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Digital Flow Meter



Short description:
For determining the amount of water passing through a plankton net. For horizontal pull only.

Diameter of propeller/counter body: 70/32 mm, length 185 mm, 5-digit counter; easy installation by a two-point connection of the nose piece.

Can be used for full oceanographic depth (6000 m).


Rigging instructions:
The digital flow meter may be used with towed equipment such as plankton nets, etc., or in stationary applications such as flow monitoring of rivers and outfalls. The digital flow meter is supplied with a towing bridle which can be used in two different ways:


1) When towed from vehicles or streamed from fixed structures, the towing bridle can be connected to a single point forward of the digital flow meter.


2) When used with plankton nets, the bridle may be attached to the net mouth ring.

Determination of the water volume passing through a plankton net

The digital flow meter incorporates a three blade impeller coupled directly to a five-digit counter which records each revolution of the impeller.

Please note that the counter is non-resetting. The number of revolutions is read by noting the difference in beginning and end readings.

The pitch of the impeller is 0,3 m per revolution, i.e., the number of revolutions mulitiplied by 0.3 makes the towing distance.

For quantitative measurements the threshold flow velocity of the impeller should not be smaller than 0,5 m/sec. For comparison measurements flow velocities smaller than 0,5 m/sec. are possible.

Example 1:
The number of revolutions is 100, this means a towing distance of 30 m.

The opening area of the plankton net must be known or has to be calculated. The water volume passed through the plankton net is determined as follows:

Indicated number of revolutions x 0,3 x net opening area (m²) x 1000 = water volume.

Example 2:
The plankton net has a diameter of 40 cm, i.e., the opening area is 0,125 m². If the number of revolutions associated with a tow is 266 (noted from the digital flow meter counter), the water volume passed through the plankton net is:

266 x 0,3 x 0,125 x 1000 = 9975 L = 9,975 m3.

caution.gifRinse with freshwater after use


Flow meter For horizontal pull only.
Rotor Polyamide, PA 6.6 Nylon rotor
Nose cone POM Plastic
Body POM plastic
Gear shaft Armaloyed stainless steel main rotor and idler gear shaft
Overall length 19,0 cm
Standard rotor diameter 7,5 cm
Other data
Depth rating Unlimited (free flooding)
Data read out Five ten-digit counter wheels reading 00000 to 99999. One count per rotor revolution
Counter 99999 counts, equal approx. 16,2 nautical miles. The counter can be reset to "0".
Mounting Universal bridle allowing two-point connection
Threshold 20 cm/sec
Range 20 cm/sec to 8,0 m/sec