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mark of manhole : MS-Q / x / y/ p/ o / k / na / hs /
Recommended PRICE LIST
Parshall flume …plus … Manhole with the ledder and
with the plastic lid
Parameters |
P1 |
P2 |
P3 |
Q min (l/s) |
0,26 |
0,52 |
0,78 |
Q max (l/s) |
6,22 |
15,1 |
54,6 |
a |
0,0609 |
0,120 |
0,178 |
b |
1,552 |
1,553 |
1,555 |
B` (cm) |
30 |
34 |
39 |
Price |
410 |
465 |
707 |
Price |
hs |
Undeground waterdrought water |
|
1 |
18 300,- |
20700,- |
|
2 |
21800,- |
23900,- |
|
Remark. :
konsumtion curve :
Q = a * hb ... [m3/s,m] /1/
h (m) …depth measured in front of the throat at the distance B´
Q (m3/s) …volume of flow
Manhole with measurement equipment is designed for determination of water flow volume in the channels with an open surface ( e.g. in the channels, tubes, partly filled pipelines, creeks). The range of measurement starts from 0,3 l/s for the smallest Parshall flume P1 up to 55 l/s for the greatest one P3.
Polypropylene manhole can be loaded with maximum weight of 260 kg on the lid ( cannot be used for the streets with car traffic). The lid of the manhole meets the standards of B125 –ČSN EN 124 class. There are two construction types, one for places with a high level of underground water table and the second one is designed for places without underground water. The maximum depth of manhole is 2 meters. Manhole is watertight (according to DIN 4034).
The flow volume is measured by using Parshall flume . The size of the flume is chosen according to its operation range.
Size of Parshall flume |
Flow (l/s) |
Type of water |
|
Qmin |
Qmax |
||
Parshall flume P1 |
0,26 |
6,2 |
Mechanically treated |
Parshall flume P2 |
0,52 |
15,1 |
Municipal sewage |
Parshall flume P3 |
0,78 |
54,6 |
|
Water coming into the flume is forced by a bottleneck and by a subsequent bottom dip to pass over a critical depth where it goes from river-speed motion into rapids-speed motion. Thanks to this transition from one regime to another, water flow can be measured from the water depth before the neck. Water levels are scanned either inside the gauge shaft, which is a part of the Parshall flume, or inside the axis of the inflow part of the flume. Inside the shaft, levels are gauged by a float linked by the mechanical transmission with a flow meter, or by the sensor of an electronic flowmeter. In the flume axis, levels of water are scanned by an ultrasonic sensor. The electronic flowmeter converts data about flume water depths to flow rates and volumes. The standard Parshall flume is produced without a gauge shaft.
New electronic evaluations units provide: data storing, statistic data treat and other calculations. Data can be sent to internet servers or directly to the computers as well as to the mobile phones. Some of the units can control the waste water treatment plant technology or control the valves or chlorine dosage pumps and etc.
2. Advantages
Manhole with flowmeter is convenient solution especially for places where simplicity of assembling is required. Manhole can be equipped and delivered with electronic sensor and electronic evaluation unit. Electronic equipment is fastened inside of manhole and protected for transport. Calibration is done at the production hall and so no further checking of measuring device is required. This solution of measuring is the most effective.
2.1. Manhole DN 1000
3. Technical parameters of manhole and Parshall flume
Exact hydraulic calculations for placement of Parshall flume can be done free of charge Pars aqua ( tel. + 420 736 686 159, pars@pars-aqua.cz).
Polypropylene Manhole DN 1000 is equipped with a flowmeter Parshall flume (sizes P1,P2 or P3). Inlet and outlet pipes vary from DN 200 up to DN 400 and can be attached to different pipe materials. Rectangular lid of the manhole (600/600 mm) is made of plastic and meets the class B 125 – ČSN EN 124. The ceiling of the manhole is placed 210 mm below the cup. Manhole is equipped with stainless ladder.
Construction is designed for two modes of applications :
a/ type with underground water -table
b/ type without underground water-table
ad a/ manhole with undegroud water…….type… MS –Q /water/
manhole is welded from 8 mm thick polypropylene plate. Cylinder shape DN 1000 mm is made with deviation ± 10 mm. Construction is watertight according to the norm DIN 4034. The bottom of the manhole is placed 306 mm under the bottom of the inlet pipe.
Strength of manhole and its resistance against the water pressure is ensured by:
ad b/ manhole without undegroud water …..type… MS –Q /drought/
the construction is similar to the one described above but without the circumferential concrete cylinder
Static calculations :
Picture describes mathematical results of tension and deformation.
