LaMotte DO 4000 User Manual

TABLE OF CONTENTS

Page

Spec i fi ca tions ......................................................................................... 4

Dis solved Ox y gen Ba sics........................................................................ 5

DO Me ter Ba sics.................................................................................... 7

As sem bling the Probe............................................................................ 8

Po lar iza tion............................................................................................. 9

Ini tial/Re place ment Probe Cal i bra tion................................................ 10

Cal i bra tion ........................................................................................... 11

Zero Cal i bra tion................................................................................... 15

Testing.................................................................................................. 16

Trou ble shooting.................................................................................... 18

Me ter Care ........................................................................................... 19

Cleaning the Probe.............................................................................. 20

War ranty In for ma tion.......................................................................... 21

Parts & Ac ces sories.............................................................................. 22

SPECIFICATIONS

MEASUREMENTS

1. Oxygen concentration expressed in parts per million (ppm) of O

2. Oxygen concentration expressed as percent (%) of oxygen saturation

3. Temperature expressed as °C

RANGE (for Specified Accuracy)

1. 0 to 19.99 ppm O

2. 0 to 199% saturation

3. 0 to 40°C

PRECISION

1. 0.01 ppm for O2 concentration

2. 1% for water saturation

3. 0.01°C for temperature

ACCURACY

1. For Oxygen Concentration 5% of reading or 0.10 ppm (whichever is

greater) when taken within 5°C of the calibration point temperature

For Temperature ±0.5°C

RESPONSE TIME

90% of final readings within 45 seconds, except at extreme temperatures

SIZE AND WEIGHT

Case: 150 x 80 x 45 mm (5t x 3c x 1n in.)

0.33 kg (n lb)

Probe: 15.5 mm diameter x 120 mm (a” dia x 6g”)

0.10 kg (c lb)

POWER REQUIREMENTS

Maximum requirement of 100 mW Source: Internal - Battery, Type 1604A (9 volt)- replaceable or

Nickel/Cadmium rechargeable with built in charge regulator External - Wall type AC adapter rated at 9VDC/50mA

(minimum) with 3.5 mm jack, “tip positive” polarity (LaMotte Code #1708)

DISSOLVED OXYGEN BASICS

Oxygen, in the form of a gas, is a major component of air. Humans, plants, and animals use this oxygen to respire, or breathe. Gaseous oxygen also occurs in the water, where aquatic life uses it to respire. Oxygen in water is often called dissolved oxygen.

Dissolved oxygen is vital to the survival of aquatic organisms. Naturally present, dissolved oxygen enters water when plants photosynthesize or through dispersion. When plants, particularly algae, photosynthesize, sunlight is converted into needed chemical energy, releasing oxygen into the water. Dispersion, the exchange of oxygen between the atmosphere and water, can be aided by wind and wave action. Oxygen can also be mechanically introduced into the water by use of an aerator.

Once in the water, oxygen is consumed in several ways, including the respiration of plants and animals and the oxidation, or chemical breakdown, of dead and decaying plants and animals. In extreme cases all available oxygen may be used in the decomposition process, so no oxygen is left for respiration, and the plants and animals eventually suffocate.

Dissolved oxygen can be measured as the concentration of oxygen present in the water (mg/L or ppm oxygen), or as the percent of oxygen actually in the water as compared to the maximum amount the water can hold. This is referred to as percent (%) saturation. The level at which water is saturated is dependent upon several factors, but two of the most important are temperature and salinity. As the temperature of the water decreases, its ability to hold oxygen increases. Likewise, as salinity levels decrease the saturation level increases.

Dissolved oxygen levels are vital in many areas, but they are of particular concern to aquaculturists, environmental analysts and wastewater treaters, who must constantly monitor levels in the water. For aquaculturists, dissolved oxygen can be the difference between a healthy, profitable crop of fish, and disaster. If sufficient levels of dissolved oxygen are not maintained fish growth can be hindered, the fish may be more susceptible to infectious diseases, or they may even suffocate. Many aquaculture systems use aerators, especially at night when DO levels are lower, to ensure sufficient oxygen for a healthy crop.

Environmental analysts are also concerned with dissolved oxygen levels. This test is one of the most important for determining the ability of a pond, lake, or other body of water to support life. It is also used as part of the biochemical oxygen demand (BOD) test to determine the pollution level of the water.

The dissolved oxygen test is also important to operators of waste water facilities, both at the operation site and in the lab. Dissolved oxygen levels are monitored at the wiers, and before the water leaves the plant after being dechlorinated. In the laboratory the dissolved oxygen test is used to analyze the BOD of the water.

DO METER BASICS

A voltage is applied across the electrodes of the Dissolved Oxygen probe. Silver ions are oxidized at the anode producing silver chloride and electrons. Oxygen is reduced at the cathode accepting electrons and producing hydroxide ions. The current generated by the chemical reactions is conducted through the filling solution. This current is proportional to the oxygen concentration and is converted by the meter to a dissolved oxygen reading.

The DO 4000 provides a digital readout of oxygen concentration in mg/L or ppm, or percent (%) saturation. The meter compensates for temperature and salinity which can effect the dissolved oxygen reading. Built-in thermistors automatically provide a readout in degrees centigrade (°C). Salinity levels from 0 to 30 parts per thousand (ppt) are set with the “Salinity Comp” knob. An altitude correction can be determined by consulting the Altitude Chart on page 13.

FUNCTIONS OF THE DO 4000 METER

ASSEMBLING THE PROBE

GOOD PRACTICE GUIDELINES

Keep the membrane wet at all times. Between readings the probe can be stored with the tip in a beaker of deionized water. For longer periods, the probe should be stored in the protective sheath. The sponge insert in the tip of the sheath should be dampened with distilled water.

MEMBRANE REPLACEMENT

1. Hold the probe in a vertical position. Carefully unscrew the

membrane module.

2. Holding the new membrane module in a vertical position with the

threaded end up, fill with DO Filling Solution (2787).

3. Keeping the module in a vertical position, carefully screw the

module onto the probe, allowing excess filling solution to escape through the screw thread. After assembly inspect the membrane. Make sure no air bubbles are present and the membrane is not creased.

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