GEORGIN uses the piezo-resistive effect sensor principle to make these products.
The distortion under pressure of a sensing element results in resistance fluctuations of a WHEATSTONE strain gauge bridge screen printed on a ceramic support. This type of sensing element is commonly called a thick film strain gauge.
Under the effect of pressure a distortion is caused. This one leads to proportional variations in the resistance bridge to obtain a 4 to 20 mA electric signal.
These pressure transmitters generally use a cylindrical format, with fixed range, 0.5% accuracy class and are not configurable.
Process pressure transmitters
Using leading edge technology in silicon chip manufacturing, ProcessX transmitters incorporate a high performance micro capacitance silicon sensor.
The differential pressure is applied to the silicon sensor and changes the two capacitance values (C1 and C2) of the sensor as a function of the measured pressure.
The silicon chip is assembled floating in the measuring cell neck and improves the static pressure and temperature stability characteristics.
The SMART pressure transmitters of this family are rangeable and offer a high level of accuracy (<0.1% class).
The TiXo family range includes 3 models of programmable temperature converters using digital technology.
TiXo allows a large range of inputs as RTDs, TC, resistance or voltage (2-wire technology):
» TiXo1 is fully dedicated to RTD100 input.
» TiXo2 and TiXo3 have a programmable universal input (RTDs, TC, resistance or voltage). They also include cold junction compensation and galvanic insulation.
This new generation of converter is fully and easily configurable through our ProgressXmanager freeware, an FDT tool or a HART� pocket.
TiXo3 uses the HART� communication protocol and accepts a signal from a Resistance Temperature Detector (RTD), a thermocouple, a resistance or a millivolt signal.
Control - Safety
Pressure and temperature switches
The pressure or temperature to be controlled is applied to a sensor (diaphragm, bellows, manometric tube). Whenever there is a change of pressure or temperature, the sensor is distorted and acts on a force balance connected to a microswitch.
Opposite this sensitive element, is an adjustable spring that enables the working point to be adjusted.
Adding a second adjustable spring permits greater or lesser increase of the hysteresis (dead-band) or to act on dislocation between the two contacts if the instrument is equipped.
Bellows: The most conventional sensing element used in our pressure and temperature switches is metallic bellows (bronze or stainless steel). Flexible by nature, it compresses or elongates axially under the effect of pressure and provides excellent transmission.
Diaphragm: For low pressure, bellows which are too rigid, are replaced by an elastomer diaphragm which is hold in place by two metal plates.
�Diaphragm� technology is also used in cases of excessively high pressure and pulsating phenomena.
Manometric tube: For very high pressure, the sensor used is a stainless steel tube curved into a C shape which is closed at one end and which changes position under the effect of pressure.
A differential pressure switch is fitted with two connections: one of them (HP) is connected to the highest pressure, the other (BP) to the lowest pressure which means, in the majority of cases, that it has to be fitted the right way round. The resultant of the two different pressures acts on the internal mechanism which then functions like a standard instrument.
The pressure switch is fitted with a differential measuring element with bellows, one of which is vacuum sealed so as not to be affected by atmospheric pressure.
Two types of bulbs are used:
» The directly connected bulb,
» The capillary bulb allowing an installation away from the sensor
Securing sites equipped with electrical installations on which hazardous atmospheres may occur is a prime requirement for any industrial company.
Several protection methods can be used for the instruments installed in potentially hazardous areas.
GEORGIN offers its customers four of those methods, i.e. flameproof enclosures, increased safety, double protection and, in particular, intrinsic safety.
This is based on the principle of the "intrinsic safety electrical circuit" defined by the CENELEC European standard as a "circuit within which no thermal effect produced under the test conditions prescribed by the standard is capable of causing inflammation in a given hazardous atmosphere."
Since the 1st of July 2003, the ATEX 94/9EC (users) and 99/92EC (manufacturers) directives have introduced requirements concerning the installation and interfacing of equipment in dangerous areas.
These intrinsic safety circuits are made up of two main parts:
» The "intrinsic safety" equipment intended for installation in the dangerous area (sensor, loop indicator, pilot lamp...)
» The "associated" equipment where only the circuits directly connected to the hazardous area are intrinsically safe. It is located in a safe area (signal conditioners, power supplies...) or installed in an area with risks of explosion (remote Inputs/Outputs)
An intrinsic safety circuit can be designed in two ways:
» either earth referenced, the so called "Zener barriers"
» or completely insulated from the earth, it is then said to be a "galvanic insulation" circuit
GEORGIN uses both methods of insulation and is thus able to meet the requirements of each type of installation.
Intrinsic safety equipment must remain safe even if faults occur in components or connections.
If the equipment's design allows it to remain safe even when a combinationof 2 faults is present, it belongs to the "ia" category.
If it remains safe when one fault is present, it belongs to the "ib" category.
Throughout its catalogue, GEORGIN offers category "ia" equipment, which means that it can be used in all areas and, in particular, in the areas of permanent danger.