Rototherm CLEARSCAN RECORDER User Manual

user manual

installation, setup, operation & calibration

With over sixty years of experience, British Rototherm continues to
be a world leader in the manufacture of industrial instrumentation
for measuring, monitoring and controlling Temperature, Pressure,
Humidity, Flow and Level.

British Rototherm products are manufactured in its modern factory
located in the South Wales region of the United Kingdom. Sited on
6 acres of land at Kenfig Industrial Estate, the company operates
from a modern 6,030 square metre (65,000 square feet) factory.

Suitable for many industrial applications, Rototherm products are
precision built to the highest quality.

Approved by major companies and contractors in the United
Kingdom and throughout the world for the supply of
instrumentation and associated products, Rototherm products are
specified and installed wherever reliability and long lasting, accu­rate performance is demanded.

Rototherm’s high quality and performance is guaranteed by an
uncompromising approach to quality.

Rototherm is supported throughout the United Kingdom by
Technical Representatives and by distributor/Stockists, who can be
relied upon for support, technical advice and service.

Rototherm also has representation in many countries throughout
the world where technical support and advice may be sought.

Other products in the Rototherm range of instrumentation include:

• Mechanical Recorders & Recorder Controllers

• Pneumatic Indicators & Recorder Controllers

• Thermometers

• Digital Thermometers

• Pressure Gauges

• Digital Pressure Gauges

• Thermowells

• Temperature Sensors & Assemblies

• Orifice & Restriction Orifice Plates

• Recorder Charts, Pens & Spares

ISO9001:2000

FM11958

British Rototherm Company Limited

Kenfig Industrial Estate, Margam, Port Talbot, SA13 2PW United Kingdom
Telephone: [phone] Facsimile: [phone] E-mail: [e-mail] Web Site: www.rototherm.co.uk

In keeping with British Rototherm’s policy for contuned product development and improvement, we reserve the right to amend specifications without notice.
© 2005 British Rototherm Co. Ltd. All rights reserved.
Trademarks: All brand names and product names used in this manual are trade names, service marks, trademarks or registered trademarks of their respective owners.

Issue 1:2005

CONTENTS

Page

Introduction
Description of Operation of Gas Pressure Recorder
Description of Operation of Temperature Recorder
Description of Operation of Differential Pressure Recorder
Receipt of Recorder
Receipt of Temperature Recorder
Installation and Mounting - wall or panel mounting
Installation and Mounting - 2” pipe or post mounting
Installation and Mounting - Differential Pressure Recorder complete with 2” pipe or post mounting
Process Connections - Pressure
Process Connections - Temperature
Process Connections - Differential Pressure Recorder
Access to the Recorder
Internal Features
Recorder Start-up Check
Differential Pressure Recorder Initial Start-up
Differential Pressure Recorder General Practices
Fitting a Chart
Inking System
Replacement of Ink Pens
Pen Friction and Zero Adjustment
Tracking Adjustment to Chart Time Line
Chart Drives
Linkage and Pivot Attachments
Basic Fault Finding
Temperature Pen Calibration
Pressure Pen Calibration - for pressure ranges 2.5 bar to 40 bar
Pressure Pen Calibration - for pressure ranges 60 bar and above
Maintenance and Calibration - Differential Pressure Recorder
Calibration of Differential Pressure Pen
Spares List

Illustrations

Fig. 1a Outline Dimensions for 12 inch chart recorder (wall or panel mounting)
Fig. 1b Outline Dimensions for 12 inch chart recorder (2” pipe / post mounting)
Fig. 1c Outline Dimensions for 12 inch chart recorder (fitted with Differential Pressure Unit)
Fig. 1b Wall mounting dimensions using optional wall bracket kit
Fig. 2 Internal Features (with chart plate in place)
Fig. 3 Measuring and recording system details
Fig. 4 Linkage and pivot attachments
Fig. 5a Temperature recorder internal layout
Fig. 5b Pressure recorder internal layout (pressure ranges up to 40 bar)
Fig. 5c Pressure recorder internal layout (pressure ranges 60 bar and above)
Fig. 5d Differential pressure recorder internal layout
Fig. 6 Typical pressure calibration setup

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INTRODUCTION

The Clearscan™ Series of circular chart recorders is designed to measure and record process variables such as
temperature, pressure and flow.

