BULK GAS MIXING SYSTEMS - MODELS 6105, 6205, 6305, 6405, 8105, 8205, 8305, 8405 |
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FEATURES
- FOR INDOOR LOCATIONS
- 0- 2,000, 0 - 5,000, 0-10,000, and 0 -20,000 SCFH Flow rate
Models
- Continuous gas analysis of the gas mixture, optional alarms
available
- Surge tank design produces a constant gas mixture proportion
from shutoff to full flow conditions
- Available in standard capacities of 0-2,000, 0 - 5,000, and
0 - 10,000 SCFH
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FEATURES
Same benefits of indoor design plus a NEMA 4 enclosure for protection
from weather or tampering.
The analysis has a heated cell chamber for functioning at outdoor
temperatures.
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APPLICATION
The Thermco gas mixer is designed to mix two nonflammable and non-corrosive
gases. The gas mixer is normally used with a process where the supply
gases are drawn from bulk sources and the mixture is produced on-site
where It is supplied to the process by a pipeline. The system is
designed for applications that require a very reliable production
for mixed gas on a continuous basis. Some of the common applications
for the gas mixer are:
PRINCIPLES OF OPERATION
Within the gas mixer, the major and minor gas streams are regulated
to the same pressure. Downstream of the regulators, the major gas
flows through a fixed orifice, and the minor gas flows through a
metering valve, which acts as an adjustable orifice. The two gas
streams are mixed together under turbulent flow conditions, and
fed into a surge tank. Once the pressure in the surge tank reaches
the upper set point on a pressure switch, the gas supplies are automatically
shutoff with solenoid valves. As mixed is required the pressure
in the surge tank falls until it reaches its lower set point. At
this point, the solenoid valves are opened and the cycle repeats.
The gas analyzer continuously monitors the mixture in the surge
tank. If the mixture adjustment is to be made, the operator turns
the minor gas-metering valve accordingly, and the gas analyzer reads
out the resulting mixture. Once the desired mixture is obtained,
the mixing system will maintain a constant mixture ratio.
With changing mixed flow rate only the cycling frequency changes;
the pressure drops across the orifices remain the same, producing
a consistent mixture.
This design is simple and rugged; controllers or flow meters on
the process gas are not required.
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SPECIAL DESIGNS
Customized designs are frequently manufactured for specific customer
requirements.
Food packaging stainless steel NEMA 4X enclosures and stainless
steel surge tanks are available for harsh wash down environments
in food processing areas. Higher than standard mixed gas outlet
pressures are available.
Leak Detection -These systems often require high mixed gas outlet
pressures (up to 400 PSIG). These applications should be discussed
with the Thermco sales engineer to determine the best design based
on available inlet pressure and required accuracy.
Blanketing Atmosphere - These applications require the creation
of an oxygen / nitrogen mixture. The mixture may be created from
air / nitrogen or oxygen / nitrogen supplies. Because the thermal
conductivity of oxygen and nitrogen are very similar, the Thermco
thermal conductivity gas analyzer can not be used in these applications.
Instead, an oxygen specific analyzer is utilized, based on the electrochemical
fuel cell or paramagnetic principle. Gas mixers for this application
are frequently built for non-standard pressure conditions and flow
rates higher than 5000 SCFH.
Lamp Filling- Precise mixture of nitrogen and argon are used for
lamp filling. Special construction to minimize particulate and impurities
in the gas mixture is available for this application.
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THERMCO GAS ANALYZER
The gas analyzer constantly monitors the mixture produced by the
system. The analysis will immediately detect an improper gas mixture
being created by conditions such as low pressure in one of the supply
gases, a malfunction in the mixing system, or gross contamination
in one of the supply gas streams.
The analyzer in the mixing system is a thermal conductivity type
manufactured by Thermco. This analyzer is ideal for measurement
of two gas mixtures. Calibration of the gas mixture with a known
gas is recommended once a year. The weatherproof type gas mixers
utilize a thermal conductivity gas analyzer with a temperature controlled
detector chamber.
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ALARM PACKAGE
A popular option with the gas mixers is automatic alarms to alert
personnel when an improper gas mixture is being created. When alarms
are ordered on the gas mixing system, the standard analog meter
is replaced with a digital meter. This alarm option is described
as the alarm package. The alarm package includes high and low alarm
contacts on the digital meter, a warning light on the analyzer,
and a horn silence button.
In certain situations it may be required that the minor gas, major
gas, or mixed gas may be shutoff on an alarm condition. This can
be accomplished with the alarm package if the factory is notified
at the time the order is placed.
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General Specifications
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GAS MIXING ACCURACY
± 2% of full range over 60ºF to 80ºF (15ºC
to 27ºC)
Temperature range
±4% of full range over 2ºF to 104ºF (0ºC to
40ºC)
Temperature range
±8% of full range of - 10ºF to 104ºF(-23ºC
to 40ºC)
Temperature range
Stated accuracy assumes that the input temperature of the gases,
are equal.
