3
012208
1.0 GENERAL DESCRIPTION
The Ronan Series X90 Point Level Monitor economically
and reliably solves many process problems in which
noise, temperature, abrasive or corrosive conditions
preclude the effective utilization of sonic, capacitative,
float or other techniques. This is a non-contact system.
Normally, a small Cesium-137 radioisotope source is
housed in a lead-filled shielding enclosure known as the
source holder. This holder is equipped with a shuttering
mechanism and the means for containing the radiation
and collimating or directing the radiated energy toward
the sensor, which is directly opposite the source along a
line or level to be measured. Radiation in all directions is
attenuated to a safe value by the lead shielding. The
source holder is mounted on or adjacent to the vessel
whose content it is desired to monitor.
When the source holder shutter is opened, radiant
energy is directed toward the sensor. In the absence of
the process, this sensor sees only a small amount of
radiation but, when the process is present, a large
percentage of this radiation is absorbed. This absorption
of radiation by the process causes a change in the
radiation at the sensor. When this occurs, a relay contact
signals that the level change has been observed.
The passage of radiant energy through the process
causes no contamination and cannot make the process
or container walls radioactive. These systems may be
used anywhere, including the food processing industries.
For most applications, all components of the system are
externally mounted. Therefore, installation is simple and
requires no major mechanical modification or down-time.
The standard Ronan Model X90-301(V) gamma switch
uses Cesium-137 as the source of gamma rays. Cesium-
137 is a 0.66 MEV gamma ray emitter with a half-life of
30 years. The radioisotope material is sealed in a
double-welded, stainless steel capsule. The source type
and strength (activity) supplied depends on the individual
application, and is printed on the yellow and magenta
caution label affixed to the 3 source holder. The standard
source holder is lead-filled and equipped with a two-
position ON/
OFF shutter mechanism. The handle and
shutter mechanism can, by means of a combination
padlock, be securely locked in the
OFF position during
shipping, installation, storage or process-down intervals.
RLL source holders have no on/off shutter, only a shield.
Well sources are supplied with actuator rods, which can
be used to extend the source into the vessel or retract
the source into the storage source holder.
CAUTION
: Any malfunction of the source holder must
be immediately reported to Ronan Engineering for repair
or replacement of the source holder. Under no
circumstances may the source holder be taken apart.
Should it be necessary to ship the source holder back to
Ronan, contact Ronan Engineering for detailed shipping
instructions.
A Geiger-Mueller tube is used as the sensor for
detecting the gamma radiation. The G-M tube consists of
a gas-filled cylinder with a central anode. The anode is
connected via a high ohmic resistance to a dc voltage of
500 V. Conduction occurs when the gamma radiation
ionizes the gas in the tube. Each ionizing event produces
a pulse, the rate of these pulses being proportional to the
field strength of the ionizing radiation, i.e., incident field
intensity. The output of the G-M tube is processed by an
electronic circuit in the SWITCH301 module and the
material level is indicated by either an ALARM or
NORMAL signal.
A scintillation detector can also be used as the sensor
for detecting the gamma radiation field. The scintillation
detector consists of a crystal which scintillates when
exposed to radiation. A photo-multiplier tube is used to
convert these scintillations of light into electrical signals.
This output is processed by an electronic circuit in the
SWITCH301 module and the material level is indicated
by either an ALARM or NORMAL signal.
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2.0 SPECIFICATIONS (STANDARD)
The X90 is a microprocessor based instrument available
in two designs. The Model X90 Detector with integral
electronics has a combined detector and switch
assembly located at the vessel. The detector with remote
electronics module may be field-located or remotely
located in a control room
Detector:
Integral:
Geiger-Mueller tube
Remote:
Geiger-Mueller tube or scintillation detector
Radiation at Detector:
Integral:
0.1 mR/hr min.
Remote:
0.1 mR/hr min. /GMTube or 0.005 mR/hr/
scintillator
Detector Housing:
Integral:
4” Schedule 40 carbon
steel pipe (type 304 stainless steel also available);
mount to flat plate bracket
Remote:
Type 304 stainless
steel; explosion-proof housing; mount with conduit clamp
Housing Classifications:
Integral:
Class I, Division 1,
Groups A, B, C, D; Class II, Division 1, Groups E, F, G
Remote:
Class I, Division 1, Groups A, B, C, D; Class
II, Division 1, Groups E, F, G
Ambient Temperature Range:
Integral:
-40° to 185°F
(-40° to 85°C)
Remote:
-40° to 185°F (-40° to 85°C)
Power:
Integral:
115/230 VAC ± 15%, 40/60 Hz
Remote:
115/230 VAC ± 15%, 50/60 Hz
Power Consumption:
Integral:
7 watts per alarm
Remote:
7 watts per alarm point
Relay Output:
Integral:
DPDT 3 A at 30 VDC; 3 A at
120 VAC
Remote:
DPDT 3 A at 30 VDC; 3 A at 120
