Nitrogen Filled
Thermometers
Stainless steel dial thermometers. According to din standards.
The stainless steel dial thermometer with gas filled measuring system is a robust instrument which is universal applicable. By using the right material and sophisticated construction the instrument is weatherproof and withstands
aggressive mediums. Both the thermometers with fixed
stem and the thermometers with capillary-tubing are available with glycerin or oil filled case (also silicone-oil).
This increases the vibration - constancy and prevents condensing at the inner side of the window (e.g. severe varying ambient temperatures). The large number of mountingpossibilities stresses the universal application.
Principle
The measuring system consists of a stem, a capillary tubing and a bourdon tube making a compact unit, which is
entirely filled with nitrogen. When the stem/bulb is heated
the nitrogen expands and is increasing the pressure in the
measuring system. By this increasing pressure the bourdon tube straightens somewhat and this movement is
turned into a rotating motion of the pointer.
Features:
 Heavy duty construction
 High accuracy
 Large number of mounting types
Type indication
 WTR - dial thermometer with fixed sensor element
(stem) at the bottom or the back of the case.

WTRG - dial thermometer with fixed stem equal to type
WTR, but case filled with glycerin.

AWTR - distance - dial - thermometer with capillary
between stem and indicator

AWTRG - distance - dial thermometer equal to type
AWTR, however, case glycerin - oil-filled
Base execution
 Case diameter 63-80-100-160 and 250mm
 Stainless steel case AISI-304 with bayonet closing
bezel
 Window made of mineral glass and sealed with synthetic rubber ring
 Dial, white sprayed with black figures and graduations,
linear scale over 270 degrees of arc. Range from –200°
up 800°C
 Black pointer
 Measuring system gas-filled (nitrogen), pollution-free
 Movement stainless steel
 Stem stainless steel AISI-321 or AISI-316 on demand
with diameter 9-10 or 12mm
 Connection stainless steel AISI-304 on demand AISI316
 Capillary stainless steel AISI-321 or AISI-316 on demand
 Adjusting device at the side of the case
 Accuracy 1% of span over the entire range. All thermometers standard calibrated on an ambient temperature of +20°C, without individual calibration certificate
(on demand possible).
 Thermometers can be overloaded up to 40%
Example
Type:
Case Diameter:
Range:
Stem diam. and length:
Connection:
Thread:
Optionals:
1503 (base execution)
100mm
0-100°C
12mm x 200mm (L length)
C4
G 1/2”
window made of laminated
safety glass, pointer with
micrometer adjustment
Consult us also for thermocouples - resistance PT100 and
PT1000 sensors and 2-wire transmitters, all as per DIN BS, etc.
Note
When ordering capillary thermometers mention also
capillary length and armouring if necessary see list
optionals.
Optional
Besides the instruments mentioned in the base execution,
on request these dial thermometers can be supplied with:
 Case glycerin filled
 Case silicone oil filled instead of glycerin

Case 100 and 160 mm in stainless steel AISI-316 (not
for contact thermometers)
 Window made of laminated safety glass
 Dial in °F or combined scale in °C/°F Also in °Reaumur
or °Kelvin. Scales also with mirror reading
 Pointer with micrometer adjustment
 Stem in polished execution
 Stem diameters: 6, 6.35, 7, 8, 12.5, 13, 14, 15, 16,
17,18 or 20mm. Also special stems for measuring air
temperatures, surface temperatures and for hygienic
use.
 Room thermometers stem inside the case. Casing with
air holes.
 Capillary made of copper, copper PVC covered, steel,
steel PVC covered, stainless stele armouring or
stainless steel armouring with PVC cover.
 Stainless steel knee joints for types 1502 and 1515,
bendable over 180° or 360°.
 Stem with anti-vibration spring between case and stem
(special for diesel engines)
 Electric or pneumatic contacts for control of alarm
 Transmitters on dial for distance reading. Output 420mA, 0-20mA or 0-100 Ohm.
 Profile cases for panel-built-in. Black execution 72x72,
96x96, 144x144, 192x192, 72x144 and 96x192mm
 Instrument with individual test certificate
 Calibration on other ambient temperature as standard
20°C
 Accuracy 0,6% (only 160 and 250mm)
 Overload till 100%, however, limited till 800°C
Version 032015 The Observator range is in continuous development and so specifications may be subject to change without prior notice