3.1.Dimensions and parameters of manhole
The dimension of manhole like depth and inlet/outlet pipes can be made individually.
3.2.Technical paramaters – metrology par
3.2.1.Parshall flume
|
P1
|
P2 | P3 | |
| Qmin | 0,26 | 0,52 | 0,78 |
| Qmax | 6,22 | 15,1 | 54,6 |
| a | 0,0609 | 0,1197 | 0,1784 |
| b | 1,552 | 1,553 | 1,555 |
| B' | 30 | 34 | 39 |
| Z Qmin % Qmax |
5,4 | 4,1 | 4,1 |
| 4,8 | 3,6 | 3,6 | |
| hd/ha | 0,6 | ||
| m | 5,7 | 7,7 | 17 |
| W | 2,54 | 5,08 | 7,62 |
| C | 9,29 | 13,49 | 17,80 |
| D | 16,75 | 21,35 | 25,88 |
| E | 23 | 26,4 | 46,7 |
| L | 63,5 | 77,5 | 91,5 |
| O1 | 2,8 | 4,2 | 5,7 |
| O2 | 4,6 | 6,4 | 8,2 |
| S | 20 | 20 | 20 |
| U | 24,8 | 26,8 | 49,2 |
| V | 30,7 | 35,35 | 39,9 |
(parameters are listed in cm, flume weights in kg)
Legenda
m - weight of flume (kg)
hd/h - ratio of water submergance ( - )
h - water depth measured at the distance B´ in front of the throat (m)
hd - water depth behind the flume (m)
W - mwindth of the throat (cm)
B´ aľ V - dimensions of flume (see pic.) (cm)
Z - deviation (probability 95 %) for Qmin, Qmax ( - )
Q - flow water (m3/s)
Consumtion curve
Standard curves Q = fce (h) are given in the table and in the enclosed graphs. Parshall flume is produced with certain deviation (Metrology rules for production TCM). Influence of this differences is eliminated with using calibration method. Each Parshall flume has its own calibration list which is at the and of this booklet.
Accurasy of measurement
Flowmeter parshall flume was tested in Czech Metrology Institute and obtain certification TCM 142/95-2075 No. 2075/95/1 from 1. june 1995 (validity periodically prolonged). The deviations of measurement is in the range from 3,8 % to 2,2% for minimum and maximum of flow on the probability level 95 %.
( deviations are calculated for depth measured with deviation ± 0,2 mm)
Design of Parshall flume
Right conditions at the inflow and at the outflow pipe determine its proper function. At the inflow should be river- speed motion conditions. Inserted Parshall flume raises water level and lowers speed motion . Velocity has to be high enough to prevent sedimentation of suspended solids. The placement of Parshall flume for creek-speed motion has to be hydraulically calculated (realize free of charge Pars aqua) .The streaming in front of flume should be smooth, free of whirls and undulation, to provide a well balanced speed distribution profile. For these reasons, the flume should be installed at a safe distance from the end of a curve (at least 12 W), or for the drop wall at least 30 W (depends on the depth and on the schape of floor) . Exact calculation of these distances are given at our web pages www.pars-aqua.cz. (only in czech version ). Complicated designs can be done at Pars aqua .
At the outflow end of flume , sufficient outflow conditions must be secured to prevent excessive submergence (maximum submergence ratio is listed in Tab. 1 – parameter hd/ha). Discharge equitation has to be adjusted if those values are exceeded !
Since correct functioning of the Parshall flume depends on correct hydraulic design of the track and on proper mounting, the job should be assigned to a specialist, or otherwise PARS aqua should be consulted. We are making these calculations free of charge and have established system of questionare which simply can solve design via email.
Maitanance and operations conditions
Parshall flume
The Parshall flume is designed to measure the flow of water and, consequently, although it is temperature-resistant, the water in the flume must not be allowed to freeze up. The maximum water temperature is 80 degrees Celsius. The flumes resist inorganic salt and acid solutions, alkaline solutions without too strong oxidising properties, and a majority of organic solvents. As far as operational maintenance is concerned, the flume requires once-a-year cleanups of its surface and of the float shaft and of the connecting pipe between shaft and flume. The maximum size of derbies which are able freely pass the flume is calculated as 0,8 x W ( 80 % of the throat). For greater quantities of unsolved substances, screens should be adjusted.