Gas mixture accuracy depends upon many variables, including frequency
of analyzer zeroing and calibration, gas mixer maintenance, and
environmental conditions around the gas mixer. These accuracy's
are presented as typical performance for these systems.
FLOW CAPACITY
Rated capacity of 0 - 2000, 0 - 5,000, 0 - 10,000, 0 - 20,000 SCFH
is at midrange setting. Less capacity is available below midrange
setting and more capacity is available above midrange setting. Consult
Thermco for details on available capacity. Midrange setting is the
middle of the gas mixer adjustment range, i.e., a gas mixer with
a range of 0-30% CO2 in argon has a midrange setting
of 15% CO2 in argon.
TEMPERATURE RANGE- Ambient and Process Gas
Indoor Models: 32ºF to 104ºF (0ºC to 40ºC)
Outdoor Models: -10ºF to 104ºF (-23ºC to 40ºC)
Some large outdoor style gas mixers (greater than 10,000 SCFH) will
have higher minimum temperature ratings. Consult factory for details.
NORMAL SUPPLY GAS INLET PRESSURE RANGE
100-125 PSIG (6.9 - 8.6 BARG) for major and minor gases for models
6105, 6205, 8105, 8205.
120-145 PSIG (8.3 - 10.0 BARG) for major and minor gases for models
6305, 6405, 8305, 8405.
Input pressures do not have to be equal.
NORMAL MIXED GAS OUTPUT PRESSURE RANGE
10-50 PSIG (0.7 - 3.4 BARG) for models 6105, 6205, 8105,8205.
30-50 PSIG (2.1 - 3.4 BARG) for models 6305, 6405, 8305, 8405. Mixed
gas pressures are adjustable with a regulator on the gas mixer.
GAS CONNECTION AND PIPING
For models 6105, 6205, 8105, 8205, 1 in. NPT female pipe for major,
minor, and mixed gas connections. For other models consult the factory.
Piping is brass and copper material.
SURGE TANK
30 gallon for models 6105, 8105; 60 gallon for models 6205, 8205;
120 gallon for models 6305, 8305; 240 gallon for models 6405, 8405;
carbon steel, ASME coded, and CRN registered; pressure relief valve
provided.
POWER REQUIREMENTS
Indoor Models: 115 VAC ± 10 VAC, 60 Hz., 0.9 Amps.
Outdoor Models: 115 VAC ± 10, 60 Hz., 1.1 Amps. (220 VAC,
50 Hz. Available on request.
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GAS ANALYZER
PRINCIPLE OF OPERATION
Thermal conductivity manufactured by Thermco.
RANGE
The range of the analyzer will be the same as the gas mixer, except
for the 0 -30% CO2 in argon gas mixer, which has analyzer
range of 0 - 50% CO2 in argon.
READ OUT
Analog versions, 4.5 inch (11.4 cm) meter, nonlinear direct reading
scale. The analog readout is only available in CO2 argon
and oxygen/argon ranges. Digital versions, resolution 0.1%, direct
readout in gas percent, built-in microprocessor-based linearity.
SIGNAL OUTPUT
4-20 mA, isolated. This signal is only available on digital models.
NOTICE CONCERNING SUPPLY SYSTEMS
Because these gas mixers operate by intermittently filling a surge
tank in the gas mixer, the gas mixer will demand the supply gases
at full gas mixer capacity for some period of time, even if the
mixed gas demand is small. For this reason, bulk gas supply systems
(not portable liquid cylinders) should be used for the major gas,
and in some circumstances, the minor gas. Please contact the Thermco
sales engineer for guidance.
WARNING
Improper use of this product can cause death, serious injury, or
property damage. Personnel dealing with this equipment should read
and understand warning labels and instruction manuals provided by
Thermco. Only personnel familiar with industrial gases should attempt
to install or service this equipment. Gases from high-pressure cylinders
must be reduced to the specified pressure before entering the gas
mixing system to prevent the possibility of equipment damage and
personal injury.
Only use oxygen in gas mixers specifically designed for oxygen
service. Gas mixers not designed for oxygen service can not be converted
to oxygen service.
Flammable or corrosive gases should not enter these gas-mixing
systems.
DOCUMENTATION
Each gas mixer is supplied with two instruction manuals, which
include complete wiring and flow diagrams. A complete data sheet
is prepared for each gas mixer specifying major parts of the gas
mixer and all pressure settings and orifices. A copy of the instruction
manual is kept on file at Thermco, and engineering assistance is
provided if required. Thermco has been providing service on gas
mixers since 1964.
ORDERING
Thermco gas mixers are available through many local industrial
gas suppliers. Thermco gas mixers may also be ordered directly from
the factory. Before ordering please generate the proper model number
by using the system on the rear page of this literature. It is especially
important to order the correct pressure conditions for the application.
If there are questions, please contact the Thermco sales engineer.
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