A leading UK scientific and technology based R&D company has developed a new beverage preparation machine using the Hydrotechnik HT-PSX2 submersible liquid level transmitter. These Intrinsically Safe level sensors have been successfully proven during an extensive program that addresses the functional, monitoring, safety, usability, legislative, manufacturing / testability and commercial requirements of the design project.
The HT-PSX2 sensor was chosen as a rugged and environmentally compliant solution for monitoring liquid level inside a storage vessel within the machine. The liquid is an ethanol / water solution with a temperature range that can vary from -15 to +30 degC and the sensor is sealed to IP68 and fully submersible for continuous / indefinite operation.
Wetted materials are compliant with FDA standards and the HT-PSX2 is ATEX certified for use in zone 0/1 rated hazardous area environments. Both of these features are key requirements for the application due to the strict hygienic and safety factors involved.
The level sensor also has to be highly sensitive to measure the relatively low pressure hydrostatic head. The sensor is immersed into the solution measuring a range of 0 to 1m H20, equivalent to 0 to 100mbar pressure, with a full range 4-20mA output. The sensor output is then used to indicate both instantaneous and min / max values during operation.
The HT-PSX2 features a highly sensitive yet inherently accurate and stable piezo-resistive silicon measuring element with diffused silicon gauge elements. Housed within a rugged stainless steel capsule this construction is ideal for reliable long term service and together with FEP coated cable ensures that the target FDA specification is met for hygienic material compliance.
Fluorinated Ethylene Propylene (FEP) is a resin coating that has a very high chemical and temperature resistance. Typically it is offered as an optional electrical cable coating on submersible pressure sensors where the liquid media is too aggressive for the more standard general purpose cable coatings such as Polyurethane or Polyethylene. FEP is also used for other liquid level measurement applications such as landfill leachate monitoring, fuel tank level and chemical storage tanks amongst others.
The HT-PSX2 is approved and certified for use as Intrinsically Safe apparatus within hazardous environment systems to ATEX Directive Ex II 1G Ex ia IIB T4 for Zone 0 classified areas (-20degC to +60 degC ambient temperature rating) or alternatively Ex II 2G Ex ia IIC T4 for Zone 1 classified areas (-40 degC to +85degC ambient temperature rating).
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