The SIA puts forward the following formula for µ : The simplified Francis formula should also be noted : where the excress width on either side of the crest must be equal to at least 3 h, the height measured at least 2 m upstream from the weir crest.
Full Answer
Which type of Weir is used to measure discharge?
The shape of the weir is actually reverse triangle like V. so, it is also called V-notch weir. This type of weirs are well suitable for measuring discharge over small flows with greater accuracy. Here also consider an elementary horizontal strip of water of thickness dh at a depth h from the water surface.
What is a water treatment calculator and units’ converter?
Pure Aqua offers water treatment calculators and units’ converters to help you evaluate and select your water treatment systems properly. With these calculators, you can calculate and convert US units to the standard units (SI-units). This is useful for Pure Aqua customers since we sell our water treatment systems all over the world.
How do you measure the length and height of a weir?
The length is found by measuring the bottom width of the weir and the height is determined from measuring the water height above the bottom of the weir.
What is the Rere value of a weir?
Re = 0.0716 < 1 (stock’s law is applicable). Height of the water above or bottom of the weir (h = 0.041 m). The details of the clarification are giv en in Figures 9 and 10:
How do you size a weir?
There should be air (not trapped) underneath the water leaving the weir. The Length is the bottom width of the weir. The height is measured from the bottom of the weir opening to the top of the water level ponded behind the weir (not the water level right as it leaves the weir).
How do you measure water in a weir?
Q = 3.33 B H3/2, where Q is the water flow rate in ft3/sec, B is the length of the weir (and the channel width) in ft, and H is the head over the weir in ft. Use of this equation is subject to the condition that H/P < 0.33 and H/B < 0.33.
What are the units for the weir coefficient?
The weir coefficient, since it is a function of the gravitational constant, is not dimensionless and therefore has different values depending on which unit system you are using. For example, a weir coefficient (C) of 3.00 in English Units would be 1.66 in SI units.
What is a standard weir?
Standard Contracted Rectangular Weirs. The fully contracted rectangular weir (figure 7-1) is the most frequent standard weir used in irrigation. To be fully contracted, all overflow plate sides and ends must be located at least a distance of 2h1max (two maximum measurement heads) from the approach flow boundaries.
How do you calculate weir loading rate?
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How Do You measure V notch weir?
V notch weirs really are just that – a thin plate weir with a 'V' notch cut into it. The weir is placed to obstruct open channel flow and allow water to flow over the notch. This enables us to accurately measure the flow, by measuring the head upstream of the V notch.
What is the coefficient of discharge for a weir?
The flat-topped low weirs generally include broad-crested weir and short-crested weir. Under the same inflow condition, the discharge coefficient of short-crested weir is approximately 0.33–0.46, while that of broad-crested weir is 0.32–0.385, hence the former is stronger than the latter in terms of discharge capacity.
How a weir can be used to measure the flow rate of a stream?
The depth of water above the base of a weir is related to the flow rate through it; therefore, the weir can be used as a flow measuring device. The relationships of flow over weirs can be obtained by applying the energy equation from a point well upstream of the weir to a point just above the weir crest.
How do you calculate the coefficient of discharge?
To calculate discharge coefficient:Multiply the hydraulic head by the acceleration due to gravity.Multiply the resultant by 2 .Find the square root of the product.Multiply the resulting value by the area of cross-section to obtain the theoretical discharge for a fluid flow.More items...•
What is the weir height?
The height of the weir from the bottom of the channel to the crest should be at least 2 times the maximum expected head of liquid above the crest. This is necessary to lower the velocity of approach. The weir height should never be less than 1 foot (0.3 m).
What is a weir in water treatment?
weir (WEER) A wall or plate placed in an open channel and used to measure the flow of water or to control flow (from settling tanks and clarifiers) to ensure a uniform flow rate and avoid short-circuiting.
How are the weirs classified?
They can be classified as rectangular, triangular and trapezoidal weirs based on the geometry of flow section. They can be classified into sharp crested and broad-crested weirs based on the sharpness of the crest.
POWER CONSUMPTION
Provided below is a set of calculation tools to aid in Projecting the power consumption of our membrane based water treatment systems.
CHEMICAL DOSING
The set of calculation tools below can be used to to determine the correct dosing rates based of your Volume and water makeup.
