PASCO PS-2195 User Manual

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Salinity Sensor
Temperature
Input port
Six pin mini-
DIN connector
Conductivity
Input port
Conductivity
BNC connector
Temperature
Input plug
Salinity Sensor
Salinity
Sensor Probe
The illustrations are not to scale.
PS-2195
Instruction Sheet
012-10546A
*012-10546*
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Included Equipment Part Number
Salinity Sensor PS-2195
Salinity Sensor Probe, 10 X, Conductivity/Temperature 699-11064
Recommended Items
PASPORT Extension Cable PS-2500
PASCO Interface Catalog or web site*
Data Acquisition Software Catalog or web site*
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Model No.PS-2195 Introduction
PS-2500 PASPORT
Extension Cable
Water Salinity
<0.5 ppt - fresh water
0.5 to 30 ppt - brackish water
30 to 50 ppt - saline water
>50 ppt - brine
Ocean Water
Ocean water is about 3.5% salt, or 35 ppt, and the salt is 90% sodium chloride.
The sensor actually mea­sures conductance, the inverse of resistance, expressed in siemens. Con­ductivity depends on the conductance and the cell constant of the probe. The cell constant depends on the geometry of the elec­trodes in the probe.

Introduction

Salinity is an ecological factor of considerable importance, influencing the types of organisms that live in a body of water. Salinity also influences the kinds of plants that can grow in a body of water, or on land fed by the body of water. A quantity of water is considered saline if it contains moderate or relatively high amounts of dissolved salts. The term is most often employed to describe water that would, if evaporated fully, leave behind salts incorporating sodium, calcium, or magnesium. Salinity is the degree to which a water is saline.
The PASPORT Salinity Sensor works with the 10X Salinity Sensor Probe to measure salinity, conductivity, and temperature. The sensor determines salinity based on elec­trical conductivity. The sensor has a built in calculation to compensate for the change in conductivity due to temperature change based on the Practical Salinity Scale (PSS). Essentially the conductivity increases as the temperature increases because ions in solution are more mobile. It is possible to approximate a calculation of total dissolved solids (TDS) using data from the sensor.
The Salinity Sensor can be connected to any PASPORT interface (such as the Xplorer GLX or PowerLink). The sensor can be used with the PASPORT Extension Cable. This cable is 2 meters in length, extending the distance a sensor can reach from a computer or portable datalogger.
Salinity is often expressed as parts per thousand (ppt) which is approximately equal to grams of salt per liter of solution. However, salinity is the sum weight of many differ­ent elements within a given volume of water; not just sodium from sodium chloride. In the 1970’s, salinity was redefined as the conductivity ratio of a water sample to a standard potassium chloride (KCl) solution.
Usage
One use for the sensor is to explore the salinity of local water sources. Another use for the sensor is to explore the interrelationship of salinity, temperature, and conductivity. The sensor can be used to measure the change in the salinity of saltwater as the water evaporates.
About the Sensor
The PS-2195 Salinity Sensor’s conductivity range is from 1,000 microsiemens (S) to 100,000 S. The temperature range is from 0 celsius (C) to 50 °C. The salinity range is from 1 part per thousand (ppt) to 55 ppt ±10% without calibration.
The temperature compensation is ±0.5 ppt from 0 C to 45 C at 33 ppt.
If the temperature of the solution is out of range, the sensor reports the salinity as 0 ppt. If the conductivity of the solution is below 1,000 S, the sensor reports the conductivity as 0 S.
The Salinity Sensor measures the electric current through a solution between the two platinized platinum electrodes in the Salinity Sensor Probe. The current through the solution is due to the movement of ions, so the higher the concentration of ions in the solution, the higher its conductivity. A voltage (AC) is applied across the two elec­trodes in the tip of the probe and the measured current is proportional to the conduc­tivity of the solution.
Platinized platinum
electrodes
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Model No.PS-2195 Setup
TIPS
DO NOT submerge the entire Salinity Sensor Probe in a liquid. The top end of the probe is not waterproof.
Use distilled water from a wash bottle to rinse the end of the probe before making another measure­ment.
DO NOT put the probe in viscous, organic liquids, such as heavy oils or eth­ylene glycol. Do not put the probe in acetone or non-polar solvents, such as pentane.
Clean the electrodes when necessary by soak­ing the tip in acid (e.g., vineagar or diluted hydro­chloric acid (muriatic acid)) and then rinsing with water.
If the tip is heavily fouled with organic material, soak the tip in alcohol or bleach and then rinse with water. Gently wipe the tip with a soft, nonabrasive cloth towel.

Setup

Hardware Setup
The following steps can be performed in any order.
1. Connect the Salinity Sensor Probe to the Salinity Sensor. Connect the Conductiv­ity BNC connector from the probe to the Conductivity input port on the sensor. Push the BNC connector onto the port and turn the connector clockwise (left-to-right) until the connector locks into place on the port.
2. Connect the Temperature input plug from the probe to the Temperature input port on the sensor.
3. Connect the Salinity Sensor to a PASPORT interface.
4. If you will be using a computer, connect the PASPORT interface to the com-
puter’s USB port.
Using the Probe
Before using the Salinity Sensor Probe, soak the probe in distilled water for 5 to 10 minutes. Use a towel to dry any water droplets that are on the probe so that the water will not dilute the sample that is to be measured.
Submerge the tip of the probe at least 5 centimeters (cm) into the sample to be mea­sured. Start recording data. Watch the display in your data acquisition program.
DataStudio Setup
If you will be using the Salinity Sensor with a computer, install the latest ver­sion of DataStudio first. Check the PASCO web site at www.pasco.com for information.
1. When you connect the Salin-
2. Select Launch DataStudio in the PASPortal window.
A Digits display for salinity, temperature, and conductivity will open automatically.
3. Click to begin data collection.
To view and change the sample rate and other sensor properties, click .
Xplorer and Xplorer GLX Setup
If you will be using an Xplorer or Xplorer GLX in logging mode (not connected to a computer), connect the Salinity Sensor to the Xplorer or Xplorer GLX, turn the inter­face on, and press to begin data collection.
ity Sensor to the computer through a PASPORT inter­face, the PASPortal window will launch automatically (if DataStudio is not already running).
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