Range: 0-19.99 and 0-199.9 NTU

Accuracy: +/- 2% or 0.05 NTU

Display: 0.5" LCD

Photodetector: 2 photo voltaic cells, centered at 90 degrees to the incident light path, spectral peak response between 400 and 600 nm.

Lamp: Tungsten, lens-end 3.5 volt, operating at a color temperature of 2230 degrees K. Distance traversed by incident light and scattered light within the sample tube is 2.5 cm.

Range Selector: 3 Positions: OFF/0-20 NTU/0-200 NTU

Zero Control: For calibration to 0 NTU

Line Operated: 120 volts, 50/60 Hz

Battery: 12-volt sealed battery with battery pack

Material: Aluminum

Dimensions: 9.25L x 6.66W x 3.20 H"

Weight: 3 lbs, Model 800; 9 lbs, Model 800-P

Models 800 and 800-P meet EPA specifications for measurement of turbidity in drinking water. Their drift-free, accurate readings make these instruments suitable for testing municipal water, food and beverage processing, and any aqueous solutions in which control of clarity is critical.

Models 800 and 800-P are true nephelometers, measuring the amount of light scattered at a right angle from a beam of light passing through the test sample. Test results are read directly in NTUs on a LCD digital readout. The turbidimeters are pre-calibrated and a simple zero adjustment is the only steps required prior to testing.

Cover the sample tube and chamber when a reading is taken. To prevent dust accumulation, leave the light shield in place on the instrument when it is not in use. Do not store sample tubes in chamber.

A function control switch turns the instruments ON and also serves as the range selector for the two ranges: 0-20 and 0-200 NTU. These meters are designed to remain on permanently. However, during long periods of nonuse, it is recommended the units be switched off to prolong lamp life. If switched off, they will require approximately 30 minutes for warm-up.

Handle the sample tubes with extreme care. Discard any tubes with scratches. It is important that the tube, especially the bottom, be wiped clean with lint-free tissues before inserting into the reading chamber. To avoid smudges, handle all tubes by the top of the tube only.

On the side of each sample tube is a vertical white index line. Make sure this index line faces the exact same position every time you insert the sample tube into the test chamber. If the index line is not in the same position, the reading on the meter will change; not because of the change in the test solution, but because of the varying optical characteristics of the sample tube. You can verify this glassware effect by rotating the sample tube in the test chamber. You will notice the meter readings change.

Caps for the sample tubes are provided. These caps should be placed on the sample tubes before the tubes are put into the reading chamber to prevent any accidental spilling of the contents into the chamber. The chamber should be kept dry and clean at all times to insure accurate readings.

Turbidity samples and standards should be thoroughly mixed before inserting either into the reading chamber. All bubbles should be removed, either by allowing the tube to stand for a few minutes or by gently tapping and swirling the contents.

Particulate matter, such as dust or lint in the sample, will cause considerable fluctuation in the meter's readings as the particles come into the path of the light beam. In most cases, the meter's readings will waver between a steady reading and a higher reading. The reading will eventually fluctuate back down to a lower reading as the particles settle. When this type of reading is evident, it is best to remove the light shield and examine the sample.

The filter holder and syringe must be conditioned, by forcing at least two syringe loads of deionized water through the filtering mechanism to remove foreign matter from the filtering apparatus. The first and second rinses are discarded.

Turbidity-free water, as prepared below, may be stored in the dark, at room temperature, in a clear glass bottle with a screw cap, or in a turbidity tube and used as required.

The storage vessels should be rinsed thoroughly with filtered-deionized water. Periodically inspect the water for foreign matter in a bright light.

1. Remove the plunger from the syringe and attach the filter holder to the bottom of the syringe.

2. Pour approximately 50 ml of deionized water into the barrel of the syringe, replace the plunger into barrel and exert pressure on the plunger to slowly force the water through the filter. Collect the water in a suitably clean container.

3. Remove filter holder from syringe then remove plunger from bottle. This procedure is required to prevent rupturing the membrane filter by the vacuum created as the plunger is removed from the barrel.

4. Replace filter holder and repeat Steps 3 and 4 until the desired amount of turbidity-free water is collected. Periodically examine the membrane filter to insure no holes or cracks are evident.

5. Repeat Steps 1 through 4 using the 1X filtered water obtained in Step 4. This will give you 2X filter water.

6. Repeat Steps 1 through 4 using the 2X filtered water of Step 5. This given you a 3X or triple-filtered water.

7. Depending up on the nature of the unfiltered water, it is possible to prepare a liter or more of turbidity-free water using a single filter. The membrane filter may be stored in the holder for an indefinite period of time and used as required.

