What tubing do I need for GreenHouse Blowdown? For the GreenHouse Blowdown Evaporator, you require suitable tubing: To connect the inert gas (nitrogen) source to the gas inlet of the GreenHouse Blowdown Head (preferably via the Flowmeter, part number RR99680) To connect the gas outlet of the GreenHouse Blowdown Head to the GreenHouse Blowdown condenser (part number RR99684 – accessory). We recommend: RR99681: Gas Connection Tubing – 5 m length