1. Introduction
To give the best performance, KROHNE flowmeters must be installed in a correct way. Important instructions should be taken into
consideration, like the inlet and outlet length, pipe to be completely filled, direction of the flow, etc. Depending on the measuring principle of each device, the guidelines will differ. In this article we will explain the installation instructions for inline Ultrasonic flow meters for liquid measurements (OPTISONIC 3400 and OPTISONIC 4400).
2. Recommended installation positions
- Ensure that the pipe is completely filled, partially filled pipelines are not allowed, as they can give fluctuating or inexact readings.
- Avoid installations where gas can be present; therefore, install in the lower pipe bend in an a vertical or slightly uphill pipe.
- Installation in front of an open discharge must be avoided since a completely filed pipe may not be guaranteed.
Upstream of an ultrasonic flowmeter in case of OPTISONIC 3400 using bends in 2 dimensions: ≥ 5 DN; when having bends in 3 dimensions: ≥ 10 DN (the diameter of the measuring tube) must be left as the inlet run. While the outlet runs must be at least 3DN (The distances are always measured from the flange).
Upstream of an ultrasonic flowmeter in case of OPTISONIC 3400 using bends in 2 dimensions: ≥ 5 DN; when having bends in 3 dimensions: ≥ 10 DN (the diameter of the measuring tube) must be left as the inlet run. While the outlet runs must be at least 3DN (The distances are always measured from the flange).
In case of OPTISONIC 4400 the outlets will be (for 2 path using bends in 2 dimensions: ≥ 10 DN; when having bends in 3 dimensions: ≥ 15 DN for 1 path using bends in 2 dimensions: ≥ 20 DN; when having bends in 3 dimensions: ≥ 25 DN)
After a T-piece that is when two pipes intersect, a 5 DN inlet run must be used for OPTISONIC 3400 and for OPTISONIC 4400 10 DN for two paths or 20 for one path.
- It is recommended to install the measuring device upstream of a control valve not downstream.
- If a shut-off device is installed downstream of the flowmeter, an outlet run of at least 40 DN should be used.
- A pump should be installed upstream, of the flowmeter with distance of greater than or equal to 15 DN for Optisonic 3400 and 30 DN for Optisonic 4400.
- All vibrations in the process should be avoided. If vibrations should occur, a compact device must preferably not be used, instead install a remote version.
- Always make sure that the converter is no more than 90° relative to the sensor.
Note: Shortening the inlet and outlet runs can, however, affect the measuring accuracy. For example, if a straight inlet run is shortened by 2 DN, so it is 8 DN long, we must expect an additional measuring inaccuracy of 0.2%; in other words, if sensor standard inaccuracy was 0.3% then total measuring inaccuracy in this case would be 0.5%.