Specifications

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Page 14
The reason for providing this adjustment is to allow the Bloodhound to generate gas readings similar to older
technologies, such as hot-wire or catalyst bead systems. In most hot-wire or catalyst bead systems, when
high levels of hydrocarbon-based gases enter the detector, the system experiences problems immediately
reacting to the high gas levels, causing carbon buildup and other damage. This causes the system to become
inaccurate or to drift. In order to keep this damage to a minimum, air dilution was introduced to “cut” or air
dilute the sample. This had the desired effect of minimizing the damage to the system and to also allow for
final adjustment to the gas units based on experience, mud weight or any other parameter. Because the
infrared detector system cannot be saturated or damaged with 100% raw natural gas, and can instantly
monitor high levels of hydrocarbon based gases, physical air dilution of the sample gas is simply not needed.
However, this adjustment was still requested as an operational parameter. Further, the ability to not only cut,
but also amplify the sample gas readings, gives new flexibility to the mud logging community
B. Chromatograph Column Temperature
The Bloodhound’s internal chromatograph periodically takes a small portion of the sample gas flowing through
the Bloodhound and separates the hydrocarbon component gases C1 (methane), C2 (ethane), C3 (propane),
IC4 (iso-butane), NC4 (normal-butane), IC5 (Iso-pentane), and NC5 (Normal-pentane). (See the Bloodhound
Chromatograph section of this manual for a more detailed discussion.)
Each chromatograph column has an ideal working temperature, typically between 140 and 190 degrees F. For
a given column, a higher temperature will cause the components to move through the column faster, but at the
price of poorer peak separation. Do not set the column temperature over 220 degrees F.
C. Gas Units Zero, Low Span and High Span
When adjusting the Gas Units Zero, disconnect the inlet hose and allow the Bloodhound to stabilize in air.
When adjusting the Gas Units Low Span and High Span, please be sure that the correct gas is injected.
When adjusting the Gas Units Low Span, you will have to inject 2.5% methane gas in air for the duration of the
adjustment.
NOTE: In the Bloodhound system 1% methane is 100 Gas Units and 2.5% methane is 250 Gas Units. We
recommend that the Bloodhound system is calibrated using 2.5% methane in air.
When adjusting the Gas Units High Span, user must inject 100% methane (or wall gas) for the duration of the
adjustment. Adjust the instrument to read as close to 8,000 ( or as the user prefers ) as possible while in
calibration mode. The reading will change after exiting the calibration mode.
D. CO2, O2, and H2S Zero and Span
When selecting a CO
2
, O
2
, or H
2
S zero or span setting, it is as simple as injecting clean air or a known sample
gas and adjusting the output to match the gas injected. Note that there is no O
2
zero adjustment. O
2
zero
adjustment is automatically performed when 100% Methane or wall gas is injected.
If adjusting the zero and span on a particular gas, always adjust the zero first, then the span. Adjusting the
span first and then zero will throw off the span adjustment.
Oxygen Sensor Notes
This sensor was included as a differential monitor as to the amount of methane in the sample. If user
observes 5% of methane then the O
2
should change about 1% no matter where it is presently.
The O
2
is an electrochemical sensor does not have a sacrificial element so it should exhibit a long life.
However, because of its construction, the O
2
sensor is highly sensitive to any exhaust back pressure. If the
user desires the O
2
sensor to work correctly, the Bloodhound must have a 1/2” exhaust line or it will fail rather
quickly. Prolonged exposure to back pressure will cause irreparable damage to the sensor and will
necessitate replacement.
The sensor is constructed using sandwiched layers of chemicals. The reactive chemical is an acid between
two electrochemical layers. As oxygen is presented, a reaction between the acid and the electrochemical