Specifications

Copyright 2014 Carl Bright Inc. All Rights Reserved
Page 15
layers is made and a voltage difference is seen on the electrical bias. The tradeoff is that it is very sensitive to
pressure changes because any pressure changes push or pull the acid onto one of the electrochemical layers
and a reaction is made as well.
Furthermore, it has cross reactivity to other chemicals that may be encountered in the drilling process. One of
the most reactive is acetylene which may be generated using carbide for a lag check. Acetylene may knock
the sensor out for up to 20 minutes. Because of these cross reactions, it is not immune to drift and should be
adjusted to 21% periodically to air. To do this just disconnect the sample line for a few of minutes and adjust to
21%.
“Fuming” mud which is emitting gases other than normally seen may cause the O
2
to appear to drift as well,
when in reality it is reacting to the loss of O
2
that the fumes have replaced. Keep in mind where the sample is
being taken from.
E. Gas Units Quick Check
If the user would like to do a quick check on the gas units output, the easiest way is to use a small hand held
cigarette lighter. Place the lighter up to the ¼” sample port and press the lever to allow gas to escape. Do not
strike the lighter. This will inject butane into the system. Doing this for 10 seconds will give a good spike
reading on the Bloodhound. The output amount of the spike will vary depending on the attenuation settings,
the damping settings, and the actual amount of butane injected. A typical spike with attenuation at 30, normal
damping, and a 10 second burst from a lighter that has ¾” a flame would be about 150 to 300 gas units,
depending on how the user holds their fingers around the lighter.
F. Oxygen and Carbon Dioxide Quick Check
The O
2
and CO
2
detectors in room air read about 21% O
2
and 0.01% CO
2
. To check the detectors, take a 2
liter or 1 gallon plastic bag and remove the air from it by squeezing it. Then take a deep breath and hold it for
3 to 5 seconds. The longer you hold it the more O
2
is removed and replaced with CO
2
. After that, breathe into
the bag until it has about 2 liters into it. Human expiratory gases are about 17-19% O
2
and 2-5% CO
2
. The
readings on the Bloodhound should reflect somewhere around these numbers. You should at least see them
change.
G. Recommended Calibration Gases
We recommend the following gases and supplier company to be used with the Bloodhound system. Each
bottle should last more than a year with regular calibrations. A regulator that is compatible with and will fit all
tanks described below: Model 620-SSC10.
MESA Specialty Gas & Equipment a Division of MESA International Technologies, Inc.
2427 South Anne Street, Santa Ana, CA 92704
Toll-Free: (866) 470-MESA (6372) Tel: [phone]; Fax [phone]
http://www.mesagas.com/
Following are the part numbers and descriptions.
High Range Calibration Gas – 99+ % Methane:
S1971 METHANE 99.0% MIN PURITY
CYLINDER:58L
VALVE CGA:C-10
CONTENTS:58 LITERS
PRESSURE:1000 PSI
SHELF LIFE:NO LIMIT
Note: wall gas (also known as city or house gas) can be used for the high range calibration. This is the fuel
that is piped to houses and business for cooking and heating. It is natural gas that has been refined to remove
moisture and most of the butane and propane, leaving mostly methane. Because the high range only needs a
very high methane concentration to generate a set point, and because the unit automatically adjusts the upper
range limit of the calibration based on the gas reactivity, a pure high range calibration gas is not necessary.