A maximum of three measuring systems can be provided in each instrument, a fluid or gas expansion system is used for
temperature recording, a bourdon tube or diaphragm/capsule for pressure measurement and a differential pressure cell for
flow reading.

The measured values are continuously recorded on a calibrated circular chart of 12 inches nominal diameter, which is
rotated at a constant speed by a chart drive mechanism.

DESCRIPTION OF OPERATION OF GAS PRESSURE RECORDER

On medium and high-pressure ranges, (i.e. approx. 2.5 bar to 2000 bar) pressure is applied at the recorder
connection through capillary tubing to a spiral wound bourdon tube.

An increase in pressure partially uncoils the bourdon tube to which is fitted a take-off assembly arm converting the
rotational movement into linear movement.

A horizontal adjustable linkage is pivoted from the take-off arm to a pen mechanism bracket, incorporating a pivot mounted
onto an adjustable ratio post, locked into position on the pen bracket.

The ratio post provides span adjustment; it's position setting the pivot distance of the centre of rotation of the pen arm itself.
Adjusting the ratio post upwards nearer the centre of rotation increases the pen travel whilst conversely adjusting the ratio

post downwards will result in less travel of the pen for the same amount of deflection from the bourdon tube
take-off arm.

The top of the pen bracket carries the pen arm mounted onto a separate adjustment plate which provides fine zero
adjustment at the pen nib and adjustment to the amount of tension on the pen arm itself; thereby ensuring a smooth pen trace
onto the chart paper.

The pen attached to the pen arm records the pressure on a calibrated chart.
A capsule stack is fitted for low-pressure ranges (i.e. below 2.5 bar) and the expansion of the system resulting from an

increase in pressure is transferred by mechanical linkage to the pen arm in a similar way.

DESCRIPTION OF OPERATION OF TEMPERATURE RECORDER

As temperature rises, the fluid/gas in the thermometer bulb expands and partially uncoils the bourdon tube fitted inside the
instrument.

This movement is transferred by a mechanical linkage to the pen arm which records the temperature on a calibrated chart.
The instrument is suitably compensated against normal ambient temperature variations by a bimetallic compensator arm

forming part of the mechanical linkage.

DESCRIPTION OF OPERATION OF DIFFERENTIAL PRESSURE RECORDER

Differential pressure (produced by an orifice plate, Dall tube, Venturi or Pitot tube etc..) is measured by a bellows
operated Differential Pressure Unit (DPU) mounted at the rear of the recorder.

The axial movement of the bellows is transferred by a torque tube within the unit to produce a rotational output which
is transferred by mechanical linkage to the recording pen.

The measured value of differential pressure is displayed in red trace on a circular chart which is rotated at a constant

speed by a mechanical, battery or electrical chart drive motor,

Clearscan™ Recorder Series - Operating and Service Manual

RECEIPT OF RECORDER

The Clearscan recorder complete with a packet of charts, door keys and pen pack(s) is dispatched in a protective casing
which should preferably be replaced after inspection, as protection until the instrument is ready for installation.

The spare pen pack(s) and door keys are inside the protective case.
To assist with inspection, a label attached on the inside face of the case door states instrument serial number, chart number,

range of each pen and the rotation speed of the chart drive.
Additional parts for pipe mounting versions are packed in the protective casing during transit.

RECEIPT OF TEMPERATURE RECORDER

The capillary tubing between the bulb and recorder is coiled for despatch purpose. Immediately prior to installation, this
tubing must be uncoiled carefully in order to avoid twisting or kinking.

INSTALLATION AND MOUNTING - wall or panel mounting

Ideally the site chosen should be free from dust, corrosive fumes, vibration and extremes of temperature.
The instrument is suitably designed for outdoor weather conditions and protected against ingress of dust and water.
The recorder is suitable for wall or panel mounting using the brackets provided.
Refer to figure 1 for overall dimensions of the recorder and general installation.

