- Grab Sampling > Accessories
The needle assembly is the foundation of the DOPAK sampler for liquids. It is a housing with two integrated needles. The sample fluid enters through one needle (process) and displaced gas / vapor leaves through the other (vent).The vent connection prevents a buildup of pressure in the sample container. The vent line should remain open at all times therefore placing valves or any other obstructions in the vent outlet should be avoided. To prevent any unwanted backflow of the waste system when the sampler is not in use a check valve could be installed.