Rototherm RTO80, RTO20, RTO10 User Manual

MODEL RTO FILLED SYSTEM
TEMPERATURE RECORDERS,

RPO PRESSURE RECORDERS &

RECORDERS CONTROLLERS

(ELECTRICAL CONTROL)

Instruction Manual

Introduction 1

Specification 1
Description of Operation 1
Receipt of Recorder 1
Dimensions and Fixing 2

Installation 2

Mounting 2
Access to Recorder 2
Electrical Connections 2
Process Connections 3

Operation 4

Fitting a Chart 4
Inking System 4
Set Point Adjustment 4
Zero Adjustment 5
Start-up Check 5
Start-up Procedure 5
Calibration 6

Maintenance 8

Replacing a Filled System 8
Replacing a Pressure System 8

Fault Finding 9
Spares List 10

The chart drive and control system on this system may be operated from
a mains voltage supply.
The mains must be switched off before any mechanical adjustments
(other than of the set pointer) or carrying out any maintenance or fault
finding procedures.
When making electrical adjustments observe the warning notes in the
text.

Accuracy +/- 1 % FSD.
Ambient -20°C to +50°C
Chart Drive Synchronous electric, battery or mechanical

spring wound. 24 hour or 7 day.
(Other rotations on request).

Inking System Disposable fibre tipped pens.

Single pen: red. Two pen: red and blue.
Three pen: red, blue and green

Case Glass filled polyester resin.

Protection rated to IP55.

Window Acrylic.
Power Supply 200 to 250 volts, 50 Hz (60Hz available);

100 to 110 volts, 50 Hz (60Hz available).
Instruments without electrical control require no
power supply provided that a clockwork drive is
fitted.
Battery operated chart drives require 1.5 volt 'C'
type cell.

Electrical Alarm and Control

Contact Rating 0.1A at 250v A.C. (non inductive)
(when fitted) 0.01A at 250v D.C. (non inductive)

Relay contact 10A at 250v 50Hz.
rating: (when fitted)5A at 415v 50Hz.
Contact
Adjustment Range2% to 100%

Weight

(approx.) Single pen: 6.5kg (14.25 Ib)

Two pen: 7 kg (15.5 Ib)
Three pen: 7.5 kg (16.75 Ib)
Portable single pen: 8.6 kg (19 Ib)
The above weight includes 3 metres (10 ft)
of capillary. For each additional 3 metres add

0.25 kg (0.5 Ib).

Mounting Suitable for surface or panel mounting.

(Pipe mounting and portable options available)

For instruments fitted with Temperature Systems

Measuring Element

Rototherm thermal bourdon tube temperature
compensated.

Capillary Microbore stainless steel tube with 3mm

diameter stainless steel cover (type C1) as
standard, other capillaries are available.

Bulb and Stem Stainless Steel BS970 316 S16.
Fittings Compression gland (adjustable).

stainless steel 8S970 316 (1/2" BSP is
standard). Other BSP NPT API etc. are
available on request.
(Suitable for pressures up to 3.5 Bar).

For Instruments Fitted with Pressure Systems

Measuring Element

Stainless Steel or Phosphor Bronze Bourdon
tube or pressure capsule as applicable.

Connection

Standard 3/8" BSP male with nut and tail pipe suitable for

6.35mm (0.25") outside diameter tube or 3/8"
inside diameter tube.

Portable 3/8" BSP male with nut and tail pipe suitable for

6.35mm (0.25") outside diameter tube or 3/8"

inside diameter tube.
Receiver type 1/4" BSP female.
input 3-15 p.s.i.
(0.2 - 1 Bar)

The RTO and RPO series of instruments are designed to measure,
record and control process variables such as temperature,
pressure and humidity. A maximum of three measuring systems
can be provided in each instrument; a fluid expansion/gas
expansion system is used for temperature recording, a wet and
dry bulb system for humidity and a bourdon or diaphragm
capsule for pressure measurement. The measured values are
continuously recorded on a calibrated circular chart which is
rotated at a constant speed by a mechanical or electrical clock.
Control of the process variable is provided electrically.

Temperature Recorder

As the temperature rises, the fluid 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.

Humidity Recorder - Wet and Dry Bulb

The relative humidity can be obtained from the temperatures
measured by the wet and dry bulb thermometer using hygrometric or
psychrometric tables.

Pressure Recorder

On medium and high pressure ranges an increase in pressure
partially uncoils a Bourdon tube fitted inside the instrument. This
movement is transferred by mechanical linkage to the pen arm
which records the pressure on a calibrated chart.

A capsule stack is fitted for low pressure ranges and the expansion
of the system resulting from an increase in pressure is transferred
by a mechanical linkage to the pen arm.

For vacuum range a contraction of the capsule stack results from
an increase in vacuum and this movement is transferred by a
mechanical linkage to the pen arm.

The temperature recorder complete with a packet of charts, case
keys and pen packs is dispatched in a protective casing which
should be preferably replaced after inspection, as protection until the
instrument is ready for installation.

The spare pen pack(s) are inside the protective case. The case
keys are attached to the bottom right hand mounting stud.

