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STANDARD MECHANICAL CURRENT METER
GENERAL

The « standard » current meter is designed for discharge measurement in rivers, channels, conduits, etc. on different fixing devices for use on rod or with a sounding weight.

According to the mean flow velocity a set of propellers of various hydraulic pitch has to be proposed. The propeller size varies generally from 80 to 125 mm and the pitch from 0.125 to 1.0 meter.

The standard current meter has to be used with a counter set for counting the propeller revolutions, according to the flow velocities.

MEASUREMENT SPECIFICATIONS

Depending on the pitch of the propellers used, different velocity ranges may be obtained. For the determination of flow velocity a calibration of the standard current meter with the relating propeller is necessary in order to determine the water velocity « v » according to the general equation :

v = a . n + b
where : a = hydraulic pitch of the propeller  (m) determined by test runs
 n = number of propeller revolution per second
 b = meter constant (m/sec) determined by test runs.
As main of the propellers have a component effect in the velocity measurement, the limited angular angle for which the propeller measures the true velocity has to be specified

CONDITIONS OF USE

The standard current meter can be used with a rod (generally 20 mm diameter), using sometimes a relocating device for an easy use in rivers, or with sounding weights from a bridge or a boat or a cable-way equipment. In these last situations some additional devices have to be ordered

TECHNICAL SPECIFICATIONS

The standard current meter should be delivered with the surrounding devices :

PROPELLERS : (delivered with the rating tables)
 Diameter  Pitch  v min  v. max  Component effect
 80 to 125 mm 0.25 to 1.0 m. 0.025 to 0.05 m/s. 2.5 to 10.0 m/s 5° to 45°
Propeller are made of brass or plastic or aluminium.

ROD : diameter about 20 mm, length from 1 to 4 metres, relocating device;
COUNTER SET ;
CONNECTING CABLE.
INSTRUMENT CASE



PYGMY MECHANICAL CURRENT METER
GENERAL

The « Pygmy type » current meter is designed for discharge measurement in rivers, small channels, conduits, etc. with low water levels (few centimetres depth) and no too high velocities.

The Pygmy current meter is generally used with a rod for discharge measurement by wadding. According to the mean flow velocity a set of propellers of various hydraulic pitch has to be proposed. The light weight of the propellers (generally aluminium made) allows a low start speed, and the propeller diameter (from 3 to 5 cm) measurements in low depth water (about 4cm).

The Pygmy current meter has to be used with a counter set for counting the propeller revolutions, according to the flow velocities
 

MEASUREMENT SPECIFICATIONS

Depending on the pitch of the propellers used, different velocity ranges may be obtained. For the determination of flow velocity a calibration of the Pygmy current meter with the relating propeller is necessary in order to determine the water velocity « v » according to the general equation :

v = a . n + b
where : a = hydraulic pitch of the propeller  (m) determined by test runs
 n = number of propeller revolution per second
 b = meter constant (m/sec) determined by test runs.
As main of the propellers have a component effect in the velocity measurement, the limited angular angle for which the propeller measures the true velocity has to be specified.

CONDITIONS OF USE

The Pygmy current meter is generally mounted on a thin rod for measurements in low depth water. It can be interesting to used also this type of current meter in higher water depth (about 1 metre) or for measurements from a bridge, in case of very low velocities. In these situations the current meter has to be mounted on a stronger rod in using an additional device to adapt it to the new condition

TECHNICAL SPECIFICATIONS

The Pygmy current meter should be delivered with the surrounding devices :

PROPELLERS : (delivered with the rating tables)
 Diameter Pitch  v min  v. max  Component effect
 30 to 50 mm 0.05 to 0.50 m. 0.025 to 0.05 m/s. 1.0 to 4.0 m/s 10° to 30 °

ROD : diameter from 10 to 20 mm, length 1 to 3 metres, relocating device for bigger rod ;
COUNTER SET ;
CONNECTING CABLE.
INSTRUMENT CASE