User manual ROTOTHERM C105 TEMPERATURE RECORDER

[. . . ] C105 Circular Case Recorder Operating Instructions Fig. INTRODUCTION Identification Specification INSTALLATION Mounting Access to Recorder Process Connections Electrical Connections OPERATION Mechanical Clock Fitting a Chart Set Pointer Adjustment Inking System Zero Adjustment Start-up Check Start-up Procedure Description of Operation Electrical alarm/control system Programme Control 2 2 3 4 4 5 5 5 6 6 6 6 6 7 7 7 8 10 10 MAINTENANCE Cutting a programme cam Pen Adjustment Calibration Servicing Wet and Dry Bulb Water Bath SPECIAL INSTRUCTIONS & DIAGRAMS FAULT FINDING SPARES LIST Page No. 11 11 11 11 12 13 14 15 15 & 16 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. [. . . ] Linearity adjustment Pivots Ratio arm Hygroscopic membrane Start-up procedure Be sure that all steps in the start-up check have been completed. Position setting pointers on desired alarm/control values. Switch on mains supply to external electric alarm/control systems. 7 Description of Operation Bourdon tube Set-up spring Linearity adjustment Ratio arm pivot Drive link striker pin Control unit Compensator Setting pointers Setting pointer clamp Coarse zero adjustment Control unit fixing screws Control arm Relays Terminal block Fig. 5. ) As the temperature rises, the fluid in the thermometer bulb expands and partially uncoils the spiral 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. 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 a mechanical linkage to the pen arm which records the pressure on a calibrated chart. A capsule stack or diaphragm system 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. 8 Temperature and humidity recorder (see Fig. 4) The air circulates around a strip of animal tissue (Goldbeater skin) the length of which varies with the relative humidity. The membrane is mounted under light spring tension and is connected by means of a bell crank lever and linkage to a pen arm which records the humidity on a calibrated chart. Temperature is measured by a fluid filled system which is mounted to the left of the humidity element and mechanically linked to a second pen arm. 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. Set up and Overload Protection Springs Overload action Movement of Bourdon Tube compensator Overload spring Ratio arm pivot Set up spring Fig. 6 Set up action To protect the pen mechanics if the measured variable goes significantly outside the span of the instrument the connecting link may incorporate "set up" and/or "overload" springs (see Fig. 5. ) is used if the measured variable is liable to go significantly below the chart zero reading, e. g. on a temperature recorder calibrated 100­600oC where the measuring element is subject to normal ambient temperatures during transit. Under these conditions the movement of the Bourdon tube compensator extends the spring allowing the pen mechanism to rest against the zero stop. The overload spring is used if the measured variable is liable to go significantly above the maximum chart reading. Under these conditions the movement of the Bourdon tube compensator extends the spring allowing the pen mechanism to rest against the top point stop. 9 Electrical alarm/control system Each relay is switched by a contact mounted on an arm linked to the setting pointer which makes or breaks with a contact attached to the recording pen linkage when the pen reaches the set point (see Fig. The striker is fixed relative to the pen arm and a spring loaded contact is fitted to the setting pointer linkage. One set of changeover contacts is available for external connection for each set point. The contacts are usually labelled "normally closed" (NC), "common" (C) and "normally open" (NO) where normally means that no current E. A. page 14 for any special wiring information. Sprung contact On wet and dry bulb humidity controllers in addition to standard control contacts for the dry temperature a contact may be fitted on the dry bulb pen linkage so that the wet bulb depression may be controlled. Alarm systems should have an independent power supply to safeguard alarm operation in the event of mains failure. [. . . ] The complete clock can be detached by unscrewing the three fixing screws when the chart plate is removed. (This operation should only be carried out by a suitably experienced person). 12 Wet and Dry Bulb Water Bath The wick should be changed frequently, the period between changes depending on the surrounding atmosphere. In wood drying kilns, etc. , the wick should be renewed once a week but in clean atmospheres, e. g. offices, it can be left as long as three weeks. [. . . ]