Titan Metraflow 240-020, Инструкция по эксплуатации

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©Titan Enterprises Ltd 2018 www.flowmeters.co.uk MetraflowManual_v1219
Low flow measurement and temperature effects
There will always be a small amount of “background noise” due to ultrasound remaining within the
tube between successive signals.
The noise affects both the low end performance and accuracy across the whole temperature range.
The meter is calibrated at ambient temperature, typically 21 to 25°C.
Details of how to compensate and improve the accuracy of the meter at different temperatures can be
found in the
Zero Null Feature
in the previous section.
Response time
The response time of the meter is not constant and is slower with lower flow rates. At full flow it is in
the order of 50ms but at lower flows several seconds. This improves repeatability for the digital
outputs and is similar in effect to the viewing filter when using the analogue outputs.
Pulsating Flow
If the meter is subjected to heavy pulsations in the flow, for example from a diaphragm pump, it is
recommended that a pressure regulator and a pulsation damper are installed upstream of the
flowmeter. A length of flexible tubing with an in-line restrictor towards the end are often effective. The
median filter should be set to 1 and it may be necessary to set the display filter to a high value. The
Metraflow’s internal cycle time is not adjustable, is independent of the response time and should this
measurement period coincide with, or be close to, the pulsations in the flow, very large errors in the
flow calculations will occur.