Rototherm C105 User Manual

C105 Circular Case Recorder

Operating Instructions

instrumentation and control

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

INTRODUCTION 2

Identification 2
Specification 3

INSTALLATION 4

Mounting 4
Access to Recorder 5
Process Connections 5
Electrical Connections 5

OPERATION 6

Mechanical Clock 6
Fitting a Chart 6
Set Pointer Adjustment 6
Inking System 6
Zero Adjustment 7
Start-up Check 7
Start-up Procedure 7
Description of Operation 8
Electrical alarm/control system 10
Programme Control 10

MAINTENANCE 11

Cutting a programme cam 11
Pen Adjustment 11
Calibration 11
Servicing 12
Wet and Dry Bulb Water Bath 13

SPECIAL INSTRUCTIONS & DIAGRAMS 14
FAULT FINDING 15

SPARES LIST 15 & 16

Page No. Page No.

CONTENTS

Fig. 1.

2

INTRODUCTION
The C105 series of instruments is designed to measure, record and control process variables such as
temperature, pressure and humidity. A maximum of two measuring systems is provided in each
instrument; a fluid expansion type or bimetallic system is used for temperature recording, a hygroscopic
element or a wet and dry bulb system for humidity and a Bourdon tube or diaphragm 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 electric clock. Control of the process variable is provided
electrically.

Basic
Type
Number

C10
Recorder
with
105mm
pen
travel
on
circular
chart

5 One

pen

6 Two

pen

1 T emperature

(Fluid
expansion
system)

2 Pressure

(‘C’ Spring–
316 st.steel)

3 Pressure

(Spiral
Bourdon –
phosphor
bronze)

4 Pressure

(Spiral
Bourdon –
321 st.steel)

5 Pressure

Capsule
Stack –
beryllium
copper)

6 Pressure

(Diaphragm
Stack –
beryllium
copper)

7 Relative Humidity

(Goldbeater skin)
– External

9 Pressure

(Coiled Tube –
316 st.steel

No. of
Measuring
Points

Programme
Control Cam
(Single Pen
only)

Measured
Variable

Each Pen

Alarm or Control Mode Set Points

No. 1 No. 2 Nos. 3 & 4

17 Record only – – – – –

Electric Alarm/Control Position of Pen in relation to
with Relay Output Set Point when Relay is energised

00 Two Step Above – None, or any – or C
01 Two Step Below – combination – or C
05 Three Step Below Below applicable –
06 Three Step Above Above to Set Points –
09 High-low Above Below No. 1 & 2 –
03 Double 2 Step Above/Above – – or C
04 Double 2 Step Below/Below – – or C

Contact Action at Set Point
Electric Alarm/Control when Pen moves towards
Contacts only – no Relay outside of Chart

60 Two Step –Contact Mode C Make – – or C
61 Two Step –Contact Mode A Break – None, or any – or C
65 Three Step –Contact Mode AA Break Break combination –
66 Three Step –Contact Mode CC Make Make applicable –
69 High-Low –Contact Mode CA Make Break to Set Points –
63 Double 2 Step –Contact Mode D Make/Make – No. 1 & 2 – or C
64 Double 2 Step –Contact Mode B Break/Break – – or C

Notes:

Code No. is built up thus:

Single Pen C105/1 1 63 C

One Pen
Temperature
Double 2 Step –
Contacts only (no relay)
Programme Cam

Two Pen C106/3 00/1 17

Two Pens
No. 1 Pen – Pressure (Bourdon)

– 2 Step Elec. Alarm

with Relay

No. 2 Pen – Temperature

– Record only

(

(

(

3

Specification

General:

Chart diameter 255mm
Writing width 105mm
Intrinsic error ± 1% span maximum (±2% R.H. for hygroscopic

membrane system)

Operating temperature limits –10

o

to +50oC Except for

Operating humidity limits 0 to 80% R.H. humidity recorders
Zero error due to ambient temp. variations ±0.05% span/

o

C typical

Chart speeds 1 rev every 12 hours, 24 hours or 7 days
Chart drive Synchronous electric motor or mechanical clock
Power supply voltage and frequency 200/250V or 100/120V, 50 or 60Hz
Mounting Wall or panel

Temperature measuring instruments:

Measuring systems Fluid expansion
Maximum length capillary 30m
Minimum span 40

o

C

Maximum span 500

o

C

Span limits – 30

o

C to +600oC

Pressure measuring instruments:

Measuring system Capsule stack, Bourdon tube or coiled tube
Minimum span 0 to 1 bar vacuum or pressure.
Maximum span 1200 bar
Span limits –1 bar to 1200 bar
Connection size Ranges up to 40 bar: a inch B.S.P.) with nut and tail

Ranges over 40 bar: 2 inch B.S.P.) piece for 8mm tube

Humidity measuring instruments:

Measuring systems Sensitive hygroscopic membrane and fluid filled system

for temperature measurement, or wet and dry bulb fluid
expansion systems.

