partialReplacement: Function to calculate Parial replacement of flow through...

Description Usage Arguments Details

View source: R/partial_replacement.r

Description

Provide 3 of 4 parameters and return the fourth

Usage

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partialReplacement(
  flowTime = NULL,
  flowRate = NULL,
  volume = NULL,
  fraction = NULL
)

Arguments

flowTime

Time of flow

flowRate

Rate of flow

volume

Volume of reservoir

fraction

Fraction replacement

Details

for use in toxicity testing from http://www.nethawaii.net/~kraul/publications/waterchange.html Practical Formulas for Computing Water Exchange Rates Scanned from a reprint of Progressive Fish-Culturist, 47(1), 1985, pp. 69-70. Reported data on water exchanges rates in aquaria and aquaculture systems are often confusing because different methods of exchange result in different amounts of water replacement. For example, in a batch or discrete replacement, if half the volume of water is removed and then replaced with new water,the tank will have 50 For some applications, it is important to know exactly how much water has been exchanged. Examples include dilution of antibiotics and other medications, and optimum dilution of excreted wastes. Sprague (1969) plotted the times for replacing 50, 75, 90, 95, and 99 1) F= 1-(1/e^(TR/v)) =1-(e^(-TR/v)) 2) T= -ln(1-F)V/R 3) R= -ln(1-F)V/T where V=volume of the system, R=rate of water input (ie, liters/hour), T = time water is flowing, and F= the fraction of new water actually replaced in the system. These formulas assume complete mixing of input water before outflow, and were verified by measuring change in salinity when mixing fresh and salt water. Note: page 70 figures not translated on scanner) Fig. 1. Percent water replaced versus percent added in a thoroughly mixed continuous flow system. The dashed line indicates the exchange achieved by discrete water replacement. Fig. 2. Flow rate (R) required for fractional (F) water replacement during any time period (T) for a tank of known volume (V). The upper horizontal axis is specifically for a tank of 4000 liters volume. Formula #1 can be used to compute the fraction of water replaced in a given time when the flow rate and container volume are known. TR/V is equal to the fraction of water added to the container. Figure 1 is based on formula #1 for converting the fraction of water added to the actual fraction retained. Note that the actual percent replaced is almost equal to the percent added below 25 Formula #2 can be used to compute the time needed to replace old water such as polluted or treated water with any fraction (F) of new water, if the container volume and water inflow rates are known. The equation expresses the relationship illustrated by Sprague (1969), and allows for computation of flow time for any desired fractional replacement. Formula #3 can be used to compute the rate of water flow needed to replace any fraction of water in a specified time. Figure 2 is similar to Sprague?s (1969) graph, and is included as one method of using these formulas. Graphs or tables can be prepared from the formulas for tank volumes and exchange rates that are most useful for each facility. References Cited: Rainey, R. H. 1967. Natural displacement of pollution from the Great Lakes. Science 155:1242. Sprague, J. B. 1969. Measurement of pollutant toxicity to fish. Part I. Water Research 3:793-821. Authors: Syd Kraul, Waikiki Aquarium, 2777 Kalakaua Ave, Honolulu, HI 96815. Jim Szyper, Hawaii Institute of Marine Biology, Coconut Island, Kaneohe, HI 96744 Bob Bourke, National Marine Fisheries Service, P.O. Box 3830, Honolulu, HI 96812 Post-publishing note:The information presented in the figures is easily derived with a TI-55 CALCULATOR, if you dont have access to the publication. Examples of Percent of volume added, with Actual replacement in parentheses: 400 95 60 20 volume=volume of the system Liters rate=rate of water input (ie, liters/hour) flow.time= time water is flowing fraction= the fraction of new water actually replaced in the system stock=concentration of stock or inflow solution


duanxd1/gfuns documentation built on March 7, 2020, 12:46 a.m.