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The Philippine Council for Agriculture, Aquaculture and Forestry and Natural Resources Research and Development - Department of Science and Technology (PCAARRD - DOST) funded the project that initiated this standard.
The Philippine Council for Agriculture, Aquaculture and Forestry and Natural Resources Research and Development - Department of Science and Technology (PCAARRD - DOST) funded the project that initiated this standard.
True
BAFS is responsible for developing standard specifications for all machinery.
BAFS is responsible for developing standard specifications for all machinery.
False
The Bureau of Philippine Standards (BPS) technically prepared this standard.
The Bureau of Philippine Standards (BPS) technically prepared this standard.
False
The word 'should' indicates a mandatory requirement for the standard.
The word 'should' indicates a mandatory requirement for the standard.
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The Agricultural and Fisheries Mechanization Law (AFMech Law of 2013) is also referred to as Republic Act 10602.
The Agricultural and Fisheries Mechanization Law (AFMech Law of 2013) is also referred to as Republic Act 10602.
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The Bureau of Agriculture and Fisheries Engineering (BAFE) approved this standard before forwarding it to the DA Secretary.
The Bureau of Agriculture and Fisheries Engineering (BAFE) approved this standard before forwarding it to the DA Secretary.
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This standard focuses on the determination of conveyance loss in closed channels using the inflow-outflow method.
This standard focuses on the determination of conveyance loss in closed channels using the inflow-outflow method.
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AMTEC initiated the formulation of this national standard.
AMTEC initiated the formulation of this national standard.
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A weir is a structure built parallel to an open channel to measure flow rate.
A weir is a structure built parallel to an open channel to measure flow rate.
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A flume is a structure built such that its center line is perpendicular to the center line of the channel in which the flow is to be measured.
A flume is a structure built such that its center line is perpendicular to the center line of the channel in which the flow is to be measured.
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An orifice is a measuring device with a well-defined, sharp-edged opening where the water level is always below the top of the opening.
An orifice is a measuring device with a well-defined, sharp-edged opening where the water level is always below the top of the opening.
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The formula for calculating the degree of submergence is (Ha/Hb) * 100
The formula for calculating the degree of submergence is (Ha/Hb) * 100
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A current meter measures discharge at the entire channel's cross section.
A current meter measures discharge at the entire channel's cross section.
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Flow measuring structures should ideally be installed at the beginning and end of a channel section.
Flow measuring structures should ideally be installed at the beginning and end of a channel section.
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If a Parshall flume has a throat width between 30.5 cm and 244 cm, the free flow limit of Hb/Ha is 70%.
If a Parshall flume has a throat width between 30.5 cm and 244 cm, the free flow limit of Hb/Ha is 70%.
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Current meters mounted on rods are more suitable for gauging large sections.
Current meters mounted on rods are more suitable for gauging large sections.
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A vaned tail piece is not necessary when mounting a current meter on a rod.
A vaned tail piece is not necessary when mounting a current meter on a rod.
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The outflow measuring structure should be placed where backwater significantly influences the flow.
The outflow measuring structure should be placed where backwater significantly influences the flow.
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When W = 25 cm, one should use figure B.3 directly to estimate the discharge when submergence is greater than the limit.
When W = 25 cm, one should use figure B.3 directly to estimate the discharge when submergence is greater than the limit.
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The rod used with a current meter should be marked for easy determination of width.
The rod used with a current meter should be marked for easy determination of width.
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The submerged discharge, Qsubmerged flow, is calculated by adding the correction to the free flow discharge, i.e., Qfree flow + Qcorrection.
The submerged discharge, Qsubmerged flow, is calculated by adding the correction to the free flow discharge, i.e., Qfree flow + Qcorrection.
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Using different types and sizes of measuring structures on the same channel is recommended to minimize errors.
Using different types and sizes of measuring structures on the same channel is recommended to minimize errors.
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If the computed degree of submergence is equal to 60% for a 20 cm Parshall flume, then free flow condition exists.
If the computed degree of submergence is equal to 60% for a 20 cm Parshall flume, then free flow condition exists.
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The flow of a channel must be measured, but it is not necessary to record its length or width.
The flow of a channel must be measured, but it is not necessary to record its length or width.
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Current meters can be mounted on rods or suspended by cables to make measurements.
Current meters can be mounted on rods or suspended by cables to make measurements.
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Weirs, flumes, and orifices are methods used for discharge evaluation.
Weirs, flumes, and orifices are methods used for discharge evaluation.
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Seepage and percolation losses are calculated using the formula: $(S&P)_{losses} = (Q_i - Q_o) / L $
Seepage and percolation losses are calculated using the formula: $(S&P)_{losses} = (Q_i - Q_o) / L $
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The variable $Q_i$ represents the outflow rate in the seepage and percolation loss formula.
The variable $Q_i$ represents the outflow rate in the seepage and percolation loss formula.
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The variable $L$ in the seepage and percolation loss formula represents the length of the channel reach.
The variable $L$ in the seepage and percolation loss formula represents the length of the channel reach.
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The multiplying factor for a Parshall flume with a throat width of 61.0 cm is 2.8.
The multiplying factor for a Parshall flume with a throat width of 61.0 cm is 2.8.
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The discharge, $Q$, in the equation $Q = C_d C_v A\sqrt{2g(h_1 - h_2)}$ is measured in cubic meters per second.
