When the service technician is called out to service a compressed air dryer, it is important to quickly get an overview of the dryer’s performance (achieved dew point by the dryer). The dew point generated by the dryer should be measured as quick as possible and, if necessary, documented. For mobile dew point measuring devices, handiness (small and portable), fast operational readiness (integrated rechargeable battery, no on-site power supply) and fast response time are essential.