Date: May 23, 2016
We have released statement to address the issues associated with electrostatic charges on plastic materials and semiconductive
liquids in potentially explosive atmospheres.
K-Patents refractometers with models PR-23-M, PR-23-MS and PR-23-W contain polytetrafluoroethylene (PTFE) sensor
body wetted parts.
The latest ATEX certification update for K-Patents PR-23-M, PR-23-MS and PR-23-W refractometers in March 2016 brought
to our attention that the liquids with conductivity lower than 10 000 pS/m (pico Siemens/meter) flowing through a PTFE
sensor body may cause the sensor body becoming electrostatically charged causing a risk of ignition hazard. In particular,
this can occur with toluene or hydrocarbons such as crude and lube oils.
Consequently, the latest ATEX and IECEx certificates for the K-Patents PR-23-M, PR-23-MS and PR-23-W refractometers
have been amended with the following special conditions of safe use:
• The process heads for PR-23-XX Series Process Refractometer types M, MS and W contain parts that are subject to
electrostatic hazard. These types shall only be used for measuring liquids with high conductivity (>10000 pS/m) in the
presence of hazardous atmospheres.
To date, K-Patents has delivered three (3) EX certified Teflon body refractometers for the semi-conductive liquid applications
and we have contacted these clients directly.
However, whenever the above risk of electrostatic hazard is found to exist, the clients should be aware of it and consider
alternative wetted parts materials. Please note that it is always the user’s responsibility to select the refractometer wetted
parts material and to ensure that the material is safe for the intended service conditions and atmospheres.