Modern pressure sensors are able to tolerate adverse temperatures, humidity and vibration conditions provided they are within design specification limits. Minimizing the effects of such conditions helps to maximize the sensor’s operational life.
Most electronic prssure sensors are suitable for ambient conditions ranging from lows of –20 to –40 °C (–4 to –40 °F) to highs of 60 to 85°C (140 to 185 °F) , although this may not always be the case for certain types.
An application’s ambient temperature conditions can significantly affect pressure transmitter accuracy. This can include not just the inherent background temperature of the installation location, but also heat generated from a process or radiated from surrounding process equipment and piping.
High temperatures can have a detrimental effect, potentially causing premature component failure. Exceeding the device’s parameters can have a significant effect on performance. Low temperatures, for example, can cause fill fluids to become more viscous, whilst high temperatures can cause them to vaporize. Variations in ambient temperature and pressure can also have an impact, particularly if the sensor’s calibrated span is a small proportion of its upper range limit.
To overcome these problems, the temperature of the transmitter should ideally be kept as close to room temperature as possible for maximum life expectancy. Careful consideration must also be exercised when installing a transmitter outdoors. Atmospheric conditions such as direct sunlight or high winds can cause heating or cooling of transmitters, which can adversely affect their operation.
Vapor caused by humid conditions can sometimes penetrate the transmitter housing and attack sensitive components. Prolonged exposure to high humidity can also result in corrosion of the transmitter housing and mountings. Sensor housings are designed to protect electrical components against the ingress of moisture caused by humidity.
- Operation or Maintenance
Many people use potting materials to protect sensor electronics from humidity. These methods do not provide a long-term solution. The only true prevention against humidity is for the transmitter housing to be hermetically sealed.
Avoid installing a transmitter in an area subject to prolonged or unnecessary levels of vibration, as this can reduce the service life of the sensor. To protect against potential damage or malfunction caused by vibration, sensors must be mounted in a location that will be unaffected by vibration when a process is in operation.