User Guide

RTH100 Series Temperature & Humidity Recorder
Instruction Manual
Page 1
1
Contents
Page
Introduction
Operation 1
Control Circuit 1
Recorder Specification 2
Installation
Mounting the Recorder 3
Commissioning
Access to Instrument 5
Electrical Connections 5
Fitting a Chart 6
Inking System 6
Contact Differential 7
Accuracy Adjustments 8
Zero Adjustment 8
Maintenance 8
Spare Parts 8
Introduction
The RTH100 Series of temperature and humidity circular chart recorders uses the proven design combination of bimetallic coil and
hygroscopic membrane for the direct measurement of temperature and humidity.
Air is drawn through the instrument and over the sensing elements by an electrically driven fan. Expansion, or contraction, of the
bimetallic coil, due to temperature change causes pen movement by direct linkage. Similarly, a change in humidity causes exten-
sion or contraction of the hygroscopic membrane and direct linkage again causes movement of the second pen.
The RTH100 Series range comprises of recorders and recorder controllers as either temperature, humidity or combination instru-
ments. Controllers can be supplied with up to four separate alarm contacts set by reference to a setting pointer adjustable over the
full chart range. Each alarm contact operates and independent output relay providing single pole changeover, voltage free, output
contacts. High and low alarm points for temperature and humidity are indicated by illumination of red LED’s positioned above the
viewing window in the upper part of the recorder door. All control instruments are fitted with an audible alarm indication of set points,
silenced in operation by pressing the switch located
Fig 1. Operation - Control / Alarm Circuit