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

To assist with inspection, a label attached on the inside face of
the case door states the instrument serial number, chart number,
ranges of each pen and the rotation speed of the chart drive. If
the chart drive is electrical the supply voltage is stated.

SPECIFICATIONS

1

INTRODUCTION

Description of Operation

Receipt of Recorder

Ideally the site chosen should be free from dust, corrosive
fumes, vibration and extremes of temperature.
The instrument is suitably compensated against normal
ambient temperature variations.

The recorder may be surface or flush panel mounted.
For surface mounting, remove the screws holding the three

brackets at the rear of the case, reverse and refit the brackets
with their ends projecting from the edges of the case.
The bracket with the keyhole slot must remain at the top of
the case.

Drill three holes in the mounting surface, of the size and at
the centres given in Fig. 1. Fit a screw (max. major diameter

6.35mm(0.25 inch)) in the top hole.
Locate the instrument on this screw and fit two smaller screws

through the remaining brackets.
For Flush Panel Mounting, make a panel cut-out to the

dimensions given in Fig 1. Drill the holes and slot to the cut-out
edge as shown. Remove the nuts and washers from the studs
projecting from behind the case flange, pass the recorder
through the cut-out and refit the washers and nuts to secure the
instrument.

To open the instrument door press the plunger of the door lock
and pull the door forward from the right. As the door is opened
the pen lifter raises the pen (or pens) away from the chart.
Remove the cotton thread that secures the pens to the pen lifter
for transit purposes.

To make electrical connections and to set contacts, remove the
chart plate by loosening the three retaining screws and carefully
lift out the chart plate via the finger hole (care is necessary to
avoid pen lifter interference with pens and control pointers).
Pull the bottom edge clear of the instrument and lower the chart
plate from behind.

Before making any electrical connections to the instrument
switch off the mains supply to be connected.

All electrical connections are made to terminal blocks in the
lower part of the case behind the chart plate.

Insert the leads through the cable glands in the underside of the
case and make connections shown on the terminal labels or the
wiring diagram supplied.

It is important to select the correct supply voltage connection.
The live line should be switched and fused with a 2 Amp fuse.
The mains supply should be earthed and connected at the
appropriate terminal within the recorder.

Alarm systems should have an independent power supply to
safeguard alarm operation in the event of mains failure.

ALARM SYSTEMS SHOULD HAVE AN INDEPENDANT POWER SUPPLY TO

SAFEGUARD ALARM OPERATION IN THE EVENT OF A MAINS FAILURE

2

Installation

Mounting

Access to Recorder

Electrical Connection

Fig. 1

all dimensions are in mm

To avoid confusion on instruments with more than one
measuring system, capillary connections to the instruments are

- marked with the same colours as the inks used for the
corresponding pens.

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(1 inch) in
radius and under no circumstances must the tubing be cut.

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

Immersion Types

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.

Capillary Type Bulb

This type of bulb should be installed by means of its end brackets
and to allow maximum circulation of air or gas around it, the coil
should be extended to a length of 610mm (2ft) or such that the
interval between the adjacent turns does not exceed 12.5mm (0.5
inch).

Any extension beyond this length may affect the zero reading at
the recorder. The bulb must be kept free of moisture.

Install the sensing elements (bulbs) where the humidity is to be
measured as described for temperature measuring instruments.

The wet bulb (red pen system) is kept moist by a fabric covering,
forming a wick which dips into a constant level water bath.

A distilled water supply tank should be connected to the inlet
feed pipe with a head of between 1 and 6 metres.

Use 0.25" (6.35mm) o.d. or 3/8"(9.5mm) bore solid drawn copper
tubing that has been well annealed cleaned and pressure test before
soldered into or over the tail pipe.

The solder joint and other joints in the pipeline must be secure and
leak proof. The use of PTFE tape is recommended for all thread
connections. Ensure that the sealing washer is in place when
assembling the tail pipe to the instrument connector.

A suitable seal must be inserted in the system if the medium
under pressure is liable to have a corrosive action on the
pressure element.

Gauge and Absolute Pressure Controllers.

It is recommended that a needle valve be installed in the pressure
line close to the instrument to enable pressures to be admitted
gradually. It can also be used to damp out any pressure pulsations.

A second needle valve, situated between the damping valve a
the controller, can be arranged to vent the instrument to enable
the zero to be checked.
This valve must not be fitted where steam or corrosive gases or
liquids are present.

Differential Pressure Controllers

There are two pipes to each differential pressure measuring unit.
Connect the lower pressure to the (-) connector and the high
pressure to the (+) connector. Three needle valves should be
installed close to the controller, one isolating valve in each pressure
line and one balancing valve as arranged in figure 2.

3

PROCESS CONNECTIONS

FOR INSTRUMENTS FITTED WITH

TEMPERATURE SYSTEMS

LOCATION OF BULB

(DETECTING ELEMENT)

PROCESS CONNECTIONS - HUMIDITY

MEASURING ELEMENTS

(WET AND DRY BULBS)

Fig. 2

PROCESS CONNECTIONS -

FOR INSTRUMENTS FITTED WITH

PRESSURE SYSTEMS