The discharge, $Q$, in the equation $Q = C_d C_v A\sqrt{2g(h_1 - h_2)}$ is measured in cubic meters per second.
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The variable $A$ in the equation for orifice discharge $Q = C_d C_v A\sqrt{2g(h_1 - h_2)}$ represents the area of the flume.
The variable $A$ in the equation for orifice discharge $Q = C_d C_v A\sqrt{2g(h_1 - h_2)}$ represents the area of the flume.
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A 122.0 cm Parshall flume will have a multiplying factor of 3.7.
A 122.0 cm Parshall flume will have a multiplying factor of 3.7.
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In the equation $Q = C_d C_v A\sqrt{2g \Delta h}$, $\Delta h$ represents the head differential across the orifice.
In the equation $Q = C_d C_v A\sqrt{2g \Delta h}$, $\Delta h$ represents the head differential across the orifice.
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The cross-sectional area for a segment extends vertically from the water surface to the channel bed.
The cross-sectional area for a segment extends vertically from the water surface to the channel bed.
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The variable $q_i$ represents the mean velocity at location i.
The variable $q_i$ represents the mean velocity at location i.
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The distance $b_{i-1}$ is the distance from the initial point to the next location.
The distance $b_{i-1}$ is the distance from the initial point to the next location.
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The velocity should be measured at a minimum of two separate points in the vertical.
The velocity should be measured at a minimum of two separate points in the vertical.
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The cross-section area for a segment extends laterally from one quarter of the distance from the preceding vertical to one quarter of the distance to the next vertical.
The cross-section area for a segment extends laterally from one quarter of the distance from the preceding vertical to one quarter of the distance to the next vertical.
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The variable $d_i$ is the depth of water at location i.
The variable $d_i$ is the depth of water at location i.
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Engr. Bonifacio S. Labiano is the Chair of the Technical Working Group.
Engr. Bonifacio S. Labiano is the Chair of the Technical Working Group.
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Dr. Elmer D. Castillo is from the Bureau of Soils and Water Management
Dr. Elmer D. Castillo is from the Bureau of Soils and Water Management
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Study Notes
Philippine National Standard: Conveyance Systems – Performance Evaluation of Open Channels – Determination of Conveyance Loss by Inflow-Outflow Method
- Scope: This standard details a method for evaluating seepage and percolation in open channels using inflow-outflow measurements.
- References: The standard references ISO 8368:1999, Guidelines for Selection of Structures for Flow Measurements in Open Channels.
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Definitions:
- Conveyance loss: Loss of water from a channel due to seepage and percolation during transport.
- Water balance: Accounting of water inflows (e.g., irrigation, rainfall) and outflows (e.g., evaporation, seepage, percolation) within the channel.
- Principle of the Inflow-Outflow Method: This method analyzes conveyance loss by measuring inflow and outflow rates in a designated channel section, utilizing a water balance approach.
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Site Selection:
- The channel section should be accessible for measurements.
- The section should be at least 50m long with a uniform cross-section and grade between inflow and outflow points.
- Sections with adjoining creeks or depressions should be avoided.
- Bends, steep slopes, and structures like turnouts, valves, or gates should be avoided.
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Flow Measuring Structures and Devices: The appropriate structures and devices for measuring flow rates should adhere to ISO 8368:1999 guidelines. Annex A details various types.
- Weir: A structure with a sharp-edged crest used to measure flow. Types include rectangular and trapezoidal weirs, considered for contracted and suppressed rectangular types.
- Flume: An enclosed channel with a constricted section designed for efficient flow measurement. Types include Long-throated Flume.
- Orifice: An opening in a wall or structure that controls water flow. Circular and rectangular sharp-edged orifices are included in the standard.
- Current Meter: A device for measuring water velocity, commonly used in conjunction with the velocity-area method for discharge calculation methods detailed in Annex C. Anemometer and propeller types, electromagnetic and Doppler types, and optical strobe types are specified in different detail.
- Flow Measurement: Measuring steps like length and width calculations, along with proper measurement instrumentation and recording of all data, are crucial for this process. Detailed techniques and discharge calculation examples for weirs and flumes are provided in Annex B, while detailed calculations based on current meter data are included in Annex C.
- Computation: Conveyance loss is determined using the formula (S&P)losses = (Qi-Qo)/L, where Qi is inflow rate, Qo is outflow rate, and L is the channel length.
- Bibliography: Included, listing major sources for hydraulic structure data utilized in the standard. Sources referenced include the Food and Agriculture Organization (FAO).
Annexes
- Annex A: Details various flow measuring structures and devices like weirs, flumes, and orifices providing detailed discharge evaluations. Specific types of weirs and orifices are detailed, in appropriate tabular formats.
- Annex B: Provides detailed procedures (B.1) for measuring discharge using weirs, flumes, and orifices, along with discharge-head relationships for various structures like rectangular weirs, Cipoletti weirs, and 90° v-notch weirs
- Annex C: Presents guidelines on discharge measurement using current meters including the velocity-area method, with specifications for the use of current meters. Includes the midsection method.
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Description
This quiz covers the national standards related to agricultural and fisheries mechanization, particularly focusing on the determination of conveyance loss in closed channels. It includes key information about the Agricultural and Fisheries Mechanization Law, standard specifications, and related structures such as weirs and flumes. Test your knowledge on the standards set by various bureaus in the Philippines.
