For other PSI sensors, select a sensor from the menu below:
Pro-Oceanus GTD-Pro™
The GTD-Pro™ Standard Model was the first instrument
developed by
Pro-Oceanus Systems and is designed for use:
In laboratories
On moorings, profilers and gliders
Aboard ships in underway mode
The PSI GTD-Pro™ is said to be the most accurate and stable
dissolved gas sensor ever developed. The GTD-Pro™ measures the sum of
the partial pressures of dissolved gases in water. It uses a small
sample volume that equilibrates with dissolved gases through a
semi-permeable membrane. Measuring the pressure of the equilibrated
gases gives the gas tension (the sum of the partial pressures or,
more accurately, fugacities of all dissolved gases).
How accurate is a GTD-Pro™?
Our GTD-Pro™ has an accuracy of better than 0.02 % per year, and a
precision of microbars. One of our standard GTD-Pro's™ was deployed
numerous times in locations that included the Labrador Sea, the
Equatorial Pacific, and the North Pacific. After six years of
demanding use, the instrument was re-calibrated and found to have
drifted from its original calibration by less than 0.01% per year.
What is the difference between the Standard GTD-Pro and the Hurricane Model (HGTD)?
The primary differences between the Standard GTD-Pro and the HGTD
are size, weight and versatility in configuration. The PSI
patented pumped fast interface, is a standard feature of the HGTD, and is
available as an option for the Standard
GTD-Pro™. This highly
innovative interface, which has been tested to 1000 meters depth,
can be configured in various ways to fit the user's application
(e.g. in a canister separate from the electronics housing). The
table below provides a summary of the differences between the
Standard and HGTD models. For more details about the Standard
GTD-Pro and HGTD, click on the links above or
contact PSI.
PSI Standard GTD-Pro Features:
Exceptional precision and accuracy
User friendly set-up and operation
RS-232/485 communications interface
Compatible with Sea-Bird Electronics CTD's (please contact PSI for
models supported)
Low power requirements
Light weight and compact size
Hard anodized aluminum housing
Shipped in high-impact carrying case
Special Order Options
Pumped Delrin plenum for flat interface: reduces the thickness of
the water-side mass transfer boundary layer and reduces the time
constant for equilibration. Note that a source of water flow is
required at 3 to 10 liters per minute (optional Sea-Bird 5-T pump at
3000 RPM available from Pro-Oceanus Systems Inc. or Sea-Bird
Electronics, Inc.). Time constant, = 10 minutes depending on flow
rate.
Tubular pumped fast interface: alternate fast interface for our
standard PSI GTD-Pro. Note that a source of water flow is required
at 3 to 10 liters per minute (optional Sea-Bird 5-T pump available
from Pro-Oceanus Systems Inc. or Sea-Bird Electronics, Inc.). = 3
minutes depending on flow rate.
For more options for measuring gas tension see
HGTD or
contact PSI.
| Spec Comparison | ||
| Feature | GTD PRO | HGTD |
| Length | 12.5 in. (31.8 cm) |
9 in. (22.9 cm) |
| Diameter | 4.5 in. (11.4 cm) |
3.25 in. (8.3 cm) |
| Weight (Air) | 15.5 lbs. (7 kg) |
3.6 lbs. (1.6kg)* |
| Weight (Water) | 7.436 lbs. (3.38 kg) |
.32 lbs (0.6 kg)* |
| * Sensor housing only | ||
Why Measure Gas Tension?
The Pro-Oceanus GTD-Pro™ and HGTD™ have been used in a broad
range of applications including studies of gas exchange, estimates
of net biological production, ocean mixing, and denitrification.
See for example:
Emerson, Steve, Charles Stump, Bruce Johnson and Dave Karl 2002. In
situ determination of oxygen and nitrogen concentrations in the
upper ocean. Deep Sea Research, 49, 941-952. - Link
HERE.
McNeil, C.L., D.R. Katz, R. Wanninkhof and B.D. Johnson 2006.
Continuous shipboard sampling of dissolved N2, O2 and CO2, Deep-Sea
Res. Let., LO1607. - Link
HERE.
McNeil, C.L., D.R. Katz, B. Ward, W.R. McGillis and B.D. Johnson,
2006. A method to estimate community metabolism from profiles of
dissolved O2 and N2. Hydrobiologia, 571, 181-190. - Link
HERE.
McNeil, Craig, Eric D’Asaro, Bruce Johnson, Matthew Horn and Steve
Emerson 2006, A fast response gas tension device, Journal of
Atmosphere and Ocean Technology; 23(11), 1539-1558. - Link
HERE.
Specifications
Download the GTD-Pro™ Product Brochure
HERE
Physical Specifications
Length: 12.5 in. (31.8 cm)
Diameter: 4.5 in. (11.4 cm)
Weight (air): 15.5 lbs. (7 kg)
Weight (water): 7.436 lbs. (3.38 kg)
Performance
Accuracy: <0.02 mb per year drift from calibration
Precision: 0.002 mb
Gas tension limits:
Min: 800 mb
Max: 2000 mb with our standard pressure sensor
Electrical Characteristics
Input voltage: 9-16 Volts DC
Power Consumption:
While measuring: 0.8 Watts (67 ma at 12 volts)
While sampling at 30 minute intervals: 27 mW overall