Liquid sensors are low maintenance for mechanical turbines
MEMS sensors are offered by Posifa Technologies as cost-effective devices that can replace mechanical turbine flow sensors. The PFF2000 series of liquid flow sensors are claimed to deliver increased accuracy and reliability, even in unstable pulsatile flow and low-flow conditions.
They are factory-calibrated for water to a minimum five per cent and typical three per cent accuracy for volume calculation. The PLF2000 series’ dual digital I²C and voltage output provides high performance, flexibility and scalability in a compact package, says Posifa.
The PLF2000 series features Posifa’s third-generation thermal flow die, which uses a pair of thermopiles to detect changes in temperature gradient caused by mass flow. The result is described as an excellent signal to noise ratio and repeatability of 0.5 per cent FS. The solid state thermal isolation structure on the sensor die eliminates the need for a surface cavity or fragile membrane, says Posifa. It can be placed directly in the liquid flow path with minimal packaging for higher sensitivity. In addition, the sensor die does not obstruct the flow path, allowing for minimal flow resistance and making it possible to circulate liquid via gravity, a boiler, or a low-power pump. There are no moving parts, so the sensor does not get stuck, suffer mechanical breakdowns, or require disassembly for cleaning and maintenance, adds the company.
Measuring flow rates up to 700ml per minute (PLF2105) and 10litres per minute (PLF2135) and the sensors have fast response times of five milliseconds typical. They operate over a +5 to +75 degree C temperature range.
The sensors comply with NSF/ANSI 61: Drinking Water System Components — Health Effects and can be used safely in water and beverage appliances.
Posifa has the scalability and production capacity to meet any high-volume application and customers are encouraged to contact the company to discuss options for customising the sensors’ specifications.
Samples and production quantities of the PLF2000 liquid flow sensors are available now.
