Specifications

Page 22

E. Chromatograph Column

The chromatograph column fits snuggly in the case at the upper right-hand side. It can be replaced in a matter

of minutes by disconnecting one electrical cable and the input and exhaust tubing. Take care to pull the tubing

straight off the connectors, because side pressure can cause the connectors to break.

7. THE BLOODHOUND CHROMATOGRAPH SYSTEM

A. Control of the Bloodhound Chromatograph System

The control of the Bloodhound system is through 2 registers and the control knob.

time expires, the Bloodhound will start another chromatograph injection and cycle. Setting the column

temperature to a higher level will allow for the separations to transfer through the column at a faster pace

which will allow the user to reduce this injection timing but may lose the C1-C2 separation.

set to 5, and should not be set greater than 10. This timer is automatically adjusted on the fly by the Brain

Board in order to keep from saturating the column with sample gas and causing distortions in the separations.

Column Temperature

When turning the control knob, one of the options displayed is column temperature. Typically the temperature

is set to around 120 to 150 degrees F. The user has the ability to adjust this temperature to compensate for

the degradation of the column over time or to adjust the performance characteristics of the chromatograph

system. Do not set the column temperature over 210 degrees F. Internally there is a thermal fuse that is

preset to operate at 240 degrees F. The closer the user sets the column temperature to this level, the more

likely this fuse will open up and the column will become useless because it will not be able to hold temperature.

If the thermal fuse opens, the protective insulation must be peeled off and the thermal fuse replaced. The

thermal fuse is provided to keep the column from overheating in case of a controller failure.

NOTE: If the user changes the column temperature, it is highly recommended that chromatograph be

calibrated as the Bloodhound employs a slope peak detector and peak timing for high accuracy. Changing the

temperature changes the elution time of the gasses and therefore changes both of these sampled

characteristics.

B. Calibration of the Bloodhound Chromatograph System

If the temperature of the column is changed to a higher or lower temperature, the user must recalibrate the

Bloodhound chromatograph system in order to maintain accuracy. To calibrate the Bloodhound

chromatograph system the user will need a recirculation bag and a tank of calibration gas. The calibration gas

is a 5 or 7 part mixture consisting of equal parts of methane, ethane, propane, iso-butane, normal butane, iso-

pentane and normal pentane. These gases are typically supplied as a 5 or 7 part mixture containing 1% of

each with the remainder nitrogen.

To prepare to calibrate the chromatograph, make recirculation bag, which is a Ziploc bag with two (2) pieces of

clear PVC tubing taped into the lower corners. This type of bag allows for the calibration gas to continuously

recirculate through the Bloodhound system for calibration and testing. To construct a recirculation bag, obtain

a 1 gallon Ziploc bag and cut off the two bottom corners. Obtain 2 pieces of clear PVC tubing from a hardware

supply house. One piece of clear PVC tubing 1/2” ID and the other 1/4” ID. Tape these pieces of tubing into

the corners of the bag, and (temporarily} put tape on the end of the ¼” tube. Squeeze air out of the bag.

Connect the regulator from a tank of 5 or 7 part calibration gas bottle to the Ziploc baggie and fill the baggie

with the 5 or 7 part calibration gas and then move to the Bloodhound.