3

Fig. 1a Outline Dimensions for 12 inch chart recorder (wall or panel mounting)

all dimensions are in mm

371

490

CASE BREATHER

41 114

PRESSURE CONNECTION
1/2" NPT STANDARD
OR 1/4" NPT OPTIONAL

56

312

WALL MOUNTING

420483

53
302
327

PANEL CUTOUT SIZE: 305 x 425

PANEL MOUNTING

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INSTALLATION AND MOUNTING - 2” pipe or post mounting

Ideally the site chosen should be free from dust, corrosive fumes, vibration and extremes of temperature.
The instrument is suitably designed for outdoor weather conditions and protected against ingress of dust and water.
The recorder is suitable for mounting onto a 60mm outside diameter post or pipe having a 2" nominal bore using the 'U' bolts

provided.
Refer to figure 1 for overall dimensions of the recorder and general installation.
The post or pipe may be vertical or horizontal to the recorder but the recorder must be installed vertically.

Clearscan™ Recorder Series - Operating and Service Manual

CASE BREATHER

53

56

371490

65

116

302

0

83

SSU

ON

D

60

OST

Fig. 1b Outline Dimensions for 12 inch chart recorder (2” pipe / post mounting)

all dimensions are in mm

mm O/D PIPE OR P

4

PRE

RE CONNECTI

1/2" NPT STANDAR

42

INSTALLATION AND MOUNTING - Differential Pressure Recorder complete with 2”
pipe/post or wall mounting

5

Fig. 1c Outline Dimensions for 12 inch chart recorder (fitted with Differential Pressure Unit)

all dimensions are in mm

Fig. 1d Wall Mounting Dimensions using optional wall bracket kit

all dimensions are in mm

371

41 114

490

STATIC
PRESSURE CONNECTION
1/2" NPT STANDARD

315

1/4"NPT FEMALE

1/4"NPT FEMALE

56

103

PORTS

PORTS

DIFFERENTIAL
PRESSURE CELL

216

60mm O/D PIPE OR POST

65

LOW

-VE

PRESSURE

302

HIGH
+VE

PRESSURE

54

53

CASE BREATHER

420

60mm O.D. PIPE

TO MOUNT RECORDER

60mm O.D. PIPE

TO MOUNT RECORDER

165

50

4 x 12 DIA. FIXING HOLES
ON 50 x 72 CENTRES

4 x 12 DIA. FIXING HOLES
ON 135 x 72 CENTRES

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135

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PROCESS CONNECTIONS - Pressure

To avoid confusion on instruments fitted with more than one measuring system, the connections are marked with the same
colour as the corresponding recording pen colour.

The recorder is fitted with NPT threaded connection(s) and all pipelines attached to it must be secure and leak proof. PTFE
sealing tape must be used to make a pressure tight join to the recorder connections.

Use pressure tubing of sufficient size and rating to make a connection from the measuring point in the flow pipe or
vessel to the fitting(s) on the recorder.

Slope the run of the pipe-work in such a way that any condensate is drained away from the recorder, and fit an
appropriate shut-off valve. For measurement of steam pressure and other hot vapours, form a condensate trap below the
recorder.

It is recommended that a needle valve be installed in the pressure line close to the instrument to enable pressure to be
admitted gradually. It can also dampen any pressure pulsation and/or fluctuation.

PROCESS CONNECTIONS - Temperature

Capillary tubing: The tubing between the bulb and recorder should be routed so that it is not subjected to large
temperature changes and should be supported in cleats. Bends must not be less than 25mm (1inch) radius and under no
circumstances must the tubing be cut.

Where the tubing is likely to be exposed to an extreme atmosphere, the exterior should be treated with corrosion resistant
paint.

Location of Bulb (Detecting Element):

Immersion type bulb

The instrument bulb should be located where it is subject to the true temperature of the measured medium. Temperature
gradient within the medium must be allowed for, and with bulbs allowing variable depth of immersion (compression gland
type), the bulb position should be varied experimentally until the optimum position is found.

The full length of the sensitive portion must at all time be immersed in the medium, but direct contact with the source of
heat to the medium must be avoided.

When securing the bulb in its location, it should be prevented from twisting.
Where a pocket is supplied, this should be securely installed before the bulb is inserted. It may be that the thermal

response of a pocketed bulb is improved by filling the intervening space with a medium such as oil.

General Maintenance

• keep the instrument clean and treat with care

• where there is a risk of corrosion the bulb should be inspected periodically

• if corrosion is evident, it should be removed by non-abrasive treatment

• any contamination on the bulb should be removed

Clearscan™ Recorder Series - Operating and Service Manual