT BOARD

Figure 2-3 Rosemount E.T.T Model 444
TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09 PAGE 7 OF 8 IN-04-02

ADNOC TECHNICAL INSTITUTE The Rosemount Model 444 consists of : Sensor The type of sensor depends on the range and application; eg:   Thermocouple - Type E , J, K, R, S, T. RTD - Copper (I0  Nickel (120  and PT 100 with 2, 3 or 4 wire ), ) connections. Electronics Unit This unit has two boards. A RANGE board, depending on the sensor in use and an AMPLIFIER / OUTPUT board which produces the standard 4 20mA signal for the control room. Local Temperature Indicator This unit may or not be included. It provides either a moving coil type display or a digital display. It gives an on site temperature reading to the operator.
WALL OF PIPE OR PROCESS CONTAINER INSULATION (If Required)

UNION OR COUPLING SENSITIVE PORTION OF SENSOR

EXTENSION ROD

TRANSMITTER

THERMOWELL

CONDUIT FOR FIELD WIRING (dc Power)

2.2” EXTENSION LENGTH

Figure 2-4 Typical E.T.T Installation
Figure 2-4 shows a typical installation for this transmitter. The accuracy of this transmitter is better than any pneumatic instrument. It is  0.2% of the calibrated span.
TEMPERATURE TRANSMITTER DATE OF ISSUE 8-DEC-09 PAGE 8 OF 8 IN-04-02


				
DOCUMENT INFO
Description: Instrumentation Course