Most customers purchase spare conductivity and temperature sensors. These sensors are exposed to ocean conditions and therefore more likely to be broken than an internal sensor. It is also very easy to change them because they are independent sensors that plug into the CTD main housing.
Most customers do not purchase spare pressure sensors for the following reasons:
- The pressure sensor is inside the CTD main housing. It is very well protected against damage of any kind, and reliability of this sensor is extremely good.
- The sensor is expensive.
- It is difficult to change the sensor in the field.