Glacier Transportable Sampler - Isco
Glacier Transportable Sampler - Isco
Glacier Transportable Sampler - Isco
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<strong>Glacier</strong> <strong>Transportable</strong> <strong>Sampler</strong><br />
Appendix D Battery Selection Guide<br />
D.1 Introduction This section provides information to assist with selecting a power<br />
source for 12 VDC battery-powered <strong>Glacier</strong> <strong>Sampler</strong>s. Teledyne<br />
<strong>Isco</strong> recommends deep-cycle marine batteries, although any 12<br />
VDC power source will work provided that it can meet the<br />
current demands of the refrigeration system.<br />
D.2 Determining the<br />
Power Consumption<br />
The <strong>Glacier</strong> requires continuous 12 VDC power for several purposes:<br />
• an idle current while the sampler is inhibited, waiting<br />
for the next sample, or after it has finished its sampling<br />
program<br />
• logging temperature readings at one-minute intervals<br />
• operating the pump<br />
• cooling the sample container.<br />
The first three are negligible when compared to the energy<br />
required to cool the liquid as it is collected and to maintain the<br />
composite sample at 3° C.<br />
The amount of energy required to cool the samples correlates to<br />
ambient air temperature. The higher the air temperature, the<br />
more the <strong>Glacier</strong> must operate the refrigeration system.<br />
The equation below may be used as a guide for selecting a<br />
battery that will meet the requirements of your sampling<br />
program.<br />
V c x A c + D m x A m = Expected power consumption, Amp-hours<br />
(<br />
6<br />
)( )<br />
Where:<br />
V c = Total sample volume, in liters<br />
A c = Amp-hours to cool sample liquid from 20° C (Fig D-1)<br />
D m = Number of days sample volume must be maintained<br />
A m = Amp-hour per day factor for maintenance (Fig D-2)<br />
Before using the equation you must know:<br />
• the total sample volume that will be collected<br />
• the number of days that the <strong>Glacier</strong> must keep the<br />
sample cooled to 3° C<br />
• and the average ambient temperature.<br />
The first group in the equation calculates the amp-hours<br />
required to cool the sample liquid as it is collected. The total<br />
sample volume, V c , can be determined by the programmed<br />
number of samples multiplied by the sample volume. If the<br />
D-1