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Wildland Fire Chemicals
Evaluation of Wildland Fire Chemicals
This procedure is used to determine the densities of fire retardants that are either too dense or contain high particulate, making it impossible to use the density meters. This method is more accurate than the syringe method.
- Pycnometers with lids, marked
- Balance, readable to 0.1 mg
- Select pycnometer flasks for the test, ensuring that each has a lid with a matching unique identification.
- Calibrate the pycnometer/lid sets using the method on the following page.
- Ensure that the liquid to be tested has been thoroughly, but gently stirred and that any entrained air has been removed.
- Weigh each empty pycnometer/lid set and record the weight.
- Carefully pour the test material into a pycnometer. The liquid should come nearly to the rim of the pycnometer.
- Carefully place the lid straight onto the flask.
- Firmly and evenly seat the lid on the flask.
A small amount
of liquid should appear from the hole in the lid.
- If the flask was properly filled, a slight amount of liquid will come out of the hole in the lid.
- If no liquid appears from the hole in the lid, remove the lid, add more liquid, and repeat the process.
- Carefully wipe the excess fluid from the lid with a disposable wipe.
- Looking through the lid, ensure that there is no air bubble remaining on the surface of the liquid.
- Weigh the flask, lid, and test sample and record the weight.
- Repeat the process with additional flasks and samples.
- Wash, dry, and carefully store all flasks and lids.
- Calculate the sample weight by subtracting the weight of the empty flask and lid from the weight of the full flask and lid.
- Calculate the density by dividing the sample weight by the flask volume determined during the calibration step.
- Average all replicates and report the final density.
Glass pycnometers can be used to determine the density of a liquid, but they must be calibrated to determine the volume of a unique flask and lid combination prior to use with test samples.
- Pycnometers, at least 3 sets of flasks and lids
- Balance, readable to 0.1 mg
- Match a lid to each flask, ensuring a good fit between the parts.
- Mark each piece with a glass etcher and record the identity of each set.
- Weigh each empty pycnometer flask and lid and record the weight.
- Carefully pour distilled water into each flask being careful to eliminate bubbles in the flask. The flask should be filled to about 1/8 inch to ¼ inch below the rim.
- Put the lid straight down onto the flask, firmly (but not strong-arm) pressing the lid down into the flask
- There should be enough sample volume that a small amount comes out through the hole in the lid and there is no air captured within the flask.
- Wipe excess fluid from the lid with a disposable tissue. The sample should be flush with top of lid.
- Weigh the full flask and lid and record weight.
- Determine the temperature of the distilled water and record.
- Determine the weight of distilled water in the flask by subtracting the weight of the empty flask/lid from the weight of the full flask/lid.
- Empty and dry each flask and lid between tests. A pipe cleaner works well to dry the hole in the lid.
- Using the temperature/density chart below, determine the density of the distilled water at the measured temperature.
- Determine the volume of the flask by dividing the weight of the distilled water by the density of the distilled water at the measured temperature.
- Repeat steps 3 through 12 at least 3 times for each flask. Average the results and record the volume for each flask/lid set.
Use this test method to determine the densities of products which cannot go through the density meter or which cannot be easily cleaned from pycnometers. This method can be fairly accurate, depending of the choice of syringe capacity, and the syringes can be disposed of easily. The method is essentially the same as with a pycnometer.
3-5 mL disposable syringes (preferred) or up to 50 mL for crude measurements Balance, readable to 0.1 mg (preferred) or 1.0 mg for crude measurements
- Place an empty syringe on the balance and zero the balance.
- Fill syringe to a predetermined mark (i.e. 2 ml or 3 ml) with test product.
- Weigh and record result.
- Discard the syringe.
- Repeat Steps 1-4, 5 times or until consistent weights are obtained.
- Find the density (g/cm3) of each sample by dividing the weight of the test product by the volume mark used to fill the syringe.
- Find the mean of the all trials.
- Examine the data for outlying values; recalculate the mean of the trials without the outlying values.
- Sign and date the test sheet. Clearly show the mean value to use for further testing. Show all data and note reasons for eliminating any values.
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