Manhole
Measuring manhole serve for measuring of water flow (newton¶ parameters) for channels where water do not freeze and flow with open surface. Manhole has to be placed under ground for cases where manhole is partly above the ground certain deformations can occure. These deformations do not influence precision of measurement . Device maintenance and control has to be done periodically (lag time vary case for case), then manhole has to be well ventilated to prevent occurrence of danger gases.
4.Assembling of manhole
Assembling of manhole is simple and easy. Follow the mounting steps :
5. Evaluation of flow
|
The following types of flowmeters are usually used to convert water-depth data in the gauge profile:
a) mechanical device without a data recorder,
b) electronic device with an ultrasonic surface scanner
Mechanical flowmeter
Parshall flume can be equipped with brass ruler with cutings to the metal plate. This equipment serve only for actual flow readings and simple checking of the electronic flowmeter function. Brass ruler hs to be ordered separately
Electronic flowmeter
The electronic flowmeter is a device which consists of a scanning probe and a microprocessor-based evaluation unit. The scanning probe with an ultrasonic transmitter/receiver is placed in the flume axis in the profile B´ . The sensor is positioned above maximum water surface (vary from 20 cm to 60 cm ). The probe has to be cleaned within six months from incrustations and other impurities. The evaluation unit is usually separated and placed at the building. Some equipment has evaluation unit as a part of sensor and so the data is displayed in the manhole. Each producer has its own regulations and conditions for instalation . Nowadays flowmeters are offered in many variants (data storing, statistic data treat and other calculations, wireless data transfer to internet servers or directly to the computers as well as to the mobile phones, control of the waste water treatment plant technology or control the valves or chlorine dosage pumps and etc.
The flowmeter is not part of the Parshall flume and has to be ordered separately.
Warranty conditions
If conditions stated above are observed, the company provides Parshall flumes with a warranty period of two years from delivery date.
Calibration List of manhole DN 1000 with Parshall flume
Costumer :
Place of usage :
Measure tool : Parshall flume P……… No.………………
Function and parameters : Parshall flume is measure tool used for determination of water flow volume in the channels with an open surface ( e.g. in the channels, tubes, partly filled pipelines, creeks or other streams). Water coming into the flume is forced by a bottleneck and by a subsequent bottom dip to pass over a critical depth where it goes from river-speed motion into rapids-speed motion. Due to this transition from one regime to another, water flow can be measured from the water depth before the neck. Water depth is measured in a certain distance B´ in front of the throat . Volume of flow is calculated using the exact mathematical formulae Q = a * hb . Parameters a, b is the matter of this calibration list.
Sort of measure tool : working measurement device ( no-legal)
Calibration method: comparison geometrical parameters with Certification TCM 142/95-2075 , approved by the Czech Metrology Institute
Used mesuring devices and its calibrations :
? steel roller, lenth 60 cm , readings 0,5 mm, deviation 0,1 mm Tajima
? roller No. č. 90124, lenth 60 cm , readings 0,1 mm, deviation 0,02 mm
Calibration Results :
Dimensions and other geometrical parameters meets the standard given by Certification TCM 142/95-2075 , approved by the Czech Metrology Institute
Average throat wideness W = cm
Consumtion curve :
Q = * h [m3/s, m ], Q= a x h b
h……(m), depth measured at the distance cm in front of the throat
Q…… (m3/s) volume of flow,
Hydraulic deviation of consumtion curve (uncertainity parametru C curve) for P2 and P1 is up to 2 %. Hydraulic deviation of consumtion curve (uncertainity parametru C curve) for P3 is up to 3 % if parameter a (above) is transformed : a´= a/ (0.981 + 0,07 x h ) pro h od 0,03 do 0,3 m
a´= a/(1,165 - 0,55 x h ) pro h od 0,3 do 0,45 m
Extended uncertainity of measurement :
Extended uncertainty of measurement of Parshall flume P1, P2 and P3 in the manhole DN 1000 vary from 2% to 5 % for P1,P2 and from 3% to 7% for P3( depended on uncertainity of the throat, of parameter C of flow, of influence of pipe connection - for uncertainity of head 0,5% minimalized). Final extended uncertainity on probability 95% of measurement ( .. with real uncertainity of the head) depend on the quality of the head evaluation unit and so can be greater.
Calculations of deviations are made according EAL-R2 a ČSN ISO 3354, ČSN ISO 9826 a ČSN ISO 5168.
Calibration executed by : Ing. Jan Vršecký, Csc , tel. + 420 736 686 159
Pars aqua Ltd, Strojírenská 260, 155 21 Praha 5
Date:
(c) 2015, PARS Aqua, s.r.o.
