Burkert Type 8081 - Manual (Page 8)

8
Type 8081
english
Description
5. descripTion
5.1. Area of application
The ultrasonic flow rate transmitter type 8081 is intended for the
measurement of water flow rates which may be slightly charged with
contaminants.
5.2. General description
5.2.1. design
The 8081 ultrasonic flow rate transmitter consists of an electronic
module and a brass fitting with a built-in measuring tube. When
combined with a controller and a control loop, it enables a control
loop to be established.
The electrical connection is made via a 5-pin M12 fixed connector.
The transmitter features, depending on the version:
• a pulse output or
• a pulse output and a 4-20 mA current output;
Each version is available for 5 different flow rate ranges:
• model QN 0.6 DN15: 0.06 to 20 l/min
(nominal flow rate 0.6 m 3 /h namely 10 l/min)
• model QN 1.5 DN15: 0.1 to 50 l/min
(nominal flow rate 1.5 m 3 /h namely 25 l/min)
• model QN 2.5 DN20: 0.16 to 82 l/min
(nominal flow rate 2.5 m 3 /h namely 41 l/min)
• model QN 3.5 DN25: 0.6 to 116 l/min
(nominal flow rate 3.5 m 3 /h namely 58 l/min)
• model QN 6 DN25: 1 to 200 l/min
(nominal flow rate 6 m 3 /h namely 100 l/min)
5.2.2. measuring item and principle
The 8081 flow meter is based on the transit time method. This con-
sists in measuring the transit times of the sound from emitter 1 to
receiver 2 and from emitter 2 to receiver 1 and subsequently com-
paring both values. The calculated transist time difference is directly
proportional to the flow speed of the fluid.
1 2
emitter-receiver emitter-receiver
Direction
of flow of
the fluid
ultrasonic
wave 1
ultrasonic
wave 2
t
0
t
1
t
2
∆t
The electronic module then delivers a pulse signal proportional to
the volume or an industry-standard 4-20mA signal, proportional to