A siphon is installed in front of the shutoff value for measured materials with temperatures above 120 °C. The form B shut-off valves have a shaft with which a measuring instrument holder can be attached. No adapter is therefore required for fastening these valves. With double shut-off values DN 5, the air-release/test connection can be shut off. This enables a zero point check on the pressure gauge. In addition, a characteristic curve test can be conducted on the pressure gauge using an external pressure sensor. The valve packing material is PTFE.