Spans 20 to 100% R.H. (hygroscopic membrane);

0 to 40

o

C (fluid filled systems)

Operating temperature limits 0 to 40

o

C

Operating humidity limits 30 to 85% R.H.
Maximum length of capillary

(wet and dry bulb system) 30m (each bulb)

Electric alarm or control:

Instrument contacts 20mA inductive or 30mA non-inductive load max.
Contact action Make above or below set point as required
Relays Delayed action double pole change-over, 5A, 240V

50Hz non-inductive load, as standard
(Refer to wiring Diagram, p.14).

Relay action Energised above or below set point as required.

Overall dimensions 350mm wide; 137mm deep; 350mm high

(Temp & R.H. 582mm high)

Panel cut-out 318mm diameter
Maximum panel thickness 25mm
Weight 10kg

667788

4

INSTALLATION

Mounting

The instrument can be wall or panel mounted using the same fixing brackets. Do not install near any very hot
apparatus, e.g. ovens, steam pipes or flues. Mount the recorder vertically in a position free from vibration and
excessive temperature.

For panel mounting remove the fixing screws and rotate the fixing brackets so that the instrument can be inserted
in the hole in the panel. Return the brackets to their original position and insert the fixing screws. Tighten the
screws until they bear against the back of the panel.

Hygroscopic measuring instruments have external measuring elements requiring a clearance of 240mm below the
case, and must be wall mounted.

Temperature Recorder

Temperature and Relative Humidity Recorder

Wall Mounting

Pressure Recorder

Panel Mounting

41 mm

83 mm

350 mm

Panel

cut-out

dia. 318 mm

Cable gland for

w” conduit

a” or 2” B.S.P. union with nut,

and tailpiece

Three holes at 120º on 340 mm p.c.d.
to take 6.4 mm diam. screws
for wall mounting

Fig. 2.

5

Access to Recorder

To open the door, unlock, and turn the latch anticlockwise. As the door is opened the pen lifter raises the pen (or
pens) away from the chart. Remove the chart (see page 6).

If the instrument is connected to the mains, switch off the mains supply before dismantling further.
For access to the terminal blocks remove the lower plastic plate from behind the chart by undoing the one

retaining screw.
For access to the relays and measuring systems, first remove the chart. Unhook the pens from their mounting

(see Fig. 3.). Remove the three screws from the outside edge of the chart plate. (The pen lifter is secured by one
of these screws and must also be removed). Lower the chart plate carefully. The chart motor is mounted on the
back of the chart plate and if the motor is an electric one it remains connected to the terminal block in the lower
part of the case.

When replacing the chart plate reverse the above procedure. The coil on the pen lifter should be against the side
of the case when the retaining screw is tightened.

Process Connections

To avoid confusion on instruments with more than one measuring system, setting pointers are labelled and
Bourdon tube capillary connections to the instrument are painted with the same colours as the inks used for the
corresponding pens.

Process connections – temperature measuring instruments:
Install the sensing element (bulb) of the instrument in the apparatus where the temperature is to be measured.

The circulation around this element should be good and it should not be too close to any heating or cooling coil or
other controlling medium. Fasten the capillary tubing at frequent intervals to rigid supports avoiding sharp bends
of less than 50mm. radius anywhere along its length. The tubing must not touch or run close to any hot apparatus
and should take the path least subject to temperature variation. If the temperature source is likely to move or
vibrate allow one or two coils of 100mm. diameter of the capillary tube to eliminate stress of the tubing.

If the atmosphere around the capillary tube is likely to be corrosive, paint the tube with anti-corrosive paint and
ensure this is maintained.

Process connections – pressure measuring instruments:
Connect the Bourdon tube sensing element to the measuring point on the apparatus using pressure tubing of the

same or similar material as the Bourdon tube and of sufficient pressure rating. Slope the run of the tubing so that
any condensate is drained away from the instrument and does not affect the accuracy of measurement. For
measurement of steam pressure or other hot vapours, form a condensate trap below the instrument.

Process connections – humidity measuring instruments (wet and dry bulb):
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. Adistilled water supply tank should be connected to the inlet feed pipe with
a head of between 1 and 6 metres.

It is important to install the bulbs in a position where the air speed is 3.6 metres per second or more. Below this
speed inaccuracies of bulb depression may occur. The air should pass over the bulbs in such a direction that the
water evaporating from the wet bulb does not pass over the dry bulb. The water must be kept clean and free from
impurities. The temperature of the bath and all piping must not fall below 0

o

C. See also page 13.

Electrical Connections

Before making any 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 lower section of the

chart plate.
Insert the leads through the cable gland in the underside of the case (see Fig. 2.) and make the connections as

shown on the terminal labels or Wiring Diagram (page 14). The live line should be switched and fused with a 2
amp fuse. If the instrument is mounted on an insulated panel the case should be earthed.