OPERATING COSTS
Operators can use the set of calculation tools below to aid in projecting the operating costs of our media and membrane based water treatment systems.
PROCESS
Process calculations for water treatment applications can be helpful in determining the optimal perfomance settings for your system.
SIZING
Below is a set of calculation tools to aid in determining appropriate sized filters required of a given set of operational requirements.
CONVERSIONS
The conversion calculators below will convert between common water quality measurement units.
What is a weir used for?
Weirs can be used to measure flow rates in open channels and rivers - common for water supply and sewage plants. Weirs are structures consisting of an obstruction such as a dam or bulkhead placed across the open channel with a specially shaped opening or notch.
What is flow rate over a weir?
The flow rate over a weir is a function of the head on the weir. Common weir constructions are the rectangular weir, the triangular or v-notch weir, and the broad-crested weir. Weirs are called sharp-crested if their crests are constructed of thin metal plates, and broad-crested if they are made of wide timber or concrete.
What is a v-notch weir?
Rectangular weirs and triangular or v-notch weirs are often used in water supply, wastewater and sewage systems. They consist of a sharp edged plate with a rectangular, triangular or v-notch profile for the water flow. Broad-crested weirs can be observed in dam spillways where the broad edge is beneath the water surface across the entire stream.
What is the best way to prevent membrane scaling?
The water needs to be as soft as possible or a scalant needs to be fed ahead of the system to prevent membrane scaling. In most cases, a water softener and backwashing carbon filter are the preferred and most cost effective method of pretreatment.
What is the hardness of raw feed water?
Sometimes Pre-Treatment of the Raw Feed Water is required : Hard Water with a hardness higher than 15 Grains will usually need a water softener or anti-scale injection. Other water quality issues (such as Barium, Silica, Strontium, etc) may neccessitate the installation of an Anti-scale chemical injection system.
How does a Flexeon reverse osmosis system work?
A Flexeon or Axeon Reverse Osmosis System (after any pre-treatment) discharges the purified water into a atmospheric storage tank (typically 75 to 1,500 gallons), at zero pressure, while also discharging the waste water to drain. A Float Switch will turn off the unit when the tank gets full. A Repressurization Pump is installed just downstream of the storage tank, and an UV Disinfection System may be installed anywhere between the Atmospheric Tank and the repressurization pump.
Can you use a carbon backwashing unit with a RO?
Customers who plan on processing large amounts of water may also opt to use a Backwashing Carbon unit upstream of the unit - instead of using ( and replacing) the carbon block cartridges that comes with the RO unit , as the cost of operation using just the carbon cartridges would be prohibitive.
Is reverse osmosis better than carbon filtration?
On the other hand, Reverse Osmosis is a much more "hands-on" technology compared to carbon filtration, and requires that you take a close look at your water chemistry to see see if you have any water quality issues that will foul the RO Membrane.
Can you use a bladder tank for food service?
In food service applications or other applications where extremely low or ZERO TDS is not critical, a bladder tank can be utilized, but if a manufacturing process calls for extremely low TDS water, then the atmospheric tank is far and away the best solution.
Do you need a pressure tank for a RO system?
Using a Pressure Tank will usually require you to purchase a larger sized RO system to keep up with your flow requirements, while a much much larger Atmospheric Storage Tank will allow you to buy a smaller RO system. Pressure Tanks require you to add a High Pressure Switch to your RO system.
What is a triangular weir?
Triangular weir: The shape of the weir is actually reverse triangle like V. so, it is also called V-notch weir. This type of weirs are well suitable for measuring discharge over small flows with greater accuracy.
What are the different types of weirs?
Types of Weirs based on Shape of the Opening. Rectangular weir. Triangular weir. Trapezoidal weir. 2. Types of Weirs based on Shape of the Crest.
What is a weir in a river?
A weir is a concrete or masonry structure which is constructed across the open channel (such as a river) to change its water flow characteristics. Weirs are constructed as an obstruction to flow of water. These are commonly used to measure the volumetric rate of water flow, prevent flooding and make rivers navigable.
What is a sharp crested weir?
Sharp-crested weir. The crest of the weir is very sharp such that the water will springs clear of the crest. The weir plate is bevelled at the crest edges to obtain necessary thickness. And weir plate should be made of smooth metal which is free from rust and nicks. Flow over sharp-crested weir is similar as rectangular weir.