Calibration of the Models 800 and 800-P are based upon Formazin, a suspension which is more reproducible in its light-scattering properties than any other suspension.

These meters have been calibrated to Formazin solutions by the factory and the calibration should not change with time. However, should the instruments indicate a need for calibration, it may be accomplished in the laboratory by using carefully prepared formazin solution as noted:

The standard Formazin solution has a value of 4000 NTU. This solution is used as the stock solution and is stable for six months in the undiluted form. Dilutions of the stock solution are made with turbidity-free water as prepared in the instructions following.

A working standard is prepared by pipetting exactly 10 mL of the stock solution into a clean, volumetric flask and diluting to 100 mL. The working standard has a value of 400 NTU and is stable for one month. Dilutions of the stock solution, resulting in values below 400 NTU, should be prepared daily for reliable results.

The following table gives the relationship between dilutions of the 400 NTU solution and the resulting values as NTU. When diluting the suspension, use only turbidity-free, triple-filtered, deionized water.

(diluted to 100 mL with turbidity-free water)

400 0

200 50

50 12.5

20 5.0

10 2.5

1 0.25

0.5 0.125

0.1 0.025

Where A = NTU found in diluted sample

B = Volume of deionized water used, mL

C = Sample volume taken for dilution, mL

D = NTU of original, undiluted sample

For example, if 10 mL of sample water is diluted with 90 mL of turbidity-free water to a total volume of 100 mL and the resulting solution measures 40 NTU, the turbidity of the original undiluted sample is:

1. First, attach the AC wall adapter's 3.5 mm plug into the instrument's jack located on the rear panel of the instrument. The AC wall adapter converts 120 volts AC to 9 volts DC, 500 milliamps. Allow Model 800 or 800-P to warm-up for 30 minutes.

2. Insert a sample tube containing a turbidity-free zero (0) reference of either triple filtered water or a 0 NTU polymer standard into the chamber and replace the light shield. Ensure cap is on tube. Permanently sealed polymer standards of 0 NTU and 10 NTU values are available for purchase from the manufacturer. Please refer to the Replacement Parts section on the last page.

3. Rotate the range switch to the position, and with the zero adjustment knob adjust meter to read. For multiple samples, it is not necessary to reset the zero for each sample.

4. Remove the zero standard from the chamber and insert the test sample. Ensure cap is on the tube.

5. Replace light shield.

6. Rotate switch until appropriate range is selected for reading the sample. If the meter shows a 1___, it is over-ranged. Change the range switch to the 200 range. If the reading is greater than 200 NTU, dilute the sample by 1/2 to obtain reading and multiple results by 2. See page 2 for dilutions instructions.

7. Remove sample from chamber and replace light shield. Samples should never be allowed to remain in the chamber for extended periods of time.

1A. Insert a sample tube with turbidity-free, triple filtered, deionized water or a 0 NTU polymer standard into the chamber and cover. Set the range switch to NTU. Set the Zero Control potentiometer on the instrument panel so that the meter reads "0". If the meter cannot be made to read zero (0), then go to Step 1B; if the meter does read zero, then go to Step 2.

1B. Set the panel "Zero Control" knob at mid-range, so the arrow on the knob points at the letter "o" on the word "Control". Locate the coarse zero potentiometer. It can be found on the right side of the instrument and is marked "0". With a small screwdriver, set the coarse zero pot so that the meter reads as closely to zero (o) as possible. An exact zero can now be set with the "Zero Control" knob.

2. Insert a 10 NTU standard solution into the chamber and cover. Set the range switch to "20". If the meter does not read 10.00, adjust the potentiometer marked "20", found on the right side of the instrument, with a screwdriver until the meter reads 10.00. The digit "1" will appear in the display when the instrument is over-range, that is over 19.99.

3. With the 10 NTU standard solution in the chamber and covered, set the range switch to "200". If the meter does not read 10.00, adjust the potentiometer marked "200", found on the right side of the instrument, with a screwdriver until the meter reads 10.00. The digit, "1____" will appear in the display when the instrument is over-range, that is over 199.9.

4. Repeat Steps 1-4 if necessary. The instrument is now calibrated in both ranges.

Treat this battery with the same respect and caution given to a car battery. Failure to do so may result in damage or injury to you or the instrument.

Model 800-P turbidity meter has a battery pack. The battery pack is a sealed, gel-filled, 12-volt DC, 1.9 amp hour battery. The battery is permanently mounted in a luggage-type carrying case and is connected to the turbidity meter via a six-inch long cablr with plugs on both ends. Either model can be used in the laboratory with the AC wall adapter supplied with the meter or in the field with the battery pack.

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