To meet the need for frequent periodic verification of measurement system calibration, the bayonet fitting allows quick sensor removal in four steps. The transmitter head is opened and sensor wires are disconnected from the transmitter; the fitting is twisted to disengage it, and the sensor slides out. The fitting can be installed in the waterproof-head or the explosion-proof head, and sensors with the fitting can be ordered individually or purchased with a complete measurement system including the AI-1000 R2 or AI-1500 transmitter. Applications include food and beverage, pharmaceutical, and HVAC installations.